OSIRIS-REx Did One Last Close Flyby of Asteroid Bennu. It’s Almost Time to Come Home – Universe Today

After greater than two years in orbit round asteroid Bennu, NASA’s OSIRIS-REx spacecraft is able to come residence. It’s with it a pristine pattern of house rocks that geologists right here on Earth are keen to review up shut. The pattern will arrive in September 2023, however we gained’t have to attend almost that lengthy for brand new knowledge from OSIRIS-REx. Final week, the probe carried out one remaining flyby of Bennu, in an effort to {photograph} the pattern assortment web site. The images are being downlinked now, and ought to be right here by midweek.

Should you’ve been following the OSIRIS-REx mission, you most likely already know why scientists are eager to see these images, however in case you haven’t, maintain on to your hats – it’s a wild story.

The primary huge shock of the mission got here again in December 2018 when the spacecraft arrived on the asteroid. The crew anticipated Bennu’s floor to be clean and sandy, however the first photographs from OSIRIS-REx revealed a rugged boulder-field, suffering from giant rocks and unfastened gravel.

The crew additionally anticipated the asteroid to be geologically quiet, however simply six days after arriving in orbit, they had been astounded to watch the asteroid ejecting bits of rock from the floor out into house. Lately, the main theories relating to the supply of the ejections are 1. that they is perhaps brought on by small meteoroid impacts, or 2. they is perhaps brought on by thermal fracturing: as Bennu rotates, the Solar repeatedly heats and cools the rocks, inflicting cracks and bursts which permit small particles to flee the asteroid’s weak gravity.

Asteroid Bennu ejecting particles into house, as seen from OSIRIS-REx on 19 March 2019. Picture score: NASA/Goddard/College of Arizona.

Bennu’s unexpectedly tough terrain, together with its shock ejections, made it troublesome to slim down a protected location to land and take a pattern. The crew initially hoped for a 25-meter-wide obstruction-free zone through which to carry out the Contact-and-Go (TAG) pattern maneuver, however the flat open areas OSIRIS-REx may discover on Bennu had been solely 10 meters throughout. Aided by citizen scientists who scoured imagery of the asteroid for protected touchdown , the crew ultimately selected a area dubbed ‘Nightingale’ because the TAG web site.

Landing occurred on 20 October 2020, and OSIRIS-REx picked up a materials that the seize mechanism was caught open. The crew rapidly stowed the capsule earlier than an excessive amount of materials was misplaced, foregoing a deliberate spin maneuver that will have measured the burden of the pattern.

However right here’s the craziest half. Through the TAG maneuver, OSIRIS-REx’s assortment arm plunged 48.eight centimeters deep into Bennu, and would probably have gone meters (sure, meters!) deeper had its thrusters not reversed the ahead movement. In different phrases, touching down on Bennu was extra like leaping right into a ball-pit than like touchdown on stable floor.

OSIRIS-REx’s TAG maneuver on 20 October 2020. Credit score: NASA/Goddard/College of Arizona.

Bennu’s extraordinarily low density – 60% of the asteroid might be empty house – has vital implications for planetary defence. If Bennu had been barreling in direction of Earth (it’s not), the methods wanted to deflect it’d differ considerably from methods used to deflect an asteroid product of a single chunk of rock. Fortunately, astronomers are fairly certain no main asteroids of both form are headed for Earth within the subsequent century or so, so the world’s house packages have a while to check varied concepts.

The pictures being downlinked this week are necessary as a result of they may how the TAG maneuver modified Bennu’s floor within the Nightingale area. “By surveying the distribution of the excavated materials across the TAG web site, we are going to study extra in regards to the nature of the floor and subsurface supplies together with the mechanical properties of the asteroid,” said Dr. Dante Lauretta, OSIRIS-REx’s principal investigator. The brand new pictures ought to arrive on 13th.

A of weeks from now, on Could 10th, OSIRIS-REx will hearth its thrusters in direction of Earth, leaving Bennu behind for good. Scientists are excited to match its pattern of Bennu to the pattern of asteroid Ryugu that the Japanese house program (JAXA) collected final December.

That will not be the top of the mission, both. The pattern capsule will re-enter Earth’s environment, however the remainder of the probe will keep in house, and will head out to rendezvous with one other asteroid later within the . The OSIRIS-REx mission has been stuffed with surprises thus far, and there could also be just a few extra surprises nonetheless to come back.

Learn extra: Rani Gran, “NASA’s OSIRIS-REx Completes Final Tour of Asteroid Bennu.NASA.

Featured picture credit score: NASA/Goddard.

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