In 1990, the meteorite known as Acfer 086 came to Earth and landed in Algeria. For the past thirty years, scientists regarded it as just another rock from outer space. But a new study reveals that this 173-gram meteorite may be much more important than that.
A team of researchers including physicist Malcolm McGeoch of PLEX Corporation, molecular and cellular biologist Julie McGeoch of Harvard, and chemist Sergei Dikler of the Bruker Scientific Corporation, were examining Acfer 086 found a protein inside the meteorite—the first extraterrestrial protein ever discovered. In February 2020 they reported their findings in a paper published to the open-source scholarly archive arXiv.
Using a high-precision mass spectrometer to examine the composition of the meteorite, the scientists were able to identify a protein that they named “hemolithin”. Comprised of two amino acids, glycine and hydroxyglycine, as well as iron, lithium, oxygen, and, more peculiarly, the heavy hydrogen isotope deuterium, hemolithin reveals a complex chemistry unlike any protein found on Earth. The ratio of hydrogen in the deuterium resembles what is seen in the Oort cloud of cosmic bodies that forms the outermost reaches of the Solar System, which suggests that the protein on Acfer 086 formed approximately 4.6 billion years ago.
Hemolithin itself is not alive, and the scientists who found are not claiming that it is positive evidence of alien life, but its discovery raises some intriguing questions and possibilities. For one, it suggests that life may exist in the reaches of space. It also implies that such life might share some similarities and some differences with life on Earth. Finally, as with all discoveries that point to how life might develop in the extreme environment of outer space, the findings reveal more about how life might have formed on Earth itself.
The discovery of the hemolithin protein is one of a number of findings that scientists have made in recent years that all point to how life might form on other worlds. Other meteorites and comets have turned up amino acids, which, when combined, are what form proteins, as well as water and the RNA-forming sugar ribose. Organic molecules made of carbon and oxygen—the building blocks of life on Earth—have been found in the atmosphere of Saturn’s largest moon, Titan. While scientists have long assumed that proteins might exist in space, before the finding of hemolithin, none had ever been found and scientists had no real idea of what their composition or structure might be.
Some scientists, however, have cautioned that more tests need to be conducted before the presence of the protein can be confirmed. They point out that the study has not yet been peer reviewed, and to the fact that the structure of the protein is unlikely to occur in nature. The authors of the study themselves have pointed out that hemolithin might, in fact, simply be another polymer and not a protein at all. Further study of Acfer 086, and other meteorites like it, will need to be conducted in order to verify the team’s findings.