A spacecraft descent capsule bearing samples of asteroid Bennu will return to Earth on Sept. 24, 2023, capping off a seven-year mission for OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer).

Canada’s contribution was the OSIRIS-REx Laser Altimeter (OLA), a crucial instrument that allowed investigators to map the surface of Bennu and select a safe landing spot nicknamed “Nightingale.” The Canadian Space Agency-funded instrument, built by MDA, will allow Canadians priority in examining the samples.

“It [the spacecraft] will essentially use the same return capsule as the NASA Stardust mission did a number of years ago,” said Michael Daly, lead instrument scientist of OSIRIS-REx OLA, in an interview with SkyNews.

Stardust was the first-ever sample return mission, which brought dust bits from the coma (atmosphere) of Comet Wild 2 back to Earth in 2006. It used a clam-shaped capsule protected by a heat shield, allowing a sample canister to come back protected through Earth’s atmosphere. The Stardust sample capsule is on display at the Smithsonian National Air and Space Museum in Washington, D.C.

As for the current mission, engineers at NASA’s Langley Research Center will coordinate the complex landing of the spacecraft, which needs to release the capsule safely towards our planet. Starting in July, and while in space, it will make several trajectory adjustments to bring the sample in for a precise landing. 

Close to Earth, the capsule will release from the spacecraft and will slam into our atmosphere at more than 48,000 km/h (30,000 mph) — roughly 16 times faster than a speeding bullet. Should all go to plan, the capsule will release a single parachute and touch down at the Utah Test and Training Range of the United States Air Force in the Great Salt Lake Desert. 

“There’ll be a mad rush to go and find it [the capsule] and collect it and to preserve the environment around it, because one of the things we don’t want is to have any contamination from Earth. So that will all be looked after very, very carefully,” said Daly, who also studies spaceflight instrumentation at York University.

The payload will be brought back to NASA’s Johnson Space Center in Houston, where investigators will learn how much material OSIRIS-REx picked up. The goal of the mission is to collect a sample with a mass of at least 2.1 ounces (59.5 grams). It is safe to say the spacecraft exceeded the mark; there was so much dust collected that the sampling mechanism at first could not properly close until it was stowed inside the spacecraft for shipment.

Daly said all sorts of investigations from OSIRIS-REx can tell us more about the early universe and asteroids like Bennu that were present there. Investigators may find more information by studying things like the size distributions of particles and inhomogeneity (or how different the particles are from each other). 

Some of the sample will be kept aside for a future generation to look at — much like the rocks from the Apollo Moon missions, some of which were only unsealed two years ago. Scientific investigative techniques have improved significantly since the last human lunar landing in 1972.

There is no word on when Canada will receive its promised four per cent of the sample, and Daly said discussions are ongoing about how the samples will be distributed and used by the Canadian investigators on the team. The investigations will take time, as each type of analysis requires different kinds of preparation that will change or expose the sample.

“For instance, one team might require thin or thick sections that will be mounted on a slide and [will be] well polished, while others will want different types of sample preparations,” said. More details will be forthcoming later in 2023 or early in 2024.

As for the spacecraft, its mission is not complete. OSIRIS-REx will be renamed to OSIRIS-APEX (OSIRIS-Apophis Explorer) and retasked to another historic journey: to examine the asteroid Apophis when the spacecraft swings within reach of geostationary satellites in April 2029. 

A new analysis shows that Apophis, once thought to be a threat to Earth, will not be a problem for at least the next century — but the opportunity to investigate an asteroid from deep space remains tantalizing nonetheless.

This biweekly column by Canadian science and space journalist Elizabeth Howell focuses on a trending news topic in Canadian astronomy and space.