The parachute deployment of OSIRIS-REx encountered an unexpected glitch attributed to a wiring error, NASA reported on December 5. Despite the flaw, the sample return capsule managed a safe landing in the Utah desert on September 24, 2023.
What happened on landing day
NASA’s examination of the landing data and vehicle documentation unveiled that the drogue parachute malfunctioned due to “inconsistent wiring label definitions.” This discrepancy hindered the intended deployment of the drogue during the capsule’s descent from an altitude of approximately 30.5 kilometers. The signal designated for drogue deployment inadvertently prompted the capsule’s systems to release the drogue prematurely, while it remained packed.
As the capsule descended below 3,000 meters, the drogue eventually deployed, having escaped its retention cord. Fortunately, the main parachute, designed robustly, subsequently deployed, stabilizing and decelerating the capsule. The safe landing occurred more than a minute earlier than the anticipated time.
On the day of the landing, officials acknowledged deviations from the planned descent but lacked visual confirmation of the drogue’s inflation and performance.
Why did that happened?
The root cause of the issue was traced back to an inconsistent definition of the term “main” in the system documentation.
NASA clarified that on the signal side, “main” referred to the main parachute, while on the receiver side, it denoted a pyrotechnic responsible for releasing the parachute canister cover and deploying the drogue. The misinterpretation of “main” on both sides resulted in an out-of-sequence deployment.
Unlike a similar incident in 2004 during NASA’s Genesis mission, where the return capsule crashed due to a drogue failure, OSIRIS-REx avoided damage. In that case, upside-down installation of “G-switch sensors” led to the failure to deploy the drogue, a flaw not identified in pre-launch reviews.
Safe capsule, important payload
OSIRIS-REx, however, landed safely, preserving its payload of approximately 250 grams of material collected from the asteroid Bennu.
The sample canister is currently housed in a NASA astromaterials facility at the Johnson Space Center, where a team has extracted over 70 grams of material. Some of this material is already under analysis by scientists.
Rich Burns, project manager for OSIRIS-REx at NASA’s Goddard Space Flight Center, anticipates important findings from the sample study in the coming year. The only challenge faced so far has been opening the main sample container, with a few fasteners proving resistant.
Efforts are underway to develop specialized tools that ensure the sample remains uncontaminated during extraction, a task made complex by the need to preserve the pristine sample. Despite this, the mission has exceeded its requirement by collecting more than 70 grams of material.