NASA mission grabs samples of an asteroid
Posted October 24, 2020 2:19 p.m. EDT
Updated October 24, 2020 3:45 p.m. EDT
NASA announced Friday evening that the touch-and-go performed by the OSIRIS-REx mission on asteroid Bennu successfully collected more than enough material to meet one of its main mission requirements. Images of the sample collector, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) head show some particles escaping.
The mission team had planned to spin the spacecraft like a top, comparing the speed with previous measurements to estimate how much sample was collected. That maneuver along with a braking burn to slow the spacecraft as it continues to distance itself from the asteroid have been canceled to minimize acceleration to the spacecraft.
“Bennu continues to surprise us with great science and also throwing a few curveballs,” said Thomas Zurbuchen, NASA’s associate administrator for science at the agency’s headquarters in Washington. “And although we may have to move more quickly to stow the sample, it’s not a bad problem to have. We are so excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”
OSIRIS-REx is currently a little more than half a mile above Bennu, nearly 208 million miles from Earth. Once the sample is safely stowed, the OSIRIS-Rex spacecraft and her team take a well disserved rest. The spacecraft will slowly drift away from Bennu with help from the solar winds until March 2021. This quiescent ops period, as the engineers call it, is part of the plan to ensure there is ample time to deal with anything unexpected, including additional attempts to gather a sample.
Slowing down to catch up
On March 3, 2021, OSIRIS-REx will fire its engine to begin the nearly 208 million mile journey back to Earth. The burn will slow it down by just 319 m/s (714 mph), but that's enough to allow Earth to catch up. This also saves fuel, leaving reserves should anything unexpected come up (like gathering more and larger samples than anticipated). This also frees up space and weight on the spacecraft for science instruments.
Bennu will cross Earth's path around the Sun about a month before Earth reaches that point on September 24, 2023.
The Sample Return Capsule (SRC) will be released about four hours ahead of touchdown. Twenty minutes later, the larger OSIRIS-REx spacecraft will fire its engine to divert into orbit around the Sun.
The SRC will enter the atmosphere at more than 27,000 mph. About 99% of that speed will be removed by friction with the atmosphere. The capsule wil follow a path that takes it south of the San Francisco Bay area, across California and Nevada, for landing in the Utah Test and Training Range (UTTR) about 80 miles west of Salt Lake City.
Just as the capsule crosses into Utah, while the capsule is still traveling at mach 1.4, a small drogue parachute will deploy to stabilize it. A 24 foot main parachute will deploy at about 10,000 ft above the desert floor. Sensors aboard the capsule sense the touchdown then fire pyrotechnics which cut the parachute cords to prevent winds from draging the capsule, causing damage.
Recovery teams will remove the sample canister from the capsule and transport it to a clean room at the Johnson Space Center in Houston, Texas where bits of