The sample container mockup during a drop test in the Utah desert. Image: NASA.
NASA is preparing to release a small asteroid sample in the desert after nearly 2.5 years of space travel. This marks the first time NASA is collecting and bringing an asteroid sample back to Earth from space, along with the previous sample from the Ryugu asteroid in Japan’s Hayabusa2 mission. The rock and soil from this new sample could reveal insights into the formation of the Solar System.
Instead of landing, the OSIRIS-REx mission will drop the asteroid sample and continue its journey to study another asteroid. NASA personnel are practicing the sample collection process, which will occur when the OSIRIS-REx spacecraft drops it in Utah’s desert on September 24th. The spacecraft is estimated to have collected around 250 grams of material from the Bennu asteroid.
The moment when the Bennu sample arrives on Earth will mark the culmination of years of hard work by thousands of individuals. During the spring and summer, teams practiced various scenarios that could occur on the spacecraft’s return to Earth. The mission’s initial goal was to retrieve a pristine asteroid sample, but if the spacecraft’s sample container were to touch the ground and become contaminated, it could pose a risk.
OSIRIS-REx, short for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, is NASA’s first mission to return an asteroid sample to Earth. The spacecraft has been on a seven-year journey, launching in 2016, orbiting Bennu in 2018, collecting the sample in 2020, and beginning its journey back to Earth in May 2021. After leaving Bennu, the spacecraft completed two orbits around the Sun to align with its Earth return trajectory.
In July, the mission control team sent a series of commands to help the spacecraft aim for the sample’s drop zone at the Utah Test and Training Range of the U.S. Department of Defense in the suburbs of Salt Lake City. On September 24th, the sample container will enter Earth’s atmosphere at 21:42 Hanoi time, traveling at a speed of 44,498 km/h.
Four hours before re-entry, the mission control team will decide whether to command the spacecraft to release the sample container or not, according to Rich Burns, the OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. This decision depends on the spacecraft’s trajectory, the safety of people in the landing area, the container’s survival after impact, the temperature during re-entry, and the accuracy of the landing site. The container will be released when the spacecraft is about 102,000 km from Earth, targeting an area of 647.5 square kilometers.
After releasing the sample container, the OSIRIS-REx spacecraft will change its course, orbit the Sun, and target another asteroid named Apophis in 2029. The spacecraft’s journey through Earth’s atmosphere will envelop the container in superheated plasma, but a heat shield will protect the sample inside.
Landing will involve deploying a parachute to slow the spacecraft down for a gentle touch down at a speed of 17.7 km/h. The sample recovery team will be on standby beforehand, according to Sandra Freund, the OSIRIS-REx program manager at Lockheed Martin Space, the company that collaborated with NASA to build the spacecraft. The landing is expected to occur 13 minutes after the spacecraft enters Earth’s atmosphere.
Recently, NASA and Lockheed Martin’s teams used a sample return aircraft, practiced retrieval and preparation for transport. They also simulated challenging scenarios from the control center, such as handling spacecraft restarts, exiting the safe mode, coordinating communication between different centers in case of network failure. Another possibility is that the spacecraft may not release the sample container on September 24th due to an incorrect landing area approach. In that case, the sample will remain on the spacecraft, and the spacecraft’s orbit will return the sample to Earth for another landing attempt in Utah in 2025.