Martian microbes could survive up to 280 million years buried underground Ancient microbes on Mars could survive up to 280 million years if they are resistant to radiation and left buried underneath the ground in frozen, moist conditions, according to a study published on Tuesday. Mars is a difficult planet to survive. Lacking a magnetic field, it cannot shield its surface from harsh cosmic …
But we were "born" about 3.5 billion years ago - documented by Dr. Neil Shubin; initially we were fish that worked their way out of the shallow water and started walking around (on four new legs) so the potential for discovering fossils on Mars that reveal a new form of evolution is very interesting. Maybe only microbes these days but in the past we might find a real physical person existed on the planet.
Given the deep biosphere here on earth having life thousands of meters underground, I could see life on Mars still being there after billions of years.
It is also quite possible that it has the same DNA. There has been quite a lot of cross contamination due to meteor strikes over the last few billion years.
Given that there are Martian meteorites on Earth, it is almost certain that there will be terrestrial meteorites on Mars. So, if a terrestrial meteorite (which we know would have a good chance of carrying terrestrial microorganisms such as D. radiodurans) landed on the Martian polar caps, it could easily have a short-lived environment after landing during which surviving bacteria could reproduce. As there is evidence for repeated melting and refreezing at the Martian Poles (e.g. "Spiders" and "trees"), it seems to me that we should EXPECT there to be bacteria or similar micro-organisms at least in the vicinity of the polar ice caps.
Given that a strike on Mars, throwing rocks into space, means that gravitation would pull them towards the sun, I suspect that any rocks thrown from the Earth might be more likely to be found on Venus. Certainly some might head towards Mars but I think the chances are low so we'll probably not find any dinosaur fragments on Mars.
Given that a strike on Mars, throwing rocks into space, means that gravitation would pull them towards the sun, I suspect that any rocks thrown from the Earth might be more likely to be found on Venus. Certainly some might head towards Mars but I think the chances are low so we'll probably not find any dinosaur fragments on Mars.?
I don't understand. Why would the delta-V provided by the impacter more likely make the ejecta head towards the sun than away from the sun?
If something gets knocked off the Earth in any direction roughly towards the sun, with enough velocity to escape Earth's gravity well, it's going to end up in a highly eccentric orbit, which at aphelion is going to be well outside Earth's orbit. At the right angle, this would easily cross Mars' orbit.
tl;dr; - the orbit of these would be elliptical and go beyond Earth's orbit. The more elliptical, the further.
It's actually quite hard to launch meteorites into space. This link suggests: "a minimum crater diameter of ~25km, even before the effects of atmospheric drag on Earth-launched projectiles is considered." and then goes on to suggest ejecta probably don't achieve the necessary escape velocities which "...questions the potential existence of terrestrial meteorites." We've not found any that have dropped back to earth - though they'd probably burn up and be hard to recognise if they survived.
But supposing it's possible, your bacterium has got to survive the impact and launch. It will then be on a ~20cm "pebble" (ibid) where it has to survive the vicissitudes of space for hundreds of thousands of years (for an earth-moon journey), or probably a few million years (for an earth-Mars journey).
It's then got to survive the entry and impact onto Mars, and land in just the right place.
If you accelerate something on Mars over 100m to a speed required to break out of its gravitational field you need to accelerate it at 50000G.Accelerating a piece of rock like that would make it quite hot.
I've yet to see anyone come up with what looks like an even vaguely plausible attempt at getting panspermia going that doesnt involve a 3 stage rocket.
The odds aren't great but we do know of at least one very large impactor here on Earth that arrived about 66 million years ago and hit and area abundant with life and left a crater estimated at 180KM in diameter. I'd imagine a decent amount of matter went spacewards and didn't come back. Would a big impactor increase the odds of something surviving the ejection into space or is it more likely the ejector was subject to so much energy as to make it less likely? I have no idea myself.
There is evidence of other similarly large impactors during previous eras, Here's a list of 40 or so of the largest craters over 25KM in diameter.
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