Samples from the asteroid Ryugu contain compounds important to life, including uracil and niacin, one of the four building blocks of RNA. This lends credence to the idea that the ingredients for life were brought to Earth by space rocks.
Japan’s Hayabusa2 spacecraft returned 5.4 grams of asteroid dust from Ryugu at the end of 2020, and various laboratories have acquired a small portion of the dust for study. Yasuhiro Ohba Hokkaido University and his colleagues first soaked the samples in hot water for 20 hours, then in hydrochloric acid, and searched for nucleobases in the resulting tea-like extract. They performed a similar procedure to search for organic molecules.
The researchers started with samples weighing less than 20 milligrams, and although only 20-30% of the extract was used for this study, they were able to find uracil and complex organic molecules. While this isn’t the first time such compounds have been found in extraterrestrial rocks, while other discoveries involved meteorites that spent time unprotected on Earth’s surface, Ryugu samples It was pristine, straight from the surface of the asteroid.
“Previous studies could not completely rule out the possibility that the detected nucleobases were terrestrial contaminants,” says Ohba. “This time, under careful contamination control, Ryugu samples were free of contamination from Earth, so this is strong evidence that uracil is indeed present in extraterrestrial material.”
If uracil is present, there may be other life-key compounds on Ryugu as well, but due to the small sample size, we were unable to see them. Fortunately, NASA’s OSIRIS The -REx spacecraft is on its way back from another asteroid called Bennu, containing more than 400 grams of asteroid dust, and is expected to arrive in September 2023.
“In addition to uracil, we very much hope that other nucleobases and more interesting molecules will be detected in Bennu samples because much higher quantities are available for laboratory analysis.” says Ohba.
Asteroids like Ryugu and Bennu were an important part of planet formation in our solar system, so if these compounds existed there, they were almost certainly present on early Earth as well. important ingredients for , may have been delivered to Earth on similar asteroids, so studying the samples could help pinpoint what prebiotic chemistry was going on when the planet was young. increase.
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