As far as we know, we're the only life in this solar system. While there are other places in the solar system where we think life could exist, nothing has been proven or even been close to proven. At this point we can't say for sure it's even possible for extraterrestrial life to exist outside our little bubble. That might soon change, however. Researchers claim that they have recently discovered the first-known extraterrestrial protein in a meteorite that fell to Earth 30 years ago.
Over the last few years, other building blocks of life have been discovered in meteorites from our Solar System. Cyanide, ribose, and amino acids have all been discovered in space rocks here on Earth. This latest find would be the first-ever whole extraterrestrial protein.
The paper detailing the discovery was uploaded to the preprint server arXiv, and it has yet to be peer-reviewed, so bear that in mind. The discovery sill has to be replicated by other scientists to prove that it is, in fact, an extraterrestrial protein. If it does check out, it would be a clue that there very well could be extraterrestrial life (of some sort) here in this solar system. While it wouldn't be direct evidence of extraterrestrial life, proteins are necessary building blocks of life and it would show that they can form outside of Earth.
The meteorite, named Acfer 086, landed in Algeria in 1990. Since then, it has been kept in a museum. It had been analyzed previously, but the authors of the paper decided to attack it again with "state-of-the-art" mass spectrometry. According to ScienceAlert, astronomer and chemist Chenoa Tremblay of CSIRO Astronomy & Space Science in Australia, who was not involved in the research says:
"In general, they're taking a meteor that has been preserved by a museum and has been analysed previously. And they are modifying the techniques that they're using in order to be able to detect amino acid inside of this meteor, but in a higher signal ratio."
According to the paper, the researchers found the amino acid glycine, which had already been discovered in the meteorite, at a higher signal ratio than previously found. They also found that the glycine was bound to other elements including iron and lithium. After modeling the structure they realized that they had an entirely new alien protein, which they named hemolithin.
While hemolithin is similar in structure to proteins found on Earth, its ratio of deuterium to hydrogen isn't found on Earth. It is found, however, in long-period comets. The researchers argue that this protein likely formed in the proto-solar disc, some 4.6 billion years ago.
They do acknowledge that they may be completely wrong, although they don't think it's likely. Another explanation is that this isn't a protein at all, but some other type of polymer, but the researchers say this is an outside possibility.
It's a bit too early to get over-excited about this. After all, it still has to pass peer-review. But there's a good chance that this is actually an extraterrestrial protein. That would mean that the chances of extraterrestrial life in our Solar System just became a bit more plausible.