Oct 8, 2020 - Science

Piecing together an asteroid's history

A global map of the asteroid Bennu in blue and red
A global map of Bennu. Photo: Simon et al., Science (2020)

The space rock that eventually gave rise to the asteroid Bennu — currently being studied from close range by NASA's OSIRIS-REx spacecraft — may have had flowing water, according to a new study in the journal Science.

Why it matters: Asteroids are thought to be building blocks leftover from the early days of the solar system, and understanding their nature could provide insights into its evolution.

State of play: Bennu is thought to have formed when a huge impact broke apart its parent body at some point in the relatively early days of the solar system.

  • That parent body — which likely formed from ice and rocky material — eventually heated up.
  • "When it heated up, the ice originally incorporated was turned into liquid water," Hannah Kaplan, one of the authors of the new study, told Axios.
  • The scientists behind the new study found veins of carbonate on Bennu, suggesting water was flowing through fractures in the parent body only a few million years after the formation of the solar system.

Yes, but: This finding doesn't mean there was some kind of life on the airless body, but it does lend further proof to the idea that our solar system is rich in water and perhaps the building blocks of life.

  • "I think more likely it is an environment that fosters liquid water and organics, which may then be delivered to a more favorable surface," Kaplan said.

What's next: OSIRIS-REx is about to set down on Bennu to sample the space rock this month.

  • That sample will then be sent back to Earth where scientists will be able to analyze it and learn even more about the history of the asteroid.
  • If the sample contains carbonate, for example, scientists may be able to learn even more about Bennu's possibly watery past.
  • "Every time we visit an asteroid, we see something unexpected... The diversity present in the asteroid population in terms of geology, chemistry, and geophysics is vast, and we have only scratched the surface," planetary astronomer Andy Rivkin, who wasn't affiliated with the new study, told Axios via email.

Of note: This study was one of six in a package released by Science and Science Advances this week. Read all of them here.

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