• The OSIRIS-REx mission to retrieve a sample of the asteroid Bennu launched in 2016 concludes on Sunday.
• A capsule containing the sample of the asteroid is expected to land in Utah after traveling through space for the better part of three years.
• The Bennu asteroid is, according to one study, expected to hit Earth between the year 2178 and 2290.

During 1999 when concerns about the Millennium Bug were peaking, an asteroid with a radius of 265.5m orbiting the Sun was discovered by astronomers. The asteroid was named 101955 Bennu and it passes close by Earth every six years.

A 2021 paper published in the journal Icarus, suggests that Bennu will eventually hit Earth although this impact would most likely only happen between the year 2178 and 2290. That theoretical collision aside, NASA wanted to study the asteroid as it may help humanity understand the origins of our solar system. And so in 2016, it launched the Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer (OSIRIS-REx) mission with the intention of grabbing a sample of the asteroid and returning it to Earth.

After a years-long journey, NASA reported that it was able to collect 60g of material from Bennu’s surface in 2020. The OSIRIS-REx has been on a path back to Earth ever since.

Now, the final phase of the mission approaches when that sample arrives on Earth this weekend.

The OSIRIS-REx spacecraft will eject a capsule upon its arrival near Earth. The spacecraft won’t be returning to Earth and is instead headed for another asteroid.

“When it approaches Earth, the OSIRIS-REx spacecraft won’t slow down as it makes its sample drop-off. Instead, when it reaches 63,000 miles (or 102,000 kilometers) above Earth’s surface – about one-third the distance from Earth to the Moon – a message from operators on the ground will trigger the capsule’s release and the capsule will be sent spinning toward the atmosphere below. Twenty minutes after the drop-off, the spacecraft will fire its thrusters to divert past Earth toward asteroid Apophis, where it will continue investigating our solar system under a new name: OSIRIS-APEX (OSIRIS-Apophis Explorer),” NASA wrote in a blog.

The spacecraft was 2.8 million kilometres away from Earth on 19th September and it was traveling at a speed of 23 000kmph.

Once ejected, the capsule containing the sample of Bennu’s surface is expected to enter Earth’s atmosphere at 16:42 SAST just off the coast of California before landing at a predetermined area in Salt Lake City, Utah.

NASA will be broadcasting the event live on all of its social media including YouTube, X, Facebook, and its own NASA App. Coverage of the event starts at 16:00 SAST on Sunday afternoon.

Once recovered the sample will be transported to a temporary clean room and from there it will be sent to NASA’s Johnson Space Center in Houston where it will be curated and studied. The sample will be unveiled at an event on 11th October where an initial analysis will also be shared.

[Image – NASA’s Goddard Space Flight Center Conceptual Image Lab]