A time capsule of the first days of the solar system may be the first clue in explaining a lengthy puzzle to those studying life: It turns out to be peculiarly asymmetrical.
The story begins in 2012, when scientists discovered a wave with large waves of rock, now known as Asuka 12236, on the icy extensions of Antarctica. Asuka 12236 was not only a rock, it was a space rock – and also not only space rock. Scientists think it’s a particularly old meteorite, perhaps material that is even older than our solar system, and that makes it the thing of scientists’ dreams.
“It’s fun to think about how these things fall on Earth and happen to be full of all this different information about how the solar system formed, what it formed from, and how the elements are structured in the galaxy. , “Conel M. O ‘D. Alexander, a meteorite scientist at the Carnegie Institution for Science in Washington, DC, and co-author of the new study, said in a statement from NASA.
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And when scientists ground a small piece of Asuka 12236 and compared the results with others meteorite examples, they realized that this particular space stone stood out. In fact, it could hold the key to a long-standing mystery about life. Life, it turns out, is asymmetric on a very small level. Amino acids – the building blocks of proteins, the large molecules that run our bodies and everyone else – each come in two mirror image forms, which scientists have called left- and right-handed. But all the life that scientists have studied has been used excluding left-handed amino acids; right-handed versions of these molecules exist, but do not make them into proteins. Nobody knows why.
Asuka 12236, the scientists knew, was very rich in amino acids, and just like life, the amino acids in the meteorite favored left-handedness. But unless the sample was polluted by terrestrial life – always a possibility that scientists should consider – there must be another reason for the imbalance in the meteorite.
“The meteorites tell us that there was an inherent bias towards left-handers amino acids before life itself began, “said Daniel Glavin, lead author of the new study and an astrobiologist at NASA’s Goddard Space Flight Center in Maryland, in the same statement.” The big mystery is why? “
Glavin and his colleagues think the key may lie in what happened to the back of the meteorite when it was part of an asteroid whispering through space. Inside asteroids, forces such as water and heat can affect the chemistry of space rock, including producing – but also destroying – amino acids.
One particular balance of such effects is probably responsible for the unusually high levels of amino acids in Asuka 12236 and may also explain the asymmetry between left and right hand races, compared to other meteorites.
“It is very unusual to have these large left-handed measurements in primitive meteorites,” Glavin said. “How they formed is a mystery. Therefore, it is good to look at a variety of meteorites so that we can build a timeline of how these organisms evolve over time and the different change scenarios.”
And if the imbalance in the meteorite is not the result of terrestrial contamination, the same responsible process could also address the mystery of the asymmetry of life, the researchers hope. Glavin and his colleagues will continue to look at meteorites in hopes of better understanding how amino acids manifest in space rocks.
But the researchers also came up with another tactic: mouse back-mission, the equivalent of spaceflight enabled meteorite deliveries. Unlike meteorites, space-bound monsters can be protected from the harsh journey through the Earth’s atmosphere, making the rock more barren than even the best-preserved meteorite.
Two asteroid missions are currently working on just such supplies: NASA OSIRIS-REx, which is preparing a sample of an asteroid called Bennu, and Japan’s Hayabusa2, who returns to Earth with pieces of an asteroid called Ryugu to deliver home in December. Performing similar analysis on these samples could help scientists better understand how amino acids form and transform into space rocks, the researchers hope.
The research is described in a paper published on August 20 in the journal Meteoritics & Planetary Science.
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.
