Asteroid Bennu surprises with rocky floor and exercise – Astronomy Now

March 20, 2019 - Comment

A high-resolution view from the OSIRIS-REx spacecraft exhibiting the rockier-than-expected floor of the asteroid Bennu, one among many surprises because the probe slipped into orbit across the tiny physique final December. Picture: NASA/Goddard/College of Arizona/Lockheed Martin NASA’s OSIRIS-REx spacecraft, intently finding out the asteroid Bennu, has discovered one shock after one other since slipping into



A high-resolution view from the OSIRIS-REx spacecraft exhibiting the rockier-than-expected floor of the asteroid Bennu, one among many surprises because the probe slipped into orbit across the tiny physique final December. Picture: NASA/Goddard/College of Arizona/Lockheed Martin

NASA’s OSIRIS-REx spacecraft, intently finding out the asteroid Bennu, has discovered one shock after one other since slipping into orbit across the tiny physique three December. Within the pattern return mission’s most dramatic discovery to this point, OSIRIS-REx has monitored not less than 11 “ejection occasions” wherein rocky streams of particles could be seen spewing into area, among the fragments transferring quick sufficient to flee the asteroid’s minuscule gravity.

“A few of these slow-moving particles have been noticed over durations of not less than every week, and they look like trapped within the asteroid’s gravity subject and are ending up in orbit round Bennu,” Dante Lauretta, the OSIRIS-REx principal investigator, advised reporters on the Lunar and Planetary Science Convention in Woodlands, Texas.

“So it’s creating its personal set of pure satellites,” he stated. “After which a few of them have been noticed to fall again onto the floor. Principally, it seems to be like Bennu has a steady inhabitants of particles raining down on it from discrete ejection occasions throughout its floor.”

Cautious evaluation signifies the fragments don’t pose a menace to OSIRIS-REx, however they could complicate navigation because the spacecraft slowly orbits and descends to the floor to gather soil samples subsequent 12 months.

In a major discovery, OSIRIS-REx’s cameras have noticed a number of ejection occasions wherein particles (middle and higher proper) are spewing away from Bennu. Picture: NASA/Goddard/College of Arizona/Lockheed Martin

One other complication? Bennu is way rockier than anticipated primarily based on radar observations from Earth, and discovering a comparatively clean space the place the probe’s touch-and-go pattern acquisition system collector, or TAGSAM, can work correctly shall be harder than anticipated.

Mission planners initially anticipated deciding on a pattern assortment space greater than 160 toes throughout, however they now might want to put TAGSAM down on a a lot smaller goal.

Wealthy Burns, the OSIRIS-REx challenge supervisor at NASA’s Goddard House Flight Centre in Greenbelt, Maryland, stated the spacecraft’s navigation system is extra exact in flight than anticipated and “we really feel assured our methods and our groups are as much as the duty of tagging to a pattern assortment website of a lot smaller than was beforehand envisioned.”

“You may think about you’re simply taking pictures at a dart board, simply making an attempt to hit the board,” he stated. “Effectively now, we’re going to attempt to hit the centre of the bull’s eye. We really feel just like the efficiency of the system and the staff helps that notion, and we’re working actively to make that occur.”

Bennu was found in 1999 and chosen as a goal for OSIRIS-REx as a result of it’s comparatively near Earth and rotating slowly sufficient for the spacecraft to “match charges” for the pattern acquisition. It is also wealthy in carbon compounds and potential natural precursors of life because it’s recognized on Earth.

OSIRIS-REx was launched in September 2016. It’ll spend greater than a 12 months mapping Bennu in extraordinary element earlier than the science staff selects a chief and backup sampling space.

If all goes effectively, the spacecraft will descend to only above the floor in the summertime of 2020, briefly urgent TAGSAM onto the soil. The pattern collector, mounted on the top of a robotic arm and formed considerably like a cake pan, will hearth nitrogen gasoline to fire up the soil instantly under, capturing mud and small rocks kicked up from the floor.

The samples then shall be saved in an aerodynamic return car for return to Earth in 2023.

Asteroid Bennu is formed considerably like a baby’s toy high. It’s a “rubble pile” asteroid, one of many few in its class recognized to be actively ejecting materials from its floor. Picture: NASA/Goddard/College of Arizona/Lockheed Martin

“Bennu doesn’t comprise the in depth patches of fine-grained regolith in keeping with which we designed the mission,” Lauretta wrote in a letter to the journal Nature this week. “Nevertheless, we recognized a number of areas, starting from 5 to 20 meters (16 to 65 toes) in extent, that seem comparatively freed from spacecraft hazards and have textures suggestive of plentiful superb particles.

“We are going to carry out a radical security evaluation of the asteroid surroundings and all potential pattern websites earlier than committing the spacecraft to descent to the floor. Though we face a actuality that differs from a lot of our predictions, we’ll try and pattern Bennu earlier than the spacecraft departs for Earth.”



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