The OSIRIS-REx spacecraft will soon bid asteroid Bennu farewell. NASA has announced that OSIRIS-REx will start its journey back to our planet on May 10th, two-and-a-half years after it rendezvoused with the near-Earth asteroid. The agency launched the spacecraft back in 2016 to collect samples from Bennu in hopes that analyzing the materials could give us more insight into the formation of the Solar System and into the beginning of life here on Earth.
OSIRIS-REx observed the asteroid’s surface for months after the rendezvous to find the perfect site for sample collection. In October 2020, it finally touched the space rock’s surface just long enough to scoop up samples of regolith that scientists can examine. In fact, it grabbed more than the mission’s requirement of 60 grams, which is why the sample container started leaking and NASA had to speed up the process to secure it.
Michael Moreau, OSIRIS-REx deputy project manager, explained that leaving for Earth in May puts the mission “in the ‘sweet spot,’ when the departure maneuver will consume the least amount of the spacecraft’s onboard fuel.” Before the spacecraft completely leaves the rock it’s been studying for the past few years, though, it may do one more flyby in early April.
The OSIRIS-REx team is currently studying whether it’s feasible to do another flyby, which will give it a way to gather data on how the touch-and-go sample collection affected Bennu’s surface. It would also give the team the chance to assess the state of the spacecraft’s instruments, including its cameras and spectrometers. OSIRIS-REx is expected to deliver the samples it collected in September 2023. As it approaches Earth, the spacecraft will jettison the sample container, which will land with the help of parachutes in Utah.