The bigger question that still remains a mystery: LINK.
That question is not valid. We have no proof life originated on Earth. The earth is comparatively young when compared to the age of the universe.
For many years, there was a scientific website with NASA images from a scanning electron microscope of asteroids cut in half. Inside were fossilized bacteria that were similar, but not identical to those found on Earth. For some time there was speculation of "seeding". I can no longer find the site.
Interestingly, we now know that simple life can last in the vastness of space for a very long time, without any trouble at all.
Also, the evidence is getting to be overwhelming for life elsewhere. Many scientists, from different countries have examples of meteorites with common Bacteria like structures, nanobacteria, diatoms, and filament like bacteria, complex organic molecules and so on.
I remember seeing the scanning electron micrographs of their evidence. Sketchy at best. I've seen filiform corrosion under the SEM that looks similar.
I do not believe we are talking about the same "facts" . The NASA based pics were on an official website. There was an in depth structural comparison of earth based bacteria, and the ones found in the rock. Nothing identical has ever been found here, yet the similarities remained stunningly obvious.. The bacteria in question is a complex structure, not a diatom or simple shape. And, there were identical multiples.
I was thinking about NASA's own Richard Hoover publications. NASA has since distanced itself from his claims, but not for scientific reasons. Remember, that's no indication of proof one way or another. I'm certainly no expert and cannot validate his claims. However, it seems that He, and a number of (often more qualified) others have some very significant evidence.
I saw this article the other day and was quite interested, I love pushing the boundaries...
The "Journal of Cosmology" has had some very interesting articles in it for many years now. It's my opinion that the evidence for life existing elsewhere is reaching the point of being conclusive.
This is not based in "belief" or "debunked facts" but in actual, real world results. Scientists all over the globe are finding clues. It really is getting hard to ignore.
For example, "Dr. Richard Hoover's" results were supposedly debunked. Not by scientific method, but by an "attack" on his status as a PhD, since he is not a PhD, only a NASA Scientist. Where the PhD status came from is likely a mistake by a magazine. Yet, that is the substance of the "debunking". It really is a weird world we live in, where someone's findings can be dismissed due to an unrelated publication error of a magazine.