This image shows the OSIRIS-REx Touch-and-Go Sample Acquisition Mechanism (TAGSAM) sampling head extended from the spacecraft at the end of the TAGSAM arm. The image was obtained by the SamCam camera on Nov. 14, 2018 as part of a visual checkout of the spacecraft’s sample acquisition system. This is a rehearsal image for an observation that will be taken at Bennu during the moment of sample collection to help document the asteroid material collected in the TAGSAM head. There are two witness plate assemblies on the top perimeter of the TAGSAM head, one of which is entirely visible in this image. These witness plates record the deposition of material on the TAGSAM head over the duration of the mission, giving scientists a record of material on the TAGSAM head that is not from Bennu.
Credits: NASA/Goddard/University of Arizona
“The TAGSAM exercise is an important milestone, as the prime objective of the OSIRIS-REx mission is to return a sample of Bennu to Earth,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “This successful test shows that, when the time comes, TAGSAM is ready to reach out and tag the asteroid.”
Years of innovation
Lockheed Martin engineers spent more than a decade designing, building, and testing TAGSAM, which includes an 11-foot (3.35-meter) arm with three articulating joints, a round sampler head at the end of the arm that resembles the air filter in a car, and three bottles of high-pressure nitrogen gas.
This test deployment was a rehearsal for a date in mid-2020 when the spacecraft will unfold the TAGSAM arm again, slowly descend to Bennu’s surface, and briefly touch the asteroid with the sampler head. A burst of nitrogen gas will stir up regolith on the asteroid’s surface, which will be caught in the TAGSAM head. The TAG sequence will take about five seconds, after which the spacecraft will execute small maneuvers to carefully back away from Bennu. Afterward, SamCam will image the sampler head, as it did during the test deployment, to help confirm that TAGSAM collected at least 2.1 ounces (60 grams) of regolith.
n mid-2020, the OSIRIS-REx spacecraft will use its TAGSAM device to stir up and collect a sample of loose material from asteroid Bennu’s surface. That material will be returned to Earth for study in 2023.
Credits: NASA/Goddard/University of Arizona
The TAGSAM mechanism was designed for the key challenge unique to the OSIRIS-REx mission: collecting a sample from the smallest planetary body ever to be orbited by a spacecraft. “First-of-its-kind innovations like this one serve as the precursor for future missions to small bodies,” said Sandy Freund, systems engineer manager and Lockheed Martin OSIRIS-REx MSA manager. “By proving out these technologies and techniques, we are going to be able to return the largest sample from space in half a century and pave the way for other missions.”
A month of testing
The unfolding of the TAGSAM arm was the latest and most significant step in a series of tests and check-outs of the spacecraft’s sampling system, which began in October when OSIRIS-REx jettisoned the cover that protected the TAGSAM head during launch and the mission’s outbound cruise phase. Shortly before the cover ejection, and again the day after, OSIRIS-REx performed two spins called Sample Mass Measurements. By comparing the spacecraft’s inertial properties during these before-and-after spins, the team confirmed that the 2.67-pound (1.21-kilogram) cover was successfully ejected on Oct. 17.
A week later, on Oct. 25, the Frangibolts holding the TAGSAM arm in place fired successfully, releasing the arm and allowing the team to move it into a parked position just outside its protective housing. After resting in this position for a few weeks, the arm was fully deployed into its sampling position, its joints were tested, and images were captured with SamCam. The spacecraft will execute two additional Sample Mass Measurements over the next two days. The mission team will use these spins as a baseline to compare with the results of similar spins that will be conducted after TAG in 2020 in order to confirm the mass of the sample collected.
Over the past month, the OSIRIS-REx team conducted a series of tests to ensure that TAGSAM, the spacecraft’s sampling mechanism, is ready to collect a sample from Bennu in 2020. This rehearsal marked the first time since launch that the TAGSAM arm has moved through its full range of motion.
Credits: NASA/Goddard/University of Arizona
Although the sampling system was rigorously tested on Earth, this rehearsal marked the first time that the team has deployed TAGSAM in the micro-gravity environment of space.
"The team is very pleased that TAGSAM has been released, deployed, and is operating as commanded through its full range of motion." said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. "It has been restrained for over two years since launch, so it is gratifying to see it out of its shackles and performing well."
OSIRIS-REx is scheduled to arrive at Bennu on Dec. 3. It will spend nearly one year surveying the asteroid with five scientific instruments so that the mission team can select a location that is safe and scientifically interesting to collect the sample.
“Now that we have put TAGSAM through its paces in space and know it is ready to perform at Bennu, we can focus on the challenges of navigating around the asteroid and seeking out the best possible sample site,” said Lauretta.
NASA OSIRIS-REx Flexes Its "Arm" Before Arriving At Asteroid Bennu
- NASA's OSIRIS-REx spacecraft completes critical engineering maneuver campaign to test out sample return mechanism - developed by Lockheed Martin.
TAGSAM, or Touch-and-Go Sample Acquisition Mechanism, completed a successful practice deployment in space on Nov. 14—an important milestone in the OSIRIS-REx mission to the asteroid Bennu. TAGSAM is the first-of-its-kind robotic arm and sampling head invented by Lockheed Martin.
Lockheed Martin engineers on the Mission Support Area (MSA) team moved TAGSAM's arm through the full range of motion of all its "joints"—shoulder, elbow and wrist. The maneuver demonstrates that TAGSAM is ready to collect surface material (regolith) from Bennu.
"Our team has been providing spacecraft operations since launch and has been conducting various checkouts over the past two years," said Sandy Freund, Lockheed Martin OSIRIS-REx MSA manager. "This was a very important milestone in checking out the hardware required to collect an asteroid sample."
Lockheed Martin engineers spent more than a decade designing, building and testing TAGSAM. The mechanism meets the unique challenges of trying to collect samples from the smallest planetary body that a spacecraft has ever orbited.
The OSIRIS-REx spacecraft cannot land on Bennu because of its small size—just 0.3 miles (500 meters) in diameter--and its microgravity environment—100,000 times less than Earth's. Instead, TAGSAM will extend its 11-foot-long (3.35-meter) arm from the spacecraft to Bennu's surface and "tag" the asteroid.
The round sampler head will agitate the surface and loosen regolith with a jet of nitrogen gas, allowing the suspended particles to pass through a filter into the sampler head. The entire operation will take about five seconds, with the TAGSAM head bouncing against the surface in a pogo-stick-type motion.
If necessary, TAGSAM can make up to three sampling attempts to collect at least 2.1 ounces (60 grams) of regolith.
"First-of-its-kind innovations like this one serve as the precursor for future missions to small bodies," said Freund. "Proving out these technologies and techniques, we are going to be able to return the largest sample from space in half a century and pave the way for other missions."
TAGSAM began its journey aboard OSIRIS-REx on Sept. 8, 2016. The spacecraft is scheduled to reach Bennu on Dec. 3, 2018, and complete a survey of the asteroid over the next two years. The window for the touch-and-go sampling operation opens on July 4, 2020. Once enough sample is collected, the TAGSAM head will be stowed and sealed in the spacecraft's sample return capsule (SRC) for the return trip to Earth, with expected arrival on Sept. 24, 2023.
NASA Goddard Space Flight Center in Greenbelt provides overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission's science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is currently providing spacecraft operations. OSIRIS-REx is the third mission in NASA's New Frontiers Program. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency's Science Mission Directorate in Washington.
Quelle: Lockheed Martin