OSIRIS-REx is NASA's first asteroid sample return mission.
It launched in September 2016 on a journey
to explore a near-Earth asteroid called Bennu.
After arriving in 2018, OSIRIS-REx spent nearly two years orbiting Bennu,
mapping and studying its rugged terrain
before carrying out its primary science objective.
On October 20th, 2020,
the spacecraft ventured to a small crater in the asteroid's northern hemisphere.
It dodged jagged rocks and towering boulders and plunged its arm
into the loose surface, excavating six tons of debris while collecting
about 250 grams of material.
OSIRIS-REx stowed its bounty and closed its sample return capsule.
It bid farewell to Bennu in May 2021,
embarking on a 1.2 billion mile cruise back to Earth.
Now, two years and four months after leaving Bennu,
OSIRIS-REx is closing in on the place where its journey began.
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On September 24th,
the spacecraft will approach to nearly 63,000 miles from Earth.
It will power up and release its sample return capsule at 4:42 a.m.
Mountain Time.
The capsule must be jettisoned within a narrow timeframe
and at just the right angle to hit its target: an area of roughly
250 square miles in Utah's West Desert.
Once the capsule is away, OSIRIS-REx will fire
its thrusters to avoid colliding with Earth.
At 8:42 a.m.,
the capsule will streak into the atmosphere at a blistering
27,000 miles per hour.
It will race across the western U.S.
and begin to glow with heat,
allowing infrared trackers on the ground to chart its progress.
As it pushes deeper into the atmosphere, the capsule will rapidly decelerate,
subjecting the Bennu samples to a punishing 32 G’s.
About 2 minutes after entry, it will slow to Mach 1.4 and deploy
its drogue parachute, stabilizing its descent.
The capsule will enter special use airspace at 8:46 a.m.,
almost ten miles above the department of Defense Utah Test and Training Range.
Radar stations will lock on and track it to
within thirty feet of its landing site. At 8:50 a.m.,
the capsule will extract and deploy its main parachute one mile above the ground.
It will make its final descent at a leisurely eleven miles per hour,
like a marathon runner savoring a victory lap,
before touching down in the desert soil at 8:55.
After ground teams retrieve the capsule,
The Bennu samples will be taken to NASA's Johnson Space Center in Houston, Texas.
The sample canister will be opened in the Astromaterials Acquisition
and Curation Facility,
and the samples will be curated, distributed, and studied
for decades to come.
Having delivered its cargo, the OSIRIS-REx spacecraft
will depart Earth, but its journey will not quite be finished.
In a daring encore, the renamed OSIRIS-APEX will enter an elliptical orbit
of the Sun, repeatedly passing within the orbit of Venus
and pushing the limits of its thermal design.
Beginning in 2029, it will chase down
and investigate Apophis, a 1200-foot stony asteroid
destined to make an exceptionally close flyby of Earth.
After thirteen years in deep space,
at the start of a new decade, alone on a new world, the journey will continue.
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