What kind of meteorite fell to Earth in 2018?
January 2018 over Strawberry Lake in the vicinity
Inside a meteorite that fell two years ago on the ice of one of the lakes in Michigan, geologists found pure reserves of organic matter that survived its flight through the Earth's atmosphere.
We are often asked if there are traces in meteoriteslife. Often they really meet there, only this life is always of earthly origin. As soon as a fragment of a celestial body falls to Earth, it is immediately colonized by bacteria or lichens. In this case, we were lucky: a meteorite fell on a frozen lake and was found quickly enough, and it did not have time to get heavily polluted.
Philip Heck, one of the study authors, assistant professor at the University of Chicago in the USA
Only recently during his research it was discoveredthat it contains rich reserves of extraterrestrial organic compounds. Substances of this kind, in all likelihood, came to the early Earth along with meteorites and, possibly, contributed to the creation of life.
In total, Heck and his colleagues collected about a dozen fragments of the Hamburg meteorite with a total mass of about a kilogram. Researchers have studied their structure, composition and origin.
Fragment of a meteorite that fell in 2018 in the US state of Michigan
What was found in it?
It turned out that this celestial body belongs toa relatively rare variety - chondrites of the H4 type, which consist of about a third of iron, nickel and olivine. Scientists suggest that such celestial bodies are fragments of the asteroid Hebe. Inside some fragments of the meteorite, scientists have found many organic substances that did not collapse during its fall to Earth.
Have there been other similar meteorites?
- ALH 84001 (Allan Hills 84001)
Meteorite found on December 27, 1984 in the mountainsAlan Hills in Antarctica. According to researchers, it is one of 34 Martian meteorites found on Earth. The mass of the meteorite is 1.93 kg. In 1996, he gained worldwide fame after NASA scientists announced the discovery of fossilized microscopic structures resembling fossilized bacteria in the meteorite material.
According to the theory, the stone broke from the surface.Mars as a result of the collision of a planet with a large cosmic body about 4 billion years ago, after which it remained on the planet. About 15 million years ago, as a result of a new shock, he found himself in space, and only 13 thousand years ago he fell into the Earth's gravitational field and fell on it. This data is established as a result of applying a variety of dating methods.
On August 6, 1996, NASA scientists announced thatthat the meteorite may contain evidence of traces of life on Mars. The article, published in the journal Science by astrobiologist David McKay, caused a lot of resonance. But the scientific community was skeptical about this version.
Electron microscope shows probable bacterial structures in ALH 84001 meteorite
In 2020, Japanese researchers stated thatfound in the meteorite traces of organic compounds containing nitrogen - a key component of biological molecules: proteins, DNA and RNA. Scientists believe that organics may be of Martian origin.
Inside ALH 84001 there are small orangeinclusions of carbonate minerals. It is believed that they precipitated from oversaturated groundwater salts about 4 billion years ago, when the meteorite was still part of the Red Planet. She collided with a large celestial body, the stone broke off and about 15 million years ago was in space. And two millennia later, he finally fell into the Earth's gravitational field and fell to its surface.
CC BY 4.0 / Koike, M., Nakada, R., Kajitani, I. et al. / Nat Commun /
Fragment of the ALH 84001 meteorite from different angles and in different magnifications. Images b and d are enlarged images of grains of carbonate minerals in which nitrogen-containing organic matter was found
- NWA 801 and the Murchison meteorite
Japanese and American astrobiologists atthe development of new methods for searching for traces of extraterrestrial organic matter took into account the mistakes of predecessors. Therefore, while studying the NWA 801 meteorite, they found many complex sugars in two celestial bodies - in the Moroccan meteorite NWA 801 and in the fragments of the famous Murchison meteorite, which fell to the southeast of Australia in the middle of the last century.
Both space bodies are of the carbonaceous typechondrites - for a long time this was the only thing that united them. In 2019, meteorite fragments fell into the hands of an international team of scientists led by Yoshihiro Furukawa of Tohoku University in Japan. With the help of X-ray diffraction analysis, scientists have found in them pentoses and hexoses - sugars contained, for example, in RNA. This molecule, like DNA, encodes genetic information, and it was on its basis that life could arise on Earth.
CC BY-SA 3.0 / User: Basilicofresco /
Murchison meteorite, in the samples of which scientists found sugars
All these meteorite sugars are notedresearchers, contained an unusually high amount of heavy carbon-13, which confirmed their cosmic and abiogenic origin. What is important, similar fractions of the isotopes of this element were characteristic of organic acids, alcohols and other molecules that scientists had previously found in these meteorites and in other chondrites.
The authors of the work note: the probability of the terrestrial origin of the compounds found in the Murchison meteorite and NWA 801 is minimal: they are enriched in the 13C isotope in quantities uncharacteristic for our planet.
What speaks in favor of the extraterrestrial origin of life?
It is believed that the newborn Earth was notorganic compounds necessary for the emergence of life. According to the researchers, they could have been brought in by space bodies. Moreover, in recent years it has become clear that they may contain alcohols and sugars, from which, according to scientists, amino acids were later formed.
Over the past ten years, scientists have collected manyevidence that, theoretically, comets and asteroids could be the source of primary terrestrial organic matter. For example, it turned out that the composition of such objects can contain alcohols, sugars and other organic compounds, from which amino acids and other compounds important for the emergence of life can be formed.
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