NASA’s Osiris-Rex spacecraft successfully delivered the US’s first asteroid samples to the Utah desert on September 24, 2023, marking the end of a seven-year journey. The spacecraft released the sample capsule from 100,000 km (63,000 miles) away from Earth during a flyby before it landed four hours later on a remote military land. The mothership, Osiris-Rex, then set off to pursue another asteroid.
Flight Control announced the successful landing three minutes earlier than anticipated, exclaiming “We have touchdown!” This was due to the orange striped parachute opening at a height of 20,000 feet (6,100m), four times higher than expected, causing the early touchdown. Scientists estimate that the capsule contains at least a cup of rubble from the carbon-rich asteroid known as Bennu. However, the actual amount will not be known until the container is opened. Some of the rubble spilled and floated away during collection three years ago when the spacecraft scooped up too much and rocks jammed the container’s lid.
Japan, being the only other country to bring back asteroid samples, gathered about a teaspoon during its asteroid missions. The samples collected on September 24 are the largest haul from beyond the moon. These preserved building blocks from the early stages of our solar system, dating back 4.5 billion years, will provide valuable insights into the formation of Earth and life itself.
The Osiris-Rex mothership embarked on this $1 billion mission in 2016. It reached Bennu in 2018 and used a long stick vacuum to gather rubble from the small, roundish space rock in 2020. By the time it returned to Earth, the spacecraft had traveled a staggering distance of 6.2 billion km (4 billion miles).
NASA’s recovery effort in Utah involved the use of helicopters, along with the establishment of a temporary clean room at the Defense Department’s Utah Test and Training Range. The samples will be transported to a new lab at NASA’s Johnson Space Center in Houston on the morning of September 25. This lab already houses hundreds of kilograms of moon rocks collected by the Apollo astronauts over half a century ago. The mission’s lead scientist, Dante Lauretta from the University of Arizona, will accompany the samples to Texas. The opening of the container in Houston in the next day or two will be a pivotal moment to determine the exact amount of material inside, given the uncertainty surrounding it prior to landing. Engineers estimate that the canister contains 250g of material from Bennu, with a margin of plus or minus 100g. Even at the lower end of this estimate, it will surpass the minimum requirement of the mission.
NASA plans to hold a public show-and-tell event in October to showcase the samples. Bennu, currently orbiting the sun 81 million km (50 million miles) away from Earth, has a size equivalent to approximately half a kilometer (one-third of a mile) and resembles a spinning top. It is believed to be a fragment of a larger asteroid. These close-up observations of Bennu will prove invaluable as it is expected to come dangerously close to Earth in 2182, possibly posing a collision risk. The data collected by Osiris-Rex will aid future asteroid-deflection efforts.
Osiris-Rex is already on its way to pursue asteroid Apophis and is set to reach it in 2029. This marks NASA’s third successful sample return from a deep-space robotic mission, with previous missions including the Genesis spacecraft in 2004, which dropped off bits of solar wind, and the Stardust spacecraft in 2006, which successfully delivered comet dust.
NASA’s plans to return samples from Mars are currently on hold following criticism from an independent review board regarding cost and complexity. However, the Martian rover Perseverance has spent the past two years collecting core samples for future transport to Earth.