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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

#131

Post by teraflop »

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…

> 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.

No it doesn't; https://en.wikipedia.org/wiki/Molecule cites that as an earlier, less precise definition than the one that's commonly used today. The definition right at the top of the page is quite clear that by the usual definition, a single atom by itself does not constitute a molecule.

> 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.

In polite discussions, attempting to "force" your conversational partner to do anything is kind of discourteous. If you're honestly seeking information, then by all means feel free to ask questions. But whether you intended to or not, your responses are coming across as very adversarial and dismissive.

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

#132

Post by dragonwriter »

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…

H₂ is pretty clearly, it seems, the most common molecule in the universe (the sources that claim something else is seem to be fairly casual sources, and seem to neglect single-element molecules entirely), but from a quick skim of results, it seems that superficially decent sources split between saying that H₂O is second most common and those saying that it is third, behind CO.

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

#133

Post by dogma1138 »

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?

I don't think the care as much about contamination in the way it might mess with the martian ecosystem, what they do care about is getting uncontaminated results.

Finding a life outside of Earth will be one of the greatest discoveries of man kind, something that will never be overshadowed by anything. They want to make sure that when we'll find something it didn't catch a ride on what ever we sent to find it.

Eventually when we start exploring space it wouldn't really matter, yes some precautions might still be kept but we wouldn't take as much care as we do now.

I for one also do not see humans contaminating an alien ecosystem as something unnatural, humans evolved, they've spread out, they seed life (intentionally or otherwise) this is just as much of a natural process as the potential for comets and meteorites to seed solar systems and beyond with organic compounds and even life it self.

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

#134

Post by bdamm »

outworlder wrote: post #127
bdamm wrote: post #125

Earlier quoted context omitted.

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".

Me too, although our morality doesn't influence their choices unless we can communicate with them and/or realistically fight for our survival. Do you think there are races out there quietly observing our behavior and preparing their verdict? If so, I sure hope we are given awareness of membership in the law before the sentencing.

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

#135

Post by [deleted] »

akiselev wrote: post #128
dangrossman wrote: post #117

Earlier quoted context omitted.

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 i…

[deleted]

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

#136

Post by oso2k »

emcrazyone wrote: post #111
oso2k wrote: post #75

Earlier quoted context omitted.

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?

JPL (& many other NASA centers) collaborate quite regularly with the International Space Community. ESA [0] being the prime example (Cassini-Huygens[1], MER [2], etc.). This also includes commercial collaborators as well like SpaceX, LMA, Ball, etc. The community is relatively small and quite professional about their work. They usually don't take shortcuts.

But to answer your first question, Yes. All HW & Planetary Protection practices are not equally applied by all collaborators. However, ISO 14644-1 [3] is now a 15 year-old standard, at least, for Clean Room work environments. Such practices and the HW & Planetary Protection Plans are for Project Managers & Principal Investigators to manage & implement. "Faster, Cheaper, Better; pick any two" [4] we always said in the Spacecraft Assembly Facility at JPL.

Agreements are in place for all projects, and, it usually in the Principal Investigator's best interest to ensure his instrument/subsystem has the best HW & Planetary Protection Plan in place. It ensures their instrument/subsystem is operating nominally and has the longest usable life possible.

[0] http://www.esa.int/ESA

[1] https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Huygen...

[2] https://en.wikipedia.org/wiki/Mars_Exploration_Rover#Related

[3] https://en.wikipedia.org/wiki/Cleanroom

[4] https://en.wikipedia.org/wiki/Daniel_Goldin#Career

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

#137

Post by akiselev »

teraflop wrote: post #131
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…

> 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. No it doesn't; https://en.wikipedia.org/wiki/Molecule cites that as an earlier , less precise definition than the one that's commonly used today. The definition right at the top of the page is quite clear that by the usua…

Ok so I'm very, very wrong along another semantic axis but in this context it's absolutely irrelevant, using the definition given in the second paragraph:

> In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules despite being composed of a single non-bonded atom.

Unless you're saying that water (or any other molecule for that matter) can form inside of a star, which would open an entirely new field of chemistry, this is the definition to use when talking about astrophysics.

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

#138

Post by mirajshah »

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…

The amount of armchair condescension on HN is appalling.

According to the reddit AMA, NASA does do some amount of sterilization before going to Mars, it is enough to justify the exploratory mission. More sterilization would probably take more man hours, more $$$, which would delay the mission to account for an (estimated) low probability of finding water. It seems like they've chosen to iterate instead of getting it perfect the first time, something we're all familiar with.

"The rovers have been sterilized for their particular landing sites where there's been no evidence of present day liquid water. To go to the RSL rovers will be required to be sterilized to a higher level. We also take samples of microbes that might be on the spacecraft before they're launched, so we can compare with any future discoveries. -RZ" [1]

Apart from that, "These features are on steep slopes, so our present rovers would not be able to climb up to them.-RZ" [2]

They will be working on moving further. Let's congratulate them for this wonderful major accomplishment at least.

[1] https://www.reddit.com/r/IAmA/comments/3mq1wl/were_nasa_mars...

[2] https://www.reddit.com/r/IAmA/comments/3mq1wl/were_nasa_mars...

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

#139

Post by DanielBMarkham »

mturmon wrote: post #109
DanielBMarkham wrote: post #103

Earlier quoted context omitted.

No, I got the key word. How the heck is that decision made? And by whom? Elon Musk gets ready to put a lander on Mars and there's a NASA office now that must give permission? Sorry, still not making sense. "Office of planetary probe sterilization" would be much more descriptive. Otherwise we're taking on a helluva lot more authority and prerogative than we probably should.

I'm puzzled about why the existence of guidelines for contamination of other planets would be surprising. Note, the concept of "Planetary Protection" also applies to contamination in the reverse direction for sample-return missions, which are very much expected to be part of Mars 2020. I didn't know this before looking, but it turns out there are UN agreements, and something called the "Outer Space Treaty" to which t…

"Presumably something will be worked out as the reality comes nearer."

One would hope so. I must point out that private space travel was entirely out of the question with NASA for many years. It's only been very recently that the idea has started to catch on -- and it's not universally lauded across the agency. Gotta wonder what kind of obstacles we're currently setting up (perhaps without fully realizing it) for anything beyond LEO.

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

#140

Post by comboy »

akiselev wrote: post #128
dangrossman wrote: post #117

Earlier quoted context omitted.

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 i…

Nice to have somebody on my side. From what I could find so far CO seems to be the second most common molecule in the interstellar space[0], and water does not seem to take part in a nuclear fusion[1], so I think that the discussed statement may not even necessarily be true.

[0] - https://en.wikipedia.org/wiki/Carbon_monoxide

[1] - https://en.wikipedia.org/wiki/Nuclear_fusion#Nuclear_fusion_...

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