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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

#111

Post by emcrazyone »

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…

"All equipment leaving Earth is sterilized"

Should that read all equipment leaving Earth from the United States? Do other countries with developing space programs adhere to the same practices? Does the US have agreements with other countries to make sure we're all on the same page so to speak?

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

#112

Post by [deleted] »

WalterBright wrote: post #107
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…

There cannot be a manned mission to Mars with this policy.

[deleted]

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

#113

Post by qb45 »

czinck wrote: post #45
lmkg wrote: post #31

Earlier quoted context omitted.

Shot in the dark: Killing organisms is not sufficient. The corpse of a bacterium is still a contaminant: It still has organic compounds that can be measured by our equipment, and potentially interact with organic compounds on Mars. For our purposes, the bacterial corpses must be fully incinerated.

I remember hearing something relatively recently about how they detected some complex molecules with one of the rovers (indicative of life creating them), but the leading theory was that they were leftover from when the rover was being built and weren't cleaned enough. So that's definitely a possibility, we aren't looking at a slide and seeing them move, we're just looking for some chemicals so dead bacteria trips th…

This happened with the Viking probes in '70s.

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

#114

Post by trose »

WalterBright wrote: post #110
david_shaw wrote: post #87

Earlier quoted context omitted.

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?

At some point we'll either have to either stop worrying about life on Mars being hidden under a rock somewhere or forever put a "humans keep out" sign on Mars.

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.

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

#115

Post by akiselev »

dangrossman wrote: post #97
akiselev wrote: post #76

Earlier quoted context omitted.

He's likely asking for a citation that shows that water is the second most common molecule in the universe, which is a quite a claim to make based on our understanding of astrophysics and astrochemistry. The most common molecule is diatomic hydrogen and the second most common is helium. That'll likely be true for hundreds of billions of years, if not trillions, due to the way stars burn their atomic fuel. Even if you…

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 that H2O is the second most prominent molecule in the universe, for any real definition of molecule? If not, do you have a citation showing that diatomic oxygen is less likely to form than water in the interstellar medium (considering the momentum of hydrogen atoms will be significantly greater than that of oxygen atoms and thus impact the chemical reactions drastically)? If not, do you have evidence to show that our capabilities to detect polar molecules like water are able to account for the absurd abundance of nonpolar molecules (for which electromagnetic detection is practicaly impossible) based solely on first principles of astro or even quantum chemistry?

I'm not trying to play devil's advocate or prove you wrong. These are questions I'd love to have the definitive answers to but I'd rather have no answers at all than a random HN post which only cites a Wikipedia article on the prevalence of atoms (not molecules, missing the entire point of chemistry) and another unreviewed HN post on astrochemistry from first principles without a single significant citation.

The purpose of [citation needed] is not to take the wind out of your statement but to force you to provide the necessary evidence to back up your assertion.

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

#116

Post by ypcx »

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…

What would you do if you wanted to postpone, as long as you possibly can, the disclosure of discovery of life on Mars? Exactly. Ridiculous question, of course, how do I even dare to have a thought like that here on HN, the bastion of reason. Unless there are reasons to suppress everything that would somehow threaten the status quo. Pause for a second and ponder the inexplicable urge to downvote this comment, which is only expressing a simple thought.

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

#117

Post by dangrossman »

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…

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 of the universe. Nor do I think an HN where questions go unanswered lest the leading expert in current theory happens to respond in person with a bibliography in hand is a better one.

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

#118

Post by WalterBright »

trose wrote: post #114
WalterBright wrote: post #110

Earlier quoted context omitted.

At some point we'll either have to either stop worrying about life on Mars being hidden under a rock somewhere or forever put a "humans keep out" sign on Mars.

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?

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

#119

Post by [deleted] »

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?

[deleted]

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

#120

Post by wtracy »

jkaunisv1 wrote: post #28
tempVariable wrote: post #27

Earlier quoted context omitted.

Interesting. I read that in Jeff Goldblum's voice as well. Were there any missions that lifted off Mars and came back to Earth ?

No, we don't have the capability to land something on Mars with enough fuel for it to take off again.

We don't need to: https://en.wikipedia.org/wiki/Sabatier_reaction#Manufacturin...
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