Even if there was heavy bombardment, it wouldn't be everywhere at once, and deep sea vents would be somewhat protected by kilometers of water. (assuming the bombardment wasn't so severe as to vapourise the ocean).
Umm... that’s a pretty remarkable finding... how is this the first time I’m hearing about this? Is their evidence considered too weak or speculative to challenge the currently accepted timeline? I thought we had this whole evolution thing (mostly) figured out...
Panspermia as a theory has been around for a while, but there’s no real evidence to support it yet. The weaker forms of the theory don’t postulste life as being extraterrestrial, but the complex organic building blocks of life could be.
Until a rigorous model of life can be developed, until life can be created in vitro from non-living stuff, or until evidence of life or complex organics can be found beyond Earth it’s hard to prove or disprove.
The same can be said of pretty much all theories concerning the origin of life on Earth though.
The ending of Clarke's Light of Other Days involves a motif that's common to his work - a civilisation of small, chitinous creatures that existed prior to the accepted cooling-and-then-life-arises theory.
How awesome would it be if it turned out to be right.
It's probably one of our best options if we fail to find a way to reach a destination faster than light (our current candidate being warp).
Microscopic life, especially bacteria, would be simple. We could simply drop off a wide variety of samples on a planet (especially extremophiles) and wait a few billion years. It would probably cost roughly the same order of magnitude as getting a satellite to wherever it is that you want to seed life. This assumes that the planet isn't entirely hostile to even extremophiles.
It also assumes that the extremophiles we have to send can also withstand several decades (or millenia) of interstellar radiation.
And it assumes that we can build a container that can supply them with nutrients and their preferred temperatures, for decades or millenia. Alternately, it assumes they can survive the absence of those things for decades or millenia.
Seems to me the better option would be to assemble the microbes from non-decaying base materials upon arrival. Not that we can do so yet, but it is almost certainly tech we will see within our lifetime.
A better question might be "should we?" Consider that we as a species seem incapable of taking care of ourselves on our own planet. Unless that changes, it seems pretty irresponsible. We would be like the dad that skipped town.
(Taking a step back, big picture, so forgive the mystical language... We ARE talking about morality here, after all...)
What if the ONLY reason humans are worth it to Gaia/life/Earth/etc is the ability to seed life on other planets? What if we're Gaia's reproductive system, the whole reason Gaia puts up with our massive extinction-causing existence?
I've definitely had this thought before. Humans are like a long shot bet. It comes at the cost of the risk of a major extinction event but, if successful, could seed life across worlds directly.
Imagine a hundred worlds all with life forms subject to evolution.
Basically two ways of that life growing past its planet:
1) A lucky asteroid strike or other outside event
2) A form of creature that can build tools to get out of the planet
Only #2 would have an inbuilt strategy for galactic survival.
We wouldn't have to take care of it. Could just seed and let life do its thing.
But to me the real "should we?" is because it might destroy evidence of other events. Maybe there are simple organisms hiding somewhere or some poorly understood phenomenon that would be obscured or destroyed by our introduction of life.
I’d tend to agree, from a sort of “Prime Directive” direction. We’re not so good at guessing really global, long term consequences in unfamiliar systems. We would have to be so sure before introducing life on a distant world. What if there was already very simple life just getting started? We could reduce universal biodiversity with the best of intentions.
My thoughts are that we should send out robust seed organisms on probes with on-board AI that can do adequate scans for evidence of existing life before attempting to release the seed organisms.
A more advanced probe would have AI that could study the target planet as it approached and get more accurate readings on the environment. If no evidence of life is present then the AI could begin to rapidly evolve the seed organisms toward fitness for the detected target environment.
On arrival it could orbit the planet for a as long while continuing to evolve and release new generations of seed candidates and observing changes in the environment. Once evidence that life has taken hold is detected it could stop seeding and just continue monitoring. I'm assuming it would send progress reports home every once in awhile, even if nobody was still here to receive them.
what if all life on earth were about to be destroyed? some killer asteroid or something and we had a couple of years to prepare. And we hadn't populated another planet.
We should probably have to ponder a lot of things before doing that. For instance what could happen if a bad flu virus embarks on a vessel that would crash back on earth in 1 century or 1 millenia ?
Sadly, we do the opposite. All the probes are sterilized first. Me, I'd send probes packed with extremophiles to every rock in the solar system that has an atmosphere.
All You Need is Kill/Edge of Tomorrow covers the worst case scenario, for the receiving planet. I think they left out the explanatory chapter in the novella out of the movie since that required an omniscient narrator or Jeff Goldblum's character from Independence Day.
That life was present as soon as earth was hospitable fits with the intriguing theory that extrapolates the origin of life to predate earth, based on the rate of increase in complexity: http://www.davidyerle.com/where-are-the-aliens/ (actual article pdf 287kb: https://arxiv.org/pdf/1304.3381)