Muso
Quote:


Science can now answer a very big question about our atoms.
Where will our atoms - we ourselves - end up?
Apparently one day the sun will swallow the earth  & we will become part
of a red giant.
Many 10's of billions of years after we will be sucked into a black hole at the center
of our galaxy.
Look up to the center of the Milky Way & that's where you're going!

Muso - I think you are drawing a long bow.

Life on earth can thrive in sea water at volcanic vents where
there is no light, and also at high temperatures & pressures.
Therefore it could possibly survive on Mars.

Surviving in such an environment, existing organisms moving into and occupying such a niche environment are a separate issue to evolving in such an environment.

It is a facinating subject and I loved listening to Carl Sagan talk about this..in fact Carl Sagan is super-nerdy-cool.

I read "Wheelers" by English mathematician Ian Stewart and reproductive biologist Jack Cohen a busy decade ago and this subject makes me want to get it back out of the box....(waiting for book shelves in our new home). I need about 10-12sqm of shelf space. Libraries make the best furniture.

Yes the moons of the gas giants are very interesting places and would dearly love to see what happens there. I know it is a lot to expect life period and complex life is in the realms of the fantastic...but I'm a sucker for a good imagination.

It's a bit more difficult to envisage such a bacterium originating from scratch - the earliest organisms were probably a lot simpler than this.

It's a bit more difficult to envisage such a bacterium originating from scratch - the earliest organisms were probably a lot simpler than this. 

Well I was talking about modern extremophiles, and we have reasonable grounds to suspect that these extremophiles that we have today came along much later in the scene.

Smaller and more primitive organisms are naturally suited to that kind of environment (hot soupy) anyway.

Bobby. wrote on Jun 28^th, 2010 at 7:10pm:


I've heard people say that before, but I'm not sure where they got it from. The first oceans probably appeared on Earth about 3.9 billion years ago.  

The first oceans on Mars appear to have formed  late in the Noachian period, around 3.5 billion years ago, although the exact timing of Martian geology is subject to considerable interpretation.  

Both Mars and Earth formed around 4.5 - 4.6 billion years ago - about the same time as the solar system itself. We can tell that from isotope analysis.

There is no evidence that conditions for life were better on Mars earlier than on Earth. The other point is that the Earth rapidly developed a geomagnetic field, unlike Mars. There is evidence of some localised magnetism in the Southern hemisphere of Mars, but it never became a strong global magnetic field.

All this becomes important when we consider that the solar wind was about 100 times stronger 3.5 million years ago and the magnetic field deflected the worst of the solar wind (towards the poles).

The first conclusive life on Earth can be dated at about 2.9 Billion years ago. There are possible indicators of life 3.5 billion years ago from highly metamorphised deposits in Greenland, but these are by no means conclusive.  

To state that it is more likely that life originated on Mars, first you need to show that life actually formed on the more hostile conditions on Mars in the first place. We have no evidence that there was ever life on Mars, and we have plenty of evidence that there was never extensive life on Mars.  

Some researchers argue that the slightly alkaline conditions of the beginning of the Noachian. However it all depends what form that hypothetical life took. If it was bacteria that used sulfur or iron for their respiration, then the prime period would have been the end of the Noachian, by which time acidic seas had started to form.

For me, even though astrobiologists like to dream, Occam's razor seems to favour abiogenesis on Earth as the more likely scenario.

Let's put radiation levels in perspective. Radiation levels in interplanetary space today can rise to as high as 100,000 milli-rems per event in a flare, and constant exposure is approximately 1,000 milli-rems per day (30 times that on Earth, 10 times that on the Shuttle) and approximately double that on the surface of Mars (because it rotates). Approximately 80% of this radiation is in the form of high energy protons. Take conditions 3.5 billion years ago and you can multiply those radiation levels by roughly 100.  

Which kind of bacteria could have made the trip? Halobacteria? They would be the most likely to survive. They do pretty well in saline conditions, but not in high radiation conditions. Deinococcus radiodurans was certainly not around then.

Like you, I'd love to know whether or not there was ever life on Mars, but even if they find fossilised evidence, will it be convincing?

Life on earth 'began on Mars'

Geochemist argues that seeds of life originated on Mars and were blasted to Earth by meteorites or volcanoes.

Evidence is mounting that life on Earth may have started on Mars. A leading scientist has claimed that one particular element believed to be crucial to the origin of life would only have been available on the surface of the red planet.

Professor Steven Benner, a geochemist, has argued that the "seeds" of life probably arrived on Earth in meteorites blasted off Mars by impacts or volcanic eruptions. As evidence, he points to the oxidised mineral form of the element molybdenum, thought to be a catalyst that helped organic molecules develop into the first living structures.