Scientific American By Jeremy Hsu on August 1, 2018
Japanese and U.S. missions could yield new discoveries about the origins of life on Earth
If all goes according to plan, two spacecraft will commence close encounters of the curious kind with two separate asteroids by the end of August. Their goal: to retrieve samples that may contain organic materials dating back to the solar system’s birth. These building blocks may be key to understanding the origins of the planets and of life on Earth—and could also make future space prospectors very rich.
As of this writing, Japan’s Hayabusa2 probe was on track to arrive at a kilometer-wide asteroid called Ryugu around June 27. On August 17 a NASA craft, OSIRIS-REx, is scheduled to arrive within sight of a roughly 500-meter-wide asteroid called Bennu. These space rocks will be the focus of approximately two years of sensor surveys and efforts to collect samples for scientists back on Earth to analyze.
“There are going to be so many groups around the world that are going to be able to study the samples for decades to come,†says Nancy Chabot, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, who is not affiliated with either mission. The new data, she says, are “really going to revolutionize what we understand about the composition and the makeup of these primitive bodies from the early solar system.†Hayabusa2 and OSIRIS-REx will not be the first missions to retrieve an asteroid sample. That honor went to Japan’s first Hayabusa spacecraft, which in 2010 returned to Earth with a tiny sample from the asteroid Itokawa after an unplanned crash on its surface. Itokawa is representative of so-called S-type asteroids, which consist primarily of stony materials.
In contrast, Ryugu and Bennu fall into the carbonaceous (C-type), or carbon-containing, class of asteroids—the most common space rocks in the solar system. Taken together, samples delivered by OSIRIS-REx and Hayabusa2 could confirm that these asteroids have a composition similar to those of “carbonaceous chondrite†meteorites discovered on Earth. Such meteorites contain organic compounds, in addition to water locked inside hydrated minerals. But these meteorites may have been contaminated by Earth’s surface. If the composition of the asteroids matches that of the meteorites, it would suggest the compounds could have been brought here from space.
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https://www.scientificamerican.com/article/asteroid-sample-return-spacecraft-are-approaching-their-targets/
