Tuesday, 20 October, 2020

Touch-and-go: US spacecraft sampling asteroid for return

An artist's rendering of NASA’s OSIRIS-REx spacecraft collecting a sample from the asteroid Bennu. Image Credit NASA  Goddard  University of Arizona An artist's rendering of NASA’s OSIRIS-REx spacecraft collecting a sample from the asteroid Bennu. Image Credit NASA Goddard University of Arizona
Sandy Nunez | 19 October, 2020, 05:20

After nearly two years circling an ancient asteroid hundreds of millions of miles away, a Nasa spacecraft will this week attempt to descend to the treacherous, boulder-packed surface and snatch a handful of rubble.

The drama unfolds from tomorrow as the United States takes its first crack at collecting asteroid samples for return to Earth, a feat accomplished so far only by Japan. A van-sized spacecraft will have to negotiate a building-sized rock around the landing pad to land in a relatively clean space with only a few parking spaces. Boulders as big as buildings loom over the targeted touchdown zone.

"OSIRIS-REx, which is about the size of a 15-passenger van, is now orbiting the asteroid Bennu 200 million miles from Earth".

Once it drops out of its 0.75 kilometer-high orbit around Bennu, the spacecraft will take a deliberate four hours to make it all the way down, to just above the surface. Video filmed on Friday shows hazy and polluted skies.

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer mission, better known as OSIRIS-REx, is set to collect samples of an asteroid named Bennu on October 20, at 6:12 p.m. EDT. Its actual contact with this ancient object would last under five seconds.

Live coverage of the spacecraft's descent toward the asteroid's surface, as well as its "Touch-and-Go" maneuver, will be provided by NASA Television and its website at 5 p.m. EDT. With an 18-minute lag in radio communication each way, ground controllers for spacecraft builder Lockheed Martin near Denver can not intervene.

Osiris-Rex has existed as a concept since at least 2004, when a team of astronomers first proposed the idea to NASA.

While NASA has brought back comet dust and solar wind particles, it's never attempted to sample one of the almost 1 million known asteroids lurking in our solar system until now.

This mosaic image of the asteroid Bennu consists of 12 PolyCam images collected by December 2, 2018 ...

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And what is the language?" she said. "We're just making a light touch , ' they said". The White House did not immediately return Business Insider's request for comment.

The tallest, largest, blackest, roundest, most carbon-rich space rock in the world, when the Solar System was formed 4.5 billion years ago.

"This is all about understanding our origins", said the mission's principal scientist, Dante Lauretta of the University of Arizona.

There are also selfish reasons to get to know Pennu better. Bennu, however, could potentially threaten Earth late in the next century, as it has a 1-in-2,700 chance of impacting the planet in one of its close approaches.

Bennu has mostly had no nuisance for billions of years, so bino can be made from material containing particles that were present when life first formed on Earth, NASA says. So the spacecraft was created to ingest small pebbles less than 2 centimetres across. OSIRIS-REx will use a "Touch-And-Go" (TAG) maneuver by briefly landing on the asteroid's surface to snag the samples before finally heading back towards Earth. And pebbles were occasionally seen shooting off the asteroid, falling back and sometimes ricocheting off again in a cosmic game of ping-pong.

With very rough terrain, the engineers aimed for a tighter space than initially expected. Nightingale Crater, the prime target, appears to have the biggest abundance of fine grains, but boulders still abound, including one dubbed Mount Doom.

The team fell behind and collided with the second and final Touch and Go costume rehearsal for the spacecraft for August.

On September 24, 2023, Osiris-Rex will land in the Utah desert to dispose of sample return capsules that will be recovered for research. Osiris-Rex is equipped with three nitrogen cones to ignite and degrade the surface, which means the team makes three attempts to capture a specimen. But not quite on the scale you might expect if you're picturing a spacecraft hauling a giant space rock.

The sampler head that will touch the asteroid is a bit larger than a dinner plate, and the goal is for it to collect anywhere from 60 grams to 2 kilograms (about 2 ounces to 4.5 pounds) of material. If that were the case, the spacecraft would automatically retract to a height of 16 feet and try again.