Evidence of life on Mars - how likely?

Earth's dinosaurs became extinct roughly 45 million years ago. If someone were looking at Earth from a telescope there would be no visible evidence that dinosaurs ever existed.

Therefore could the same be true of Mars? Could there have been intelligent civilizations that died out many millions of years ago that have been since hidden?

Is it possible that if archaeologists were able to dig beneath the surface we'd find evidence of once great civilizations that have been forgotten by time? Could Mars have supported life many millions of years ago?

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Maybe there were aliens. But who cares if they weren't intelligent?

Reply 3

username1539513

Original post by Kittyboy

Maybe there were aliens. But who cares if they weren't intelligent?

Finding any alien life, intelligent or not, would be amazing

Reply 4

Kittyboy

Really? You know there are certain species of bacteria that can survive in really severe conditions, with high temperatures and pressures present, like those found deep down in a volcano. I wouldn't be surprised if mars is found to have sustained life whether in a previous era or even currently. In fact, I think the way people perceive life is overrated, it's pretty common if just carbon-based lifeforms are taken into account, let alone the other types that likely exist. Didn't nasa reveal like 70 or so other earth like planets the other day?

No, that would not interest me personally. What would interest me is if that alien life was intelligent, and that's a much more unlikely outcome. It's definitely not as common an occurrence as just the presence of life - yet of course still a little probable. But unfortunately, if you briefly look up the fermi paradox and reasons why we have yet to discover other intelligent life, it's quite unlikely that such an eventuality will ever happen :/

(edited 7 years ago)

Reply 5

username1539513

Original post by Kittyboy

Yes, I am aware of the existence of extremophiles but the environment of Mars as it stands as present is extremely hostile to life of any sort. Bare in mind that earthly extremophiles still evolved in the relatively gentle conditions of earth that have been conducive to life for millions of years. How could life have even started on Mars, even with water present wouldn't they need organic compounds such as alkanes etc, currently only present on Titan and possibly Enceladus

Reply 6

Kittyboy

Not necessarily, didn't you read what I said? I don't think life has to be carbon-based, but that's debatable and you digress from what I outlined.

Look up the fermi paradox - the wiki page is actually unusually good. Forget mars for the moment.

Reply 7

username1539513

Original post by Kittyboy

No other chemical element, bar maybe Silicon at a push, has the capacity to form compounds complicated enough to rival the sheer complexity that carbon-based life has. What alternative biochemistry do you think there might be?

Even Silicon (the most likely alternative to Carbon) is wrought with problems of its own.

Considering we haven't found any credible scientific evidence of intelligent extra-terrestrial life as of yet, speaking in hypothetical and probabilities in meaningless. Most of the explanations for the paradox listed on the wikipedia are borderline conspiracy theory-ish.

Reply 8

Kittyboy

Why focus on an element that's similar to carbon? Why not one of the noble gases for instance?

Everything we're talking about is hypothetical. Pointing out that the fermi paradox is borderline conspiracy theory-ish is itself meaningless in our debate.

Reply 9

username1539513

Original post by Kittyboy

Because the noble gases don't have the chemical properties needed to support life in any form, let alone intelligent life. Thus we are limited in the number of elements which have the chemical capability to support life

Talking about intelligent life vs non-intelligent is meaningless aswell until we actually find any

Reply 10

Kittyboy

Awfully sure of yourself. Is there some kind of research for this? And if so, then again, why does the element have to be similar to carbon?

I'm not so sure. I reckon simple life is a lot more abundant than intelligent life. Just look at earth. Humans are barely intelligent, and are massively outnumbered by all of the simple species. Plus humans have only just appeared on earth and a nuke or two, which we've manufactured, could easily end it all.

(edited 7 years ago)

Reply 11

Alexion

I can guarantee there was no intelligent civilisations on Mars. Bacterial lifeforms though, I'm sure there are :yep:

Reply 12

IYGB

I think they will find evidence of past life, but not intelligent

Reply 13

username1539513

Original post by Kittyboy

I'm a chemistry undergraduate, I could not be more sure of something if I tried. It's due to the unique properties of the group 4 elements and Carbon in particular. Because I don't know what your general knowledge of chemistry is I shall assume you have studied no further than GCSE level.

Carbon, as you might know, is tetravalent (It can form 4 bonds with 4 seperate atoms.) Outside of Group 4, no other element from any other group can do this with such stability as elements such as carbon and silicon. The capacity of an element to be able to form multiple bonds is very important when considering alternative biochemistry but also the stability of the compounds formed.

If you have studied the biochemistry of life on earth, even the simplest of living organisms (such as an ameobe) are composed of chemical compounds and processes vastly more complicated than most elements of the periodic table can form. It is just not possible, for example, to have an organism made of gold, or titanium, because the mode of bonding in metals is completely different to the mode of bonding required for life.

Not only does an element have to be able to form 4 bonds, but the constituent compound formed has to be very stable for it to be able to withstand the rigours imposed upon it, by, for example, environmental stress and radiation.

Nobody is denying that non-intelligent life vastly outnumbers intelligent life on earth but wasn't your original point that you didn't care about non-intelligent life, only intelligent alien life? Even the extremophiles you mentioned will be carbon based life

Reply 14

Plagioclase

Original post by kalclash

I did a little literature research project on this earlier this year. The early Martian surface (and by early I'm talking about over 3500 million years ago) was very likely a lot more habitable than it is now, comparable to the early Earth. There is good evidence for extensive river systems and lakes that lasted at least tens of thousands of years and potentially even millions of years. Mars would have had a significant magnetic field at this time which would have protected life from ultraviolet radiation more effectively. So it definitely is possible that life could have emerged on early Mars, although obviously this isn't the same thing as saying that life did emerge. There is no evidence that life has ever existed on Mars. However, the Martian environment became more inhospitable to life as time went by so by around 3500 million years ago, any life that existed would very likely be restricted to very simple forms that lived underground, possibly in aquifers. It's a similar story today. We know that there are very possibly underground aquifers on Mars and water on the surface has even been detected, but it is highly ephemeral and hypersaline. It is potentially habitable - there are some extremophiles on Earth that probably could survive on Mars but again, this doesn't mean that life is there or that we should expect it.

However, there is basically zero chance of finding complex life. The conditions on Mars degraded way too early for complex life to have the opportunity to flourish. It took close to three billion years for complex life to emerge on Earth and the conditions on Earth were vastly more favourable than those on Mars. Someone observing the Earth 45 million years ago may not have seen the Dinosaurs but they would have seen a green planet that was infinitely more habitable than Mars ever was.

(edited 7 years ago)

Reply 15

Kittyboy

Fascinating. Yet all of that is based off of earth as the example, no? I know that boron and nitrogen compounds can form similar bonding to carbon to carbon covalent bonds - why won't they be compatible for life too if molecule stability is so ostensibly key?

Reply 16

username1539513

Original post by Kittyboy

Boron is unstable, even explosive in earth-like conditions.

Nitrogen can only form 3 bonds, not 4. Big difference

Reply 17

Kittyboy

Nitrogen can form a dative bond with boron. It can form 4. "Earth like conditions". Again, all of this is based on the earth. Your argument is flawed :P

Reply 18

Plagioclase

Original post by Kittyboy

Nitrogen can form a dative bond with boron. It can form 4. "Earth like conditions". Again, all of this is based on the earth. Your argument is flawed :P

You will not find a respectable scientist on this planet who thinks that Boron or Nitrogen based life is remotely likely. For the reasons that AngryRedhead explained and more, it is very likely that any life that emerges in the universe will be carbon based. This is neither controversial nor is it earth-centric, it's a simple conclusion made from chemistry and physics. Carbon chemistry is vastly more complex than any other element, vastly more so than Nitrogen, and Boron-based life is even less likely because of its incredibly low cosmic abundance.

What is possible is life based around a solvent that isn't water.

(edited 7 years ago)

Reply 19

Siberiaan

Original post by Kittyboy

Nitrogen can form a dative bond with boron. It can form 4. "Earth like conditions". Again, all of this is based on the earth. Your argument is flawed :P