Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

nytimes.com

Post reply on HN
Print view View original

91–100 of 193 posts

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

#91

Post by DanielBMarkham »

ChicagoBoy11 wrote: post #24
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…

And that someone seems to be this lady, with this most BAMF job responsibility ever: “These are ongoing conversations,” said Catharine A. Conley, NASA’s planetary protection officer, who coordinates the efforts to minimize the chances of life inadvertently crossing the solar system.

I must be missing something. How would you ever land men on mars if you are striving not to allow life to cross between planets?

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

#92

Post by zokier »

kenbellows wrote: post #43
nsxwolf wrote: post #42

Earlier quoted context omitted.

Not a new discovery in itself, either.

yes it is...?

not really, these dark lines were identified like five years ago or something and flowing water has been number one explanation ever since.

> NASA Spacecraft Data Suggest Water Flowing on Mars > 08.04.11

http://www.nasa.gov/mission_pages/MRO/news/mro20110804.html

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

#93

Post by a3n »

icoder wrote: post #46
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 ?

I think your parent post was talking about that we may have taken earth-life to Mars (not vice versa)

Correct.

But there are Mars rocks that have been busted loose from Mars, and orbited down to Earth.

https://en.wikipedia.org/wiki/Martian_meteorite

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

#94

Post by a3n »

Florin_Andrei wrote: post #81
a3n wrote: post #26

If there is water of any sort on Mars, ice, liquid, salty, whatever, I think finding life on Mars is inevitable. Life is very, very persistent, and niches will be filled. Unfortunately it's also all but inevitable that we'll bring some with us, if we haven't already. Life is persistent, and ever-surprising.

> 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.

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

#95

Post by danenania »

dangrossman wrote: post #68
comboy wrote: post #53

Earlier quoted context omitted.

"Water is the only molecule that fits the bill, and happens to be the second most common molecule in the universe." [citation needed]

What an annoying meme. What part did you find so surprising that you want additional references, but couldn't find a better way to ask for them? As to the first part, there are uncountable examples of water-based life, and zero examples of non-water-based life. That doesn't rule out its existence, but basic chemistry makes it unlikely, and it won't look anything like life as we know it. No other liquid has the proper…

In terms of of non-water based life being "unlikely", I think it's a bit of a fallacy to make inferences on the likelihood of a possibility that we have so little understanding of.

True, we've only seen water-based life firsthand, but our "sample" of reality is so infinitesimally minute relative to the whole that we cannot properly use that as a basis to make assertions about what the overall proportional makeup of types of life might be. Doing so is pure speculation.

It would be sort of like randomly picking up one tiny pebble at random from anywhere on the earth, identifying its elements, and then concluding that it's "unlikely" any other non-identified elements exist on the entire planet because they aren't in that particular pebble.

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

#96

Post by JimmaDaRustla »

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…

"signs of life" versus "life", big difference.

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

#97

Post by dangrossman »

akiselev wrote: post #76
dangrossman wrote: post #68

Earlier quoted context omitted.

What an annoying meme. What part did you find so surprising that you want additional references, but couldn't find a better way to ask for them? As to the first part, there are uncountable examples of water-based life, and zero examples of non-water-based life. That doesn't rule out its existence, but basic chemistry makes it unlikely, and it won't look anything like life as we know it. No other liquid has the proper…

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 logfromblammo: https://news.ycombinator.com/item?id=10292067

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

#98

Post by logfromblammo »

dangrossman wrote: post #68
comboy wrote: post #53

Earlier quoted context omitted.

"Water is the only molecule that fits the bill, and happens to be the second most common molecule in the universe." [citation needed]

What an annoying meme. What part did you find so surprising that you want additional references, but couldn't find a better way to ask for them? As to the first part, there are uncountable examples of water-based life, and zero examples of non-water-based life. That doesn't rule out its existence, but basic chemistry makes it unlikely, and it won't look anything like life as we know it. No other liquid has the proper…

Start off by populating the universe with loose atoms.

You're going to have quite a lot of H, some He, and ever decreasing quantities of larger atoms. The abundance of atoms in our galaxy by mass is 74% H, 24% He, 1% O, 0.5% C, 0.1% Ne & Fe & N, 0.05% Si & Mg & S. When you break it down by quantity of atoms, the spread only grows wider. 92% H, 7.5% He, 0.1% O, 0.05% C, 0.01% N & Ne, and ~0.003% Mg & Si & Fe & S.

Now, for each atom, you're going to work the room at the universal party. If you're an H, you show up early to the party, and you're very likely to run into another H and really hit it off. So most of the H in the universe is going to pair up as H2 before anyone else even shows up. He and Ne don't really want to be at the party. They hang out in the corners and stare at their own quarks. So let's just pair up all those H atoms into H2 and ignore the He and Ne.

We're now at 99.6% H2, 0.2% O, 0.1% C, 0.02% N, ~0.005% Mg & Si & Fe & S among atoms that actually want to bond.

So C, N, Mg, Si, and Fe are pretty chill. If they happen to meet up with a lone H, they get along together pretty well. Otherwise, they're content to circulate around the party and meet other atoms looking for a good bond.

But O and S are a little crazy. They are not going home alone, ever. And usually, they're going to hook up with the first other atom (or molecule) they meet at the party. Almost every O that joins the party is going to end up as the meat in an H sandwich and leave the party. By coincidence, some will become O2 and be content. A bit less will become CO, or NO, and a very tiny amount will end up in MgO, SiO, FeO, or SO. And those will stay at the party, looking to bond more.

So just by random meetings based on relative abundance, it is clear that H2O is going to be third among discrete chemical units, and second among bonded molecules. If O were less abundant, or less ravenous for electrons, it might be different, but it's pretty safe to say that O will try to react with anything it meets, and it's very likely to meet an H2.

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

#99

Post by coldpie »

DanielBMarkham wrote: post #91
ChicagoBoy11 wrote: post #24

Earlier quoted context omitted.

And that someone seems to be this lady, with this most BAMF job responsibility ever: “These are ongoing conversations,” said Catharine A. Conley, NASA’s planetary protection officer, who coordinates the efforts to minimize the chances of life inadvertently crossing the solar system.

I must be missing something. How would you ever land men on mars if you are striving not to allow life to cross between planets?

The key word there is "inadvertently".

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

#100

Post by jerf »

eddd wrote: post #33

I know that without water life would have never begun, but I still don't fully understand why it is necessary. It is still big discovery though, if life is that common I think we should be more careful during migration there, "Marsian" common cold could wipe out the entire human colony.

You know that science fiction trope of the deadly planet full of life where every last life form is trying to kill every other life form, and they've evolved a frightful array of offenses and defenses to do it?

That planet is Earth. The real Earth. We perceive our ecosystem as friendly only because we've co-evolved with it. It is in objective terms a vicious, vicious place, with every cubic centimeter of any useful resource contended for by thousands or millions of organisms, fighting each other in every conceivable chemical, biological, and physical manner, and in particularly sophisticated corners of the Earth ecosystem, even social manners. It may look peaceful from the apex, but it's not when you get close.

The likelihood of some sort of Martian bacteria getting here and causing amazing problems can never quite be eliminated, but it's very, very low. Plus, if Martian life ever existed, it actually won't be entirely disconnected from Earth life due to what you could call "transpermia": http://users.tpg.com.au/users/horsts/swaprock.html

In fact if life is discovered on Mars, the next question is whether it is just Earth life that hitched a ride and managed to adapt to conditions that aren't necessarily all that much harsher than conditions we've found life on here on Earth. It's interesting either way, but the implications are hugely different between some hitchhiking Earth life vs. life that clearly came from a different abiogenesis event.

Post reply on HN