About 4 hours after leaving orbit, the spacecraft slewed to the sample collection attitude with the TAGSAM arm and cameras pointed toward the surface. The spacecraft next pointed its navigation camera toward Bennu and began recording images to process in the natural feature tracking autonomous navigation system.
It acts as a reverse vacuum cleaner, with high-pressure nitrogen gas mobilizing surface material that is then forced into the containment area of the “head.” “Touch and go” describes the concept of operations for sample collection: the TAGSAM head is in contact with the surface for only a few seconds. 2018) was specifically designed to solve the unique problem of sample acquisition from the microgravity environment of a small asteroid. The Touch and Go Sample Acquisition Mechanism (TAGSAM Bierhaus et al. Image credit: NASA/Goddard/University of Arizona.Ī 3-meter-long robotic arm was deployed, with a mechanism for sample acquisition attached to the end (figure 1). TAGSAM = Touch and Go Sample Acquisition Mechanism. It departed Bennu in May 2021 and will return the sample capsule to Earth in September 2023. The spacecraft spent over 2 years in close proximity to Bennu, first conducting detailed surveys and reconnaissance passes to characterize the asteroid and select the TAG site, then preparing for the sample collection activity.
In the microgravity environment of Bennu, this small velocity change caused the spacecraft to make a hard right turn, leave the safety of the terminator plane orbit, and venture out over the sunlit side of Bennu.įIGURE 1 OSIRIS-REx mission timeline. From this point on, members of the operations team in Denver could only listen for bits of telemetry sent back as the spacecraft autonomously navigated through the sample collection sequence.Īt about 10:30 am Mountain Standard Time, the spacecraft fired its attitude control thrusters to perform a maneuver resulting in a 6 cm/s velocity change. The mood in the OSIRIS-REx Mission Support Area at Lockheed Martin was tense, but with excitement-just a few hours from an event that had been more than 14 years in the making: the first attempt by NASA to collect a bulk sample of material from the surface of an asteroid for return to Earth.Ī few hours earlier, command sequences had been loaded on board the spacecraft with final adjustments to the critical parameters that would guide the spacecraft to contact with the surface of tiny Bennu (its mean diameter is less than 500 m). For the preceding several weeks, the 1400 kg (3000 lb) spacecraft had slowly orbited near-Earth asteroid Bennu from 600 meters (0.37 mile) above the surface, with ground controllers at Lockheed Martin’s facility in Littleton, Colorado, carefully tweaking the plane and phasing of the orbit with millimeter-per-second precision to set up for this moment.
On October 20, 2020, the OSIRIS-REx spacecraft began a maneuver that had been envisioned years prior by scientists and engineers at the University of Arizona, NASA’s Goddard Space Flight Center, Lockheed Martin, and KinetX Aerospace (Lauretta et al. The diverse science and engineering perspectives and experiences of the OSIRIS-REx team were key to overcoming the challenges of asteroid Bennu.
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