NASA’s ambitious $800 million OSIRIS-REx mission, launched in September 2016, is on the cusp of revealing unprecedented insights into our solar system’s past. The spacecraft, tasked with the monumental job of collecting and returning a sample from the distant asteroid Bennu, is currently en route home, its precious cargo in tow. The first sighting of the spacecraft during its return journey was captured last week, marking a significant milestone in this ground-breaking mission.

Bennu, the asteroid at the heart of this mission, is a rubble-pile asteroid believed to have detached from a larger asteroid between 700 million and 2 billion years ago. Located approximately 105 million miles from the Sun, Bennu’s rocky surface offers valuable clues about the formation of the solar system. From 2018 to 2021, OSIRIS-REx observed and analyzed Bennu, capturing images and recording measurements of its spin, shape, and composition. However, to truly unlock Bennu’s secrets, a physical sample was necessary, sparking the genesis of this sample return project.

NASA’s OSIRIS-REx Mission: Bringing Asteroid Samples Back Home

Mission Overview

Launched in September 2016, NASA’s $800 million OSIRIS-REx mission had a straightforward yet challenging goal: to travel to a distant asteroid and return with a sample of it. The spacecraft is now on its homeward journey, and scientists had their first glimpse of it last week as it began its return trip.

The target of the mission was Bennu, a "rubble-pile" asteroid thought to have separated from a larger asteroid between 700 million and 2 billion years ago. With an average orbit of about 105 million miles from the Sun, Bennu completes its journey around the Sun every 1.2 years. The asteroid was approximately 200 million miles away when OSIRIS-REx arrived to collect a piece of it.

The Value of Bennu

From December 2018 until May 2021, OSIRIS-REx observed Bennu. It captured images of the asteroid and measured its spin, shape, and composition. Bennu’s rocky surface offers clues about how our solar system formed, but only so much information can be gleaned from observations alone, thus making the sample return project necessary.

Course Correction and Sample Collection

Last week, mission planners adjusted the spacecraft’s course to accurately aim OSIRIS-REx towards the sample drop-off site on Earth. A minor tweak was made to the spacecraft’s velocity – about 0.5 miles per hour – to ensure it would indeed reach Earth and not miss our planet. The Bennu sample was collected by the spacecraft in 2020, and it embarked on its return journey in April 2021. On September 16, the European Space Agency’s Optical Ground Station (OGS) telescope, located on the island of Tenerife, spotted the spacecraft when it was 2.9 million miles away from Earth.

The Potential Impact of Bennu

Interestingly, Bennu is considered a potentially hazardous asteroid (PHA) because it could potentially collide with Earth in 161 years. However, the probability of this occurrence is exceptionally low. The most significant impact Bennu will have on Earth is likely to be through the OSIRIS-REx samples, which could reveal invaluable information about the formation of our universe.

Takeaways

The OSIRIS-REx mission is a significant step forward in our understanding of the solar system’s formation and the role of asteroids in it. The successful return of the sample will not only provide scientists with a wealth of new data but also pave the way for future asteroid missions. It also highlights the importance of international cooperation in space exploration, shown by the role ESA’s OGS telescope played in tracking the spacecraft. Despite the inherent risks, the potential scientific rewards make these ambitious missions worthwhile.