Ancient "ocean world" may have seeded meteorites with life's ingredients
In what sounds like the beginning of an 80s adventure movie, in 1998 a group of kids had their basketball game interrupted by a meteorite crashing to Earth just yards away. It turns out that this space rock, along with another that fell in Morocco that same year, contained traces of liquid water and organic compounds vital to life. Now, a comprehensive chemical analysis of the two meteorites suggests their organic matter could come from an ancient ocean world, giving them the potential to kickstart life wherever they land.
Although we don't know the full recipe, the key ingredients of life include liquid water and a host of organic compounds like amino acids. Evidence of these have been found out in space and in meteorites before, but never in the same place at the same time. Previous studies of these two meteorites marked the first time that pairing was found together.
That makes them enticing for further study, so an international team of scientists analyzed the organic compounds in 2-mm long salt crystals inside the two meteorites. The rocks had been preserved at NASA's Johnson Space Center, and fragments were carefully removed and then tested with an X-ray beamline and microscope, as well as other chemical experiments.
Along with traces of liquid water, the tests detected the presence of organic matter like carbon, oxygen and nitrogen, and more complex compounds like hydrocarbons and amino acids.
"This is really the first time we have found abundant organic matter also associated with liquid water that is really crucial to the origin of life and the origin of complex organic compounds in space," says Queenie Chan, lead author of the study. "We're looking at the organic ingredients that can lead to the origin of life."
Using that information, the researchers examined the evidence to piece together the meteorites' histories, and how they may have picked up their organic payloads. Like most space rocks, these two would have been remnants from the formation of the Solar System, but their chemistry was more complex than most. The researchers theorized that the crystals may have been deposited on the rocks by plumes of ice and water shooting into space, like those seen on Saturn's moon Enceladus, or from ancient oceans on Ceres.
"We revealed that the organic matter was somewhat similar to that found in primitive meteorites, but contained more oxygen-bearing chemistry," says Yoko Kebukawa, co-author of the study. "Combined with other evidence, the results support the idea that the organic matter originated from a water-rich, or previously water-rich parent body – an ocean world in the early solar system, possibly Ceres."
From there, the team says, it's possible that biomolecules or even microscopic life could be trapped in the salt crystals and transported around the cosmos. Collisions between asteroids could spread the organics, and eventual impacts with planets like Earth could kick off the evolution of more complex life.
"Everything leads to the conclusion that the origin of life is really possible elsewhere," says Chan. "There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system's organic composition."
Future studies may examine other crystals in the meteorites that haven't yet been looked at. The research was published in the journal Science Advances.
Source: Berkeley Lab