After a year of tracking the Benou asteroid “sneak”, nasa’s probe has finally identified the sampling site. OSIRIS-Rex, which was launched in September 2016 on NASA’s first asteroid sampling return mission, has been around the asteroid after a nearly two-year trek to get close to Benu.
On December 12, NASA announced a site code-named “Nightingale”, and if all goes well, OSIRIS-Rex will spray a cloud of nitrogen to blow off the surface dust and extend out to the robotic arm to collect samples.
OSIRIS-Rex probe investigating Benu asteroid
Fossils of the Solar System
Bennu has been closely monitored by astronomers since it was first discovered in 1999. It is 500 meters in diameter and orbits the sun every 1.2 years, approaching the Earth every six years. NASA has calculated that between 2175 and 2199, Benu had a one in 2,700 chance of hitting Earth.
But that’s not the only reason NASA chose Benu for its nearly half a million asteroids. It is one of the oldest known asteroids, a remnant of the solar system at the beginning of its formation, known as a fossil of the solar system. Taking dust samples from Benu allows scientists to learn more about the original composition of the solar system.
At the end of 2018, NASA announced that the probe had found traces of water on Benu, which was locked in the asteroid’s clay. This suggests that Benu’s former mother, a larger asteroid, once had liquid water.
For OSIRIS-Rex, Benu is dangerous. At first, scientists expected it to find an open sand, because more than 2 cm of stone could cause obstacles. As a result, OSIRIS-Rex flew to Benu only to discover that the asteroid’s surface was covered with boulders that could not be reached.
In frustration, engineers are constantly enhancing the probe’s autonomous navigation capabilities and narrowing its target. To do this, OSIRIS-Rex has been diving close over the past period of time to take back images to scientists for analysis.
The final selected “nightingale” is located in a crater in the northern hemisphere of the asteroid. The crater is 140 meters in diameter and the imageshows the terrain is relatively smooth, cool and dark, which is conducive to preserving surface material. The crater is suspected to be relatively young, the topsoil has only recently been exposed, and it is more likely to collect original samples.
Although the crater itself is 140 meters wide, the safety range for the detector is only 16 meters, which is highly demanding for aiming accuracy. In addition, there is a boulder on the eastern edge of the crater, which may pose a threat.
Sampling site “Nightingale”
In addition to the Nightingale, NASA has circled ospreys in a smaller crater near Benou Equator. In any case, NASA engineers want the probe to find dangerous situations in a timely manner and retreat.
The sampling mission is scheduled for August 2020. OSIRIS-Rex will then return to Earth in 2023 with the spoils.