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Does the notion that the first cell came from outer space hold any scientific merit?

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One of the ways in which origin of life researchers try to get around the insurmountable problems

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with explaining the origin of life here on Earth is to appeal to a delivery of life from

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an extra-planetary or extra-solar source.

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This is called panspermia, and the idea is that life didn't originate on Earth but was

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delivered to Earth through some kind of transport mechanism.

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The problem with those scenarios are legion, though.

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For example, if a bacteria is traveling through outer space, it's going to be exposed to high

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energy radiation, and its survivability is going to be rather short-limited.

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And once there's an entry mechanism, the frictional heating for something to travel through our

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atmosphere to arrive on the Earth would be so intense that it would sterilize any kind

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of organism that would be present in that delivery vehicle.

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So it's very difficult to envision how life could survive that transportation, how it could

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survive entry to the Earth.

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When those impactors strike the Earth, huge amounts of energy are liberated, which would

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incinerate those life forms.

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So it's a mechanism of desperation in my mind.