Water on Mars - Clues to Life?

PHPee writes: "Reports of water on Mars say that huge amounts of water gushed through the surface of the red planet fairly 'recently'. (Recently being as little as 10 million years ago) This is big news, because it may lead to finding some simple forms of life on the planet. For more info, check out: (story #1) and (story #2)."

Comments

Re:Why we look for water and life on Mars

[Ubi_NL]

It is to estimate the likelyhood of more life in the universe,

It is a misconception that water is a requirement for life. Sure, life without water is practically impossible on earth. This is mainly because the melting point and boiling point of water are in the range of temeratures encountered here. That is also where carbon-based lifeforms are usefull.
Now on a much hotter planet for instance, COH lifeforms won't hack it, as the COH bindings are too weak to hold on at very high temperatures. In such cases it would be wise to adapt a Si-based form, which has quite similar characteristics to C when placed at a higher temperature.
On the other hand, when a planet is much cooler, water is pretty useless as it's only present as ice. Mind you: ice is no good when you are dealing with cell-like organisms (as we are). In such case another liquid is more practical (maybe some very apolar fluid)

We shouldn't decide whether something can be called 'life' just because it looks like us. Life should be quantified in terms of energy and entropy instead

Re:Consider the fact

[skilef]

Although we are limited as humans in our theoretical resources, there are strong indications that the chances for carbon-hydrogen based life on mars are bigger than for an unknown form. If you look at Mars' atmosphere, you see a 50x higher concentration of carbondioxide compared to earth. If you combine the fact that life needs some kind of energy (geothermal, sunlight) for its metabolic pathways, and that those sources for energy are available at places where water and carbondioxide are present, carbon-hydrogen based life seems to be the most plausible form. Because of the low temperatures on the surface there is a bigger chance for finding some kind of subterranean thermophilic lifeform than anything on the surface.
The chance is very small however; therefore, I think it's more important that the presence of water enables us to create colonies on Mars in the near future: water can be used as a source of energy and offcourse to quench our thirst..

Re:Life on Mars...

[mcfiddish]

Scientists actually finding that unlikely piece of Mars on Earth, in dirt.

I believe the meteorite you're talking about was found in Antarctica. I have a friend who was doing research there one season, and she said one of the things they would do when they were bored was look for meteorites. Pretty much anything that wasn't snow was a meteorite!

Re:Why we look for water and life on Mars

[meiocyte]

One of the key characteristics of life as we know it is chirality [chiral.com], which is...(snip)



I don't understand this at all..

First of all, it's very hard for a molecule beyond a certain size to not be chiral - if you have an atom coordinated to 4 different groups, that's all you need.
And although organisms are full of chiral molecules, that doesn't mean that chirality is somehow a "key characteristic of life" - it's just a trivial consequence of the fact that you need big, complicated molecules to build robustly self-reproducing objects.

Carbon-based organic molecules have this property but phosphorus-nitrogen ones do not.

But the polyphosphazene polymers you provide a link to could easily be chiral, if the R groups are different!

Chirality suggests that organic molecules might need to embody certain mathematical characteristics that are fundamental to life. What we would need, therefore, is a mathematical definition of life.

But why do we need a mathematical definition of life, or indeed any definition of life at all? It's not as if, should we find something on Mars that reproduced and grew, and had a sophisticated metabolism to extract energy, but didn't fit some dimly imagined 'mathematical definition', we would shrug our shoulders and say, "Well, that's quaint, but it isn't life, you know.. let's ignore it.". The word "life" is like the word "game" - it's a word we have no problem using in daily life, but coming up with a precise definition is both pointless and impossible.