As the times depend right down to NASA’s OSIRIS-REx spacecraft’s Contact-And-Go asteroid pattern assortment try, Southwest Analysis Institute scientists have helped decide what the spacecraft can count on to return from the near-Earth asteroid Bennu’s floor. Three papers revealed on-line by Science on Oct. 8 focus on the colour, reflectivity, age, composition, origin and distribution of supplies that make up the asteroid’s tough floor.
On October 20, the spacecraft will descend to the asteroid’s boulder-strewn floor, contact the bottom with its robotic arm for a couple of seconds and accumulate a pattern of rocks and mud — marking the primary time NASA has grabbed items of an asteroid for return to Earth. SwRI scientists performed a job within the choice of the pattern websites. The primary try might be made at Nightingale, a rocky space 66 ft in diameter in Bennu’s northern hemisphere. If this historic try is unsuccessful, the spacecraft will strive once more at a secondary website.
Because the spacecraft arrived at Bennu in 2018, scientists have been characterizing the asteroid’s composition and evaluating it to different asteroids and meteorites. The mission found carbon-bearing compounds on Bennu’s floor, a primary for a near-Earth asteroid, in addition to minerals containing or fashioned by water. Scientists additionally studied the distribution of those supplies, globally and on the pattern websites
“Our latest research present that organics and minerals related to the presence of water are scattered broadly round Bennu’s floor, so any pattern returned to Earth ought to include these compounds and minerals,” mentioned SwRI’s Dr. Vicky Hamilton, a coauthor on all three papers. “We are going to examine the pattern’s relative abundances of organics, carbonates, silicates and different minerals to these in meteorites to assist decide the situations that greatest clarify Bennu’s floor composition.”
Asteroid Bennu is a darkish, rubble pile held collectively by gravity and regarded as the collisional remnant of a a lot bigger main-belt object. Its rubble-pile nature and closely cratered floor signifies that it has had a rough-and-tumble life since being liberated from its a lot bigger mother or father asteroid hundreds of thousands and even billions of years in the past.
“Boulders strewn about close to the Nightingale website have brilliant carbonate veins,” Hamilton mentioned. “Bennu shares this compositional trait with aqueously altered meteorites. This correlation means that at the least some carbonaceous asteroids have been altered by percolating water within the early Photo voltaic System.”
The boulders on Bennu have numerous textures and colours, which can present details about their variable publicity to micrometeorite bombardment and the photo voltaic wind over time. Learning colour and reflectance knowledge present details about the geologic historical past of planetary surfaces.
“Bennu’s numerous floor consists of ample primitive materials probably from totally different depths in its mother or father physique plus a small proportion of overseas supplies from one other asteroid household littered about its floor,” mentioned SwRI’s Dr. Kevin Walsh, a coauthor of one of many papers. “As well as, each the first and back-up pattern websites, Nightingale and Osprey, are located inside small spectrally reddish craters which are regarded as extra pristine, having skilled much less house weathering than most of Bennu’s bluish floor.”
The OSIRIS-REx crew can also be evaluating Bennu to Ryugu, one other near-Earth asteroid. Each asteroids are thought to have originated from primitive asteroid households within the interior major belt. The Japan Aerospace Exploration Company launched Hayabusa2 in 2014 and rendezvoused with near-Earth asteroid Ryugu in 2018. After surveying the asteroid for a 12 months and a half, the spacecraft collected samples and is predicted to return to Earth December 6, 2020.
The pattern returned by OSIRIS-REx, mixed with the floor context maps OSIRIS-REx has collected, will enhance interpretations of obtainable floor and house telescope knowledge for different primitive darkish asteroids. Evaluating returned Bennu samples with these of Ryugu might be instrumental for understanding the variety inside, and historical past of, asteroid households and the whole asteroid belt.