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Signs of Liquid Water Found on Surface of Mars, Study Says

nytimes.com

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Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#121

Post by Retric »

mrec wrote: post #90
Symmetry wrote: post #73

Earlier quoted context omitted.

There have certainly been metioroids starting on Mars that made it to Earth without being sterilized[1]. Now, Earth does have a deeper gravity well which might make a difference but Earth microbes have had geological epochs to make the trip to Mars wheres you'd only expect a meteoroid to remain recognizable on Earth's surface for that long in comparison. So I figure that if contamination of Mars by Earth life was a p…

Well, calling Allan Hills 84001 "unsterilized" is a bit of a stretch, since even the most optimistic theory is that it contains fossilized lifeforms, not live ones. I dunno. I agree that something like the K/T impactor probably blasted bits of our planet all over the Solar System, but I suspect the depth of the gravity well brings more factors into play than just "how long it would take for ejecta to get to X". For e…

Large asteroids are generally frozen on the inside when they impact the earth, similarly any large ejecta would likely contain pockets that remain relatively cool. Polar ice would actually be a great candidate for such a transit.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#122

Post by emp_zealoth »

oso2k wrote: post #75
crusso wrote: post #12

R.S.L.s are treated as special regions that NASA’s current robotic explorers are barred from because the rovers were not thoroughly sterilized We're not going to sterilize our research equipment going to Mars and we're not going to search likely sites where we could find life because we don't want to contaminate them. And yet, looking for signs of life native to Mars (or even water which might support life) is the to…

I'll first refer you to my previous post about Clean Room Operations at JPL [0]. All equipment leaving Earth is sterilized. The thoroughness of sterilization varies from project to project, instrument to instrument, and the agreed to HW & Planetary Protection Plans. It helps ensure that equipment is not giving false readings. Serious money is also laid out for HW & Planetary Protection (there's a whole division of pr…

Im pretty sure ive read in one of a books that through sterilisation was curbed in,as it was causing excessive hardware failures

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#123

Post by Symmetry »

mrec wrote: post #90
Symmetry wrote: post #73

Earlier quoted context omitted.

There have certainly been metioroids starting on Mars that made it to Earth without being sterilized[1]. Now, Earth does have a deeper gravity well which might make a difference but Earth microbes have had geological epochs to make the trip to Mars wheres you'd only expect a meteoroid to remain recognizable on Earth's surface for that long in comparison. So I figure that if contamination of Mars by Earth life was a p…

Well, calling Allan Hills 84001 "unsterilized" is a bit of a stretch, since even the most optimistic theory is that it contains fossilized lifeforms, not live ones. I dunno. I agree that something like the K/T impactor probably blasted bits of our planet all over the Solar System, but I suspect the depth of the gravity well brings more factors into play than just "how long it would take for ejecta to get to X". For e…

The hypothesis, I believe, is that the stuff in Allan Hills 84001 was fossilized back when Mars was wet but it was only ejected a few million years ago. The important part is that the inside of the rock never got too hot. As long as there are bacteria which can take being frozen for long periods of time they ought to be able to survive.

As to larger impacts I really can't speak with any authority and I'm not aware of any studies which would say. But my intuition would be that the greater volumes in large the ejecta from large impacts would heat up less due to more insulation. I should probably put this on /r/askScience and see if anybody knows more.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#124

Post by mtdewcmu »

david_shaw wrote: post #87
Symmetry wrote: post #73

Earlier quoted context omitted.

There have certainly been metioroids starting on Mars that made it to Earth without being sterilized[1]. Now, Earth does have a deeper gravity well which might make a difference but Earth microbes have had geological epochs to make the trip to Mars wheres you'd only expect a meteoroid to remain recognizable on Earth's surface for that long in comparison. So I figure that if contamination of Mars by Earth life was a p…

That makes sense, but wouldn't it be reasonable to assume that there's a major difference between natural seeding of life on other planets via meteors, and humans bringing it over while trying to find natural life? Furthermore, what if life on Mars were fragile enough that Earthly microscopic organisms destroyed it?

>> wouldn't it be reasonable to assume that there's a major difference between natural seeding of life on other planets via meteors, and humans bringing it over while trying to find natural life?

There would definitely be a difference vis-a-vis reconstructing the natural history of Mars.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#125

Post by bdamm »

WalterBright wrote: post #118
trose wrote: post #114

Earlier quoted context omitted.

I'm kinda of this thought process as well. If there are hospitable conditions there and we haven't found microbes after a while, I think we should just start dumping tons of them over there. We need something to put some atmosphere there for us. Algae seems to be a really good bet.

And suppose we do find some biological slime there? Does that then make Mars off limits to all of humanity for all time?

It's time for us to accept that we implicitly modify everything we touch. Prime directive needs to have some detectability metric by which we decide it's OK for us to go gangbusters. If the native martian amoebas cannot survive with us present then they lose the evolution race, sorry.

Besides, if there are primitive life forms on Mars, it's quite presumptuous of us to assume we could so easily wipe them out.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#126

Post by hugh4 »

akiselev wrote: post #115
dangrossman wrote: post #97

Earlier quoted context omitted.

Atomic helium is not a molecule. Oxygen is significantly more abundant than either nitrogen or carbon in the universe. In the interstellar clouds that give rise to stars, hydrogen runs into a lot more oxygen than carbon or nitrogen, so you're going to end up with more water than any other molecule but hydrogen gas. https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem... Also see this delightful comment by log…

Ok I was wrong (very wrong) as long as we're arguing with unrealistic semantics because Wikipedia defines a molecule as "the smallest particle in a chemical element or compound that has the chemical properties of that element or compound" which means that atomic helium is a molecule. Hence the "element or compound" bit. Assuming your definition holds: Do you have an actual (peer reviewed) citation that demonstrates t…

Regardless of what Wikipedia says, chemists distinguish between molecules and atoms.

Diatomic oxygen is extremely rare in the universe, because it's extremely unstable. Oxygen would rather be bonded to pretty much anything rather than itself, including hydrogen. [citation: go burn some hydrogen]. It's common round these parts due to some rather bizarre nonequilibrium chemistry [aka life].

What we know about the prevalence of various molecules is a combination of what we know about the prevalence of atoms combined with what is thermodynamically stable. It goes hydrogen, water, methane, ammonia, carbon monoxide, I think? At this point it depends on local conditions, temperature and so forth, but the stability of water combined with the prevalence of oxygen makes it basically unassailable as the second most common molecule after H2.

Can you see why instead of "forcing someone to provide references" it would be better to ask someone nicely for references?

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#127

Post by outworlder »

bdamm wrote: post #125
WalterBright wrote: post #118

Earlier quoted context omitted.

And suppose we do find some biological slime there? Does that then make Mars off limits to all of humanity for all time?

It's time for us to accept that we implicitly modify everything we touch. Prime directive needs to have some detectability metric by which we decide it's OK for us to go gangbusters. If the native martian amoebas cannot survive with us present then they lose the evolution race, sorry. Besides, if there are primitive life forms on Mars, it's quite presumptuous of us to assume we could so easily wipe them out.

While I agree with the general idea, I also hope that, if there are more advanced civilizations out there and they find us, that they don't consider us "native amoebas".

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#128

Post by akiselev »

dangrossman wrote: post #117
akiselev wrote: post #115

Earlier quoted context omitted.

Ok I was wrong (very wrong) as long as we're arguing with unrealistic semantics because Wikipedia defines a molecule as "the smallest particle in a chemical element or compound that has the chemical properties of that element or compound" which means that atomic helium is a molecule. Hence the "element or compound" bit. Assuming your definition holds: Do you have an actual (peer reviewed) citation that demonstrates t…

It was a casual answer to an astronomy question buried in a comment thread on a message board for startup enthusiasts. The level of rigor you're demanding is unnecessary. [Citation not needed], truly. I'm absolutely sure that I won't run into trouble with HN's moderators or community for having commented despite having no "definitive answers with better-than-wikipedia citations" to give you about the chemical make-up…

We're not debating the multiverse theory or alternatives to the standard model, we're literally literally talking about the stoichiometric ratios and chemistry of the universe, a field of knowledge that is as fundamental to astrophysics as the concept of fusion itself.

If you can't provide a single citation to support such fundamental statements as "H20 is the second most common molecule in the universe" outside of irrelevant Wikipedia articles, they are worthless, HN moderator and community standards notwithstanding.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#129

Post by 13thLetter »

gee_totes wrote: post #19
gambiting wrote: post #15

Earlier quoted context omitted.

The article mentions how equipment that needs to be sterilized is baked to a very high temperature - but I wonder, can it not be sterilized with radiation, like we already do with food? All electronics on a rover are already radiation hardened, after all Curiosity has to work while having a chunk of plutonium strapped to its back. Is this not an option of some reason?

What happens when Curiosity contaminates the RSLs with radiation?

That's not how radiation works.

Re: Signs of Liquid Water Found on Surface of Mars, Study Says

#130

Post by hugh4 »

a3n wrote: post #94
Florin_Andrei wrote: post #81

Earlier quoted context omitted.

> Life is very, very persistent, and niches will be filled. But I think it's safe to assume it's quite fragile at the very beginning, and therefore conditions must be milder for it to appear at all. Once it takes off it's probably much more sturdy.

There's strong speculation that there was an ocean on Mars, many years ago. Possibly mild enough to get started.

We simply don't know how likely life is to arise given the right chemical conditions. We also don't know what those conditions are.

It may still be that life is so unlikely that it only happens on one out if every billion planets where the right conditions exist.

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