Wednesday, 19 December, 2018

NASA’s first asteroid sample-collector arrives at target, Bennu

Theresa Hayes | 04 December, 2018, 20:17

NASA's OSIRIS-REx spacecraft, the space agency's first effort to bring a sample of its dust from an asteroid back to Earth, reached its target today, two years after its launch in Florida. "When we understand Bennu, we will understand something fundamental about our solar system".

Coverage of the event will be streamed live starting 11:45 a.m. ET. Achievement unlocked and "we have arrived", NASA announced on its official Twitter account. McMahon explained that as OSIRIS-REx brushes past Bennu this time, the asteroid will exert a minute gravitational pull on the spacecraft. At 17:00 UTC, with the spacecraft just 20 kilometers away from its 500-meter-wide target asteroid, OSIRIS-REx lit its engines for a 20-second burn that put it on course for an initial close flyby of Bennu's north pole tomorrow.

In mid-2020, scientists will direct Osiris-Rex to drop down to the object and grab at least 60g of regolith, or "top soil".

Scientists estimate there is a one-in-2,700 chance of the asteroid crashing into Earth 166 years from now. OSIRIS-REx is scheduled to return the sample to Earth in September 2023.

On December 1 it was close enough to Bennu, about 35 km, that the asteroid's gravity dominated over the Sun's. The aircraft positioned itself within 12 miles (19 kilometers) of the diamond-shaped space rock.

This meeting will provide scientists with a rare window to look back at the beginnings of Earth's solar system, said Jay McMahon, an assistant professor in aerospace engineering at CU Boulder.

Asteroid Bennu, which Osiris-Rex will spend the next few years studying, is said to be a carbon-rich hunk of rock that might contain organic materials or molecular precursors to life.

After the polar passes, OSIRIS-REx will move on to Bennu's midsection for an equatorial survey, and spend most of 2019 getting a comprehensive look at the entire world.

The mission marks the first attempt by a USA craft to successfully land on an asteroid following Japan's recent success with the Ryugu asteroid, which is approximately double the size of Bennu.

Asteroids are of extreme interest to scientists.

The OSIRIS-REx, after some moments of drama caused by the explosion of a Falcon 9 on a nearby launch pad and some quick work to ensure that this incident would not cause a loss of cooling capability to the spacecraft on its launch pad, launched successfully on September 8, 2016, at 7:05 pm Eastern Daylight Time.

On Monday, the United States space agency's OSIRIS-REx spacecraft arrived at a nearby asteroid that's of great importance to scientists: it might have answers about what early Earth was like, but there's a decent chance it might hit us, too. The probe will get within just 1 mile (1.6 km) of Bennu's surface on December 31, she said. "Bennu is also one of the most potentially hazardous asteroids, as it has a relatively high probability of impacting the Earth late in the 22nd century". Carbon is the hinge upon which organic molecules hang. This will help finding the most interesting and richest sample sites to a resolution of about two metres. Water, another vital component to the evolution of life, may also be trapped in the asteroid's minerals. Recovery crews will deliver the capsule to the Astromaterials Acquisition and Curation Office at the Johnson Space Center in Houston where Apollo moon rocks are stored. The spacecraft won't land, but rather use a 3-meter mechanical arm in 2020 to momentarily touch down and vacuum up particles.

The craft will obtain somewhere between 2 ounces and 4.4 pounds of soil sample from the surface of Bennu using a robotic arm that will blast the surface with a puff of nitrogen gas and collect the pieces that fly off. "You have a pristine sample of what the solar system was like billions of years ago", said Michelle Thaller, a spokeswoman for NASA's Goddard Space Flight Center.