“It’s about making the dream Drake had a reality,” says NASA’s Thomas Zurbuchen, who was close friends with Drake. “I’m sure he would have thought it was a great performance and would have been extremely proud of the team if he had been with us, which we think he still is in a way.”
After the launch of OSIRIS-REx, on September 8, 2016, the spacecraft traveled hundreds of million kilometers to arrive at Bennu in December 2018. Bennu is the smallest celestial object ever studied by a spacecraft from orbit, and is little more than a loose pile of debris (about 518 meters in diameter) held together by the very weak gravity of the celestial body. Under such fragile circumstances OSIRIS-RExcan be thrown off course even by minimal forces, such as the radiation pressure of the sunlight hitting the space probe.
That meant that the OSIRIS-REx team had to calculate the behavior of the probe and its orbit with unprecedented precision. Without regular corrections, tiny deviations in the range of OSIRIS-REx quickly add up and give the scientists a misleading picture of the correct position of the spacecraft.
“We broke the world record for the smallest orbit ever and for the smallest celestial object ever studied from an orbit. There is a reason why people have never tried this before: it is very difficult, ”said Olivia Billet of Lockheed Martin, one of the systems engineers on the OSIRIS-REx mission. “It’s a completely new way of working.”
The landscape on Bennu has also given NASA some headaches. Before the launch of OSIRIS-REx the researchers expected the asteroid to have a smooth surface with ‘sandy beaches’ of very fine grit. But once the spacecraft reached Bennu, NASA discovered that the asteroid was littered with towering boulders.
The terrain was much rougher than when it was designed OSIRIS-REx was planned, so engineers had to update the Sonde’s navigation software mid-mission. To provide this new software with as much information as possible, the OSIRIS-REx team mapped the entire surface of Bennu to within five centimeters – the most detailed ‘world map’ ever created by a spacecraft of an alien celestial body. “We really had to sharpen our pencils,” said Mark Fisher of Lockheed Martin, chief engineer of the OSIRIS-REx mission.
Back home
While the team has yet to confirm that soil samples have been collected, data previously collected by the spacecraft shows that the entire surface of Bennu – including the ‘landing site’, codenamed ‘Nightingale’ – contains carbonaceous molecules. Scientists around the world are already preparing their laboratories to analyze this material, which they will examine for possible clues to the origin of life in the solar system.
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