Space Exploration - Science topic

I know there's often a debate about whether we should focus our resources on fixing Earth instead of setting our sights on Mars. It’s a valid concern—our oceans are filled with plastics, near space is cluttered with debris, and we still face numerous challenges here on Earth. But I believe it doesn’t have to be an “either-or” situation. Expanding our horizons beyond Earth can also inspire solutions to the problems we face here.

Exploration has always been a driving force. Just as explorers once roamed Earth in search of new frontiers, Mars could be our next great leap. Plus, from a survival perspective, expanding to another planet more than doubles our odds as a species. A fresh start on Mars might also give us a chance to learn from our mistakes on Earth.

Thoughts?

It would be interesting to see, how an artificial "Kordilewsky"-satellite serves in exploration of the vicinity of the L4 and L5 libration regions of the Earth-Moon system.

The previous comments well summarize some of the reasons the breakthrough doesn't indicate something that can address the climate problem. I listened Monday to Miles O'Brien, PBS's science expert, on the PBS News Hour discussing the fusion announcement. He ended a good description by saying an old physics joke was the statement:

Unfortunately, I believe this is correct. When I came to Los Alamos in 1969 there was a magnetic confinement division called SYLLAC. There is now a related effort using a Tokamak machine in Europe, ITER, which is now about to go on line.

Several decades ago there was a LASER FUSION effort at LanL, smaller than NIF but a similar approach. The group leader of the group studying the theory involved was my best friend. This group was in one of my group's buildings. He told me they felt they had proved that the laser on a D-T pellet would not work in a practical energy production.

Dear Dr. Filipe Wiltgen , Thank you for this brilliant scientific & technical question.

I think there is one impediment. It is about radiation.

Also, I believe the technology is already there, and some countries have made enough progress on incorporating this technology in their war machinery (as pointed out by Dr. Pedro L. Contreras E. )

Apart from this, I dream, one day I would be driving my bike or car that runs on nuclear fuel.

Best wishes and regards

Yoganandan

I did confuse confuse bandwidth with delay a bit, but not in recent comments, I think, because I realised I was doing it.

Unless the entangled pairs are prepared on earth and then half are sent to Jupiter on the satellite, which would require coherence lifetimes of years (many orders of magnitude above present lifetimes), a signal has to be sent from Jupiter at lightspeed (for instance a photon entangled with the state on Jupiter) to convey the entanglement information between the two sites before the quantum measurement, so that the half of the entangled state can be set up on earth. This means that the actual data rate is still limited by the bandwidth of the lightspeed signals, even if data can be sent with no delay,

I guess if zero delay was possible, it would still be useful, for things like steering a remote vehicle, or conversation.

I expect that each entangled state will carry 1 bit, one Q-bit.

I am not sure instantaneous communication will ever happen. It may. I don't understand it enough to be sure it can't work. I hope it may be possible. It would also raise lots of interesting problems with relativity. I wouldn't invest my pension on it, but I might invest fun money.

Souvik Manna

Mmm.

At that altitude the concentration is ~10^11 molecules per cc.

https://www.chegg.com/homework-help/questions-and-answers/z-km-o3-profile-ozone-layer-stratosphere-piocewise-lincar-approximation-peak-number-concen-q33322032

I doubt that a COTS ozone sensor designed for use in 1 bar would be useful.

(at rtp there being 10^20 molecules per cc, give or take)

So a sensor would need to have 1ppb as its upper range, and have a resolution ten times better than that at least.

A spectral absorption method appears to be the best bet:

And you may need to 'fold' the optical path a few times to reduce the upper detection limit to the desired value. A Heriott or White cell may help.

The absorption of interest is in the 250nm range:

https://slideplayer.com/slide/16277008/

...and LEDs are available nowadays that can provide significant flux at those wavelengths - so no need to look at D2 or Xe lamps!

To do the same for what they did to Earth? Wherever we go; death will follow us . It is wiser to work for the other life; the Eternal one.

Interesting question

If i may add my 5 cents to this:

--> Depends how you want to see Elon Musk: as the visionary who wants humanity to thrive and improve? Or just as the one who seeks fame and fortune for being the first in doing things?

In my humble opinion, humanity has yet to reach a level of mindset to overcome cultural and religious differences. We might have satellites and smart phones, but in our thinking we still behave like cave-men.

For example, the Americans, when setting foot on the Moon, put an American flag there. Not one showing Earth. How would it be on Mars, when Chinese, Indians, Europeans and Americans set foot there? Whom will it belong to? For sure not the entire humanity, so we would just bring all of our archaic thinking into a new world. All our problems and issues, and soon the new planet will suffer all the same problems as we have on Earth.

As long as we do not manage to live as one humanity on one planet (i.e. having a global government), there is no point in making humanity multi-planetary.

--> As mentioned above: if you want to colonise something, who does it belong to? Is there indigenous life (whether intelligent or not)? Or is it a barren rock?

Now given the barren rock case: Who does it belong to? Imagine it has a huge amount of rare minerals on it. Is it "whoever finds it can keep it"? In the outer space treaty from the 1960s, they addressed this topic, saying that space belongs to all humanity, yet not all nations have signed this and yet when it comes to mining/farming/inhabiting these space environments, how is that regulated? And if violated, who prosecutes the violators?

There is a huge legal issue in regards to occupying space environments.

Now given the planet is not a barren rock, but an obviously inhabited planet: Now we can either develop yourselves as species and not touch the ecosystems of these planets, leaving them pristine for the indigenous life. Or we can act in the human way and do the same mistakes as we did in the past over and over again and just go there, exploit and trash the planet until its depletion.

The most difficult and realistic case is actually the case of Mars:

Why is Mars so interesting? Because in its past it was very similar to Earth, it had a denser atmosphere, a magnetic field, volcanism, starting plate tectonics, liquid water and all chemical ingredients for forming life. Mars might have gone through a similar evolution as Earth, forming microbial life, or maybe even be the origin of terrestrial life, as interplanetary transportation of rocks after impact events is proven to occur. Now, Mars is the perfect (and maybe only) place to actually study how life on Earth could develop and if life could develop on other planets as well, if life is unique or if it appears quite common throughout the universe.

But, if we send now a bunch of colonists there, who will bring lots and lots of organic material from Earth, we might spoil Mars to a degree where we cannot study this anymore, loosing a very unique opportunity.

Given the case there is still life around, wouldn't it be best to first study it, before building houses, schools and hospitals next to it?

And then there is another ethical consideration that needs to be taken into account:

Sending colonists to space with current technologists would use up significant amounts of terrestrial resources. Sending just 30000 colonists to Mars would already use up all the remaining mineral oil reserves on Earth, not to mention the metals, materials, supplies, etc shipped with the settlers. In order to send these few privileged people to Mars, the rest of humanity will have to sacrifice their lifestyle, their future and their environment. Is that ethical?

--> If we could terraform Mars, why not first terraform Earth? Reverse the effects of climate change, stop and reverse desertification. Earth is better studied than Mars, but as long as here high-ranked people make money with pollution and deny scientific facts, nothing will happen for the better. The money that Musk wants to spend on the colonisation could as well be spent to cover parts of the Earth's desert areas with solar power plants, providing humanity with CO2-free energy. That would benefit more people.

Also, terraforming Mars will not be sustainable. Mars is loosing its atmosphere, because of the lack of a global magnetic field. it might become a home for a while, but thinking into the far future, Mars will be back to where it is now.

Plus, how do we know we can potentially manage to create stable living conditions on Mars, when we are all about destabilising every environment we enter?

--> Maybe because it is easier messing up something new, rather than fixing something old?

--> Musk's rockets use RP1 (refined kerosine) like all other rockets, and as long as this remains the cheapest fuel, nothing will change. Rockets are basically 95% fuel that is burnt. Using synthetical fuels is a huge cost factor. And especially since the CO2-concentrations (despite being high enough to significantly influence the climate) in the atmosphere are too low for economical use, I do not see any of this happening any time soon.

--> No. We need to politically, economically and ecologically get our shit together first. We need to all reduce our negative imprint on the environment on Earth, foster international collaboration not wars, fear or hate, we need to change our thinking not towards maximising the monetary output, but in maximising our own happiness and humanity towards others.

Also, we should (must) explore Mars first. The right step is to first send a small groups of astronauts to carefully study Mars (and come back) over an extended period of time (~20 years) to really answer all our open scientific questions, before we can even think of inevitably spoiling the pristinity of the planet.

==> this would be the right way, and would avoid many of the mistakes that human explorers on Earth have done in the past (i.e. settling at their first arrival to a new place)

This project is an engineer's dream. It has elements that require the project team members to creatively blend established (even old) techniques with new ones, in "outside the box" ways. Teleoperation in real-time is not possible, so giving detailed directions to the onsite exploration vehicle won't work. So, develop primitive routines that can be strung together like beads using higher-level commands. The rover should understand general commands from mission control, like "explore quadrant G31 and report", leaving details of how to accomplish that task to itself. An expert system would be an excellent starting point, with the "experts" being the development engineers and scientists. The rover sensors would allow monitoring planning and execution. Any exceptions to a routine, such as bumping into a rock, or approaching a precipice, would be reflected to control on Earth, to facilitate improvement to existing routines and addition of new ones. Then, creating a "curiosity" attribute to blend a variety of exploration methods would be helpful. How would a robot look for interesting planetary features and objects, or avoid weather? Imitating human behavior is a great place to start: nature has provided the plan. I gave a 3-hour presentation at MIT on this approach 7 years ago: “Tutorial: Biologically-Inspired Object-Oriented Design & Object-Oriented Programming for Robotics and Artificial Intelligence”, 15th IASTED Intl Conf on Robotics & Applic, MIT, Cambridge MA, Nov 1-3, 2010. I've given 26 presentations at NASA Houston since 2006, most involving artificial intelligence and robotics for space applications.

The most fundamental environmental factors while terraforming a planet are temperature and pressure (which drive climate and weather), global energy balance, cryospheric-hydrological content and cycles, biogeochemical cycles and atmospheric composition. The ecology of a planet is then derived from these environmental conditions, as each species works together to adapt and evolve in their environment. We have only scratched the surface of potential planetary pathways. 

Apart from Mars, the most viable planet (or moon) for terraforming would be 1) the Earth's moon, 2) Titan, 3) Venus, 4) Ganymede, and many other potential possibilities, depending all on assumed technological abilities (see my project link below). 

I have also attached great publications in helping you answer your question. You may also refer to the 73 references listed on my project page: 

See these articles. . . 

The sun extends far beyond the visible diameter, and the outer layers are plasma in continual fluctuation of irregular shape, not a definable diameter. If you get an exact answer it will probably be wrong part of the time, and only approximately correct on average.

Laser communication should give better reliability near opposition. If Mars is visible the lasers should pass through with data streams.

Hi Paul,

Just a quick point in the past if we have been concerned about the radiation susceptibility of certain parts we have used spot shielding using Tantalum, I think we did this over an ADC at one point for the Cluster mission. This combined with the aluminium chassis helped reduce the risk to an acceptable level.

We used Mariner 1972 dust instrument data to calc column density for UVS data. Look for it in PDS Atmospheres data bases.

Jorge, please only post information that is relevant to the question. 

For space agency missions they tend to be custom-made, making nailing down the cost a little difficult. However, Busek has CubeSat to SmallSat-scale engines, which can give you a good idea.

 In a sense it has already happened. Think of large scale "Big Science" research projects involving hundreds of specialized collaborators from a variety of disciplines. No individual researcher can have an in-depth knowledge of the whole, yet conceivably all the detailed knowledge can be integrated within an expert system that can be used to answer questions beyond the intellectual capacity (intelligence) of any of the individual researchers. 

Remember the Skylab fallout in the 70's? how much stress and terror it has created in the minds of people, even during the Print-Age media. What could have been the fear instilled in this digital media era, should such threat emerge ?

The usual definition of "hyperbolic excess velocity" is a scalar speed so I'm unclear what extra information you have that lets you call it a vector. If you only have a direction, you get a family of asymptotes like the blue dashed lines on the diagram to the right in the link. If you are approaching say from the bottom left then you need some positional information to work out the eccentricity from which you get the turning angle. Just a direction on its own is not enough, obviously the closer you approach the planet, the greater the change of direction. If you can work out how close the asymptote passes to the planet, working out the eccentricity is just solving the trigonometry.

I am not quite clear about your question. Anyway, in planetology, comparing the environment (such as mountains stability) for example on Pluto, one simply compares the Pluto's gravity (0.067 of the Earth's gravity) which is 15-times smaller than the Earth's gravity. Comparing flowing media, such as wind on Venus, it is useful to calculate the settling rate of typical sand particles under the high gas viscosity and density at surface to see that that atmosphere's thickness, similar to honey, has incredible carrying capacity. For calculation of the settling rate use my Universal Sedimentation Equation (Brezina, 1979 http://www.granometry.com/index.php/en/variables/settling-velocity/sedimentation-equation ). For simple handling, I am using the table of my program SedVarNC - single number conversion.  My PARTEC 1979 paper is downloadable  here, if you wish, I could gladly send you a paper reprint if you email me (to jb@grano.de) your airmail address- 

Best wishes, 

Jiri

Probably not.

I wrote my code to calculate the "inclination" using the traditional definition: the angle of the Juno orbit plane relative to Earth's equatorial plane.

So that 28.006deg is the angle of the velocity vector at the time of perigee relative to the equatorial plane of earth. The velocity vector at perigee should be a vector in the plane of the orbit and at the maximum angle from the equatorial plane.

So the smallest angle from the orbit plane to Earth's spin axis should be 61.994deg.

The angle between Earth's spin axis and the normal to the orbit plane is again 28.006deg.

I can add to above conciderations the following factors.1 In microgravity Marangoni convection might control crystal microstructure in the case of detached growth. The effect of this type of convection depends on the extention of free surface and temperature gradient along this surface. 2. vibrational convection might play essential role in solidification pattern formation dependently on geometry of the sample and parameters of low-friquecy vibration (g-gitter) Both effects might be more significant then gravitational convection in ground conditions.

I only know of CubeSat projects which use some combination of whole and half unit structures. For example, a FIREBIRD is a 1.5U CubeSat. This is generally how 0.5 U structures are used.I am aware of a design project to dock two identical 0.5U CubeSats with one another:

I think a 0.5U CubeSat may be difficult to use unless it is being designed as an engineering exercise. A structure that small will most likely eliminate the possibility of certaing subsystems like attitude determination and control, which may result in a poor communications link. 

Will there be a payload or is there any room after power, on-board computer, thermal control (heaters)?  If a CubeSat does not have a payload, then what is it's purpose?

I would say that the gravity-dependence of chemical reactions can be neglected for two reasons:

1) the enthalpy has to be used with a little bit carefullnes in this context. The enthalpy is defined as the energ content of thermodynamical systems. However, this holds for every system, regardless of the occurence of a chemical reaction. If you want to study chemical reactions, you have to use the change of enthalpy dH. This is defined by: dH = TdS + V dp (T being the absolute temperature, dS the change of entropy and V the volume). If you work at constant pressure dp = 0. This is mostly the case, as you have no pressure variation for solids and nearly no variation in liquids or gases (as long as you are not dealing with very large volumes (i.e. some km³ or so).

and, even more important

2) all chemical reactions are driven by the electrons, or, more generally, by electric forces between charged particles. As the electric force between, say, an electron and a proton, is around forty! orders of magnitude stronger than their gravitational force, one can immediately see that gravitation is neglible compared to electrical forces.

Oh this was a fantastic answer Paul. I was trying to understand

this redshift for last few months but never had enough time to

dig into the literature.

Hi Bernardo you can count on us. You know our potentiallity in a possible collaboration. We can stay in touch and have a meeting if you feel necessary.

All the best Miguel

Could you put your question in clearer terms?

The usual role of small countries in space exploration comes in various forms:

a) Cube-Sat and Nano-Sat projects (creating small satellite payloads and launch them piggyback with larger missions)

b) creating a single instrument for a larger research mission

c) deliver key hardware elements (e.g. thermal insulation, thrusters) for larger missions

d) create added value products (especially in the fields of remote sensing, disaster monitoring or navigation)

e) very occasionally they may have had an astronaut in orbit (usually through international programmes like INTERCOSMOS or ISS and usually its not repeated for decades)

f) are often international experts in defined, specialized fields of space exploration (having to concentrate on certain aspects for budget and manpower reasons)

Small Countries are basically never

a) prime contractors for anything but the smallest space missions

b) having a permanent manned space programme

c) supporting ALL aspects of space exploration equally

Ad astra

Sundaresan,

If you posit an orbiting station around the Earth then you automatically save about a tonne per person of entry capsule.

But.

And it's a big but, you still need to brake into a LEO - and without using aerocapture, that means fuel. So it's not at all clear that a 'returning to a space station' model has a smaller launch mass than a ballistic aerocapture return.

The only way to be sure is to grind through the numbers, using the rocket equation and some plausible stored fuel combinations.

If you have a station orbiting the moon, then trips back and forth to the surface are a simpler exercise to calculate. You've got the rocket equation, a choice of Isp, and go from there with some plausible vehicle dry masses.

I suspect all of the above has been done to death at least 40 years ago. The NASA technical report server is online at:

Or find an old hand to chat to at the LPI in Houston each spring.

Typical differential star velocities are of the order of 20Km/sec. Typical distances to the stars of constellations are about 1000 parsecs. At such distances, the projected separations in the plane of the sky for the individual stars that make up the constellation are about 150 parsecs. Now at 20 Km/sec, a star moves 20 parsecs

in a million years, or about 1/7 of the separation of constellation stars.

As a result, constellations will appear to show subtle changes over periods of about 100,000 years, and when a constellation star is nearby, it will be seen to move

substantially over periods as short as 1000-2000 years. This is how Halley noticed that Sirius and Arcturus had moved from their positions recorded in Ptolemy's catalog.

made some 1500 years earlier