Does the notion that the first cell came from outer space hold any scientific merit?
One of the ways in which origin of life researchers try to get around the insurmountable problems
with explaining the origin of life here on Earth is to appeal to a delivery of life from
an extra-planetary or extra-solar source.
This is called panspermia, and the idea is that life didn't originate on Earth but was
delivered to Earth through some kind of transport mechanism.
The problem with those scenarios are legion, though.
For example, if a bacteria is traveling through outer space, it's going to be exposed to high
energy radiation, and its survivability is going to be rather short-limited.
And once there's an entry mechanism, the frictional heating for something to travel through our
atmosphere to arrive on the Earth would be so intense that it would sterilize any kind
of organism that would be present in that delivery vehicle.
So it's very difficult to envision how life could survive that transportation, how it could
survive entry to the Earth.
When those impactors strike the Earth, huge amounts of energy are liberated, which would
incinerate those life forms.
So it's a mechanism of desperation in my mind.