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Asteroid sample soon to return to Earth

Bennu asteroid
Mosaic view of Bennu created using NASA’s OSIRIS-REx spacecraft (Image credits: NASA/Goddard/University of Arizona)

NASA's OSIRIS-REx mission, the first American mission to gather samples from an asteroid, is poised to make its return to Earth on September 24, 2023. This eagerly anticipated homecoming will witness the OSIRIS-REx spacecraft releasing its precious cargo – a sample capsule containing material gathered from the asteroid Bennu – onto the safe terrain of the Utah desert.

The spacecraft's sample capsule, which has been on a remarkable journey since its launch in 2016, will encounter Earth's atmosphere once more. Safeguarded within this capsule is a payload of approximately 250 grams of rocky material meticulously collected from Bennu's surface in 2020 – an unprecedented feat marking NASA's first asteroid sample retrieval and the largest ever conducted in space.

Succession of events planned from the time the OSIRIS-REx spacecraft releases its sample capsule to the time it lands in the Utah desert (Image credit: Lockheed Martin)

As the OSIRIS-REx spacecraft approaches Earth at an altitude of 63,000 miles (approximately 102,000 kilometers) above Earth's surface a signal from ground-based operators will initiate the capsule's release, propelling it into a spinning descent towards Earth. Twenty minutes after this critical release, the spacecraft will engage its thrusters, redirecting itself towards a new mission: the exploration of asteroid Apophis under the moniker OSIRIS-APEX (OSIRIS-Apophis Explorer).

Meanwhile, the capsule will hurtle through the vast expanse of space for four hours until it encounters Earth's atmosphere at 8:42 a.m. MDT (10:42 a.m. EDT), traveling at a speed of approximately 27,650 mph (44,500 kph). This swift reentry will generate an intense compression of Earth's atmosphere, enveloping the capsule in a searing ball of fire. To protect the precious cargo, a heat shield will play a crucial role in regulating the capsule's internal temperature, ensuring it remains akin to Bennu's own surface conditions.

The capsule's descent will be a carefully orchestrated dance with gravity. First, a drogue parachute will deploy approximately two minutes after entry into the atmosphere, stabilising the descent as it transitions to subsonic speeds. Six minutes later, at an altitude of about one mile (approximately 1.6 kilometers) above the desert, the main parachute will unfurl, guiding the capsule to its final destination within a designated 36-mile by 8.5-mile (58-kilometer by 14-kilometer) area on a military range. At touchdown, the capsule's velocity will have diminished to a gentle 11 mph (18 kph).

Just 13 minutes after its fiery reentry, the capsule will find itself back on Earth's surface, marking its return after a seven-year odyssey. Awaiting its arrival will be a dedicated recovery team, ready to spring into action.

Recovery teams tour the site in Utah ahead of the planned sample recovery (Image Credit: NASA/Keegan Barber)

Approximately 20 minutes prior to the capsule's landing, while it still hovers high above Earth's atmosphere, the recovery field team will embark on a mission of their own. Boarding four helicopters, they will track the capsule's infrared heat signature until it becomes visible to optical instruments. This meticulous tracking process is crucial to trace the capsule's precise path to Earth and minimise any potential contamination from our planet's environment.

Once located and carefully prepared for transport, the capsule will embark on a helicopter journey to a temporary clean room situated on the military range. Here, it will undergo initial processing and disassembly in preparation for its subsequent air travel to NASA's Johnson Space Center in Houston. There, the sample will be meticulously documented, nurtured, and made available for analysis to scientists around the world, offering a remarkable window into the mysteries of our solar system's origins.

Information source: Nasa

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