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In the space of the entire universe, the only conclusive evidence of life, is found on Earth. Although the ultimate source of all life is unknown, many investigators believe Earth, Mars, and Venus may have been seeded with life when these planets, and the sun, were forming in a galactic cluster of thousands of stars and protoplanets. Yet others hypothesize that while and after becoming established members of this solar system, these worlds became contaminated with life during the heavy bombardment phase when struck by millions of life-bearing meteors, asteroids, comets and oceans of ice. Because bolide impacts may eject tons of life-bearing debris into space, and as powerful solar winds may blow upper atmospheric organisms into space, these three planets may have repeatedly exchanged living organisms for billions of years. In support of these hypotheses is evidence suggestive of stromatolites, algae, and lichens on Mars, fungi on Mars and Venus, and formations resembling fossilized acritarchs and metazoans on Mars, and fossilized impressions resembling microbial organisms on the lunar surface, and dormant microbes recovered from the interior of a lunar camera. The evidence reviewed in this report supports the interplanetary transfer hypothesis and that Earth may be seeding this solar system with life.
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Open Astron. 2020; 29: 124–157
Review Article
Rhawn G. Joseph*, Olivier Planchon, Carl H. Gibson, and Rudolph Schild
Seeding the Solar System with Life: Mars, Venus,
Earth, Moon, Protoplanets
Received Jul 08, 2020; accepted Aug 25, 2020
In the space of the entire universe, the only conclusive evidence of life, is found on Earth. Although the
ultimate source of all life is unknown, many investigators believe Earth, Mars, and Venus may have been seeded with life
when these planets, and the sun, were forming in a galactic cluster of thousands of stars and protoplanets. Yet others
hypothesize that while and after becoming established members of this solar system, these worlds became contaminated
with life during the heavy bombardment phase when struck by millions of life-bearing meteors, asteroids, comets and
oceans of ice. Because bolide impacts may eject tons of life-bearing debris into space, and as powerful solar winds may
blow upper atmospheric organisms into space, these three planets may have repeatedly exchanged living organisms for
billions of years. In support of these hypotheses is evidence suggestive of stromatolites, algae, and lichens on Mars, fungi
on Mars and Venus, and formations resembling fossilized acritarchs and metazoans on Mars, and fossilized impressions
resembling microbial organisms on the lunar surface, and dormant microbes recovered from the interior of a lunar
camera. The evidence reviewed in this report supports the interplanetary transfer hypothesis and that Earth may be
seeding this solar system with life.
Mars; Venus; Earth; Moon; Meteors; ALH 84001; Algae; Cyanobacteria; Fungi; Lichens; Stromatolites; Meta-
zoans; Fossils; Interplanetary transfer of life; lithopanspermia; Planetary nebulae
1Seeding the Solar System with
Life: Protoplanets, Mars, Venus,
Earth, Moon
How and when life began, is unknown. Sir Fred Hoyle
(1982) Nobel laureates Svante Arrhenius (1908), Francis
Crick (1981), Harold Urey (Arnold et al. 1995; Urey 1962,
1966), and other investigators, have theorized that life is
widespread in this universe and was delivered to Earth
via solar winds, meteors, asteroids, and comets from older
planets in distant solar systems (Hoyle and Wickramas-
inghe 2000; Joseph 2009; Joseph and Schild 2010a; Val-
tonen et al. 2008). Yet others have proposed that proto-
Corresponding Author: Rhawn G. Joseph:
Astrobiology Research
Center, Stanford, California, United States of America;
Olivier Planchon:
National Center for Scientic Research, Biogéo-
sciences, University of Bourgogne, France
Carl H. Gibson:
Scripps Center for Astrophysics and Space Sciences;
Dept. Aerospace Engineering, University of California, San Diego,
United States of America
Rudolph Schild:
Harvard-Smithsonian Center for Astrophysics (Emer-
itus), Cambridge, MA, United States of America
planets, including Earth, were seeded with life when these
worlds rst formed in a galactic cluster within a nebular
cloud amongst thousands of other new born stars (Adams
and Spergel 2005; Fragkou et al. 2019; Johansen and Lam-
brechts 2017; Jones et al. 2019). Therefore, according to
this scenario, as worlds were formed and destroyed (Boyle
and Redman 2016; Stephan et al. 2020) life within this cos-
mic debris may have spread between these protoplanets
(Adams and Spergel 2005; Gibson et al. 2011; Joseph 2009;
Joseph and Schild 2010b; Valtonen et al. 2008) and what
would become Mars, Venus, Earth and its moon, may have
become infested with life before this solar system was es-
tablished. It has also been hypothesized that life may have
been repeatedly transferred between these worlds during
the heavy bombardment phase of this solar system’s sta-
bilization (Gladman et al. 1996, 2005; Mileikowsky et al.
2000a,b) and intermittently thereafter (Beech et al. 2018;
Joseph 2009; Joseph and Schild 2010a; Schulze-Makuch et
al. 2005) via powerful solar winds and life-infested bolides
ejected into space that later crash upon the surface of these
In support of all these theories and scenarios, is
evidence—but no proof—that between 4.2 to 3.7 bya, dur-
ing the heavy bombardment phase, life may have taken
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |125
root on Mars (Clement et al. 1998; Noke 2015; Thomas-
Keprta et al. 2009) and Earth (Nemchin et al. 2008; Nutman
et al. 2016; O’Neil et al. 2008; Rosing and Frei 2004); and
then, over the ensuing billions of years, the inner planets
were repeatedly intermittently seeded with life (Beech et al.
2018; Joseph 2019). Moreover, Earth may have been seeding
the inner planets when tons of rock and soil—and adher-
ing organisms—were ejected into space via powerful solar
winds (Joseph 2009) and following impacts by comets, as-
teroids and meteors (Beech et al. 2018; Gladman et al. 2005;
Joseph 2000; Mileikowsky et al. 2000a,b).
If life was delivered via debris from outside this solar
system, and/or if impacts on Earth also caused the dispersal
of life, this may explain why specimens similar to terres-
trial fungi have been observed on Mars (Joseph et al. 2019,
2020a) and Venus (Joseph 2019; Ksanfomality 2013). This
would also account for why specimens resembling algae,
lichens, stromatolites, and fossilized algae and metazoans
have been observed on Mars (Joseph and Armstrong 2020;
Joseph et al. 2019, 2020a,b; Kaźmierczak 2016, 2020; Noke
2015; Rabb 2018; Rizzo 2020; Rizzo and Cantasano 2009,
2017; Ru and Farmer 2016). The interplanetary transfer
of life would also explain why fossilized impressions re-
sembling "nanobacteria," terrestrial bacteria and micro-
Ediacarans, have been respectively identied in a lunar me-
teorite (Sears and Kral 1998) and lunar soil samples (Joseph
and Schild 2010a; Zhmur and Gerasimenko 1999); and why
dormant spores were found within a lunar camera that had
been sitting on the moon for three years (Mitchell and Ellis
Nevertheless, it must be stressed that there is no con-
clusive proof of current or past life on any planet other than
Earth. As the denitive evidence of life exists only on Earth,
it is also reasonable to hypothesize that after this solar sys-
tem was formed, Earth may have repeatedly seeded neigh-
boring planets and moons with life; the ultimate source of
which, is unknown.
2Genetics and the Improbable
Origins of Life
Be it in the ancient past or following the classic experi-
ments of Miller and Urey (1959a,b) all attempts to fashion
life from non-life have failed. There are published estimates
that it would have taken 100 billion to trillions of years
to fashion the nucleotides that comprise a single macro-
molecule of DNA (Crick 1981; Dose 1988; Horgan 1991; Hoyle
1982; Joseph and Schild 2010a; Kuppers 1990; Yockey 1977).
Further, once that rst DNA molecule had been created,
and based on complex genetic statistical analyses, it could
have taken from 10 to 13 billion years for that rst gene to
undergo sucient duplicate and recombination events to
fashion a minimal genome capable of maintaining the life
of the simplest organism on Earth (Anisimov 2010; Jose et
al. 2010; Joseph and Wickramasinghe 2011; Sharov 2010).
Carsonella, for example, maintains the smallest genome of
all living organisms: 160,000 base-pairs of DNA, and 182
separate genes (Nakabachi et al. 2006); and thus this can
be considered the minimal number of genes necessary to
sustain life. However, Carsonella is parasitic and depends
on a living host, a psyllid insect, to survive. By contrast, the
genome of Mycoplasma genitalium (Fraser et al. 1995), the
smallest free-living microbe, has over 580,000 base pairs
and over 213 genes, 182 of these coding for proteins; and
beginning with the rst gene, it would have taken up to
13 billion years of recombination and duplicative events
to fashion a minimal life-sustaining genome (Joseph and
Wickramasinghe 2011). Estimates are that Earth is only 4.6
billion years in age (Lugmair and Shukolyukov 2001). There-
fore, the rst minimal gene set sucient to sustain life, was
formed at least 6 billion years before Earth and this so-
lar system were established. The establishment of DNA,
however, is just the one step in fashioning a single living
Single cellular microbes are comprised of more than
2,500 small molecules, nuclei acids and amino acids
consisting of 10 to 50 tightly packed atoms, and macro-
molecules and polymeric molecules which precisely inter-
act as a cohesive whole and function together as a living mo-
saic of tissues (Cowan and Talaro 2008; Joseph and Schild
2010a). The thousands of dierent molecules that comprise
a single cellular creature perform an incredible variety of
chemical reactions in concert with that cell’s protein (en-
zyme) products; whereas the smallest of single celled crea-
tures consists of and requires over 700 proteins (Cowan and
Talaro 2008).
Yockey (1977) calculated that the probability of achiev-
ing the linear structure of one protein 104 amino acids long,
by chance, is 2
. The probability of forming just a
single protein consisting of a chain of 300 amino acids is
, or 1 chance in 2.04
(Hoyle 1982). The prob-
ability of creating 700 proteins—the number necessary to
fashion a living mosaic of tissues–might be in excess of 700
(Joseph and Schild 2010a,b). According to "Borel’s
Law" any odds beyond 1 in 10
have a zero probability of
ever happening: "phenomena with very small probabilities
do not occur" (Borel 1962).
As argued by Dose (1988), it appears nearly impossi-
ble for a single cell to have been fashioned by chance or
on Earth. "The diculties that must be overcome are at
126 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
present beyond our imagination." The chairman of a Na-
tional Academy of Sciences committee which investigated
the evidence, Dr. Harold Klein, concluded it is impossible
to determine how even the simplest bacterium could have
been created (Horgan 1991). As summed up by Kuppers
(1990): "The expectation probability for the nucleotide se-
quence of a bacterium is thus so slight that not even the
entire space of the universe would be enough to make the
random synthesis of a bacterial genome probable."
The logical conclusion is that life, and the genes nec-
essary to maintain life, must have originated on planets
much older than our own.
3Galactic Clusters, Protoplanets,
Solar Systems, and
Interplanetary Transfer of Life
It is completely improbable that life was fashioned and
originated on this planet or in this solar system (Crick
1981; Dose 1988; Hoyle 1982; Yockey 1977) as there was
not enough time and all the constituent elements for the
manufacture of DNA were missing. It would take over 10
billion years to fashion a complete life-sustaining genome
from a single gene; and this solar system is believed to have
formed at least 4.570 Ga when the necessary materials and
elements in the solar nebula began to condense (Lugmair
and Shukolyukov 2001). However, if we accept, as a hypo-
thetical, that life was created somewhere in this galaxy
which has been estimated to be 13 billion years in age (Pace
and Pasquini 2004; Pasquini et al. 2004)—and/or that the
conditions of nebular clouds somehow fortuitously pro-
duce DNA-equipped living organisms (Joseph and Schild
2010a,b), then it can be predicted that once life began to
replicate, diversify, and evolve, that living organisms were
dispersed to other planets and solar systems in this galaxy,
and infected protoplanets being fashioned in those nebular
Quantitative studies estimate that about one third
of the debris circulating in space between planets will
be ejected from solar systems with Jupiter-sized worlds
(Melosh 2003). Given that some of that some of this de-
bris is ejected from an impacted surface following meteor
strikes, if that debris contains living matter then, hypotheti-
cally, one solar system might seed another; so long as living
organisms or their spores are safely embedded deep within
the matrix of a large meteor, asteroid or comet that is at
least (
10 kg), thereby providing a thick shielding against
UV and cosmic rays (Belbruno et al. 2012; Horneck 1993;
Nicholson et al. 2000).
However, it’s been argued that there is a very low proba-
bility that life can be transferred between solar systems due
to the distance, time, low interstellar density, and because
solar systems are in motion (Melosh 2003). As estimated
by Melosh (2003) of all the meteorites that are ejected from
terrestrial planets following impacts by bolides, only about
one-third are ejected out of the solar system via the gravi-
tational inuences of Jupiter and Saturn. Even during the
heavy bombardment phase of solar system development,
the ejected rocks originating from the surface of one terres-
trial planet would have only a 10
probability of landing in
a terrestrial planet in another solar system. Melosh (2003)
concluded that lithopanspermia between solar systems is
“overwhelmingly unlikely.” Other investigators believe the
odds are actually much greater (Belbruno et al. 2012) par-
ticularly when involving transfer between stellar systems
forming in galactic clusters as they are much closer together
(Adams and Spergel 2005).
Although various scenarios abound, it’s been proposed
that stars and protoplanets rst form in galactic clusters
within turbulent nebular clouds amongst thousands of
other new born stars (Adams 2010; Fragkou et al. 2019;
Johansen and Lambrechts 2017; Jones et al. 2019) with plan-
ets taking up to 10my to become established (Lissauer 1993).
These protoplanets are presumably fashioned in these stel-
lar nurseries by the accumulation of stellar debris, and with
protoplanets of varying size crashing into one another prior
to and after initially becoming captured by a newly forming
stellar system (Boyle and Redman 2016; Joseph and Schild
2010a,b; Stephan et al. 2020). For example, Adams (2010)
calculated that stars are born in clusters of 1,000–10,000
other stars; and with increased density, the probable suc-
cessful transfer of life-bearing debris increases accordingly.
It has been hypothesized that stars and planets re-
main in those clusters for 10my to 30 My or longer (Adams
and Myers 2001). Therefore, as worlds are formed and de-
stroyed (Adams and Spergel 2005; Boyle and Redman 2016;
Stephan et al. 2020) life may be repeatedly transferred be-
tween these protoplanets, carried by the billion trillion tons
of debris that ricochet between these worlds during this
10 to 30 mya episode of supreme chaos and turbulence
(Gibson et al. 2011; Joseph and Schild 2010b; Valtonen et
al. 2008). Therefore, after becoming contaminated with
life, these stars (and billions of planets) will drift away or
are ejected thereby becoming independent, albeit, initially
relatively chaotic solar systems until they stabilize.
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |127
4Habitability and the Heavy
Bombardment Phase of Solar
System Formation
The proto-planets that would become Earth, Mars, and
Venus may have become contaminated with life before and
after this solar system was established. The early solar sys-
tem was repeatedly subjected to cataclysmic events and
cosmic collisions, which led to major changes aecting the
habitability of the planets orbiting within the inner solar
Mars, Venus, Earth and the Moon, were repeatedly
and continually bombarded by meteors, asteroids, comets,
oceans of ice, and moon-sized debris until approximately
3.8 billion years ago (Chambers and Lissauer 2002; Levison
et al. 2001, 2002; Zappalà et al. 1998). The Late Heavy Bom-
bardment period is believed to have been triggered by the
capture and rapid inward migration of the planets which
resulted in cosmic collisions and the chaotic displacement
of surrounding and adjacent debris elds, thereby trigger-
ing the delivery of planetesimals, asteroids, meteors, and
oceans of water to the inner solar system (Kring and Cohen
2002; Tagle 2008); debris and water that may have harbored
Because Earth was continually bombarded, surface
rocks already established prior to 4.2 bya were pulverized
and vaporized erasing any evidence of life on the surface.
However, once surface rocks, minerals, and metals began
to cool and solidify, biochemical residue indicative of life
began to fossilize, and thus there is evidence of life within
Earth’s oldest rocks, minerals and metals, dated to over 4.2
bya (Nemchin et al. 2008; O’Neil et al. 2008); and which
suggests, life was present from the very beginning. There-
after, and because Earth orbits within the habitable zone,
life began to proliferate and terraform the biosphere (by re-
leasing oxygen and other gasses), and evolve (Joseph 2000,
Earth, Mars, and Venus, all orbit within the habitable
zone, the inner and outer edges of which are located respec-
tively at distances of 0.836 and 1.656 AU from the Sun (Kane
and Gelino 2012). Therefore, Mars (1.52 AU) is located near
the outer edge, while Venus (0.72 AU) is located just within
the inner edge of the habitable zone (Kasting et al. 1993).
Hence, if each of these planets had become contaminated
with life during the protoplanetary stage of development,
then, at least initially, life may have also begun to prolifer-
ate and evolve once their orbits stabilized.
Many scientists agree that ancient Mars was wet and
habitable (Ehlmann et al. 2011; Grotzinger et al. 2014;
Squyres and Knoll 2005; Thomas-Keprta et al. 2009; Vago
et al. 2017). Paralleling the onset and proliferation of life on
Earth, there is evidence—but no conclusive proof–of life on
Mars between 3.7 to 4.2 bya (Clement et al. 1998; Noke 2015;
Joseph et al. 2019; Thomas-Keprta et al. 2009). Moreover,
Martian life may have proliferated and evolved to the level
of metazoans (Joseph and Armstrong 2020; Joseph et al.
2020a; McKay 1996); after which, due to cosmic collisions
or unknown catastrophic events, the Martian geodynamo
was negatively impacted resulting in the loss of its magnetic
shield (Acuña et al. 1999; Arkani-Hamed and Boutin 2004;
Roberts et al. 2009). For example, it is believed that billions
of years ago a planet or moon slammed into the northern
plains of Mars creating an elliptical depression 6,600 miles
long and 4,000 miles wide (Andrews-Hanna et al. 2007)
and which may explain the extreme elliptical orbit or Mars.
However, when and why it lost its geodynamo is unknown;
but in consequence, Mars was no longer protected from so-
lar winds and UV Rays, and suered atmospheric loss and a
cooling and aridication of its climate (Fairén 2017; Jakosky
et al. 2018). Mars, therefore, became a failed Earth; though
how long before the Martian oceans began to evaporate or
freeze, is unknown.
Venus may have also been habitable billions of years
ago (Abe et al. 2011; Cockell 1999; Joseph 2019), and may
have remained habitable and able to sustain a variety of life
forms until at least 700 million years ago, before it lost its
oceans (Way et al. 2016) and its atmosphere exceeded the
ultimate stage of the “moist greenhouse” eect: Ts
330 K
(Wolf et al. 2017). When and what caused this catastrophic
alteration in the habitability of Venus is unknown. In conse-
quence, the environment of Venus became so toxic that only
hyper-extremophiles would be able to survive; i.e. fungi
and organisms beneath the surface (Joseph 2019; Ksan-
fomality 2013), or those dwelling in the clouds (Konesky
2009; Limaye et al. 2018; Sagan and Morowitz 1967; Schulze-
Makuch et al. 2004); and for which there is evidence, but
no proof.
It is also believed that over 4.4 billion years ago a Mars-
sized planet may have struck Earth with so much force that
the ejected mass formed the moon (Belbruno and Gott III
2005). Therefore, Earth was originally a super Earth, much
larger in size, before this solar system stabilized. If life had
already taken root on Earth during the proplanetary phase
of development, then, according to this hypothesis, what
would become the moon would have also been infested
with life that later became extinct, after this Earth-moon
impacting-ejection event.
Considered as a hypothetical, if various protoplanets
had become contaminated with life, there is no guaran-
tee life would survive. Life, at least on the surface of these
128 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
worlds, may be subject to mass extinctions if these planets
assume orbital trajectories outside the habitable zone and
under conditions where water completely evaporates or
becomes permanently frozen. For example, it’s been esti-
mated that the highest surface temperature threshold for a
planet’s habitability is most likely 82
C. Above this thresh-
old, the loss of water by vaporization is irreversible and the
oceans disappear completely in a few million years (Inger-
soll 1969; Kasting 1998; Kasting et al. 2014; Wolf and Toon
2015). However, this does not preclude the possible exis-
tence of "alien" life forms with an adaptive biochemistry
completely unlike the life of Earth.
Although those events leading to the possible ejection
of what became the moon may have led to the extinction of
any life on the lunar surface, this same catastrophic event
may have enhanced the evolutionary potential for life on
Earth. After ejection and/or after the moon began to orbit
Earth, the Earth-Moon system’s tidally driven processes de-
creased Earth’s rotation period over the ensuing billions
of years according to the following estimates: 4.5 bya = 6.1
h; 3 bya = 10.5 h; 2 byr - 14.2 h (Arbab 2009). The presence
of the moon also altered the stabilization of Earth’s obliq-
uity (Laskar et al. 1993) which is subject to variations of
around a mean value of 23.3
. If there was no moon,
these variations would range from nearly 0
up to about
, causing cataclysmic alterations in the climate and bio-
sphere. As Earth would have also been larger—if the moon
had not been ripped from the surface–so to would be the
eects of gravity. In total, without the moon, there would
have been profound eects on the trajectory and evolution
of life such that humans may have never evolved on this
5Meteors, Ejecta, and the
Interplanetary Transfer of Life
It is believed that Earth, Mars, and Venus were struck mil-
lions of times during the period of heavy bombardment
which ended around 3.8 bya (Melosh 2003; Schoenberg et
al. 2002). Given evidence of life on Earth between 4.2 and
3.7 bya (Nemchin et al. 2008; Nutman et al. 2016; O’Neil
et al. 2008; Rosing and Frei 2004), and evidence of life on
Mars during this same time period (Clement et al. 1998;
Noke 2015; Thomas-Keprta et al. 2009) each of these im-
pacts would have also ejected tons of life-bearing debris
into space (Beech et al. 2018; Belbruno et al. 2012; Worth et
al. 2013). As argued by Belbruno et al. (2012): This period of
massive bombardment, therefore, provided a major “win-
dow of opportunity” for the transfer of life-bearing debris
between planets. According to Worth et al. (2013): "such
transfers were most likely to occur during the Late Heavy
Bombardment." Hence, the parallels in the possible mi-
crobial colonization of Earth and Mars between 3.7 and 4.2
bya. However, the interplanetary transfer of life, within this
solar system likely continued over the ensuing billions of
years following meteor strikes (Beech et al. 2018; Belbruno
et al. 2012; Worth et al. 2013) and due to powerful solar
winds (Joseph 2009; Joseph et al. 2019).
It is well established that an ounce of soil contains bil-
lions of microbes, as well as protozoa, algae, fungi, lichens,
and nematodes (Alexander 1991; Sylvia et al. 2004). If a
ton of compacted soil were ejected into space, an estimated
32,000,000,000,000 adhering organisms might be buried
inside and then subsequently deposited on another planet.
As will be explained, a variety of species, including bacte-
ria, algae, fungi, and lichens can survive a violent ejection
from the surface of a planet, direct exposure to space, and
then the crash landing onto the surface of a planet; though
if they survive would depend on how long they are aloft,
the matrix in which they are buried, and the habitability of
the planet upon which they might be deposited.
According to calculations by Beech et al. (2018), given
an impact velocity greater than 23 km/s, this microbial-
laden ejecta could enter the orbits of and intercept Venus,
Mars and other planets within a few weeks, months or years.
Moreover, studies have demonstrated that bolide ejecta pro-
vides nutrients that can sustain trillions of microorganisms,
including algae and fungi, perhaps for thousands of years
(Mautner 1997, 2002). However, ejecta may remain in orbit
for millions of years, whereas yet others may never strike
another planet and instead fall into the sun (Gladman et al.
1996; Melosh 2003).
There are currently 200 known terrestrial impact
craters that are still visible (Earth Impact Database 2020).
Following the end of the great bombardment period, this
planet may have been struck thousands of times (Melosh
1989), which resulted in the ejection of millions of rocks,
boulders and tons of debris into space over the course of
the last 4 billion years (Beech et al. 2018; Gladman et al.
1996; Melosh 1989, 2003; Van Den Bergh 1989). On Earth,
in the last 550 million years there have been a total of 97
major impacts, leaving craters at least 5 kilometers across
(Earth Impact Database 2020), and it’s been estimated that
approximately "10
kg of potentially life-bearing matter
has been ejected from Earth’s surface into the inner solar
system" (Beech et al. 2018). These impacts may have ejected
not just microorganisms, but metazoans, as well as seeds
and plants resulting in the interplanetary transfer of even
complex organisms between planets and inuencing and
impacting the evolution of life on alien worlds as well as on
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |129
Earth due to the possible survival and proliferation of any
organisms buried in those meteors, asteroids and comets,
that struck this planet (Joseph 2000).
Consider, for example, the Chicxulub crater, formed
approximately 66 Mya, and which has a 150 km diameter
(Alvarez et al. 1980). If that impacting asteroid also con-
tained viruses, bacteria, and other living organisms as part
of its cargo, is unknown; but if so, it is reasonable to ask
if surviving extraterrestrial bacteria and viruses may have
sickened life on this planet (Joseph and Wickramasinghe
2010) perhaps contributing to the demise of the dinosaurs
and/or inuencing the evolutionary trajectory of survivors
via horizontal gene transfer (Joseph 2000). In addition to
the possible extraterrestrial delivery of living organisms to
Earth 66mya and creating conditions that led or contributed
to the demise of the dinosaurs (Alvarez et al. 1980), it’s been
estimated, given a 25 km/s impactor velocity, that up to 5.5
kg of debris may have been ejected into space when
that asteroid struck (Beech et al. 2018). That debris may
have included unknown volumes of water, and perhaps
millions of trillions of organisms buried within this ejecta.
Those that survived and were deposited within a habitable
environment, would have likely gone forth and multiplied.
The Chicxulub crater is just one example of an impact-
ejection event. Earth, Mars and Venus were repeatedly
stuck by asteroids and meteors. Over 635,000 impact craters
at least 1 km (0.6 miles) wide, have been located on Mars
(Robbins and Hynek 2012), approximately 1000 impact
craters have been detected on Venus by the Magellan space-
craft (Schaber et al. 1992) and 200 large terrestrial impact
craters have been located on Earth (Earth Impact Database
2020)—whereas the number of those that did not survive
weathering or were eventually buried, is unknown. Of the
60,556 meteorites so far found on Earth, 227 are believed to
have originated on Mars, and 360 are from the Moon (Mete-
oritical Bulletin Database 2020). Meteors from Venus have
not yet been identied. Clearly these planets have been
repeatedly impacted by meteors which survived descent
through the atmosphere without vaporization. Innumer-
able organisms embedded deep within those impacting
meteors may have also survived.
6Surviving Impact, Ejection,
Exposure to Space and Crash
It is well established that microbes buried within debris,
can survive extreme and violent shocks and impact pres-
sures of 100 GPa, and the subsequent hyper-velocity launch
into space (Burchell et al. 2004, 2001; Hazael et al. 2017; Hor-
neck et al. 2008; Mastrapa et al. 2001). By forming spores,
they can even survive long term direct exposure to the frigid
temperatures and vacuum of space despite the cosmic rays,
gamma rays, UV rays, ionizing radiation they encounter
(De la Torre Noetzel et al. 2017, 2020; De Vera et al. 2014,
2019; Horneck et al. 2002; Olsson-Francis et al. 2009). There
is also a high probability of survival after the crash landing
onto the surface of a planet (Burchell et al. 2001; Horneck
et al. 2002; Szewczyk et al. 2005).
Although innumerable meteors disintegrate, it’s been
estimated that those at least ten kilometers across will
punch a hole in the atmosphere and continue their descent;
and upon striking the surface eject tons of dust, rocks, boul-
ders and other debris into space (Covey et al. 1994; Hara
et al. 2010; Van Den Bergh 1989); with some of that debris
possibly passing through that atmospheric hole before air
can rush back in thereby preventing excessive heating (Van
Den Bergh 1989). Other than initial shock pressures, these
masses of ejecta, and surviving organisms buried within,
would not be subject to extremes in heat.
When a comet, asteroid, or meteor passes through
the atmosphere and strikes the surface, rocks, boulders
and debris that are blown upward and ejected by the im-
pact, may pass back through the atmosphere; and in con-
sequence they may be heated to temperatures in excess
of 100
C if they pass through after that "hole" has closed
up (Artemieva and Ivanov 2004; Fritz et al. 2005). These
temperatures are well within the tolerance range of ther-
mophiles (Baross and Deming 1983; Kato and Qureshi 1999;
Stetter 2006). Spores can survive shock temperatures of
over 250
C (Burchell et al. 2004; Horneck et al. 2002). There-
fore, if the hole in the atmosphere closes up before that
ejecta can pass through, the friction-generated heat might
only kill those organisms riding on the surface. In addi-
tion, exterior heating may only last a few seconds, whereas
ejecta may be covered by a heat-induced fusion crust of
at least 1 mm, which acts as a protective heat shield for
organisms deep within (Cockell et al. 2007); as the thermal
pulse may only extend a few millimeters below the surface
due to low thermal conductivity. Thus, organisms buried
within will not be aected. In fact, the interior may never
be heated above 100
C as the ejecta-surface is acting as a
heat shield (Burchell et al. 2004; Horneck et al. 2002).
Microbes can also resist the shock of a violent impact
casting them into space (Mastrapa et al. 2001; Burchell et
al. 2004, 2001). Bacteria, yeast spores and microorganisms
can survive impacts with shock pressures of the order of
gigapascals (Burchell et al. 2004; Hazell et al. 2010; Meyer
et al. 2011; Willis et al. 2006). Meyer et al. (2011) has demon-
130 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
strated that bacteria and lichens can survive powerful shock
waves and pressures up to 45 GPa, whereas cyanobacteria
withstand up to 10 GPa; so long as these organisms are
embedded within low porosity rocks.
Further, a substantial number of organisms could eas-
ily survive not just the ejection from a planet, but the de-
scent to the surface (Burchell et al. 2001; Horneck et al.
2002; McLean and McLean 2010). In one study, granite
samples were permeated with spores of Bacillus subtilis
and attached to the exterior of a rocket and launched into
space, reaching a maximum atmospheric entry velocity of
1.2 km/s and temperatures of 145
C (Fajardo-Cavazos et
al. 2005). Although a massive die o was recorded, up to
4.4% directly exposed to these conditions survived—and
one survivor can easily reproduce billions of microbial o-
spring. By contrast, studies have shown that a signicant
number of organisms buried within a meteor will not be
unduly harmed even when crashing into a planet (Burchell
et al. 2001; Horneck et al. 2002; McLean and McLean 2010).
Moreover, there are high survival rates following high at-
mospheric explosions, i.e. the Columbia space shuttle ex-
plosion (Szewczyk et al. 2005), and despite reentry speeds
of up 9700 km h
(McLean et al. 2006). Thus, innumerable
microbes may remain viable despite violent impact-induced
ejection into space and the rapid descent to the surface of
another planet.
Earth is an obvious source of living organisms that
may have been ejected, jettisoned, cast into space, only
to crash onto the surface of other worlds in this solar sys-
tem beginning over 3.8 bya, thereby repeatedly seeding
Venus, Mars, and other planets with life (Beech et al. 2018;
Fajardo-Cavazosa et al. 2007; Hara et al. 2010; Melosh 2003;
Mileikowsky et al. 2000a,b; Schulze-Makuch et al. 2005)
and vice-versa. Asteroids and meteors striking Earth may
have repeatedly sheared away masses of earth and rock,
and blasted this material (and presumably any adhering
microbes, fungi, algae, and lichens) into space (Beech et al.
2018; Gladman et al. 1996; Hara et al. 2010; Melosh 2003;
Mileikowsky et al. 2000a,b), where they can survive (Hor-
neck et al. 2002; Onofri et al. 2012; De Vera et al. 2019; De
la Torre Noetzel et al. 2020; Novikova 2009; Novikova et
al. 2016; Olsson-Francis et al. 2009). Some of this microbe-
laden debris may have later crashed on Mars (Hara et al.
2010; Schulze-Makuch et al. 2005) where, as demonstrated
by simulation studies, a variety of organisms can also sur-
vive (Cockell et al. 2005; Mahaney and Dohm 2010; Osman
et al. 2008; Pacelli et al. 2016; Sanchez et al. 2012; Selbman
et al. 2015); and the same may be true of organisms de-
posited in the upper clouds of Venus (Joseph 2019; Konesky
2009; Limaye et al. 2018; Sagan and Morowitz 1967; Schulze-
Makuch et al. 2004). Coupled with solar winds blowing high
altitude atmospheric organisms into space (Arrhenius 1908;
Joseph 2009) the interplanetary transfer of microorganisms
within our Solar System is overwhelmingly likely (Beech et
al. 2018; Joseph et al. 2019; Mileikowsky et al. 2000a,b).
7Spores and Space Travel
In the absence of water, nutrients, or under extreme life-
neutralizing conditions, microbes, lichens, fungi and other
organisms may instantly react by forming highly min-
eralized heat or cold shock proteins that enclose and
wrap around their DNA, thereby eliminating all need for
metabolism and altering the chemical and enzymatic reac-
tivity of its genome making it nearly impermeable to harm
(Marquis and Shin 1994; Setlow and Setlow 1995; Sunde et
al. 2009). A dormant spore survives exposure to extreme
heat, cold, desiccation, the vacuum, UV and ionizing radi-
ation of space with just minimal protection (Horneck 1993;
Horneck et al. 1995; Mitchell and Ellis 1971; Nicholson et al.
2000). Survival rates also increase signicantly, up to 70%,
if coated with dust or salt crystals (Horneck et al. 1994).
Although the full spectrum of UV rays are deadly against
spores, some spores, including B. subtilis can even survive
a direct hit (Horneck et al. 2002). If buried below 30 cm of
surface material the eects of heavy ions and secondary
radiation depreciates signicantly and survival rates dra-
matically increase (Horneck et al. 2002). Because of their
small size, it’s been estimated that even those near the sur-
face of ejecta may survive in space for millions of years
being struck by radiation; and up to 25 million years in
space if shielded by 2 meters of meteorite (Horneck et al.
Many species of microbe form colonies. If traveling
through space, those in the outer layers would therefore
create a protective outer colonial crust that blocks out radia-
tion and protects those in the inner layers from the hazards
of space (Nicholson et al. 2000). Therefore, colonies of liv-
ing microbes provide their own protection and need not
form spores.
As noted, ejected debris may orbit in space for millions
of years before striking another planet. Microbes, lichens,
and fungi may survive life in space for tens of millions of
years via the formation of spores. Cano and Borucki (1995)
have reported that spores, embedded in amber, may remain
viable for 25- to 40-million-years. Vreeland et al. (2000)
have reanimated 250 million-year-old halotolerant bacteria
from a primary salt crystal, whereas Dombrowski (1963)
reanimated spores "isolated from salt deposits from the
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |131
Middle Devonian, the Silurian, and the Precambrian" that
were over 600 million years in age.
Therefore, even if ejecta circulates in orbit for millions
or tens of millions of years, spores embedded beneath the
surface might survive; and if they land on Mars and in the
clouds of Venus, those which can adapt would likely go
forth and multiply.
8Evidence of Life and
Stromatolites on Mars: Parallels
with Earth
Although considered controversial, NASA’s 1976 Viking La-
beled Release studies, at two landing sites 4,000 miles apart
on Mars, detected evidence of surface biological activity
that could be attributed to a very wide range of microorgan-
isms including aerobic and anaerobic bacteria, as well as
lichens, fungi, and algae (Levin and Straat 1976, 1977, 2016).
Via the Viking "Gas Exchange" experiments, soil samples
were also humidied at ~10
C and a signicant quantity of
was released (Oyama and Berdahl 1977). On Earth, the
humidication of soil will cause a massive proliferation of
photosynthesizing algae/cyanobacteria and an increase in
oxygen production (Lin et al. 2013; Lin and Wu 2014). Levin
et al. (1978) also observed "green patches" on rocks and
hypothesized these may be algae. Therefore, the responses
produced by the LR instruments and the "Gas Exchange"
experiments, and the observations of Levin et al. (1978)
support the likelihood of life.
In 1996, McKay and colleagues reported the discov-
ery of "nanobacteria" in Martian meteorite ALH 84001;
specimens so small that if they had a genome, it could
only house RNA. These ndings were immediately chal-
lenged. As summed up by Martel et al. (2012), "...structures
resembling terrestrial life forms known as nanobacteria–
can be deemed ambiguous at best." Although also sub-
ject to dispute (see Treiman 2003; Steele et al. 2012), evi-
dence of biological residue, carbonates, and fossilized poly-
Figure 1.
(Top row): Lake Thetis stromatolites with collapsed domed (Photo credit: Courtesy Government of Western Australia Department
of Mines and Petroleum). (Bottom row) Left: Sol 529. Right: Sol 308. Photographed in Gale Crater: Martian specimens with evidence of
concentric lamination and fossilized fenestrae. (From Joseph et al. 2020a, reproduced with permission).
132 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Figure 2.
(Top): Lake Thetis stromatolites with collapsed domed
(Photo credit: Lyn Lindeld And TheTravellingLind, re-
produced with permission). (Bottom) Left: Sol 122. Sol 308. Pho-
tographed in Gale Crater: Martian specimen with evidence of con-
centric lamination and fossilized fenestrae. (From Joseph et al.
2020a, reproduced with permission).
cyclic aromatic hydrocarbons (PAHs)–a byproduct of cellu-
lar decay–were also discovered in Martian meteorite ALH
84001 (Clement et al. 1998; McKay et al. 1996, 2009) at least
25% of which appears to be biological (Thomas-Keprta et al.
2009). Thomas-Keprta et al. (2009) has argued these nd-
ings are indicative of life on Mars over 4.2 bya. As summed
up by Martel et al. (2012) "the presence of polycyclic aro-
matic hydrocarbons, magnetite crystals, carbonate glob-
ules... are compatible with living processes."
In 2002 DiGregorio reported what he believed to be
biosignatures compatible with cyanobacteria in an ancient
paleolake; a hypothesis based on the detailed analysis
of images photographed at Utopia Planitia and Chryse
Planitia—in the same locations where the Viking LR ex-
periments detected biological activity and algae-like green
patches were observed (Levin and Straat 1977, 2016). Di-
Gregorio (2002), observed what he interpreted to be "rock
varnish" typically produced by a wide variety of microor-
ganisms "including epilithic and edolithic cyanobacteria."
DiGregorio hypothesized that Martian cyanobacteria could
have cemented sediments together, fashioning microbial
mats and stromatolites in these ancient Martian lakes. Sub-
sequently, in 2009, Rizzo and Cantasano (2009, 2017) re-
ported evidence of fossilized microbialites based on a de-
tailed examination of Martian sediments resembling stro-
matolites. Additional evidence of microbialites, microbial
mats, thrombolites and stromatolites were subsequently
provided by numerous investigators (Bianciardi et al. 2014,
2015; Joseph et al. 2019, 2020a,c; Ru and Farmer 2016;
Small 2015).
Gale Crater is believed to have been host to several lakes
which were repeatedly replenished, and these ancient bod-
ies of water have been likened to the Lake Thetis of Western
Australia which is also home to living and fossilized dom-
ical stromatolites. In March of 2020, a team of 14 experts
in astrobiology, astrophysics, biophysics, geobiology, mi-
crobiology, lichenology, phycology, botany, and mycology
conducted an extensive search of the NASA Mars Gale Crater
image data base and found six concentric-domical Martian
specimens that closely resemble Lake Thetis stromatolites;
ve of which appeared fossilized (Joseph et al. 2020a). This
team also observed numerous other concentric structures,
that although severely decomposed, still retained patterns
similar to domical-concentric stromatolites.
Therefore, over a dozen surface features quite similar
to stromatolites have been observed on Mars. It’s been esti-
mated that the oldest of these Martian stromatolites may be
3.7 billion years in age (Noke 2015); a time period which
coincides with the fashioning of what may be the rst stro-
matolites on Earth 3.7 bya (Garwood 2012; Nutman et al.
2016)—though not all investigators accept this evidence.
Hence, there is evidence (but no proof) that life may
have appeared on Mars between 3.7 to 4.2 bya (Noke
2015; Thomas-Keprta et al. 2009), and that stromatolite
constructing-organism were proliferating (Joseph et al.
2020a); and this parallels the evidence, based on chem-
ical and physical fossils, that life had also appeared on
Earth during this same time period (Nemchin et al. 2008;
O’Neil et al. 2008; Rosing and Frei 2004), some of which
were also constructing stromatolites (Garwood 2012; Nut-
man et al. 2016), during and upon the close of the heavy
bombardment phase when Earth, Mars, and Venus were
pummeled with meteors, asteroids, comets and oceans of
water that may have harbored life.
9Fossils on Mars? Evolution and
Interplanetary Transfer?
Beginning billions of years ago, life on Earth diversied,
adapted to the changing environment, and evolved. By 800
to 600 mya, oxygen levels had signicantly increased to
about 0.1%–3% O
, of modern atmospheric levels (Ader
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |133
Figure 3.
(First row): Sol 809 and Sol 869. (Second row) Sol 905 and Sol 905. Specimens photographed in Gale Crater and that are quan-
titatively and statistically nearly identical to Ediacaran fossils of Namacalathus (two, bottom left) and (with the exception of tail length)
Cambrian fossils of Lophotrochozoa (three bottom right). Photos of Namacalathus reproduced from and courtesy of Kontorovich et al. 2008.
Photos of Lophotrochozoa reproduced from and courtesy of Zhang et al. 2014.
134 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Figure 4.
(First row) fossilized remains of Ediacaran Kimberella. (Bottom two rows): Specimens photographed in Gale Crater, quantitatively
and statistically nearly identical to Ediacaran fossils of Kimberella. Sol 809, Sol 809, Sol 809; Sol 880, Sol 905, Sol 905. Note proboscis
and "zipper-like" appendages.
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |135
et al. 2014; Lyons et al. 2014) thereby leading to an explo-
sion of oxygen-breathing life (Brocks et al. 2017; Lenton et
al. 2014), that included acritarchs followed by Ediacaran-
metazoans (Erin 2015; Xiao et al. 2014; Zhou et al. 2001).
Moreover, despite repeated catastrophic extinction events,
life on Earth never became completely extinguished. In-
stead, each episode of mass extinction was followed by
repopulation and evolutionary innovation (Eldredge and
Gould 1972; Elewa and Joseph 2009; Joseph 2010a,b). There-
fore, if life had taken root, then beginning after 3.7 bya life
may have also evolved on Mars, up until that point in Mar-
tian history when catastrophic events negatively impacted
its internal dynamo, thereby resulting in the loss of its mag-
netic shield, followed by the evaporation and freezing of its
oceans and continual bleeding of atmosphere into space.
However, although speculation abounds, it is unknown as
to when these catastrophes occurred.
Paralleling events on Earth, Kaźmierczak (2016, 2020)
upon searching the Mars Meridiani Planum data base, dis-
covered specimens that resemble mineralized tri-star and
globular fossils with central vesicle-like ornamental cham-
bers. These mineralized spiny bimorphic structures have
thin walls with a cell-like appearance and were discovered
in hydrated sediments that may have once been an ancient
lake, i.e. Endeavor Crater. According to Kaźmierczak (2016)
analyses, morphologically they are similar to terrestrial
fossils variably described as acritarchs (meaning “of un-
certain origin”). The rst acritarchs may have evolved, on
Earth, over 700 million years ago (Arouri et al. 2000; Zhou
et al. 2001). In addition, Kaźmierczak (2020) has presented
evidence of Martian fossils that are strikingly similar to
daughter colonies characteristic of Terran volvocalean al-
gae as well as cell-like enclosures similar to chloroplasts
and modern unicellular green and yellow green algae.
Martian fossils resembling metazoans have also been
observed; many of which resemble one another and were
found in the same location or on adjacent mudstones in
Gale Crater (Joseph et al. 2020b). Subsequent, ongoing stud-
ies have identied over a dozen fossil-like impressions that
are morphologically and statistically identical to Ediacaran
fossils; i.e. Namacalathus and Kimberella (Joseph and Arm-
strong 2020). These fossils were embedded within and atop
Martian mudstones upon the lower lake surface of Gale
Crater; an area that other investigators believe was con-
ducive to the proliferation and fossilization of marine or-
ganisms (Grotzinger et al. 2014, 2015). These metazoan-like
fossils, most protruding from the surface, included spiral,
spherical, and tubular specimens often atop or immedi-
ately adjacent, and many nearly identical to one another
(Joseph et al. 2020a). As determined by molecular clock
studies, metazoans began populating Earth 750 to 800 mya
(Erin 2015) although the rst fossil evidence of metazoans
(the Doushantuo embryos) do not appear in the geological
record until 600 mya (Xiao et al. 2014).
It must be stressed: There is no conclusive proof these
are Martian metazoan fossils. Nevertheless, it is reasonable
to ask: Is it possible that metazoans evolved on Mars? Or
were they deposited on the Red Planet following meteor
strikes and ejection from Earth?
McKay (1996) has argued that "after the origin of life
the key evolutionary steps could have occurred much more
rapidly on Mars than on Earth" and that within a billion
years after life appeared, Mars may have "experienced the
range of biological evolution that would be duplicated on
the Earth only with the start of the Cambrian."
However, if metazoans independently evolved on Earth
and on Mars, then this would suggest that "evolution" is not
random and does not unfold according to Darwinian prin-
ciples, but is genetically coded and follows precise genetic
principles; such that similar species inevitably "evolve" on
planets that are similarly habitable; a genetically governed
and regulated process that Joseph (2000) has likened to
embryology and "evolutionary metamorphosis."
Joseph (2000) has also speculated that since so many
Ediacaran and Cambrian species were of unknown origin,
that possibly the Cambrian explosion may have been due to
the interplanetary transfer of life: "until around 600 million
years ago, just prior to the Cambrian era, the vast major-
ity of life forms sojourning on Earth consisted of single
celled organisms and simple multi-celled creatures com-
posed of less than 11 dierent types of cells. And then
there was a sudden explosion of complex life, including
rather "bizarre" life forms that appeared simultaneously
and multi-regionally throughout the oceans of the Earth"
including numerous species that have an "unknown ori-
gin." Joseph (2000) goes on to argue: "Many creatures (in-
cluding even complex multicellular plants, insects, frogs
and lizards) can also live in a dormant form and withstand
otherwise life neutralizing conditions. Indeed, the capac-
ity to live in a dormant state even under environmental
extremes, may well account not only for the origin of life
on Earth, but to the sudden emergence of at least some of
the complex species during the Cambrian Explosion. In
other words, even complex animal life may have been de-
posited on Earth from outer space, including, perhaps at
least some of the "bizarre" life forms that emerged during
the Cambrian Explosion."
Caenorhabditis elegans is a metazoan, approximately
1mm in length and has a mouth, intestine, male and female
reproductive organs, and an ancestry that extends back
to the Ediacaran era. C. Elegans is a nematode, and some
species of nematode prefer frigid climates (Mullin et al.
136 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
2002), where temperatures may fall below
C (
Conversely, those that dwell in arid environments can enter
a state of dormancy for up to 28 years if deprived of water
and then become metabolically active when provided mois-
ture (Fielding et al. 1951). Caenorhabditis elegans, therefore,
might be capable of adapting to life on Mars. They can also
survive exposure to space, an explosive reentry into the
atmosphere, and a subsequent crash landing.
On February 2, 2003, numerous members of this
species, ensconced within canisters, survived an explosion,
at speeds of Mach 19, approximately61 km above Earth’s sur-
face, that destroyed the space shuttle Columbia. And these
C. elegans survived an unprotected 660–1,050km/h velocity
reentry into Earth’s atmosphere and the subsequent crash
upon the surface (Szewczyk et al. 2005). After these C ele-
gans were retrieved from the crash site all but two displayed
normal growth and reproductive egg laying behavior. As
argued by (Szewczyk et al. 2005), what they experienced is
analogous to being embedded on the surface of an asteroid
that breaks into fragments upon striking the atmosphere,
and then surviving after those fragments smash into the
Eight hundred million years ago, the Moon and Earth,
were struck by a urry of asteroids that likely profoundly
aected the biosphere (Terada et al. 2020). As summarized
by Terada et al. (2020): "Based on crater scaling laws and
collision probabilities... meteoroids, approximately 30–60
times more powerful than the Chicxulub impact, must have
plunged into the Earth-Moon system."
Soon thereafter, acritarchs, Ediacarans, and thus, the
rst metazoans, began to proliferate in Earth’s oceans,
many having a bizarre appearance, many eventually dy-
ing out and becoming extinct, and many have a completely
unknown ancestral origin—as if they were deposited here
from another planet.
If the hypothesis of McKay (1996) and Joseph (2000) are
correct, it is reasonable to ask: is it possible that Martian
metazoans were transported to Earth, thereby contribut-
ing to or giving rise to the Cambrian Explosion? Or, might
the (presumed) metazoans on both planets have originated
from another world; possibly buried in those meteors that
struck 800mya? Or, conversely, did ejecta from Earth trans-
port metazoans to Mars? One can only speculate.
10 Fossils on the Moon?
In support of the interplanetary transfer hypothesis is the
discovery of fossilized impressions on the surface of the
moon. Specically, in 1970 lunar soil samples were returned
to Earth by the Luna 16 spacecraft in a hermetically sealed
container (Rode et al. 1979) and one of the specimens was
observed to closely resemble a spiral lamentous micro-
Ediacaran, a species which became extinct over 500,000
years ago (Joseph and Schild 2010a). Zhmur and Gerasi-
menko (1999), also identied what they believed to be lu-
nar microfossils of coccoidal bacteria; i.e. siderococcus and
sulfolobus. It is not probable that Ediacarans and coccoidal
bacteria evolved on the moon. Therefore, if these fossilized
impressions are true fossils, they must have been trans-
ported to the lunar surface, possibly while still alive, and
became fossilized.
Moreover, what appears to be microfossils of ovoid and
elongated nanobacteria were also discovered in a lunar me-
teorite (Sears and Kral 1998). These lunar "nanobacteria"
however, were even smaller than the "nanobacteria" discov-
ered in Martian meteorite ALH8401. In general "nanobacte-
ria" are so small it would be impossible for them to host a
DNA-based genome, but only an RNA-based genome, like
a virus. If we employ life on Earth as a standard, it is not
likely that the Martian or Lunar "nanobacteria" are true
cellular organisms (Joseph and Schild 2010b).
11 Lunar Life and Survival of the Fit
After sitting 3 years on the moon, a TV camera from the
lunar Surveyor Space Craft was retrieved by Apollo 12 astro-
nauts, and dormant bacterium (Streptococcus mitis) were
found within. Mitchell and Ellis (1971), the scientists who
made this discovery, ruled out contamination due to a sci-
entist’s sneeze or cough because a single droplet of saliva
contains an average of 750 million organisms and billions of
bacteria and a "representation of the entire microbial pop-
ulation would be expected," rather than a single species
that was dormant and then came back to life. Mitchell and
Ellis (1971) therefore, left open the possibility that the cam-
era was contaminated on the moon by lunar Streptococcus
mitis; and not before the camera was sent and not after it
was returned from the lunar surface.
It is possible, however, that there was contamination
and that billions of diverse moisture-dwelling bacteria were
coughed or sneezed into this equipment prior to sending
the TV camera to the moon. Possibly, a diverse colony of
organisms were subsequently transported to the lunar sur-
face within that camera, and only Streptococcus mitis sur-
vived by forming spores and all other bacteria died leaving
not a trace of their existence. Likewise, it can be argued
that only those organisms which can survive ejection from
Earth, Mars, or some other planet, and that can survive the
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |137
subsequent exposure to the intense UV and gamma radia-
tion of space, may go forth and multiply when deposited
on a habitable, watery moon or planet. By contrast, those
that cannot survive a journey through space and which are
deposited on completely uninhabitable moons or planets,
will die, decompose, or, more rarely, their remains may be
12 Solar Winds vs Microbes in the
Stratosphere and Mesosphere
Fungi, lichens, and algae and over 1,800 dierent types of
bacteria ourish within the troposphere, the rst layer of
Earth’s atmosphere (Brodie et al. 2007). Microbes, algae,
fungi, lichens, spores, insects, larva, pollen, seeds, water,
dust and nematodes are often transported to the strato-
sphere and mesosphere due to tropical storms, monsoons,
thunderstorms, hurricanes, tornados, volcanic eruptions
and seasonal and electrostatic upwellings of columns of
air (Dehel et al. 2008; Holton et al. 1995; Randel et al. 1998;
Rohatschek 1996; Van Eaton et al. 2013). Microorganisms,
fungi, and spores have been recovered at 40 km, 61 km
and 77 km above Earth (Imshenetsky et al. 1978; Soen
1965; Wainwright et al. 2010). And once within the strato-
sphere they may be blown into space by powerful solar
winds (Joseph 2009, 2019) where, as shown experimentally,
they can survive (De la Torre Noetzel et al. 2020; De Vera et
al. 2019; Horneck et al. 2002; Nicholson et al. 2000, 2003,
2005; Novikova et al. 2016; Olsson-Francis et al. 2009).
If the dispersal of upper atmospheric organisms into
space occurs continually or only periodically every few
years, decades or centuries, is unknown. However, on
September 24, 1998, a series of coronal mass ejections cre-
ated a shock wave and powerful solar winds that struck
the magnetosphere with such force that oxygen, hydrogen,
helium, water molecules and surface dust gushed from the
upper atmosphere into space (Moore and Horwitz 1998;
Schroder and Smith 2008). For most of every year, the solar
pressure is around two or three nanopascals. However, on
September 24, the pressure increased to ten nanopascals.
Similar events may have occurred repeatedly and more fre-
quently throughout Earth’s history.
For example, data derived from the observation of so-
lar proxies with dierent ages and reconstructions of the
Sun’s radiation and particle environment from 3.5 bya to the
present "indicates a solar wind density up to 1000 times
higher at the beginning of the Sun’s main sequence life-
time" and that gradually dropped to current levels (Lam-
mer et al. 2003). Thus, beginning billions of years ago air-
borne microbes, fungi, lichens, and algae, as well as water
and dust lofted into the upper atmosphere, may have been
swept into space by solar winds and dispersed through-
out the solar system some of which may have landed on
Mars, the Moon, and in the clouds of Venus (Arrhenius
1908; Joseph 2009, 2019).
13 Life in the Clouds of Venus
The clouds of Earth are saturated with water and life (re-
viewed by Joseph 2019). Venus has three cloud layers that
contain high levels of deuterium and trace amounts of wa-
ter (Barstow et al. 2012; Donahue and Hodges 1992), which
could sustain life (Clarke et al. 2013; Cockell 1999; Grin-
spoon and Bullock 2007; Konesky 2009; Seckbach and
Libby 1970; Schulze-Makuch et al. 2004). According to Li-
maye et al. (2018): "The lower cloud layer of Venus" pro-
vides "favorable conditions for microbial life, including
moderate temperatures and pressures (~60
C and 1 atm)."
Konesky (2009) has suggested that organisms similar to
plankton may dwell in the upper atmosphere. Schulze-
Makuch et al. (2004) hypothesized that Venusian clouds,
48 to 65 km above the surface, could harbor aeroplank-
ton which engage in photosynthesis. Sagan and Morowitz
(1967) hypothesized that complex multi-cellular organisms
swim between the thick layers of Venusian clouds where
they metabolize and generate hydrogen as propellants and
a means of oatation. These scenarios are not unreason-
able as trillions of billions of organisms dwell in the clouds
of Earth and are therefore adapted to living in the upper
If life is being deposited in the clouds of Venus via
bolides and solar winds from Earth, it is therefore possible
that some of these organisms that survive the journey may
adapt to life on Venus. However, the possibility of life in
the clouds of Venus is a hypothesis, and not fact.
14 Life Upon and Beneath the
Surface of Venus
The Russian probe Venera 13 landed in the Beta-Phoebe
region of Venus in an area described as a "stony desert"
(Surkov et al. 1983). On Earth, endolithic microorganisms
ourish in hyper-arid stony deserts and under extreme en-
vironmental conditions by colonizing the interior and un-
dersides of rocks (Weirzchos 2012; Pointing and Belnap
2012) within which water molecules may be trapped. Gen-
138 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
erally, these hot desert micro-habitats are dominated by
lichens, fungi, algae, cyanobacteria and heterotrophic bac-
teria (Pointing and Belnap 2012).
The surface temperature of Venus, as determined by
Venera 7, is 739 K
C (Avduevsky et al. 1971). There
are no known terrestrial organisms which can survive these
temperatures, except, perhaps, as spores. However, basalt
is common on Venus, and basalt has high thermal insu-
lating properties (Eppelbaum et al. 2014). Temperatures
beneath these rocks, and up to 10 m below the surface,
would be much cooler than the surface (Joseph 2019) as
documented on Earth (Al-Temeemi and Harris 2001; Smer-
don et al. 2004). In high temperature environments heat
transfer reduction from the surface to 10 m down can be
as much as 57% (Al-Temeemi and Harris 2001); i.e. 43% of
surface temperature. As calculated by Joseph (2019), at a
depth of 1 m temperatures on Venus might average 407.4
whereas at 10 m, the subsurface temperature may average
C which is within the limit for the hardiest hyper-
thermophiles on Earth (Kato and Takai 2000). Some hy-
perthermophiles have been discovered thriving adjacent to
C thermal vents (Stetter 2006). However, there are no
known terrestrial species which can survive direct exposure
to temperatures above 300
C (Kato and Qureshi 1999; Kato
and Takai 2000).
Venus orbits in the habitable zone, and in addition to
comets, asteroids, and meteors, large amounts of frozen wa-
ter was likely delivered to the surface early in this planet’s
history. Possibly, Venus had oceans as recently as 700 mil-
lion years ago (Way et al. 2016) and was likely habitable
billions of years ago (Abe et al. 2011; Cockell 1999). If the
catastrophic change in the biosphere of Venus was sudden
or took place over millions of years is unknown. However,
if Venus was habitable and inhabited billions of years ago,
from what we know of the adaptive nature of microbial and
other forms of life, even a drastically changing environment
does not obliterate all life. Some organisms form spores,
others evolve and adapt. Likewise, if there had been life on
Venus, to survive they would have had to adapt and evolve
to these hyper-extreme conditions.
15 Fungal Life on Venus?
Any organisms that evolved in response to the changing
Venusian biosphere would require water which also might
be available in the clouds and below ground. For example,
just as occurs in the deserts of Kuwait, moisture and water
may be drawn up from the subterranean depths (Al-Sanad
and Ismael 1992). If so, Venusian organisms living below
ground may be continually supplied with water as it rises
to the surface and before it completely evaporates.
It is also well established that numerous species are
able to colonize and ourish within even the most toxic and
seemingly-life-neutralizing environments, including pools
of radioactive waste (Armstrong 2017; Dighton et al. 2008;
Durvasula and Rao 2018; Gerday and Glansdor 2007; Zh-
danova et al. 2004). It’s also been demonstrated that some
species can survive in Venusian analog environments (Seck-
bach et al. 1970). It’s been hypothesized that thermophilic
photothrophs (Arrhenius 1908; Cockell 1999), algae (Seck-
bach and Libby 1970) and acidophilic microbes (Schulze-
Makuch et al. 2004) could ourish within the Venusian bio-
sphere. Moreover, as reported by Joseph (2019) it appears
that fungi are hyper-extremophiles capable of colonizing
even the most extreme alien environments; and there is
evidence of fungi on Venus (and Mars).
Ksanfomality (2013), based on his examination of en-
hanced panoramic images from the 1975 and 1982 Soviet
VENERA-10, VENERA-13 and VENERA-14 images of the Venu-
sian surface, observed what he interpreted to be a fungal-
shaped specimen at a distance of 15 to 20 cm from the buer
of the landing module and which he estimated to be ele-
vated 3 cm above the surface and with a diameter of approx-
imately 8 cm. Ksanfomality (2013) concluded: "The object
exhibits explicit similarity to terrestrial mushrooms and is
supplied with folded caps."
Examination of panoramic color images from the
1982 VENERA-13 mission, also reveals several well-dened
mushroom-shaped specimens with stalks that protrude
approximately 3 cm from the surface, and with caps that
are approximately 5 cm in diameter, and which resem-
ble the classic terrestrial mushroom (Joseph 2019). These
mushroom-shapes are bordered by a crescent of similarly
shaped specimens, all of which are similar to terrestrial
mushrooms. Moreover, several of these specimens resem-
ble what may be fungal organisms growing on Mars (Joseph
et al. 2019, 2020b). Does this prove there is life on Venus?
16 Fungi on Mars?
Several investigators have reported observations of forma-
tions on Mars that resemble white fungi growing beneath
rock shelters in the dried lake bed of Gale Crater (Joseph
2014; Joseph et al. 2019; Rabb 2018; Small 2015). In addition,
23 specimens similar to fungal "puballs" have been pho-
tographed by the rover Opportunity in Meridiani Planum,
increasing in size over a three days period, twelve of which
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |139
Figure 5.
Venus: Specimens resembling fungal-mushrooms. Photographed near the landing struts of the 1982 Soviet probe VENERA-13.
(Reproduced with permisison from Joseph 2019).
Figure 6.
Mars. Photographed in Eagle Crater by the rover Opportunity. Comparing Sol 1145-left vs Sol 1148-right: Growth of twenty-three
Martian specimens over three days, twelve of which emerged from beneath the soil and all of which increased in size. Ground level wind
speeds between 40 to 70 m/h are required to move coarse grained soil on Mars, and no strong winds, dust clouds, dust devils, or other in-
dications of strong winds were observed, photographed, or reported during those three days in this vicinity of Mars. Nor does the Sol 1148
photograph show any evidence that the surface has been disturbed by wind, as there are no parallel lineaments, ripples, waves, crests,
or build-up of soil on one side of the specimens as would be expected of a directional wind. Dierences in photo quality are secondary to
changes in camera-closeup-focus by NASA. (Reproduced with permission from Joseph et al. 2020a).
140 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Figure 7.
Mars. Sol 182. A majority of experts identied these spec-
imens as basidiomycota: fungal "puballs" (Joseph 2016). Note
what appears to be spores littering the surface. (Reproduced with
permission from Joseph et al. 2019).
emerged from beneath the coarse-grained rocky-sandy sur-
face as based on comparisons of Sol 1145 and Sol 1148
(Joseph et al. 2020b) Although on Earth, 20 km/h winds can
displace ne grained sand (Kidron and Zohar 2014) these
specimens are buried in coarse-grained rocky soil, and no
evidence of wind-blown dust in the air, dust devils, dust
storms, or wind-driven soil displacement or buildup was
observed in that vicinity during those three days (Joseph
et al. 2020b). Although it is unknown if these are in fact
living organisms, these observations favor the possibility
that fungi have colonized Mars.
17 Algae and Lichens on Mars?
Oxygen and Photosynthesis
Observations of what may be algae on the surface of Mars
were rst reported by Levin, Straat and Benton in 1978 and
who observed changing patterns on "greenish rock patches"
which were "green relative to the surrounding area." Levin
et al. (1978) speculated that these greenish areas may rep-
resent "algae" or "lichens" growing on Mars.
Figure 8.
Mars. Sol 871. Green sphericals upon Martian sand, soil,
rocks and pinnicle-columnar structures resembling terrestrial
stromatolites and thrombolites and algae growing in shallow water,
but may be frozen. On Earth, the greenish-coloration of sand and
rock is due to green cryptoendolithic cyanobacteria. The darkening
in soil coloration may indicate moisture. Photographed in Gale
Crater. (Reproduced with permission from Joseph et al. 2020a).
Figure 9.
Mars. Sol 853. Thick-layered clumps of algae-like sub-
stance and "tubular" specimens on top of and adjacent to speci-
mens resembling fossilized bacterial mats, and adjacent to "dim-
pled" lichen-like organisms. Photographed in Gale Crater. (Repro-
duced with permission from Joseph et al. 2020a).
Subsequently, a number of investigators have pub-
lished photos taken by the Mars rovers Spirit and Curiosity,
depicting what they believed to be green algae (Joseph 2014;
Joseph et al. 2020a; Rabb 2018; Small 2015). For example,
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |141
Figure 10.
Mars. Sol 305 and Sol 305. Algae-like substances upon fungal-tubular-like specimens, and forming thin layers upon adjacent
rocks. Photographed in Gale Crater. (Reproduced with permission from Joseph et al. 2020a).
Krupa (2017) presented evidence of specimens resembling
green photosynthetic organisms in the Columbia Hills area
of Gusev Crater, adjacent to water pathways that may in-
termittently ll with water. Krupa (2017) noted that "the covered by a very thin layer of green material"
and "green spherules" which resembles algae in the soil.
In addition, a team of 14 established experts conducted an
extensive investigation of the Gale Crater image depository
(Joseph et al. 2020a) and identied specimens resembling
terrestrial algae and lichens. The algae-like specimens ap-
peared as clumps and spherules, and formed cake-like lay-
ers, thin sheet-like layers and thick layered leafy vegetative
masses of material that partially covered Martian rocks,
sand, and fungi-like surface features.
At some point in the evolutionary history of life on
Earth, algae and fungi formed a symbiotic relationship,
thereby fashioning lichens. Lichens consist of at least one
alga that can be a green algae or cyanobacterium (photo-
biont) and at least one fungus (mycobiont). The fungus is
responsible for the lichens’ mushroom shape, bulbous cap,
thallus, and fruiting bodies, whereas the alga photobiont
engages in photosynthesis (Armstrong 2017; Brodo et al.
Lichen-shaped specimens observed in Gale Crater take
a variety of forms, the most common: mushroom-shaped
and nucleated with a visible "dimple" at the center of each
specimen (Joseph et al. 2020a). If these are in fact living
organisms, is unknown. However, hundreds of these lichen-
142 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Figure 11.
(Top Left): Earth. Lichens growing on the west coast Ireland clis of Moher (Photographed by Dr Jessica M Winder, https:
// Reproduced with permission). (Top right and bottom) Gale Crater Sol 298: Specimens resembling dimpled lichens
with what may be hyphae along the surface/subsurface. Note hollow apertures in the upper right corner and lower center of photo, and
which resembles an oxygen-gas vents typically produced by photosynthesizing organisms.
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |143
Figure 12.
(Top) Sol 232: Specimens similar to gas-vent apertures for the release of oxygen secondary to photosynthesis within microbial
mats; photographed in Gale Crater. (Bottom) Cone-like tubes for the venting of oxygen produced by photosynthesizing algae (reproduced
with permission from Freeman SE, Freeman LA, Giorli G, Haas AF (2018) Photosynthesis by marine algae produces sound, contributing to
the daytime soundscape on coral reefs. PLoS ONE 13(10): e0201766).
Figure 13.
Mars. Sol 88 and Sol 37: Specimens resembling the mushroom-shaped lichen Dibaeis baeomyces Photographed in Eage Crater.
(Reproduced with permission from Joseph et al. 2020b).
144 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Figure 14.
Mars. Sol 35 and Sol 85: Specimens resembling the mushroom-shaped lichen Dibaeis baeomyces and examples of colonies of
lichen-shaped organisms. Photographed in Eagle Crater. (Reproduced with permission from Joseph et al. 2020b).
Figure 15.
Mars. Sol 85: Examples of vast colonies of lichen-shaped organisms attached to rocks, and oriented skyward similar to photosyn-
thesizing lichens. Photographed in Eagle Crater. (Reproduced with permission from Joseph et al. 2020b).
like surface features were observed adjacent to specimens
resembling green algae and bubble-like open-cone aper-
tures (Joseph et al. 2020a). It is well established that pho-
tosynthesizing organisms, such as cyanobacteria, respire
oxygen and release gas bubbles via the surrounding ma-
trix and which may become mineralized and fossilized as
open cone apertures (Bengtson et al. 2009; Sallstedt et al.
2018). Therefore, it’s possible that the open-cone apertures
observed in Gale Crater serve to ventilate oxygen respired
during photosynthesis.
Vast colonies consisting of thousands of lichen-
mushroom-shaped specimens that resemble the lichen,
Dibaeis baeomyces, have also been observed in Eagle Crater,
attached by thin stems to the tops of rocks and oriented sky-
ward as is typical of photosynthesizing organisms (Joseph
et al. 2020b). Terrestrial fungi do not engage in photosynthe-
sis; and thus, if these colonies are living photosynthesizing
organisms, then they are most likely lichens.
If the algae and lichen-like Martian structures are in
fact photosynthesizing organisms, this would account for
the distinct seasonal variations in the oxygen content of the
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |145
atmosphere (England and Hrubes 2004) which increases by
approximately 30% in the Summer, and for which no abio-
genic source has been found (Trainer et al. 2019). Earth’s
atmospheric oxygen levels also vary according to the season
and increase during the Spring and Summer due to the bio-
logical activity of photosynthesizing organisms; and these
parallels support the likelihood that oxygen on Mars is also
produced biologically, even more so since Martian atmo-
spheric oxygen is continually replenished despite leaking
into space (Joseph et al. 2020b).
18 Conclusions
In the space of the entire universe the only conclusive evi-
dence of life is found on Earth. Although the ultimate source
of all life is unknown, many investigators believe Earth,
Mars, and Venus may have been seeded with life before and
after becoming established members of this solar system.
In support of that hypothesis is evidence, but no proof, that
life appeared, in parallel on Mars and Earth 4.2 by and that
stromatolites were being constructed on both planets 3.7
bya. Moreover, there is evidence, but no proof, that life on
Mars may have evolved as suggested by the fossil-like spec-
imens resembling metazoans. There is also evidence—but
no conclusive proof– that fungi have colonized Mars and
Venus, and algae and lichens are ourishing on Mars. By
contrast, only the moon appears to be completely uninhab-
itable and uninhabited—other than by dormant spores—at
least on the surface.
It must be stressed that it is unknown if the surface
features observed on Mars and Venus are abiotic, fossils,
or represent living organisms. Conrmation requires direct
examination, extraction and microscopic analysis. Never-
theless, although there is no denitive, conclusive proof
of life except on Earth, the evidence reviewed in this re-
port, supports the hypothesis that the planets of the inner
solar system may have repeatedly exchanged living organ-
isms beginning billions of years ago, and that Earth may
be seeding the solar system with life.
No Competing Interests:
The authors have no competing
or nancial or non-nancial interests and no funding to
report and will not benet nancially from this article.
Author Contributions:
All authors have either contributed
directly to the research reviewed, and/or assisted in the
analysis, writing, editing, and /in searching for and refer-
encing the works cited.
Abe Y, Abe-Ouchi A, Sleep N, Zahnle K. 2011. Habitable Zone Limits
for Dry Planets. Astrobiology. 11(5):443–460.
Acuña MH, Connerney JEP, Ness NF, Lin RP, Mitchell D, Carlson
CW, et al. 1999. Global distribution of crustal magnetization
discovered by the Mars Global Surveyor MAG/ER Experiment.
Science. 284:790–793.
Adams FC. 2010. The birth environment of the Solar System. Annu
Rev Astron Astrophys. 48:47–85.
Adams FC, Myers PC. 2001. Modes of Multiple Star Formation. Astro-
phys J. 553(2):744.
Adams FC, Spergel DN. 2005. Lithopanspermia in star forming
clusters. Astrobiology. 5:497–514.
Adcock CT, Hausrath EM. 2015. Weathering Proles in Phosphorus-
Rich Rocks at Gusev Crater, Mars, Suggest Dissolution of
Phosphate Minerals into Potentially Habitable Near-Neutral
Waters. Astrobiology. 15(12):1060–1075.
Ader M, Sansjofre P, Halverson GP, Busigny V, Trindade RIF, Kun-
zmann M, et al. 2014. Ocean redox structure across the late
Neoproterozoic oxygenation event: a nitrogen isotope perspec-
tive. Earth Planet Sci Lett. 396: 1–13.
Adeli S, Hauber E, Klein-Hans M, Le Deit L, Platz T, Fawdon P, et
al. 2017. Amazonian-aged fluvial system in the southern mid-
latitude regions, Mars. Lunar Planet Sci. XLVIII:2 p.
Adhikari A, Reponen T, Grinshpun SA, Martuzevicius D, LeMasters
G. 2006. Correlation of ambient inhalable bioaerosols with
particulate matter and ozone: A two-year study. Environ Pollut.
Agee CB., Wilson NV, McCubbin FM, Ziegler K, Polyak VJ, Sharp
ZD, et al. 2013. Unique Meteorite from Early Amazonian Mars:
Water-Rich Basaltic Breccia Northwest Africa 7034. Science.
Aharon P. 2005. Redox stratication and anoxia of the early Precam-
brian oceans: Implications for carbon isotope excursions and
oxidation events. Precambrian Res. 137(3–4):207–222.
Alexander M. 1991. Introduction to Soil Microbiology, 2nd Edition.
Malabar, FL: Krieger Publishing Company.
Al-Sanad H, Ismael NF. 1992. Thermal properties of desert sands in
Kuwait. J University of Kuwait. 19:207–215.
Al-Temeemi AA, Harris DJ. 2001. The generation of subsurface
temperature proles for Kuwait. Energy Build. 33:837–841.
Alvarez LW, Alvarez W, Asaro F, Michel HV. 1980. Extraterrito-
rial cause for the Cretaceous -Tertiary extinction. Science.
Andrews-Hanna J, Phillips R, Zuber M. 2007. Meridiani Planum and
the global hydrology of Mars. Nature. 446:163–166.
Angel R, Matthies D, Conrad R. 2011. Activation of Methanogenesis
in Arid Biological Soil Crusts Despite the Presence of Oxygen.
PLoS ONE. 6:e20453.
Anisimov V. 2010. Principles of Genetic Evolution and the ExtraTer-
restrial Origins of life. J Cosmol. 5:843–850.
Arbab AI. 2009. The length of the day: A cosmological perspective.
Prog Phys. 1: 8–11.
Arkani-Hamed J, Boutin D. 2004. Paleomagnetic poles of Mars:
Revisited. J Geophys Res. 109:E03011.
Armstrong RA. 1976. The influence of the frequency of wetting and
drying on the radial growth of three saxicolous lichens in the
eld. New Phytol. 77:719–724.
146 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Armstrong RA 1981. Field experiments on the dispersal, estab-
lishment and colonization of lichens on a slate rock surface.
Environ Exp Bot. 21:116–120.
Armstrong RA. 2017. Adaptation of Lichens to Extreme Conditions.
In: Shukla V, Kumar S, Kumar N. Editors. Plant Adaptation
Strategies in Changing Environment. Springer, Singapore.
Armstrong RA. 2019. The Lichen Symbiosis: Lichen "Extremophiles"
and Survival on Mars. J Astrobiol Space Sci Rev. 1:378–397.
Arnold J, et al. 1995. Harold Clayton Urey, 1893-1981. A Biographical
Memoir by National Academy of Science Press.
Arouri KR, Greenwood PF, Walter M. 2000. Biological anities of
Neoproterozoic acritarchs from Australia: microscopic and
chemical characterisation. Org Geochem. 31:75–89.
Arrhenius S. 1908. Worlds in the Making. Harper & Brothers, New
Arvidson RE, Squyres SW, Anderson RC, Bell III JF, Blaney D, Brück-
ner J, et al. 2006. Overview of the Spirit Mars Exploration Rover
mission to Gusev Crater: Landing site to Backstay Rock in the
Columbia Hills. J Geophys Res. 111:E02S01.
Artemieva N, Ivanov B. 2004. Launch of Martian Meteorites in
Oblique Impacts. Icarus. 171:84–101.
Ash RD, Knott SF, Turner G. 1996. A 4-Gyr shock age for a martian
meteorite and implications for the cratering history of Mars.
Nature. 380:57–59.
Avduevsky VS, Marov MY, Rozhdestvensky MK, Borodin NF,
Kerzhanovich VV. 1971. Soft landing of Venera 7 on the Venus
surface and preliminary results of investigations of the Venus
atmosphere. J Atmos Sci. 28:263–269.
Bange HW, Uher G. 2005. Photochemical production of methane in
natural waters: implications for its present and past oceanic
source. Chemosphere. 58:177–183.
Bange HW, Bartell U, Rapsomanikis S, Andreae MO. 1994. Methane
in the Baltic and North Seas and a reassessment of the marine
emissions of methane. Global Biogeochem Cy. 8:465– 480.
Barnhart CJ, Howard AD, Moore JM. 2009. Long-term precipitation
and late-stage valley network formation: landform simulations
of parana basin, Mars. J Geophys Res: Planets. 114:E01003.
Baross JA, Deming JW. 1983. Growth of black smoke bacteria at
temperature at least 250 Celsius. Nature. 303:423–426.
Barstow JK, Tsang CCC, Wilson CF, Irwin PGJ, Taylor FW, McGouldrick
K, et al. 2012. Models of the global cloud structure on Venus
derived from Venus Express observations. Icarus. 217:542–
Bastviken D, Cole J, Pace ML, Tranvik L. 2004. Methane emissions
from lakes: dependence of lake characteristics, two regional
assessments, and a global estimate. Global Biogeochem Cy.
Bastviken D, Tranvik LJ, Downing JA, Crill PM, EnrichPrast A. 2011.
Freshwater methane emissions oset the continental carbon
sink. Science. 331(6013):50.
Beech M, Comte M, Coulson I. 2018. Lithopanspermia – The Ter-
restrial Input During the Past 550 Million Years. Am J Astron
Astrophys. 7(1):81–90.
Belbruno E, Gott III JR. 2005. Where Did the Moon Come From?
Astron J. 129:1724–1745.
Belbruno E, Moro-Martín A, Malhotra R, Savransky D. 2012. Chaotic
Exchange of Solid Material Between Planetary Systems: Impli-
cations for Lithopanspermia. Astrobiol. 12(8):754–774.
Bengtson S, Belivanova V, Rasmussen B, Whitehouse M. 2009. The
controversial “Cambrian” fossils of the Vindhyan are real but
more than a billion years older. PNAS. 106(19):7729–7734.
Bianciardi G, Rizzo V, Cantasano N. 2014. Opportunity Rover’s
image analysis: Microbialites on Mars? Int J Aeronaut Space
Sci. 15(4):419–433.
Bianciardi G, Rizzo V, Farias ME, Cantasano N. 2015. Microbialites at
Gusev Craters, Mars. Astrobiol Outreach. 3(5): 1000143.
Bibring J-P, Langevin Y, Mustard JF, Poulet F, Arvidson R, Gendrin A,
et al. 2006. Global Mineralogical and Aqueous Mars History
Derived from OMEGA/Mars Express Data. Science. 312:400–
Biemann K, Oro J, Toulmin III P, Orgel LE, Nier AO, Anderson DM,
et al. 1977. The search for organic substances and inorganic
volatile compounds in the surface of Mars. J Geophys Res.
Bogard MJ, del Giorgio PA, Boutet L, Chaves MCG, Prairie YT, Mer-
ante A, et al. 2014. Oxic water column methanogenesis as a
major component of aquatic CH4 fluxes. Nat Commun. 5:5350.
Borel E. 1962. Probability and Life, Dover.
Boyle LA, Redman MP. 2016. Planet Destruction and the Shap-
ing of Planetary Nebulae. Proceedings of the International
Astronomical Union Symposium 323, Planetary Nebulae: Multi-
Wavelength Probes of Stellar and Galactic Evolution.
Bridges N, Núñez JI, Seelos FP, IV, Hook SJ, Baldridge AM, Thom-
son BJ. 2015. Mineralogy of evaporite deposits on Mars: Con-
straints from laboratory, eld, and remote measurements of
analog terrestrial acid saline lakes. American Geophysical
Union, Fall Meeting 2015, abstract id. P31A-2022
Bruhn D, Mikkelsen TN, Øbro J, Willats WGT, Ambus P. 2009. Eects
of temperature, ultraviolet radiation and pectin methyl es-
terase on aerobic methane release from plant material. Plant
Biol. 11:43–48.
Borg L, Drake MJ. 2005. J Geophys Res Planets. 110:E12S03.
Borg LE, Draper DS. 2003. A petrogenetic model for the origin and
compositional variation of the Martian basaltic meteorites.
Meteoritics & Planetary Science. 38:1713–1732.
Boynton WV, Taylor GJ, Evans LG, Reedy RC, Starr R, Janes DM,
et al. 2007. Concentration of H, Si, Cl, K, Fe, and Th in the
low- and mid-latituderegions of Mars. J Geophys Res Planets.
Brocks JJ, Jarrett AJM, Sirantoine E, Hallmann C, Hoshino Y, Liyan-
age T. 2017. The rise of algae in Cryogenian oceans and the
emergence of animals. Nature. 548:578–581.
Brodie EL, DeSantis TZ, Parker JPM, Zubietta IX, Piceno YM, Ander-
sen GL. 2007. Urban aerosols harbor diverse and dynamic
bacterial populations. PNAS. 104:299–304.
Brodo IM, et al. 2001. Lichens of North America. Yale University
Press. pp. 50, 55, 173-4.
Bruhn D, Møller IM, Mikkelsen TN. Ambus P. 2012. Terrestrial plant
methane production and emission. Physiol Plant. 144:201–
Burchell JR, Mann J, Bunch AW. 2004. Survival of bacteria and
spores under extreme shock pressures. Mon Not R Astron
Soc. 352:1273–1278.
Burchell MJ, Mann J, Bunch AW, Brandão PFB. 2001. Survivability of
bacteria in hypervelocity impact. Icarus. 154:545–547.
Buz J, Ehlmann BL, Pan L, Grotzinger JP. 2017. Mineralogy and
stratigraphy of the Gale crater rim, wall, and floor units. J
Geophys Res Planets. 122:1090–1118.
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |147
Cabrol NA, Grin EA. 1999. Distribution, classication, and ages of
Martian impact crater lakes. Icarus. 142(1):160–172.
Cabrol NA, Herkenho K, Knoll AH, Farmer J, Arvidson R, Grin E, et
al. 2014. Sands at Gusev Crater, Mars. J Geophys Res: Planets.
Cai Y, Zheng Y, Bodelier P, Conrad R, Jia Z. 2016. Conventional
methanotrophs are responsible for atmospheric methane
oxidation in paddy soils. Nat Commun. 7:11728.
Caneld DE, Poulton SW. 2011. Ferruginous Conditions: A Domi-
nant Feature of the Ocean through Earth’s History. Elements.
Cano RJ, Borucki MK. 1995. Revival and identication of bacterial
spores in 25– to 40-million-year-old Dominican amber. Science.
Cardona T, Sanchez-Baracaldo P, Rutherford AW, Larkum AWD. 2019.
Early Archean origin of Photosystem II. Geobiology. 17:127–
Carr MH. 1987. Water on Mars. Nature. 326:30–35.
Catling DC., Zahnle KJ. 2020. The Archean atmosphere. Sci Adv.
Catling DC, Claire MW. 2005. How Earth’s atmosphere evolved to
an oxic state: A status report. Earth and Planetary Sci Lett.
Catling DC, Kasting JF. 2017. Atmospheric Evolution on Inhabited
and Lifeless Worlds. Cambridge: Cambridge University Press.
Catling DC. 2001. Biogenic Methane, Hydrogen Escape, and the
Irreversible Oxidation of Early Earth. Science. 293(5531):839–
Chambers JE, Lissauer JJ. 2002. A new dynamical model for the lunar
Late Heavy Bombardment. Lunar Planet Sci. Conf. XXXIII, abstr.
1093, 2 p.
Chen H, Wu Y, Yuan X, Gao Y, Wu N, Zhu D. 2009. Methane emissions
from newly created marshes in the drawdown area of the Three
Gorges Reservoir. J Geophys Res. 114:D18301.
Clarke A, Morris GJ, Fonseca F, Murray BJ, Acton E, Price HC. 2013. A
low temperature limit for life on Earth. PLoS One. 8:e66207.v.
Clayton RN. 1993. Oxygen isotopes in meteorites. Annu Rev Earth
Planet Sci. 21:115–149.
Clayton RN, Mayeda T. 1983. Oxygen isotopes in Eucrites, Shergot-
tites, Nakhlites, Chassignites. Earth Planet Sci Lett. 62:115–
Clayton RN, Mayeda T. 1996. Oxygen isotopes studies on achon-
drites. Geochim Cosmochim Acta. 60:19992017.
Clement SJ, Dulay MT, Gillette JS, Chillier XD, Mahajan TB, Zare
RN. 1998. Evidence for the extraterrestrial origin of polycyclic
aromatic hydrocarbons in the Martian meteorite ALH84001.
Faraday Discuss. 109:417–436.
Cockell CS. 1999. Life on venus. Planet Space Sci. 47:1487–1501.
Cockell C. S, Brack A., Wynn-Williams D. D, Baglioni P, Brandstätter
F, Demets R, Edwards HGM, et al. 2007 Interplanetary Trans-
fer of Photosynthesis: An Experimental Demonstration of A
Selective Dispersal Filter in Planetary Island Biogeography,
Astrobiology, 7,
Cockell C.S, Less P. Lim D.S.S, Osinski G.R, Parnell J, Koeberl C,
Pesonen L, and Salminen, J. 2005. Eects of asteroid and
comet impacts on habitats for lithophytic organisms – a syn-
thesis. Meteoritics Planet. Sci. 40(12), 1901–1914.
Conrad R. 1999. Contribution of hydrogen to methane production
and control of hydrogen concentrations in methanogenic soils
and sediments. FEMS Microbiol Ecol. 28:193–202.
Conrad R. 2009. The global methane cycle: recent advances in
understanding the microbial processes involved. Environ
Microbiol Rep. 1:285–292.
Covey C, Thompson SL, Weissman PR, MacCracken MC. 1994. Cli-
matic eects of atmospheric dust from an asteroid or comet
impact on Earth. Glob Planet Change. 9:263–273.
Cowan MK, Talaro KP. 2008. Microbiology: A Systems. Approach.
McGraw-Hill Science.
Craddock RA, Maxwell TA. 1993. Geomorphic evolution of the Mar-
tian highlands through ancient fluvial processes. J Geophys
Res. 98(E2 25):3453–3468.
Crick F. 1981. Life Itself. Its Origin and Nature. Simon & Schuster,
New York.
Damm E, Kiene R, Schwarz J, Falck E, Dieckmann G. 2008. Methane
cycling in Arctic shelf water and its relationship with phyto-
plankton biomass and DMSP. Mar Chem. 109:45–59.
Damm E, Helmke E, Thoms S, Schauer U, Nöthig E, Bakker K, et
al. 2010. Methane production in aerobic oligotrophic surface
water in the central Arctic Ocean. Biogeosci. 7:1099–1108.
de Angelis MA, Lee C. 1994. Methane production during zooplank-
ton grazing on marine phytoplankton. Limnol Oceanogr.
Dehel T, Lorge F, Dickinson M. 2008. Uplift of microorganisms by
electric elds above thunderstorms. J Electrostat. 66:463–466.
Delaney JS, Dyar MD. 2003. Comparison of synchrotron microXANES
determination of Fe
Fe with Mossbauer values for clean
mineral separates of pyroxene from Martian meteorites (ab-
stract 1979). 34th Lunar and Planetary Science Conference,
Deleon-Rodriguez N, Lathem TL, Rodriguez RL, Barazesh JM, Ander-
son BE, Beyersdorf AJ, et al. 2013. Microbiome of the upper
troposphere: species composition and prevalence, eects of
tropical storms, and atmospheric implications. Proc Natl Acad
Sci USA. 110:2575–2580.
Deppenmeier U, Müller V, Gottschalk G. 1996. Pathways of en-
ergy conservation in methanogenic archaea. Arch Microbiol.
De la Torre Noetzel R, Miller B, Cubero AZ, Sancho, LG, Jordão L,
Rabbow E, et al. 2017. Survival of lichens on the ISS-II: ultra-
structural and morphological changes of Circinaria gyrosa
after space and Mars-like conditions. EANA2017: 17th Euro-
pean Astrobiology Conference, 14-17 August, 2017 in Aarhus,
De la Torre Noetzel R, Ortega García MV, Miller AZ, Bassy O, Granja
C, Cubero B, et al. 2020. Lichen Vitality After a Space Flight on
Board the EXPOSE-R2 Facility Outside the International Space
Station: Results of the Biology and Mars Experiment. Astrobiol.
De Vera J-P, Dulai S, Kereszturi A, Koncz L, Lorek A, Mohlmann D, et
al. 2014. Results on the survival of cryptobiotic cyanobacteria
samples after exposure to Mars-like environmental conditions.
Int J Astrobiol. 13:35–44.
De Vera J-P. 2012. Lichens as survivors in space and on Mars. Fungal
Ecol. 5:472–479.
De Vera J-P, Alawi M, Backhaus T, Baqué M, Billi D, Böttger U, et al.
2019. Limits of Life and the Habitability of Mars: The ESA Space
Experiment BIOMEX on the ISS. Astrobiol. 19(2):145–157.
Diehl RH. 2013. The airspace is habitat. Trends Ecol Evol. 28:377–
148 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Dighton J, Tatyana Tugay T, Zhdanova N. 2008. Fungi and ionizing
radiation from radionuclides, FEMS Microbiol Lett. 281:109–
DiGregorio B. E. 2002. Rock Varnish As A Habitat For Extant Life On
Mars, Instruments, Methods, and Missions for Astrobiology IV;
Dombrowski H. 1963. Bacteria from Paleozoic salt deposits. Annals
of the New York Academy of Sciences, 108, 453.
Donahue T.M., Hodges R.R. Jr. 1992. Past and present water budget
of Venus. J. Geophys. Res. 97, 6083–6091.
Dose K. 1988. The origin of life: More questions than answers.
Interdiscip Sci Rev. 13:348–356.
Dreibus G, Wänke H. 1985. Mars, a volatile-rich planet. Meteoritics.
Duran S, Coulthard TJ, Baynes ERC. 2019. Knickpoints in Martian
channels indicate past ocean levels. Sci Rep. 9:15153.
Durvasula RV, Rao DVS. 2018. Extremophiles: From Biology to
Biotechnology. CRC Press.
Dyar MD, Mackwell SJ, Seaman SJ., Marchand GJ. 2004. Evidence for
a wet, reduced Martian interior (abstract 1348). 35th Lunar and
Planetary Science Conference, CD-ROM.
Dyar MD, Treiman AH, Pieters CM, Hiroi T, Lane MD, O’Connor V.
2005. MIL 03346, the most oxidized Martian meteorite: a rst
look at spectroscopy, petrography, and mineral chemistry. J
Geophys Res. 110:E09005, 2005JE00246.
Earth Impact Database, 2020.
Edgar LA, Fedo CM, Gupta S, Banham SG, Fraeman AA, Grotzinger
JP, et al. 2020. A lacustrine paleoenvironment recorded at Vera
Rubin ridge, Gale crater: Overview of the sedimentology and
stratigraphy observed by the Mars Science Laboratory Curios-
ity rover. J Geophys Res - Planets. 125(3):e2019JE006307.
Ehlmann BL, Mustard JF, Murchie SL, Bibring JP, Meunier A, Fraeman
AA, et al. 2011. Subsurface water and clay mineral formation
during the early history of Mars. Nature. 479:53–60.
Eigenbrode JL. Summons RE, Steele A, Freissinet C, Millan M,
Navarro-González R, et al. 2018. Organic matter preserved
in 3-billion-year-old mudstones at Gale crater, Mars. Science.
Eldredge N, Gould SJ. 1972. Punctuated equilibria: an alternative to
phyletic gradualism. In: Schopf TJM. Editor. Models in Paleobi-
ology. San Francisco: Freeman Cooper. p. 82–115.
Elewa AMT, Joseph R. 2009. The History, Origins, and Causes of
Mass Extinctions. J Cosmol. 2:201–220.
El-Mashad M. 2013. Kinetics of methane production from the codi-
gestion of switchgrass and Spirulina platensis algae. Biore-
sour Technol. 132:305–312.
England C, Hrubes JD. 2004. Molecular oxygen mixing ratio and
its seasonal variability in the Martian atmosphere, paper
presented at Workshop on Oxygen in the Terrestrial Planets.
NASA Technical Report.
Eppelbaum L, Kutasov I, Pilchin A. 2014. Thermal Properties of
Rocks and Density of Fluids. In: Applied Geothermics. Lecture
Notes in Earth System Sciences. Springer, Berlin, Heidelberg.
Epstein S, Mayeda T. 1953. Variation of O18 content of waters from
natural sources. Geochim Cosmochim Acta. 4(5):213–224.
Erin DH. 2015. Early metazoan life: divergence, environment and
ecology. Philos Trans R Soc B. 370(1684):20150036.
Fairén AG. 2017. Icy Mars lakes warmed by methane. Nat Geosci.
Fairén AG, Stokes CR, Davies NS, Schulze-Makuch D, Rodríguez JAP,
Davila AF, et al. 2014. A cold hydrological system in Gale crater,
Mars. Planet Space Sci. 93–94:101–118.
Fajardo-Cavazos P, Link L, Melosh HJ, Nicholson WL. 2005. Bacillus
subtilisspores on articial meteorites survivehypervelocity at-
mospheric entry: implications for lithopan-spermia. Astrobiol.
Fajardo-Cavazosa P, Schuerger AC, Nicholson WL. 2007. Testing
interplanetary transfer of bacteria between Earth and Mars as
a result of natural impact phenomena and human spaceflight
activities. Acta Astronaut. 60:534–540.
Farmer CB, Davies DW, Holland AL, Laporte DD, Doms PE. 1977.
Mars—Water vapor observations from the Viking orbiters. J
Geophys Res. 82:4225–4248.
Farquhar J, Thiemens MH. 2000. Oxygen cycle of the Martian
atmosphere-regolith system: Delta 17O of secondary phases in
Nakhla and Lafayette. J Geophys Res. 105:11991–11998.
Farquhar J, Bao H, Thiemens M. 2000. Atmospheric influence of
Earth’s earliest sulfur cycle. Science. 289:756–758.
Fassett CI, Head JW, 2008. Valley network-fed, open-basin lakes on
Mars: Distribution and implications for Noachian surface and
subsurface hydrology. Icarus. 198(1):37–56.
Fawdon P, Gupta S, Davis JM, Warner NH, Adler JB, Balme MR, et al.
2018. The Hypanis Valles delta: The last highstand of a sea on
early Mars? Earth Planet Sci Lett. 500:225–241.
Fazli P, Man CH, Shah UKM, Idis A. 2013. Characteristics of
Methanogens and Methanotrophs in Rice Fields: A Review.
AsPac J Mol Biol Biotechnol. 21(1):3–17.
Fedorova AA, Montmessin F, Korablev O, Luginin M, Trokhimovskiy
A, Belyaev DA, et al. 2020. Stormy water on Mars: The distri-
bution and saturation of atmospheric water during the dusty
season. Science. 367(6475):297–300.
Fielding MJ, Observations on the length of dormancy in certain plant
infecting nematodes. Proc. Helminth. Soc. Wash. 1951(18):110–
Formisano V, Atreya S, Encrenaz T, Ignatiev N, Giuranna M. 2004.
Detection of methane in the atmosphere of Mars. Science.
Fragkou V, Parker QA, Zijlstra AA, Crause L, Barker H. 2019. A high-
mass planetary nebula in a Galactic open cluster. Nat Astron.
Franz HB, McAdam AC, Ming DW, Freissinet C, Mahay PR, Eldridge
DL, et al. 2017. Large sulfur isotope fractionations in martian
sediments at Gale crater. Nat Geosci. 10:658–662.
Franz, HB, Mahay PR, Webster CR, et al. 2020. Indigenous and
exogenous organics and surface–atmosphere cycling inferred
from carbon and oxygen isotopes at Gale crater. Nat Astron.
Franchi IA, Wright IP, Sexton AS, Pillinger CT. 1999. The oxygen
isotopic composition of Earth and Mars. Meteorit Planet Sci.
Fraser CM, et al. 1995. The Minimal Gene Complement of My-
coplasma genitalium. Science. 270:397–404.
Fritz J, Artemieva NA, Greshake A. 2005. Ejection of Martian Mete-
orites. Meteoritics & Planetary Science. 40(9–10):1393–1411.
Fröhlich-Nowoisky J, Pickersgill DA, Després VR, Pöschl U. 2009.
High diversity of fungi in air particulate matter. Proc Natl Acad
Sci USA. 106:12814–12819.
Frydenvang J, Gasda PJ, Hurowitz JA, Grotzinger JP, Wiens RC, New-
som HE, et al. 2017. Diagenetic silica enrichment and late-
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |149
stage groundwater activity in Gale crater, Mars. Geophys Res
Lett. 44:4716–4724.
Garwood RJ. 2012. Patterns In Palaeontology: The rst 3 billion
years of evolution. Palaeontol Online. 2(11):1–14.
Gellert R, Rieder R, Brückner J, Clark BC, Dreibus G, Klingelhöfer G,
et al. 2006. Alpha Particle X-Ray Spectrometer (APXS): Results
fromGusev crater and calibration report. J Geophys Res Planets.
Geminale A, Formisano V, Sindoni G. 2011. Mapping methane in
Martian atmosphere with PFS-MEX data. Planet Space Sci.
Gerday C., Glansdor N. 2007. Physiology and Biochemistry of
Extremophiles, ASM press.
Gibson C., Schild R, Wickramasinghe NC. 2011. The origin of life
from primordial planets. Int J Astrobiol. 10:83–98.
Gillena E, Rimmera PB, Catling DC. 2020. Statistical analysis of
Curiosity data shows no evidence for a strong seasonal cycle of
martian methane. Icarus. 336:113407.
Gladman B, Burns JA, Duncan M, Lee PC, Levison HF. 1996. The
exchange of impact ejecta between terrestrial planets. Science.
Gladman B, Dones K, Levison HF, Burns JA. 2005. Impact seeding
and reseeding in the inner solar system. Astrobiol. 5(4):483–
Gomes R, Levison HF, Tsiganis K, Morbidelli A. 2005. Origin of the
cataclysmic Late Heavy Bombardment period of the terrestrial
planets. Nature. 435:466–469.
Goudge TA, Fassett CI, Head JW, Mustard JF, Aureli KL. 2016. In-
sights into surface runo on early Mars from paleolake basin
morphology and stratigraphy. Geology. 44(6):419–422.
Graham LE, Graham JM, Wilcox LW, Cook ME. 2016. Algae. LJLM
Press, Madison.
Grant JA, Irwin RP, Grotzinger JP, Milliken RE, Tornabene LL, McEwen
AS, et al. 2008. HiRISE imaging of impact megabreccia and
sub-meter aqueous strata in Holden Crater, Mars. Geology.
Grin DW. 2004. Terrestrial microorganisms at an altitude of
20,000 m in Earth’s atmosphere. Aerobiologia. 20:135–140.
Grin DW, Kubilay N, Kocak M, Gray MA, Borden TC, Shinn EA. 2007.
Airborne desert dust and aeromicrobiology over the Turkish
Mediterranean coastline. Atmos Environ. 41:4050–4062.
Grin EA, Cabrol NA. 1997. Limnologic Analysis of Gusev Crater Paleo-
lake, Mars. Icarus. 130(2):461–474.
Grinspoon DH. 1993. Probing Venus’s cloud structure with Galileo
NIMS. Planet Space Sci. 41:515–542.
Grinspoon DH. 1997. Venus Revealed: A New Look Below the Clouds
of Our Mysterious Twin Planet. Addison Wesley, Reading, MA
Grinspoon DH, Bullock MA. 2007. Astrobiology and Venus explo-
ration. In: Esposito LW, Stafan ER, Cravens TE. Editors. Explor-
ing Venus as a Terrestrial Planet. American Geophysical Union,
p. 191–206.
Grotzinger JP, Bell III JF, Calvin W, Clark BC, Fike DA, Golombek M, et
al. 2005. Stratigraphy and sedimentology of a dry to wet eolian
depositional system, Burns formation, Meridiani Planum, Mars.
Earth Planet Sci Lett. 240:11–72.
Grotzinger JP, Sumner DY, Kah LC, Stack K, Gupta S, Edgar L, et al.
2014. A habitable fluvio-lacustrine environment at Yellowknife
Bay, Gale Crater, Mars. Science. 343(6169):1242777.
Grotzinger JP, Crisp JA, Vasavada AR, MSL Science Team. 2015.
Curiosity’s mission of exploration at Gale crater. Elements.
Grotzinger JP, Gupta S, Malin MC, Rubin DM, Schieber J, Siebach
K., et al. 2015. Deposition, exhumation, and paleoclimate
of an ancient lake deposit, Gale Crater, Mars. Science.
Guo Q, Strauss H, Kaufman AJ, Schröder S, Gutzmer J, Wing BA, et
al. 2009. Reconstructing Earth’s surface oxidation across the
Archean–Proterozoic transition. Geology. 37(5):399–402.
Halevy I, Head III JW. 2014. Episodic warming of early Mars by punc-
tuated volcanism. Nat Geosci. 7(12):865–868.
Hara T, Takagi K, Kajiura D. 2010. Transfer of Life-Bearing Meteorites
from Earth to Other Planets. J Cosmol. 7:1731–1742.
Harri A-M., Genzer M, Kemppinen O, Gomez-Elvira J, Haberle R,
Polkko J, et al. 2014. Mars Science Laboratory relative humidity
observations: Initial results. J Geophys Res - Planets. 119:2132–
Haskin LA, Wang A, Jolli BL, McSween HY, Clark BC, Des Marais DJ,
et al. 2005. Water alteration of rocks and soils on Mars at the
Spirit rover site in Gusev crater. Nature. 436:66–69.
Hausrath EM, Ming DW, Rampe EB. 2018. Reactive transport and
mass balance modeling of the Stimson sedimentary formation
and altered fracture zones constrain diagenetic conditions at
Gale crater, Mars. Earth Planet Sci Lett. 491:1–10.
Havig JR, Hamilton TL, Bachan A., Kump LR. 2017. Sulfur and carbon
isotopic evidence for metabolic pathway evolution and a four-
stepped Earth system progression across the Archean and
Paleoproterozoic. Earth Sci Rev. 174:1–21.
Hazael R, Fitzmaurice BC, Fogilia F, Appleby-Thomas GJ, McMilan
PF. 2017. Bacterial survival following shock compression in the
GigaPascal range. Icarus. 293:1–7.
Hazell PJ, Beveridge C, Groves K, Appleby-Thomas G. 2010. The
shock compression of microorganism-loaded broths and
emulsions: experiments and simulations. Int J Impact Eng.
Herkenho KE, Squyres SW, Arvidson R, Bass DS, Bell III JF, Ber-
telsen P, et al. 2004. Evidence from Opportunity’s Microscopic
Imager for Water on Meridiani Planum, Science. 306:1727–
Hogancamp JV, Sutter B, Morris RV, Archer PD, Ming DW, Rampe EB,
et al. 2018. Chlorate/Fe-bearing phase mixtures as a possible
source of oxygen and chlorine detected by the sample analy-
sis at Mars instrument in Gale Crater, Mars. J Geophys Res –
Planets. 123:2920–2938.
Holland HD. 2006. The oxygenation of the atmosphere and oceans.
Phil Trans Roy Soc B-Biol. Sci. 361:903–915.
Holton JR, Haynes PH, McIntyre ME, Douglass AR, Rood RB, Pster
L. 1995. Stratosphere-troposphere exchange. Rev Geophys.
Hoover RB. 1997. Meteorites, Microfossils, and Exobiology in In-
struments, Methods, and Missions for the Investigation of
Extraterrestrial Microorganisms. In: Hoover RB. Editor. Proc
SPIE. 3111:115–136.
Hoover RB, Rozanov AY, Zhmur SI, Gorlenko VM. 1998. Further
evidence of micro-fossils in carbonaceous chondrites, in:
Hoover RB. Editor. Instruments, Methods and Missions for
Astrobiology. Proc SPIE. 3441:203–215.
Hoover RB, Jerman G, Rozanov AY, Sipiera PB. 2004. Indigenous
microfossils in carbonaceous meteorites. In: Hoover RB, Levin
150 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Gilbert V, Rozanov AY. Editors. Instruments, Methods, and
Missions for Astrobiology. Proc SPIE. 5555:1–17.
Horgan J. 1991. In the beginning. Scientic American. 264:116–125.
Horneck G. 1993. Responses of Bacillus subtilis spores to space
environment: Results from experiments in space. Orig Life Evol
Biosph. 23:37–52.
Horneck G, Becker H, Reitz G. 1994. Long-term survival of bacterial
spores in space. Adv Space Res. 14:41–45.
Horneck G, Eschweiler U, Reitz G, Wehner J, Willimek R, Strauch G.
1995. Biological responses to space: results of the experiment
Exobiological Unit of ERA on EURECA I. Adv Space Res. 16:105–
Horneck G, Stoler D, Ott S, Hornemann U, Cockell CS, Moeller R, et
al. 2008. Microbial rock inhabitants survive hypervelocity im-
pacts on Mars-like host planets: rst phase of lithopanspermia
experimentally tested. Astrobiol. 8:17–44.
Horneck G., Stöler D, Eschweiler U, Hornemann U. 2001a. Bacterial
spores survive simulated meteorite impact. Icarus. 149(1):285–
Horneck G, Rettberg P, Reitz G, Wehner J, Eschweiler U, Strauch K,
Panitz C, Starke V, Baumstark-Khan, C. 2001b. Orig Life Evol
Biosph. 31:527–547.
Horneck G, Mileikowsky C, Melosh HJ, Wilson JW, Cucinotta FA,
Gladman B. 2002. Viable Transfer of Microorganisms in the
solar system and beyond. In: Horneck G, Baumstark-Khan C.
Astrobiology, Springer.
Holmes AJ, Roslev P, McDonald IR, Iversen N, Henriksen K, Murrell
JC. 1999. Characterization of Methanotrophic Bacterial Popu-
lations in Soils Showing Atmospheric Methane Uptake. Appl
Environ Microbiol. 65(8):3312–3318.
Homann M. 2019. Earliest life on Earth: Evidence from the Barberton
Greenstone Belt, South Africa. Earth Sci Rev. 196:102888.
Homann M, Sansjofre P, Van Zuilen M, Heubeck C, Gong J,
Killingsworth B, et al. 2018. Microbial life and biogeochem-
ical cycling on land 3,220 million 1052 years ago. Nat Geosci.
Hoyle F. 1982. Evolution from Space (The Omni Lecture). Enslow
Publishers, USA
Hoyle F, Wickramasinghe NC. 2000. Astronomical Origins of Life.
Steps Towards Panspermia. Klewer Academic Publishers.
Humayun M, Nemchin A, Zanda B, Hewins RH, Grange M, Kennedy
A. et al. 2013. Origin and age of the earliest Martian crust from
meteorite NWA 7533. Nature. 503:513–516.
Hurowitz JA, McLennan SM, Tosca NJ, Ming DW, Schröder C. 2006. In
situ and experimental evidence for acidic weathering of rocks
and soils on Mars. J Geophys Res. 111:E02S19.
Hynek BM, Beach M, Hoke MRT, 2010. Updated global map of mar-
tian valley networks and implications for climate and hydro-
logic processes. J Geophys Res - Planets. 115:E09008.
Imshenetsky AA, Lysenko SV, Kazakov GA. 1978. Upper boundary of
the biosphere. Appl Environ Microbiol. 35:1–5.
Ingersoll AP. 1969. The runaway greenhouse: A history of water on
Venus. J Atmos Sci. 26:1191–1198.
Irwin III RP, Howard AD, Craddock RA, Moore JM. 2005. An intense
terminal epoch of widespread fluvial activity on early Mars: 2.
Increased runo and paleolake development. J Geophys Res -
Planets. 110(E12):E12S15.
Jakosky BM, Brain D, Chan M, Curry S, Deighan J, Grebowsky J, et
al. 2018. Loss of the Martian atmosphere to space: Present-
day loss rates determined from MAVEN observations and
integrated loss through time. Icarus. 315:146–157.
Jagoutz E, Sorowka A, Vogel JD, Wenke H. 1994. ALH 84001: Alien or
progenitor of the SNC family? Meteoritics. 29:478–479.
Johansen A, Lambrechts M. 2017. Forming Planets via Pebble Accre-
tion. Annu Rev Earth Planet Sci. 45(1):359–387.
Johnston DT, Poulton SW, Goldberg T, Sergeev VN, Podkovyrov V,
Vorob’eva NG, et al. 2012. Late Ediacaran redox stability and
metazoan evolution. Earth Planet Sci Lett. 335:25–35.
Jones D, Pejcha O, Romano P, Corradi LM. 2019. On the triple-star
origin of the planetary nebula Sh 2-71. Mon Not R Astron Soc.
Jose MV. Morgado ER, Govezensky T, Aguilar I. 2010. How Universal
is the Universal Genetic Code? A Question of ExtraTerrestrial
Origins. J Cosmol. 5:854–874.
Joseph R. 2000. Astrobiology, the Origins of Life, and the Death of
Darwinism. University Press, California.
Joseph R. 2009. Life on Earth Came from Other Planets. J Cosmol.
Joseph R. 2010a. Climate Change: The First Four Billion Years. The
Biological Cosmology of Global Warming and Global Freezing. J
Cosmol. 8:2000–2020.
Joseph R. 2010b. Extinction, Metamorphosis, Evolutionary Apop-
tosis, and Genetically Programmed Species Mass Death. In:
Wickramasinghe C. Editor. The Biological Big Bang. Science
Publishers, Cambridge, MA (USA).
Joseph R. 2014. Life on Mars: Lichens, Fungi, Algae. J Cosmol.
Joseph R. 2016. A high probability of life on Mars, the consensus of
70 experts. Cosmology 25, 1–25.
Joseph R. 2019. Life on Venus and the Interplanetary Transfer of
Biota From Earth. J Cosmol. 27 (1):191.
Joseph RG, Dass RS, Rizzo V, Cantasano N, Bianciardi G. 2019. Ev-
idence of Life on Mars? Journal of Astrobiology and Space
Science Reviews. 1:40–81. Reprinted in: Beech M, Gordon R,
Seckbach J. Editors. Astrobiology Perspectives on Life of the
Universe, Wiley-Scrivener, Beverly, Massachusetts (USA).
Joseph R, Graham L, Budel B, Jung P, Kidron GJ, Latif K, et al. 2020a.
Mars: Algae, Lichens, Fossils, Minerals, Microbial Mats and
Stromatolites, in Gale Crater. Journal of Astrobiology and
Space Science Reviews. 3(1):40–111. Reprinted in: Beech M,
Gordon R, Seckbach J. Editors. Astrobiology Perspectives on
Life of the Universe. Wiley-Scrivener, Beverly, Massachusetts
Joseph R, Armstrong R, Kidron G, Gibson CH, Schild R. 2020b. Life
on Mars? Colonies of Mushroom-shaped specimens in Eagle
Crater. J Astrobiol Space Sci Res. 5:88–126.
Joseph R., Planchon O, Duxbury N.S, Latif K, Kidron G. J, Consorit L,
Armstrong R. A, Gibson C. G, Schild, R. 2020c. Oceans, Lakes
and Stromatolites on Mars. Advances in Astronomy, In press.
Joseph R, Armstrong R. 2020. Metazoan Fossils on Mars? Submitted
(under peer review).
Joseph R, Schild R. 2010a. Biological Cosmology and the Origins of
Life in the Universe. J Cosmol. 10:40–75.
Joseph R, Schild R. 2010b. Origins, Evolution, and Distribution of
Life in the Cosmos: Panspermia, Genetics, Microbes, and Viral
Visitors From the Stars. J Cosmol. 7:1616–1670.
Joseph R, Wickramasinghe C. 2010. Diseases from Space. In: Wick-
ramasinghe C. Editor. The Biological Big Bang. Science Publish-
ers, Cambridge, MA (USA).
R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets |151
Joseph R, Wickramasinghe C. 2011. Genetics Indicates Extraterres-
trial Origins for Life: The First Gene. J Cosmol. 16(21):6832–
Kane SR, Gelino DM. 2012. The Habitable Zone and extreme plane-
tary orbits. Astrobiol. 12(10):940–945.
Kankaala P, Kaki T, Ojala A. 2003. Quality of detritus impacts on
spatial variation of methane emissions from littoral sediment
of a boreal lake. Archiv für Hydrobiologie. 157:47–66.
Karlsson HR, Clayton RN, Gibson EK Jr., Mayeda TK. 1992. Water in
SNC meteorites—Evidence for a martian hydrosphere. Science.
Kasting JF. 1998. Runaway and moist greenhouse atmospheres and
the evolution of Earth and Venus. Icarus. 74:472–494.
Kasting JF, Whitmire DP, Reynolds RT. 1993. Habitable zones around
main sequence stars. Icarus. 101(1):108–128.
Kasting JF, Kopparapu R, Ramirez RM, Harman CE. 2014. Remote
life-detection criteria, habitable zone boundaries, and the
frequency of Earth-like planets around M and late K stars.
PNAS. 111(35):12641–12646.
Kato C, Qureshi MH. 1999. Pressure Response in Deep-sea
Piezophilic Bacteria. J Molec Microbiol Biotechnol. 1(1):87–
Kato C, Takai K. 2000. Microbial diversity of deep-sea
extremophiles-Piezophiles, Hyperthermophiles, and sub-
surface microorganisms. Biol Sci Space. 14(4):341–352.
Kaźmierczak J. 2016. Ancient Martian biomorphs from the rim of
Endeavour Crater: similarities with fossil terrestrial microalgae.
In: Rozhnov SV. Editor. Paleontology, Stratigraphy, Astrobiol-
ogy, in commemoration of 80th anniversary of A. Yu. Rozanov.
Borissiak Paleontological Institute RAS, Moscow, p. 229–242.
Kaźmierczak J. 2020. Conceivable Microalgae-like Ancient Martian
Fossils and Terran Analogues: MER Opportunity Heritage. J
Astrobiol Outreach. 8(1):167.
Keeling RF, Shertz SR. 1992. Seasonal and interannual variations
in atmospheric oxygen and implications for the global carbon
cycle. Nature. 356:723–727.
Keppler F, Vigano I, McLeod A, Ott U, Früchtl M, Röckmann T. 2012.
Ultraviolet-radiation-induced methane emissions from mete-
orites and the Martian atmosphere. Nature. 486(7401):93–96.
Kidron GJ, Zohar M. 2014. Wind speed determines the transition
from biocrust-stabilized to active dunes. Aeolian Res. 15:261–
Kieer HH, Jakosky BM, Snyder CW. 1992. The planet Mars: From
antiquity to present, in Mars. In: Kieer HH et al. Editors. Univ.
of Ariz. Press, Tucson, Ariz. (USA), p. 1–33.
Kim H, Takayama K, Hirose N., Onitsuka G, Yoshida T, Yanagi T. 2019.
Biological modulation in the seasonal variation of dissolved
oxygen concentration in the upper Japan Sea. J Oceanogr.
Kite ES, Sneed J, Mayer DP, Wilson SA. 2017. Persistent or re-
peated surface habitability on Mars during the late Hesperian-
Amazonian. Geophys Res Lett. 44(9):3991–3999.
Kite ES, Williams JP, Lucas A, Aharonson O. 2014. Low palaeopres-
sure of the martian atmosphere estimated from the size distri-
bution of ancient craters. Nat Geosci. 7(5):335–339.
Kite ES, Mayer DP, Wilson SA, Davis JM, Lucas AS, Stucky de Quay G.
2019. Persistence of intense, climate-driven runo late in Mars
history. Sci Adv. 5:eaav7710.
Kontorovich AE et al. 2008. A section of Vendian in the east of
West Siberian Plate (based on data from the Borehole Vostok
3), Russian Geology and Geophysics 49(12):932-939 DOI:
Konesky G. 2009. Can Venus shed microorganisms? Proc. SPIE
7441, Instruments and Methods for Astrobiology and Planetary
Missions XII, 74410H (3 September 2009).
Korablev O, Vandaele AC, Montmessin F, Fedorova AA, Trokhi-
movskiy A, Forget F, et al. 2019. No Detection of Methane
on Mars from Early ExoMars Trace Gas Orbiter Observations.
Nature. 568:517–520.
Kring DA, Cohen BA. 2002. Cataclysmic bombardment throughout
the inner Solar System 3.9-4.0 Ga. J Geophys Res – Planets.
107(E2, 5009):4–10.
Kritzberg ES, Cole JJ, Pace ML, Graneli W, Blade DL. 2004. Au-
tochthonous versus allochthonous carbon sources of bacteria:
results from whole-lake C-13 addition experiments. Limnol
Oceanogr. 49:588–596.
Kritzberg ES, Cole JJ, Pace MM, Graneli W. 2005. Does au-
tochthonous primary production drive variability in bacte-
rial metabolism and growth eciency in lakes dominated by
terrestrial C inputs? Aquat Microb Ecol. 38:103–111.
Krasnopolsky VA, Maillard JP, Owen TC. 2004. Detection of
methane in the Martian atmosphere: Evidence for life? Icarus.
Krupa TA. 2017. Flowing water with a photosynthetic life form in
Gusav Crater on Mars. Lunar Planet Soc, XLVIII.
Klingelhöfer G, Morris RV, De Souza Jr. PA, Rodionov D, Schröder C.
2006. Two Earth years of Mössbauer studies of the surface of
Mars with MIMOS II. Hyperne Interact. 170:169–177.
Ksanfomality LW. 2013. An Object of Assumed Venusian Flora. Dokl
Phys. 58(5):204–206.
Kump LR. 2008. The rise of atmospheric oxygen. Nature. 451:277–
Kuppers BO. 1990. Information and the origin of life. MIT Press,
Cambridge, MA (USA).
Krupa TA. 2017. Flowing water with a photosynthetic life form in
Gusav Crater on Mars. Lunar Planet Soc, XLVIII.
Lammer H, Lichtenegger HIM, Kolba C., Ribas I, Guinan EF, Abart
R, et al. 2003. Loss of water from Mars:: Implications for the
oxidation of the soil. Icarus. 165(1):9–2.
Lenhart K, Bunge M, Ratering S, Neu TR, Schüttmann I, Greule M,
et al. 2012. Evidence for methane production by saprotrophic
fungi. Nat Commun. 3:1046.
Lenhart K, Klintzsch T, Langer G, Nehrke G, Bunge M, Schnell S, et
al. 2016. Evidence for methane production by the marine algae
Emiliania huxleyi. Biogeosci. 13:3163–3174.
Lanza NL, Wiens RC, Arvidson RE, Clark BC, Fischer WW, Gellert
R, et al. 2016. Oxidation of manganese in an ancient aquifer,
Kimberley formation, Gale crater, Mars. Geophys Res Lett.
Lanza NL. 2015. Oxidation Of Manganese At Kimberley, Gale Crater:
More Free Oxygen. In: Lanza NL et al. Editors. Mars’ Past? Lunar
And Planetary Science And Exploration, Chemistry And Mate-
rials (General). 46th Lunar and Planetary Science Conference,
March 16, 2015 - March 20, 2015, The Woodlands, TX, USA.
Laskar J, Joutel F, Robutel P. 1993. Stabilization of the Earth’s obliq-
uity by the Moon. Nature. 361:615–617.
Lefèvre F, Forget F. 2009. Observed variations of methane on Mars
unexplained by known atmospheric chemistry and physics.
Nature. 460(7256):720–723.
152 |R. G. Joseph et al., Seeding the Solar System with Life: Mars, Venus, Earth, Moon, Protoplanets
Lenton TM, Boyle RA, Poulton SW, Shields-Zhou G, Buttereld NJ.
2014. Co-evolution of eukaryotes and ocean oxygenation in the
Neoproterozoic era. Nat Geosci. 7:257–265.
Leshin LA, Epstein S, Stolper EM. 1996. Geochim Cosmochim Acta.
Levin G, Straat PA. 1976. Viking Labeled Release Biology Experi-
ment: Interim Results. Science. 194:1322–1329.
Levin GV, Straat PA. 1977. Life on Mars? The Viking labeled release
experiment. Biosyst. 9(2–3):165–174.
Levin GV, Straat PA. 2016. The Case for Extant Life on Mars and its
Possible Detection by the Viking Labeled Release Experiment.
Astrobiol. 16(10):798–810.
Levin GV, Straat PA, Benton WD. 1978. Color and Feature Changes at
Mars Viking Lander Site. J Theor Biol. 75:381–390.
Levison HF, Dones L, Chapman CR, Stern SA, Duncan MJ, Zahnle K.
2001. Could the Lunar “Late Heavy Bombardment” Have Been
Triggered by the Formation of Uranus and Neptune? Icarus.
Levison HF, Thommes EW, Duncan MJ, Dones LA. 2002. A Fairy Tale
about the Formation of Uranus and Neptune and the Lunar
Late Heavy Bombardment. In: Caro L, Moon LJ, Backman D,
Praton E. Editors. Debris Disks and the Formation of Planets: A
Symposium in Memory of Fred Gillett, Tucson: Arizona, 11-13
April 2002, p. 152–167.
Limaye SJ, Mogul R, Smith DJ, Ansari AH, Słowik GP, Vaishampayan
P. 2018. Venus’ Spectral Signatures and the Potential for Life in
the Clouds. Astrobiol. 18(9):1181–1198.
Lin CS, Chou TL, Wu JT. 2013. Biodiversity of soil algae in the farm-
lands of mid-Taiwan. Bot Stud. 54(41).
Lin CS, Wu JT. 2014. Environmental factors aecting the diversity
and abundance of soil photomicrobes in arid lands of subtropi-
cal Taiwan. Geomicrobiol J. 31(4):350–359.
Lissauer J.L, 1993. Planet formation, Annual review of astronomy
and astrophysics. Vol. 31 (A94-12726 02-90), p. 129–174.
Lyons TW, Reinhard CT, Planavsky NJ. 2014. The rise of oxygen in
Earth’s early ocean and atmosphere. Nature. 506:307–315.
Lugmair G.W. Shukolyukov A. 2001. Early Solar System events and
timescales. Meteorit Planet Sci. 36:1017–1026.
Mahaney WC, Dohm J. 2010. Life on Mars? Microbes in Mars-like
Antarctic Environments, J Cosmol. 5:951–958.
Malin MC, Edgett KS. 2000. Sedimentary Rocks of Early Mars. Sci-
ence. 290:1927–1937.
Malin MC, Edgett KS. 2003. Evidence for persistent flow and aque-
ous sedimentation on early Mars. Science. 302(5652):1931–
Man-Yin T, Yao W, Tse K. 2020. Oxidized silver cups can skew oxy-
gen isotope results of small samples. Exp Results. 1(e12):1–6.
Manning CE, Mojzsis SJ, Harrison TM. 2006. Geology. age and
origini of supracrustral rocks at Akilia, West Greenland. Am J
Sci. 306:303–366.
Marquis RE, Shin SY. 1994. Mineralization and responses of bacte-
rial spores to heat and oxidative agents. FEMS Microbiol Rev.
Martel J, Young D, Peng H-H, Wu C-W, Young J D. 2012. Biomimetic
Properties of Minerals and the Search for Life in the Martian
Meteorite ALH84001-042711-10540. Annu Rev Earth Planet Sci.
Martínez G, Fischer ME, Rennó NO, Sebastián E, Kemppinen O,
Bridges N, et al. 2015. Likely frost events at Gale crater: Analy-
sis from MSL/REMS measurements. Icarus. 280:93–102.
Martínez GM, Renno NO. 2013. Water and Brines on Mars: Current
Evidence and Implications for MSL. Space Sci Rev. 75(1–4):29–
Martínez GM, Newman CN, De Vicente-Retortillo A, Fischer E, Renno
NO, Richardson MI, et al. 2017. The Modern Near-surface Mar-
tian Climate: A Review from In-situ Meteorological data from
Viking to Curiosity. Space Sci Rev. 212:295–338.
Martín-Torres FJ, Zorzano MP, Valentín-Serrano P, Harri AM, Genzer
M, Kemppinen O, et al. 2015. Transient liquid water and water
activity at Gale crater on Mars. Nature. 8:357–361.
Masson P, Carr MH, Costard F, Greeley R, Hauber E, Jauman R. 2001.
Geomorphologic Evidence for Liquid Water. Space Sci Rev.
Mastrapa RME, Glanzberg H, Head, JN, Melosh HJ, Nicholson WL.
2001. Survival of bacteria exposed to extreme acceleration:
implications for panspermia. Earth Planet Sci Lett. 189(30):1–
Masursky H, Batson RM, Carr MH, McCauley JF, Milton DJ,
Soderblom LA, et al. 1972. Mariner 9 Mars television exper-
iment. Bull Am Astron Soc. 4:356.
Matsubara Y, Howard A.D, Gochenour JP. 2013. Hydrology of
early mars: valley network incision. J Geophys Res - Planets.
Mautner MN. 1997. Biological potential of extraterrestrial materi-
als. 1. Nutrients in carbonaceous meteorites and eects on
biological growth. Planet Space Sci. 45:653–664.
Mautner MN. 2002. Planetary bioresources and astroecology. 1.
Planetary microcosm bioassays of Martian and carbonaceous
chondrite materials: Nutrients, electrolyte solutions, and algal
and plant responses. Icarus. 158:72–86.
McLean RJC, Welsh AK, Casasanto VA. 2006. Microbial survival in
space shuttle crash. Icarus. 181:323–325.
McLean RJC, McLean MAC. 2010. Microbial survival mechanisms
and the interplanetary transfer of life through space. J Cosmol.
McLennan SM, Anderson RB, Bell III JF, Bridges JC, Calef III F, Camp-
bell JL, et al. 2014. Elemental Geochemistry of Sedimentary
Rocks at Yellowknife Bay, 558 Gale Crater, Mars. Science.
McEwen AS, Dundas CM, Mattson SS, Toigo AD, Ojha L, Wray JJ, et
al. 2013. Recurring slope lineae in equatorial regions of Mars.
Nature Geosci. 7:53–58.
McKay CP. 1996. Oxygen and the Rapid Evolution of Life on Mars. In:
Chela-Flores J, Raulin F. Editors. Chemical Evolution: Physics of
the Origin and Evolution of Life. Springer, Dordrecht.
McKay CP. 2010. An Origin of Life on Mars. Cold Spring Harb Per-
spect Biol. 2(4):a003509.
McKay DS, Gibson EK, Thomas-Keprta KL, Vali H, Romanek CS,
Clemett SJ, et al. 1996. Search for past life