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Surprise! Bennu's "Active Asteroid" is a rare space rock that ejects particles



The asteroid near the Earth Bennu is much more strange and more interesting than scientists have thought.

1650ft (500m) of space ejects particles of dust and gravel into space. several times over the last few months, the recently announced observations from the NASA OSIRIS-REx spacecraft reveal. Thus Bennu is one of a dozen or so-called "active asteroids" – and the only one that is closely monitored.

The discovery "is perhaps the biggest surprise of the early stages of the OSIRIS-REx mission, and I would say that this is one of the biggest surprises in my scientific career," said Osiris-Rex's chief researcher Dante Loretta of the University in Arizona at a press conference today (March 1

9).

OSIRIS-REx: NASA mission to take asteroid samples in photos

OSIRIS- REX worth $ 800 million Launched in September 2016 and arrived in orbit Bennu on Dec. 31 last year.If everything goes according to plan, in by mid-2020, the probe will sink and take a sample of Bennu's material that will fall to Earth in a reverse capsule in September 2023.

An analysis of this virgin cosmic dirt and gravel will help scientists better understand the early days of the solar system, which can also help uncover the role that dark, carbon-rich asteroids like Bennu can play in delivering water and the chemical building block of life on our planet, OSIRIS- REx. about how potentially dangerous asteroids move through space, and which of the rocky spaces of miners may want to go down the road, among other things. Indeed, there are numerous auxiliary goals, as indicated by the full name of the mission: "Origin, Spectral Interpretation, Resource Identification, Security Survey-Regolith."

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But the team did not expect to consider more closely an active asteroid. So, it was a great surprise when OSIRIS-REx photos showed particles that were emanating from Bennou's healthy surface on January 6th, just a week after the probe arrived in orbit around space rock.

And this was hardly an isolated incident: The members of the mission team have now identified 11 such events, three of which are "substantial" involving dozens to more than 100 particles, Lauretta said. And researchers continue to view the images.

Ejection events include pieces of space rock ranging from a few centimeters to tens of centimeters in diameter, Lauretha said. And particle velocities also vary widely. Some move at speeds of up to 11 km / h, fast enough to avoid Bennu's weak gravity and travel to the interplanetary space. Other pieces just got out, trapped in orbit around Bennu to spell, and then fallen back to the surface of the asteroid.

"In principle, it seems that Bennu has a continuous population of particles floating on it from discrete ejection events on his surface," said Lauret. "This is incredibly exciting."

The team does not know what stimulates events Discharges were observed during the closest passage of Bennu to the Sun during the elliptical orbit of the asteroid that happened this year on January 10. So, the solar warming of the surface of the asteroid and near it can be the main engine (19659002) (BENNU's orbit accepts the cosmic scale of 0.9 astronomical units, or AU, up to the sun and up to 1.36 AU Reminder: One AU is the distance Sun-Sun, which is about 93 million miles, or 150 million kilometers.)

Related: Asteroid Basics: Space Rock Quiz

But let's go back to those particles that manage to get rid of Bennu's weak grip. It is possible that these small asteroid pieces cause meteor shower here on Earth every year, Lauretta said. The alleged Bennid shower will appear in September and will be best viewed from the southern hemisphere

The mission team is working with meteor experts from the SETI Institute to search for Bennids, Lauretta said.

After a series of analyzes, the OSIRIS-REx team concludes that the discarded particulates do not pose a serious risk to the spacecraft or the objectives of its mission. But other complications have arisen, suggesting that sampling by 2020 will be more difficult than previously thought.

Scientists from Osiris-Rex announced today in a series of papers that Bennu is far more robust and boulder than ground radar imaging and modeling work. The original mission project called for OSIRIS-REx to take a sample of material from a fairly flat, flat surface of Bennu with a width of at least 165 feet (50 m). But the asteroid does not seem to have such oases; the largest flat area appears to be in the range of 20 feet (20 feet), mission team members said today. , Said Lauretha at Space.com. The team will probably have to take more high-resolution photos from the sampling site than expected.

But Lauretta and his colleagues believe that OSIRIS-REX will face the challenge. demanded, said Project Manager Ossiris-Rex Rich Burns of the NASA Space Flight Center in Greenbelt, Maryland, during today's press conference. "We feel confident that our systems and our teams are ready to do the job." Out There "(Grand Central Publishing, 2018, illustrated by Karl Tate ) is now out. Follow it on Twitter @michaeldwall . Follow us on Twitter @Spacedotcom or Facebook .


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