Space

Ancient "ocean world" may have seeded meteorites with life's ingredients

A tiny blue crystal containing organic compounds, taken from one of the meteorites
A tiny blue crystal containing organic compounds, taken from one of the meteorites
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These X-ray images show organic matter (magenta, bottom image) and carbon (top)
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These X-ray images show organic matter (magenta, bottom image) and carbon (top)
A tiny blue crystal containing organic compounds, taken from one of the meteorites
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A tiny blue crystal containing organic compounds, taken from one of the meteorites
An artist's concept of the plumes at Enceladus' south pole
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An artist's concept of the plumes at Enceladus' south pole

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.

An artist's concept of the plumes at Enceladus' south pole
An artist's concept of the plumes at Enceladus' south pole

"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

3 comments
SimonClarke
It would be interesting to find DNA, or at least evidence of, in similar meteorites. it would open up a whole new world as it is considered one of the theories of how life started on earth.
highlandboy
So with options of early earth conditions not appearing conducive to the development of DNA & RNA we are back to panspermia. Scientific method is great at repeating experiments and moving from hypothesis to theory, but imagination is still required to propose scenarios that we can then “test”. Sometimes I wonder if science-fiction does not provide a better starting point than theories. Humans get more attached to their theories and then they have something they feel they must prove. The ability to play with ideas in fiction allows much more scope and less loss of face when they don’t pan out. “Scientific Theorising” with little real evidence is really only science fiction with a pretend dressing of “respectable science”. Many of us would love to know we are not alone in the universe, but let’s not twist the empirical scientific method into a servant that supports fantasy. It is helpful to ask questions based on our observations, but worse than folly to start pretending science justifies the confirmation of our imaginations.
John C Ky
I have read of this on another website which did not allow comments. Did it occur to anyone that the meteorites may have been fragments of a larger rock that shattered either on contact with our atmosphere or impact on the ground, sending shards off at possible orbital or escape velocities? After all, the only analog in our solar system for life and the nearest analog for water is the Earth itself. DNA rich in both water vapor in the upper atmosphere and on the ground in soil. These may not be 'invaders' but returning 'exiles.'