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There is a long history of the microbe-collection experiments at high altitude. Microbes have been collected using balloons, aircraft and meteorological rockets. Spore forming fungi and Bacilli, and Micrococci have been isolated in these experiments. It is not clear how high do microbes go up. If the microbes might have been present even at higher altitudes, the fact would endorse the possibility of interplanetary migration of life. TANPOPO, dandelion, is the name of a grass whose seeds with floss are spread by the wind. We propose the analyses of interplanetary migration of microbes, organic compounds and meteoroids on Japan Experimental Module (JEM) of the International Space Station (ISS). Ultra low-density aerogel will be used to capture micrometeoroid and debris. Particles captured by aerogel will be used for several analyses after the initial inspection of the gel and tracks. Careful analysis of the tracks in the aerogel will provide the size and velocity dependence of debris flux. The particles will be analyzed for mineralogical, organic and microbiological characteristics. Aerogels are ready for production in Japan. Aerogels and trays are space proven. All the analytical techniques are ready. The TANPOPO mission was accepted as a candidate experiments on Exposed Facility of ISS-JEM.
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TANPOPO: Astrobiology Exposure and Micrometeoroid Capture Experiments
, Hajime YANO
2, 3, 4)
Shin-ichi YOKOBORI
, Makoto TABATA5
, 7)
, Hideyuki KAWAI
, Masamichi YAMASHITA
, Hiroshi NARAOKA
, Hajime MITA
1) Department of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1Horinouchi, Hachioji-shi, Tokyo 192-0392, Japan
2) Department of Planetary Science, ISAS/JAXA, 3-1-1 Yoshinodai, Sagamihara-shi,Kanagawa 229-8510, Japan
3) Program Office & Research and Development Office, JAXA Space Exploration Center,JSPEC/JAXA, 3-1-1 Yoshinodai, Sagamihara-shi, Kanagawa 229-8510, Japan
4) Department of Space and Astronautical Science, Graduate University for AdvancedStudies, 3-1-1 Yoshinodai, Sagamihara-shi, Kanagawa 229-8510, Japan
5) Department of Space Information and Energy, I SAS/JAXA, 3-1-1 Yoshinodai,Sagamihara-shi, Kanagawa 229-8510, Japan
6) Department of Chemistry and Biotechnology, Yokohama National University,Hodogaya-ku, Yokohama 240-8501, Japan
7) Graduate School of Science and Technology, Chiba University, 1-33 Yayoi-cho,Inage-ku, Chiba-shi, Chiba 263-8522, Japan
8) Department of Physics, Chiba University, 1- 33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba263-8522, Japan
9) ISAS/JAXA, 3-1-1 Yoshinodai, Sagamihara-shi, Kanagawa 229-8510, Japan
10) Department of Earth Sciences, Okayama University, Tsushima- Naka 3-1-1, Okayama,700-8530 Japan
11) Department Enviromenta Life Scinece, Fukuoka Institute of Technology, 3-30-1Wahakutou, Higasihiku, Hukuoka, 811-0295 Japan
There is a long history of the microbe-collection experiments at high altitude. Microbes have been collected using
balloons, aircraft and meteorological rockets. Spore forming fungi and Bacilli, and Micrococci have been isolated in these
experiments. It is not clear how high do microbes go up. If the microbes might have been present even at higher altitudes,
the fact would endorse the possibility of interplanetary migration of life.
TANPOPO, dandelion, is the name of a grass whose seeds with floss are spread by the wind. We propose the analyses of
interplanetary migration of microbes, organic compounds and meteoroids on Japan Experimental Module (JEM) of the
International Space Station (ISS). Ultra low-density aerogel will be used to capture micrometeoroid and debris. Particles
captured by aerogel will be used for several analyses after the initial inspection of the gel and tracks. Careful analysis of the
tracks in the aerogel will provide the size and velocity dependence of debris flux. The particles will be analyzed for
mineralogical, organic and microbiological characteristics. Aerogels are ready for production in Japan. Aerogels and trays
are space proven. All the analytical techniques are ready. The TANPOPO mission was accepted as a candidate experiments
on Exposed Facility of ISS-JEM.
Key Words: Astrobiology, micrometeoroid capture experiments, interplanetary migration of microbes, ISS-JEM, organic compounds
1. Introduction
There has been a hypothesis on the origin of life called
“panspermia” ([1], [2]). According to this hypothesis, life has
migrated between the Earth and other extra terrestrial objects.
The finding of life-like structure in a meteorite originated
from Mars recalled the possibility. There is also a possibility
that the life on the Earth may have ejected from the Earth by
volcanic eruption or by meteorite impact. We have been
analyzing the presence of microbes at high atmosphere by
aircraft and balloons. Microbes have been captured by these
experiments. The microbe-sampling experiments could be
extended to lower Earth orbit by using ISS. It is also
important to test if the microbe ejected from the Earth may
survive during the voyage to other planets. We also propose
the survival test of microbes on ISS.
Another important subject on the origin of life is related to
the pre-biotic production of organic compounds. The
extra-terrestrial and outer-solar area can be the place for the
pre-biotic organic compound synthesis. To test the possible
pre-biotic organic compound synthesis, simulation has been
conducted. However, more direct evidence could be obtained
by the intact meteoroid capture experiment. It is also
important to know what kind and degree of denaturation
could occur on the complex organic compounds which are
expected to be formed in extra-terrestrial area. To test the
kind and degree of denaturation process, simulated complex
organic compounds are proposed to be exposed on ISS.
The development of extra-low density aerogel is an
important subject for the micrometeoroid capture
experiments. Silica aerogel is made of SiO
and is transparent
solid. Aerogel have been used for the collection of artificial
debris and interplanetary dust. For the proposed ISS project,
we developed extra-low density aerogel and will test the
aerogel on ISS. The developed extra-low density aerogel will
provide proof of the applicability of the aerogel, which can
be used for the next generation sample return mission in the
Solar system.
Our debris capture mission will collect many types of
debris. They will include debris of artificial objects, exhaust
form ISS, micrometeoroid, and micro particles from the
Earth. Much important information will be obtained from the
analysis of the many types of particles collected on ISS.
2. Collection of Microbes in Space
There is a long history of the microbe-collection
experiments at high altitude. Microbes have been collected at
the altitude from 3 to 58 km, using balloons, aircraft and
meteorological rockets from 1936 to 1976 ([28]-[30]). Spore
forming fungi and Bacilli, and Micrococci have been isolated
in these experiments. However, the experiments have been
done before the development of modern molecular biology
and only the taxonomic affiliation has been analyzed on the
isolates. It is not clear how high do microbes go up. If the
microbes might have been present even at higher altitudes,
the fact would endorse the possibility of interplanetary
migration of life.
Previously, we have conducted microbe-sampling
experiments using aircraft. Microbes were isolated from the
particles collected at the altitudes form 0.8 to 12 km. The
genes of the isolated microbes were analyzed. The analysis
revealed that the isolates belong to spore formers
(Streptomices, Bacillus and Paenibacillus) and Deinococcus
related species. Previously Deinococcus radiodurans has
been classified to be Micrococcus. Accordingly, the
Micrococcus strains isolated at high altitude in previous
experiments may be or may include Deinococcus species.
Deinococcus radiodurans is the species that is known to
be most radio-resistant. Then, we have analyzed the UV
resistance of high altitude isolates. Two of the high
atmosphere isolates showed the UV resistance similar to or
higher than Deinococcus radiodurans. The flux of UV light
at high atmosphere is expected to be much higher than
ground surface. Accordingly, it is reasonable that the
microbes isolated at high atmosphere shows high UV
We have also conducted microbe-sampling experiments
using balloons. The sampling device consists of vacuum
pump and filtration system. The air was incorporated by a
vacuum pump and passed through an ultra-membrane filter.
The air intake was controlled by a valve placed in front of the
filter. About 10 m
(corresponding mass at SPT) air was
sampled at the altitude from 20 to 35 km. Four strains were
isolated from the balloon sampling experiments. Analysis of
the isolates is now on progress.
To extend the sampling altitude we propose the microbe
collection experiment on ISS-JEM. The microbe/particle
collection on ISS needs totally different strategy. We are
going to use ultra low-density aerogel for the sampling
experiments. If there are microbes at ISS altitude, they have
to have the earth orbit velocity. The expected mutual velocity
of the microbes against aerogel is up to 16 km/s depending
on the direction of the microbe relative to the ISS movement.
We have tested the possibility of microbe sampling using a
two-stage light-gas gun.
Another point which has to be considered is the survival of
microbes in the environment where the UV dose is high. The
single cell of microbe is not expected to survive under the
high UV dose. However, if the microbes are present in the
mineral particles, there will be much higher possibility of
survival. We have tested the possible survival of microbes
using the montmorillonite particles containing microbial cells.
The particles were accelerated to 4 km/s by a two-stage
light-gas gun. Microbes were pre-stained with fluorescent
pigment. The particles were targeted to aerogel. The aerogel
was inspected by fluorescence microscopes. The fluorescent
particles were detected in the aerogel. Now, we are trying to
assure that the fluorescent particles are really microbial cells
we have used.
3. Survival of Microbes in Space
To evaluate the possibility of migration between planets
including the Earth and Mars, the survivability of microbes
in space must be tested. As a part of this project, we plan to
test the survivability of microbes in space by direct exposure
The exposure experiment of microbes in space has been
performed (e.g. [31], [32]). Most of experiments were not
direct exposure experiments: windows that shield EUV were
used to cover microbes. Therefore, these experiments might
underestimate the effects of light on the microbial cells.
In such exposure experiments, Bacillus sp., which is
spore-forming bacteria, was used ([31]). Spore is a stage of
cells that is most tolerant to extreme environments. On the
other hand, bacterial species such as Deinococcus
radiodurans have been known to show extreme tolerance to
the UV-light and gamma radiation. Recently, we have
isolated several bacterial species from the high-altitudes (ca.
10 km) (Itahashi, Yang, Yokobori, & Yamagishi, manuscript
in preparation). They showed higher tolerance to the
UV-light than D. radiodurans. Such extreme UV-tolerant
bacteria might be able to survive at higher altitudes.
The microbes that are directly exposed to the space have
lower possibility of survival. However, some microbial cells
may survive, if the cells were shielded by other microbe cells
and/or clay minerals. UV light will not reach several tens to
hundreds of micrometers in depth (cf. [31]).
In our project, various microbial cells including D.
radiodurans and our newly isolated UV-resistant bacteria
will be used for exposure experiments. Cells will be
freeze-dried with/without clay mineral. In the space
environment, the cells are expected to be freeze-dried
(dehydrated, in another term). The cells will be dehydrated in
a hole of a metal plate. The dehydrated cells will be tightly
fixed to the metal plate without any covers that might shield.
The cell will be exposed to the space at least for 1 year. The
cells in the metal holder of the exposure apparatus of
TANPOPO will be retrieved and will be returned for the
The returned samples will be used for various tests for
checking the survival of microbes. Most direct test is the
cultivation of exposed microbes. The possible contamination
of microbial cells during the operation will be tested by PCR
analysis of genes. The method will tell whether the recovered
bacterial colonies are those of original species or not.
4. Collection of Organic Compounds in Space
A wide variety of organic compounds have been found in
such extraterrestrial bodies as meteorites (carbonaceous
chondrites) and comets. Chyba and Sagan estimated that
more than 100 kt of carbon had been delivered to the Earth
on extraterrestrial bodies [17]. It could be an important
source of carbon for the first biosphere on the Earth.
Bioorganic compounds like amino acids and nucleic acid
bases were detected in the hot water extracts from
carbonaceous chondrites. Cronin and Pizzarello reported that
Murchison meteorite contains more L-isomers of some
amino acids than D-isomers [18], and such enantiomeric
excesses could be a seed for homochirality of bioorganic
compounds in our world. Nakamura-Messenger et al. have
found proto-cell-like organic globules in Tagish Lake
Meteorite [19]. Complex organic compounds were also
found in comets by the direct analysis of the dust from
Comet Halley with mass spectrometer on spacecraft [20].
Preliminary organic-compound analysis of cometary dusts
returned by Stardust mission also showed the presence of
complex organic compounds in Comet Wild 2 [21].
There is the possibility that organic compounds in
interplanetary dusts (IDPs) have contributed more for the
generation of terrestrial life than those in meteorites and
comets because of the following reasons: (i) much more
organic compounds could be delivered by IDPs than by
comets and meteorites, (ii) organic compounds in IDPs could
be delivered to the Earth less destructive while those in
comets and meteorites could be destroyed on their impacts.
Though many IDPs have been collected in deep-sea and in
Antarctica, there is high probability of terrestrial
contamination. We propose the collection of IDPs for the
analysis of organic compounds as a part of TANPOPO
4.1 Simulation Experiment of High-Velocity Impact
For the analysis of organic compounds on IDPs, the major
problem is how to collect IDPs with ultra high velocity. We
are going to use aerogel with ultra low density. We have
performed simulation experiments by using the two-stage
light-gas gun at ISAS / JAXA. The following samples were
used for the analysis. (i) Porous silica gel (PSG) used as a
blank, (ii) powder of R-2-aminobutyric acid (AABA) with
sizes from 220 to 350 μm, (iii) AABA adsorbed to PSG.
AABA was chosen due to its low possibility of accidental
detection from contamination, since it is non-proteinous
amino acid and scarcely found in living organisms. Each
sample was placed in a “sabot” made of polycarbonate, and
targeted to aerogel at 4 km/s. The aerogel with a track made
by the impact was digested with 5 M HF - 0.1 M HCl mixed
acid at 383 K for 24 h, hydrolyzed with 6 M HCl at 383 K
for 24 h, desalted with AG-50X-X8 cation exchange resin,
and then analyzed with an amino acid analyzer (Shimadzu
LC-10A). AABA detected in (iii) was much more than that
in blank (i). AABA was not detected, however, in (ii). The
results suggest that amino acid itself is not stable against
impact even if aerogel is used, but amino acid associated
with inorganic matrix is more stable.
4.2 Alteration of Organic Compounds in Space
Where did organic compounds in meteorites, comets and
IDPs come from? Greenberg [22] proposed the following
scenario. The Solar System is formed in a dense cloud
(molecular cloud). Since temperature in dense clouds is as
low as 10-20 K, most molecules are frozen onto surface of
interstellar dusts (ISDs). Such “ice mantle” of ISDs contains
such molecules as water, carbon monoxide, methanol and
ammonia. When frozen mixtures simulating the ice mantle
were irradiated with high-energy particles or ultraviolet light,
amino acid precursors (molecules which give amino acids
after hydrolysis) were formed ([23]-[25]). Organic molecules
containing amino acid precursors formed in dense clouds
would be altered by cosmic rays and ultraviolet light before
they were incorporated in parent bodies of meteorites and/or
comets. They were again altered in the Solar System small
bodies. IDPs seem to have been made from the small bodies,
and organic compounds in IDPs were irradiated with cosmic
rays and strong solar ultraviolet light before fallen into the
It is of interest to examine how organic compounds alter in
actual space environments. There have been a great number
of experiments on radiochemical and photochemical
alteration of organic compounds. In these experiments, either
a light source or a radiation source was used on ground. In
addition, extreme ultraviolet light (EUV) has never been used
on ground, since there are no appropriate windows to pass
EUV. ESA has conducted several exposure experiments in
space, e.g., LDEF and BIOPAN, but target samples were still
covered with windows and space EUV did not reach to the
samples [26].
We are planning to expose organic compounds on
ISS-JEM Exposure Facility. The exposure unit is set next to
the aerogel unit. Here, samples such as amino acids and
“simulated interstellar organic compounds” will be adsorbed
onto a metal substrate and there will be no covering. The
simulated interstellar organic compounds will be made from
possible interstellar molecules like carbon monoxide,
ammonia and water by proton irradiation [27]. The proposed
setup could make it possible to irradiate samples with cosmic
radiation and ultraviolet light including EUV simultaneously,
and could give information how cometary / meteoritic
organic compounds alter in IDPs. These samples will be
made of isotopic atoms to avoid the faulty identification of
the compounds for the exposure experiments as organic
compounds of ISD.
5. Micrometeoroid Intact Capture
Meteoroid observation and collection have been conducted
to study their parent bodies in planetary science. Several
types of analyses have been conducted on meteoroids.
Zodiacal dust cloud could be observed from the Earth surface.
Cosmic spherules have been found in Antarctic ice core.
Stratospheric interstellar dust particles have been captured by
aircraft. Meteoroid impacts have been noted on the surface of
LEO spacecrafts. Analysis of these particles has provided
information on their origin and the parental bodies. However,
intact and contamination-less collection of micrometeoroids
is desired.
Measurement and modeling of debris flux have another
importance: It is important to know the debris flux to
evaluate the risk of LEO spacecraft. Debris with relatively
lager sizes has been monitored by ground observation. Debris
with smaller sizes have been detected and analyzed on the
surface of retrieved parts of spacecraft. Retrieved spacecraft
have been analyzed in the following missions: LDEF (84-90,
NASA/ESA), EuReCa (92-93, ESA), HST (89-93,
NASA/ESA), SFU (95-96, JAXA) ([3]-[11]). Passive
particle collection apparatus have been also deployed and
analyzed: Euro-Mir (96-97, ESA), ODC (97-98, NASA),
MPAC-SEED (02-05, JAXA). However, the number of
debris is increasing and continuous monitoring is needed.
The key technology for TANPOPO is the particle intact
captures using aerogel. The aerogel is amorphous SiO2 with
low bulk density (below 0.03 g/cm3), is optically transparent
and thus most suitable for hypervelocity particle capture
experiments. The aerogel is also an excellent thermal
insulator: thermal conductivity is about 0.017 W/mK.
Accordingly, aerogel is suitable for space utilization. The
aerogel tiles have been used for EuReCa, Euro-Mir, ODC,
MPAC-SEED, Stardust, etc, and thus can be said space
For example, the aerogel has been used in Stardust project
([12], [13]). In the Stardust project, cometary and interstellar
dust were captured intact and the samples were returned for
analysis. The spacecraft was launched on 1999. Interstellar
dust was collected on 2002. The cometary particles were
collected from the Comet Wild-2 coma during the fly-by on
2004. The samples were returned on January 2006. The
particles with hypervelocity, 6.1 km/s, were successfully
captured. The initial analysis of the overwhelming success
has been reported.
Japanese aerogel has been also used in ISS-MPAC-SEED.
In the mission, sampling devices were launched on 2001
placed on the Russian Service Module of ISS in LEO of
about 400 km. Sampling devices were retrieved sequentially
on 2002, 2004 and 2005. However, the sampling device was
exposed only on one face of ISS. It is known that the type of
the particles collected depend on the face of the exposure
relative to the direction of ISS movement. East face, which is
the direction of ISS orbital, has the highest possibility of
capturing debris of man-made origin. West face and space
face are most suitable for collecting interplanetary dust.
One of the TANPOPO teams has already tested the
possibility of collecting hypervelocity meteoroid by aerogel.
CM2 Murchison powder was accelerated to be 6.2 km/s by a
two-stage light-gas gun and targeted on aerogel [14]. The
track of the particle in the aerogel was inspected and the
particle was found at the tip of the track. The thin section of
the particle was inspected by an electron microscope. The
peripheral area of the particle consisted of amorphous
nodules that are typical to melting phenomena. However,
crystal structures were retained at the central part
representing the original mineral structures of the Murchison
powder. The result shows that it is possible to capture
hypervelocity meteoroid partially intact.
The aerogel tiles are going to be attached on several faces
of integrated experimental rack that will be placed on
ISS-JEM Exposure Facility. No signal-connection is
required during the whole exposure period. After more than
1-year exposure in LEO, the trays will be retrieved manually
by EVA crew and sealed in the ISS pressurized module for
the Soyuz Earth return.
Interface has been designed based on the discussion with
EVA director.
6. Aerogel for Microparticle Collection
Silica aerogel is an amorphous solid with a void volume up
to 99.5%. Aerogel has been widely used as optical radiators
for PID (particle identification) devices in high energy and
nuclear physics experiments, since it is optically transparent
and has very low refractive index among solids. One of the
advantages of our aerogel is that it is possible to make
aerogel hydrophobic, which makes the handling easier. We
have been developing aerogel in cooperation with the High
Energy Accelerator Research Organization (KEK) and
Matsushita Electric Works, Ltd. in Japan [15]. At present, we
are able to produce aerogel at a wide range of densities i. e.
0.01-1.2 g/cm3 [16]. The aerogel that were made with our
production method were actually used in MPAC-SEED
which was a Japanese contributory experiment exposed at
ISS Russian Service Module. Because of the extremely low
bulk densities, transparencies and thermal insulation
properties, aerogel is the most suitable medium for the
nondestructive capture of hypervelocity particles in space.
In TANPOPO mission, it is important to reduce the
thermal metamorphism of micro particles captured in Earth
orbit upon impact. The key to the successful scientific
analysis is the performance of aerogel with extremely low
densities. For this purpose, we developed an aerogel with the
lowest density (0.01 g/cm
or less) in our current production
method. Until now, typical density of aerogel employed in
space is 0.03 g/cm
. The density is suitable for easy mounting
and handling. However, for micro particles with relative
incident velocities over 6 km/s, the density would not be low
enough for nondestructive collection. We developed the way
of installing the ultra low-density aerogel in a module. The
layer of the extremely low-density aerogel for micro particle
capture was cast on a base layer of higher density. We have
already succeeded in developing a monolithic aerogel block
consisting of multiple layers with different densities.
Our primary purpose is to obtain information not only on
meteoroids and space debris but also on migration of organic
compounds and microbes through space. In addition, we aim
to demonstrate the ability of the aerogel-based micro particle
collecting apparatus in the space environment. Aerogel units
with different density structures will be tested on ISS
Japanese Experiment Module, which will extend a reach of
the micro particle capture operation. Extra low-density
aerogel used in TANPOPO will provide an innovative
technique for planetary expedition in the future.
3. Conclusions
The group member of Chiba University in TANPOPO
mission has the ability to produce ultra low-density aerogel.
The aerogel made in the method has been used on ISS
Russian Service Module for particle sampling experiment.
The basic design of aerogel tray has been also tested in the
JAXA mission MPAC-SEED. The TANPOPO mission
needs neither signals nor mechanism during the whole
exposure period. The TANPOPO mission is selected as one
of the second stage experiment of ISS-JEM EF. After more
than 1-year exposure in LEO, the trays will be retrieved
manually by EVA crew and sealed in ISS.
The TANPOPO mission teams already have long
experiences in bacterial analysis, organic compound analysis
and micrometeoroid analysis. Accordingly, all the analytical
techniques are ready.
Interface between TANPOPO apparatus and ISS-JEM EF
have been basically designed based on the coordination of EF
designers and EVA directors. This coordination must be
completed within the development time frame of ISS-JEM
EF coordination experiment project. However, all of above
requirements are feasible.
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... Cosmic dust samples returned to laboratories on the ground for analysis using state-of-the-art techniques are of importance in astrobiology, planetary science, and space debris research. In 2007, the Tanpopo project was proposed as Japan's astrobiological space mission comprising composite experiments to be performed aboard the International Space Station (ISS) in LEOs [9,10]. One of the experiments involves exposure of silica aerogel to space for the collection of cosmic dust, including natural terrestrial dust grains, interplanetary dust particles, possible interstellar dust particles, and artificial space debris. ...
... Previously we succeeded in reliably producing hydrophobic and monolithic aerogel tiles with ρ = 0.01 g cm −3 [4]. We planned to use this 0.01 g cm −3 aerogel at least as the upper-most layer of the aerogel capture medium [9,10,11]. The dimensions for one Tanpopo capture panel module are 100 × 100 × 20 mm 3 . ...
... Micro-Fourier transform infrared and micro- Raman spectroscopy methods were established for analysis of the organic matter in meteoritic dust grains extracted from the impact tracks in the aerogel [26]. HPLC can also be used to analyze captured volatile dust grains without the need to extract them from the aerogel [9,10]. To develop a method for detecting microbes contained in the captured dust, particles made of smectite clay were also used as a model for terrestrial dust. ...
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The fabrication of an ultralow-density hydrophobic silica aerogel for the intact capture cosmic dust during the Tanpopo mission is described. The Tanpopo experiment performed on the International Space Station orbiting the Earth includes the collection of terrestrial and interplanetary dust samples on a silica aerogel capture medium exposed to space for later ground-based biological and chemical analyses. The key to the mission’s success is the development of high-performance capture media, and the major challenge is to satisfy the mechanical requirements as a spacecraft payload while maximizing the performance for intact capture. To this end, an ultralow-density (0.01 g cm−3) soft aerogel was employed in combination with a relatively robust 0.03 g cm−3 aerogel. A procedure was also established for the mass production of double-layer aerogel tiles formed with a 0.01 g cm−3 surface layer and a 0.03 g cm−3 open-topped, box-shaped base layer, and 60 aerogel tiles were manufactured. The fabricated aerogel tiles have been demonstrated to be suitable as flight hardware with respect to both scientific and safety requirements. Graphical Abstract
... Amino acids in the aerogel with a track made by the impact were analyzed after digestion with 5 M HF-0.1 M HCl and acid-hydrolysis. These simulations showed that AABA could be recovered in the aerogel tracks (Yamagishi et al., 2011). Alteration of complex organics in meteorites during capture of Murchison meteorite powder with aerogel was also studied. ...
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The Tanpopo experiment was the first Japanese astrobiology mission on board the Japanese Experiment Module Exposed Facility on the International Space Station (ISS). The experiments were designed to address two important astrobiological topics, panspermia and the chemical evolution process toward the generation of life. These experiments also tested low-density aerogel and monitored the microdebris environment around low Earth orbit. The following six subthemes were identified to address these goals: (1) Capture of microbes in space: Estimation of the upper limit of microbe density in low Earth orbit; (2) Exposure of microbes in space: Estimation of the survival time course of microbes in the space environment; (3) Capture of cosmic dust on the ISS and analysis of organics: Detection of the possible presence of organic compounds in cosmic dust; (4) Alteration of organic compounds in space environments: Evaluation of decomposition time courses of organic compounds in space; (5) Space verification of the Tanpopo hyper-low-density aerogel: Durability and particle-capturing capability of aerogel; (6) Monitoring of the number of space debris: Time-dependent change in space debris environment. Subthemes 1 and 2 address the panspermia hypothesis, whereas 3 and 4 address the chemical evolution. The last two subthemes contribute to space technology development. Some of the results have been published previously or are included in this issue. This article summarizes the current status of the Tanpopo experiments.
... The scientific information about this strain has been accumulated, especially about high tolerances to several extraterrestrial environments and their related chemicals. This strain has been used in the 'Tanpopo misson' (Yamagishi et al., 2007Yamagishi et al., , 2009Kawaguchi et al., 2016).Kimura et al. (2015ab)reported that this strain is suitable to introduce into Mars' environment as the first organism for the preparation of manned space activities. So, we are thinking that the scientific name of Nostoc sp. ...
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The exact life cycle of cells in a terrestrial cyanobacterium, Nostoc sp. HK-01 which has several different types of cells, was confirmed by microscopic observation. All of types of cells were individually observed during 30-days of liquid incubation. The germination process from akinetes was recognized twice during the incubation period. The contribution of extracellular polysaccharides, EPS, for tolerance to heat in the dried colonies of Nostoc sp. HK-01 was also investigated. The survival rate of dried colonies of Nostoc sp. HK-01 with and without EPS were examined after exposure to temperatures at 100℃. The contribution to heat tolerance of EPS was tested and verified by the cell staining method. The survival rate of both groups of cells, with EPS and without EPS, of Nostoc sp. HK-01 was not remarkably different and they both lived under these conditions for 12 hours. These results indicate that the contribution of EPS to their heat tolerance would be very low. The amounts of sucrose and trehalose in the dry colonies were investigated to determine the contribution to heat tolerance in akinete as a compatible solute. The amount of trehalose was lower than that of sucrose in the dry colonies. It can be assumed that trehalose did not contribute to their heat tolerance.
... To investigate the panspermia hypothesis and possible space origin of organic compounds, we conducted exposure and capture experiments at the Exposed Facility (EF) of the Japanese Experiment Module ( JEM) KIBO of the International Space Station (ISS), which is orbiting at an altitude of about 400 km (Fig. 1aand Yamagishi et al., 2009). The mission is called Tanpopo, which means dandelion in Japanese . ...
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Unlabelled: The Tanpopo mission will address fundamental questions on the origin of terrestrial life. The main goal is to test the panspermia hypothesis. Panspermia is a long-standing hypothesis suggesting the interplanetary transport of microbes. Another goal is to test the possible origin of organic compounds carried from space by micrometeorites before the terrestrial origin of life. To investigate the panspermia hypothesis and the possible space origin of organic compounds, we performed space experiments at the Exposed Facility (EF) of the Japanese Experiment Module (JEM) of the International Space Station (ISS). The mission was named Tanpopo, which in Japanese means dandelion. We capture any orbiting microparticles, such as micrometeorites, space debris, and terrestrial particles carrying microbes as bioaerosols, by using blocks of silica aerogel. We also test the survival of microbial species and organic compounds in the space environment for up to 3 years. The goal of this review is to introduce an overview of the Tanpopo mission with particular emphasis on the investigation of the interplanetary transfer of microbes. The Exposed Experiment Handrail Attachment Mechanism with aluminum Capture Panels (CPs) and Exposure Panels (EPs) was exposed on the EF-JEM on May 26, 2015. The first CPs and EPs will be returned to the ground in mid-2016. Possible escape of terrestrial microbes from Earth to space will be evaluated by investigating the upper limit of terrestrial microbes by the capture experiment. Possible mechanisms for transfer of microbes over the stratosphere and an investigation of the effect of the microbial cell-aggregate size on survivability in space will also be discussed. Key words: Panspermia-Astrobiology-Low-Earth orbit. Astrobiology 16, 363-376.
... To investigate the panspermia hypothesis and possible space origin of organic compounds, we conducted exposure and capture experiments at the Exposed Facility (EF) of the Japanese Experiment Module ( JEM) KIBO of the International Space Station (ISS), which is orbiting at an altitude of about 400 km (Fig. 1aand Yamagishi et al., 2009). The mission is called Tanpopo, which means dandelion in Japanese . ...
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The mechanical thermometer using a bimetallic strip coil was developed for the Tanpopo mission. The Tanpopo mission is a multi-year passive exposure experiment for astrobiology exposure and micrometeoroid capture onboard the Exposed Experiment Handrail Attachment Mechanism (ExHAM) at the Japanese Experiment Module ‘Kibo’ (JEM) Exposed Facility (EF) on the International Space Station (ISS). The Tanpopo mission apparatuses were launched by the SpaceX-6 Dragon CRS-6 on April 14 2015, from the Cape Canaveral Air Force Station in the U.S.A. Since its microbial exposure experiment requires recording the maximum temperature that the Tanpopo exposure panel experiences, we have developed a mechanical thermometer with no electric power supplied from the ExHAM. At a given time and orbital position of the ISS, the thermometer indicator was video-imaged by the extravehicular video camera attached to the Kibo-EF and controlled from the ground. With these images analyzed, we were able to derive the maximum temperature of the Tanpopo exposure panels on the space pointing face of the ExHAM as 23.9±5 °C. Now this passive and mechanical thermometer is available to other space missions with no electric supplies required and thus highly expands the possibility of new extravehicular experiments and explorations for both human and robotic missions.
... There is an existing plan to compare the impact frequency predicted from the debris environment models and the craters formed on the panels exposed in space, to assess the validity of the distribution model. This is known as the " Tanpopo " mission [2] [3], that will involve experiments to capture: a) intact organic-bearing micrometeoroids that reached low-Earth orbit altitudes, i.e., possible aerosol particles containing terrestrial microbe colonies inside them, and b) debris accumulated at the Exposure Facility of the Japanese " Kibo " Module of the International Space Station (ISS). This study is a part of this planned mission. ...
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This study is a part of ‘Tanpopo’ mission, which is to be mounted on the Exposure Facility of the Japanese “Kibo” Module of the International Space Station. The purpose of this study is to comparing the impact frequency that is predicted from the debris environment model and the impact craters on the exposed instrument. There are two approaches to achieve this plan. The first is to predict the impact frequency of the micron-sized debris onto the Tanpopo capture panels which is exposed to space. The second is to establish methods for calculating key parameters in relation to impacting debris particles from excavated craters on the capture panel material. The debris impact frequency on the capture panels was predicted using the impact-risk analysis tool. It was found that impact of particles of 10 μm or less in diameter was expected on the panels. Additionally, the relationship between the debris impact energy and crater was also derived by hypervelocity impact experiments. It was found that regardless of the projectile materials and impact speed, the relationship between the impact energy and the crater volume is nearly proportional.
... We have proposed the Tanpopo mission-an experiment to be performed on the Japanese Experiment Module (JEM) of the International Space Station (ISS), which orbits 400 km above the Earth-to investigate possible interplanetary transfer of microbes and organic compounds (Yamagishi et al. 2008). To do so, the experimental protocol is designed to capture microparticles that might contain microbes. ...
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We have proposed an experiment (the Tanpopo mission) to capture microbes on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for more than 1 year. After retrieving the aerogel, particle tracks and particles found in it will be visualized by fluorescence microscopy after staining it with a DNA-specific fluorescence dye. In preparation for this study, we simulated particle trapping in an aerogel so that methods could be developed to visualize the particles and their tracks. During the Tanpopo mission, particles that have an orbital velocity of ~8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into the aerogel from a two-stage light-gas gun (acceleration 4.2 km/s). The shapes of the captured particles, and their tracks and entrance holes were recorded with a microscope/camera system for further analysis. The size distribution of the captured particles was smaller than the original distribution, suggesting that the particles had fragmented. We were able to distinguish between microbial DNA and inorganic compounds after staining the aerogel with the DNA-specific fluorescence dye SYBR green I as the fluorescence of the stained DNA and the autofluorescence of the inorganic particles decay at different rates. The developed methods are suitable to determine if microbes exist at the International Space Station altitude.
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To investigate whether terrestrial life (TL) can survive in interstellar and interplanetary space, an experiment was performed to simulate conditions in the Earth's orbit. There are many factors which influence survivability. Among them, the effects of temperature fluctuations and UV irradiations were addressed in this paper. Six species of moss spores and 3 species of fungal spores were selected as target TL. Temperature was fluctuated between 80˚C and -80˚C once every 90 min, whereas UV at 254nm was irradiated for 10 min (471mJ/cm 2) and 30 min (1,413mJ/cm 2). The moss spores of Funaria hygrometrica (exp 1) and Pogonatum inflexum (exp 2) were the most tolerable species to the thermal cycle treatment, with germination rates of 3.3±1.2% (n=5) and 7.9±3.2% (n=6), respectively, af ter 3 we eks of treatment. Germination occurred even after the spores had been UV irradiated for 30 min (0.7% to 23.5%). Only a slight difference in the germination rate was observed using different culture media. The treated spores were transferred to soil where they grew into gametophytes, then sporophytes, and finally formed new capsules after 7-8 months. Two species of fungal spores were allowed to adsorb onto beads before the beads were directly irradiated for 10 min and 30 min, respectively. Colonies developed the spores irradiated for 30 min. On the other hand, a colony did not develop if the spores were taken off the beads and irradiated for 10 min. This indicates that UV does not penetrate to the other side of the beads, and so the spores on that side can be protected from UV radiation.
Conference Paper
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New production methods of silica aerogel with high and low refractive indices have been developed. A very slow shrinkage of alcogel at room temperature has made possible producing aerogel with high refractive indices of up to 1.265 without cracks. Even higher refractive indices than 1.08, the transmission length of the aerogel obtained from this technique has been measured to be about 10 to 20 mm at 400 nm wave length. A mold made of alcogel which endures shrinkage in the supercritical drying process has provided aerogel with the extremely low density of 0.009 g/cm<sup>3</sup>, which corresponds to the refractive index of 1.002. We have succeeded producing aerogel with a wide range of densities.
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This paper reviews major results of present studies and recent developments for future missions in the Japanese space program regarding in-situ measurement and collection of micrometeoroids and orbital debris in the near Earth space. Japan's contribution in this area began with the post flight impact analysis of the Space Flyer Unit (SFU) satellite which was returned to Earth in 1996 after 10-month exposure in space. Despite a decade later than similar efforts first conducted in the USA and Europe, it resulted in a record of over 700 hypervelocity impact signatures, which now forms the nation's first database of real space impacts being open to public in the Internet. Together with laboratory impact tests, both morphological and elemental analyses of the impact craters yielded new insights of the meteoroid to debris ratio as well as flux variation compared with the previous spacecraft. The next step was a passive aerogel exposure in the STS-85 shuttle mission in 1997. No hypervelocity impact was found there but its experience has been incorporated for designing a microparticle collector to be on-board the Japan Experiment Module-Exposed Facility of the International Space Station. All of such "passive" collection of micro-impact features, however, still leave the significant uncertainty in the quest of their origins. Therefore an aerogel-based "hybrid" dust collector and detector (HD-CAD) is currently under the development. It measures time of impact and deduces impactors' orbital and physical parameters by detecting impact flash while still capturing them intact. The system is suitable for both (1) sample return missions in LEO as well as to parent bodies of meteoroids, i.e., comets and asteroids, and (2) one-way mission to where the thermal and plasma environment is such that impact induced plasma detectors may suffer from significant noise, e.g., a Mercury orbiter and a solar probe. Together with unambiguous dust samples from a comet by STARDUST and an asteroid by MUSES-C as references, the HD-CAD in the LEO will be able to deduce the accretion rates of the cometary and asteroidal dust grains on the Earth.
The Space Flyer Unit (SFU) was retrieved from space after its 10-month mission in January 1996. Here we report the first findings from the post flight analysis of its Kapton MLI and Teflon radiators in terms of impact flux, crater morphology and implications of impactors' origins. The impact flux on the Sun face is also compared with the LDEF, EuReCa and HST data. On the Kapton MLI, some directional information can be deduced and its capture cell structure promises a high survivability of residues for chemical analysis. The peripheral flux variation is not inconsistent with the EuReCa data favouring for the Earth's apex. The anti-Sun face flux exceeded the Sun face by a factor of 1.7. The size distribution index of the impact features on the Sun face Teflon agreed with the certain size ranges of the previous spacecraft. Plans of forthcoming studies such as detailed CCD/laser scanning, calibration impact experiments and chemical analysis are also addressed.
Following the encounter of the Vega 1 spacecraft with comet Halley, the composition of cometary dust has been analysed by mass spectroscopy. Most particles consist of a predominantly chondritic core with an organic mantle composed mainly of highly unsaturated compounds.
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