WASHINGTON — The drogue parachute on the OSIRIS-REx sample return capsule failed to deploy properly because of a design error, a flaw that did not prevent a safe landing of the capsule.
In a Dec. 5 statement, NASA said a review of data from the capsule’s Sept. 24 landing in the Utah desert and documentation about the vehicle led the agency to conclude that “inconsistent wiring label definitions” prevented the drogue from deploying as intended during the capsule’s descent.
The drogue was designed to deploy at an altitude of about 30.5 kilometers, helping to slow and stabilize the capsule before the larger main parachute was deployed. A signal intended to deploy the drogue, though, instead caused the capsule’s systems to cut the drogue free while it was still packed inside.
The capsule continued to fall without the drogue until it descended below 3,000 meters, when NASA said the drogue then deployed. Since its retention cord was already cut, the drogue escaped.
The main parachute then deployed, NASA stated, and “its design was robust enough to stabilize and slow the capsule, resulting in a safe landing more than a minute earlier than expected.”
It was clear the day of the landing that the descent had not gone according to plan. Officials said then that they did not have any visual confirmation of the drogue inflating and thus it was not clear how well it had performed.
“Something in our sequence may or may not have behaved itself exactly the way we expected it to, but the subsequent things in the sequence made up for it,” said Tim Priser, chief engineer for deep space exploration at spacecraft manufacturer Lockheed Martin, at a press conference shortly after the landing. “At the end of the day, when that main chute deployed, it basically corrected anything that may have happened ahead of it.”
NASA said in the statement that the problem was linked to an inconsistent definition of the term “main” in…
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