68

Once we introduce microorganisms into an environment, it makes it more difficult to study any microorganisms that might already be there, and it's basically impossible to undo. We won't be able to tell if any products of biological processes came from our contamination or from what was there before us. We won't be able to tell whether a particular ...


61

The answer to your formal question is: we cannot be certain we haven't already contaminated another world with our life, although we try not to. See NASA's notes on planetary protection protocols (1) for more information about that. However, I think it is more important to address the other question you propose. Paraphrasing, you ask: "Why wouldn't we ...


31

There are probably many answers, but for guesstimating hypothetical missions a look at delta-V/subway maps like this are highly informative in terms of problem scale. Working from that getting into LEO is 9.4 km/s, these are the rockets you see launching regularly, and can get about 5% of their launch mass into orbit. Earth escape needs another 3.41 km/s, ...


26

Absolute 100% sterilization is impossible. There's always a tiny chance that some microbe lands on a component during manufacturing, gets entombed inside the packaging, and therefore is unreachable by sterilization. Getting such a microbe out to the environment would require breaking the spacecraft in a very peculiar way, without incinerating or damaging ...


23

@GremlinWrangler's answer sums up several important points; Getting a low mass rover from Earth all the way to landing on the surface of one of those Moons requires much much more rocketry (delta-v) than landing a much heavier and more capable/diverse probe on the surface of Mars. Solar won't work well there and RTG's are quite scarce Let's also consider ...


17

No, it is not possible to make it 100% sterile. Especially if you consider self-replication as only requirement to classify something as life (It's complicated. See obligatory xkcd reference) Few issues to consider: In addition to other answer, one would likely use chips and PCBs in your spacecraft. Those are usually manufactured outside Space agencies, and ...


13

One of the challenges of trying to live on another planet is finding or producing the essentials for human life there rather than having to ship everything. If we can free water, oxygen and building materials from regolith or rock from that planet then we might be able to be self-sustaining. If we find life on another planet it may have figured out how to do ...


11

Go ask an Aussie about rabbits. They've been trying to get quit of them for, I think, well over 100 years - but they breed, well, like rabbits, and getting them OFF the damned continent is thoroughly uphill work. Get a Terran microorganism in an alien environment, you've just contaminated that environment, and your studies are already skewed. And you'll ...


10

One tool in the astrobiology toolbox is chirality, the property that many chemical compounds exist as "left-handed" and "right-handed" mirror images. These have the exact same properties of course, as they are the exact same compounds. But biochemical processes will typically only be able to produce one of them. Which means that if a ...


10

Update: There is a thorough and well-sourced summary too long and detailed to reproduce here published in Nature Feb. 13, 2020: Lessons in space regulations from the lunar tardigrades of the Beresheet hard landing Why are we trying to prevent (Earth) life from spreading via landers rather than actively encouraging it? I've added "Earth" to the ...


9

There would be intangible benefits and potentially tangible benefits. The intangible benefit for some would simply be the knowledge that Earth is not the only cosmic ball of rock to host life. "We are not alone". For some, that would be a psychological boost. For others not so. As to the potentially tangible benefits, that depends on what is found ...


8

The motive for the exploration of Enceladus and Europa is different from that of Mars. The primary motive for exploration of the two moons is the possibility of finding an independent instance of life, while the exploration of Mars also includes gathering information for likely future human colonization. Of the three worlds, Enceladus is the most ...


7

There would be significant philosophical impact in that mankind is not alone in the universe, but it is impossible to give a clear answer into what real physical benefits might be gained, as it would depend on what was found. It might also take more than 50 years to see the full benefit of such a basic discovery. It is a bit like asking: between two ...


7

For free, but low-resolution: Small versions of all1 the images are included in the book Murmurs of Earth by Sagan etc. Chapter 3 "Pictures of Earth" includes a visual index and then slightly higher quality versions of each picture1. Some are even in color. Descriptive text is included for each image. You can check it out and see them at the ...


7

Ignoring the infrared radiation aspect of your question, what you are describing is a situation not too dissimilar to what exists in many parts of Australia. The extreme degree of weathering that has occurred in Australia over millennia has left the soils in many parts of Australia leached of nutrients. Over time, native plants adapted to this situation to ...


5

Google searching for "carol stoker chlorophyll" found this Slashdot comment from April 2002 commenting on the controversy, particularly around a BBC article that described the situation in slightly overhyped detail. The comment included a verbatim quote of a poster abstract that was to be presented at the second Astrobiology Science Conference ...


5

I think the answer to this question is concise and can apply broadly to any similar situation. If both experiments are valuable, they should be performed in a manner that allows them both to be done. Seeding a foreign world with terrestrial life would, at the very least, make it more difficult to study any native life. It could be possible to simulate extra-...


5

As we have yet to find life beyond Earth, one can only speculate what life would be like elsewhere. However, there are good arguments that unicellular life would be more common than multicellular life. Single-celled life is simpler than multicellular life. The latter requires not only all of the properties of the former, but also the ability of the cells ...


5

The answer as to whether the discovery of a second instance of life would affect Joe Average is "quite possibly". Although why this is so is not immediately apparent. For an example, take a major scientific event that actually happened recently. On August 17, 2017, the LIGO gravitational wave sensor detected a gravitational wave event due to the ...


4

In general space based plants will probably be hydroponics so most likely initial agriculture will be indoors in vertical farms. Possibly using mechanically harvested/processed materials to carefully expand the setup but certainly more productive of human labor to grow high yield plants in optimal conditions than hardier specimens outdoors. If the outdoors ...


3

Several answers have already identified strong ethical and scientific arguments for valuing and preserving possible extraterrial life. But even supposing for the sake of argument that we were able to satisfy ourselves that there was no life on Mars whatsoever, and everybody was agreed that we ought to go ahead with terraforming it... surely we would want to ...


3

This is a late answer, but ... Budget wise I believe the missions would cost the same as that of Mars. You have grossly underestimated the cost of a Europa lander. The increased delta V needed to get to and land on Europa alone vastly increase the cost of a lander mission to Europa compared to a lander mission to Mars. The enhanced radiation protection ...


3

Apparently some people in Japan think so! From today's BBC's Japan developing wooden satellites to cut space junk: Sumitomo Forestry said it has started research on tree growth and the use of wood materials in space. The partnership will begin experimenting with different types of wood in extreme environments on Earth. and later "We are very ...


2

There are a number of issues that I can envisage. Chemical reaction rates can be temperature dependent: the colder the temperature the slower the rate of reactions. This applies to life forms. The cold temperatures on Mars could result in microbes having a slower "metabolism" and the rate of perchlorate consumption could be slower than envisaged. ...


2

One key aspect not mentioned so far is the possibility of contamination of Mars with Earth life that is not due to a failure of planetary protection. Carl Sagan was one of the first to suggest the possibility of cross contamination of life between Mars and Earth due to asteroid impacts as mentioned in his Cosmos series and as chronicled in "Carl Sagan'...


2

First of all, some effort is made to prevent contamination by earth organisms for precisely this reason, but it is not perfect. But, if scientists do detect life it will probably be possible to tell that it is not of earthly origin. Here are some possible lines of evidence: Biochemistry is complicated. We don't know that DNA is the only way genetic ...


2

TL;DR: Mars had a long-term increase in eccentricity from a minimum of 0.079 about 19 millennia ago and will be about 0.105 after about 24 millennia from now (perihelion distances about 1.3621 AU). During its early stages, the orbit was nearly circular (0.002 at 1.35 million years ago, and will be about 0.01 a million years into the future. This change in ...


2

This question highlights the challenge in explaining “Average Joe” the long-term benefits of scientific researches. I can imagine the difficulty a NASA representative may have in the US Congress when Average Joe asks why part of his tax money goes to researches whose potential returns he can’t benefit in his lifetime (the explanation for the “50 years” time-...


2

If life is found on Mars, I would be prepared for the possibility that it came from Earth; that perhaps some early bacteria survived being propelled into space from an asteroid impact or volcanic eruption. In this case, the abiogenesis event(s) likely happened here on Earth. We're still alone in the universe, it's just the crucible of life consists of more ...


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