A sample of asteroid material stored inside NASA’s spacecraft is set to return to Earth by parachuting into the desert after nearly 2.5 years in space.
This marks the first time NASA has collected and returned an asteroid sample to Earth from space. Alongside a previous sample from the asteroid Ryugu during Japan’s Hayabusa2 mission, the rock and soil in this new sample could reveal the formation process of the solar system, according to CNN.
A mock sample return capsule in a drop test on the Utah desert. (Photo: NASA).
Instead of landing, the OSIRIS-REx mission will drop the sample of rock and soil and continue its journey to study another asteroid. NASA staff are rehearsing the sample collection procedures taken from the near-Earth asteroid Bennu as the OSIRIS-REx spacecraft releases it over the Utah desert on September 24. It is estimated that OSIRIS-REx collected about 250 grams of material from Bennu.
The moment the Bennu sample arrives on Earth will mark the culmination of many years of hard work by thousands of people. Throughout the spring and summer, teams practiced every potential scenario, both good and bad, that could occur on the day of the spacecraft’s return. The initial goal of the mission was to retrieve primitive asteroid samples. However, if the capsule impacts the ground and opens, the sample could be contaminated.
OSIRIS-REx (short for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is NASA’s first mission to return asteroid samples to Earth. The spacecraft is on a seven-year journey. After launching in 2016, OSIRIS-REx began orbiting Bennu in 2018, collected samples in 2020, and started its journey back to Earth in May 2021. Since leaving Bennu, the spacecraft has orbited the Sun twice to follow the correct trajectory back to Earth.
In July, the mission control team sent a series of commands to help the spacecraft aim accurately at the drop zone for the sample return capsule at the Utah Test and Training Range, located on the outskirts of Salt Lake City. On September 24, the sample return capsule is expected to enter the Earth’s atmosphere at 9:42 PM Hanoi time, traveling at a speed of 44,498 km/h.
Four hours before reentry, the mission control team will decide whether to send the command for the spacecraft to release the sample return capsule, according to Rich Burns, the OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The decision depends on the spacecraft’s trajectory, safety of people in the landing area, the capsule’s ability to survive the descent angle, reentry temperature, and landing precision. The capsule will be released when OSIRIS-REx is 102,000 km from Earth, targeting a wide area of 647.5 km2.
After releasing the sample return capsule, OSIRIS-REx will redirect on its trajectory around the Sun, aiming for another asteroid named Apophis in 2029. The reentry through the Earth’s atmosphere will envelop the capsule in a superheated fireball, but the heat shield will protect the sample inside.
Upon landing, a parachute will deploy to slow the capsule down for a gentle touchdown at a speed of 17.7 km/h. The sample recovery team will be on standby, according to Sandra Freund, OSIRIS-REx program director at Lockheed Martin Space, the company collaborating on the spacecraft’s construction with NASA. The landing process is expected to occur 13 minutes after the capsule enters Earth’s atmosphere.
Recently, teams at NASA and Lockheed Martin have used drop planes to practice capsule release, recovery, and preparation for transport. They have also simulated challenging scenarios from the control center, such as how to handle a spacecraft restart, how to exit safe mode, and transition communications between different centers in case of a network loss. Another possibility is that the spacecraft may not release the sample return capsule on September 24 due to not correctly approaching the landing zone. In that case, the sample would remain on the spacecraft, and its orbit would bring it back to Earth for the next landing attempt in Utah in 2025.
