Bad Wiring Almost Ruined NASA's Asteroid Sample Mission

The design plans gave engineers the wrong information.

Seven years is a long time to wait for a small amount of space rocks. That’s how long NASA’s OSIRIS-REx mission took, from its launch on September 8, 2016 to its return to Earth on September 24, 2023.

The mission succeeded in collecting samples from a nearby asteroid and bringing them back for scientists to study. But a wiring mix-up almost crashed the whole plan.

NASA said it found that inconsistent wiring label definitions in the design plans likely caused engineers to incorrectly wire the parachutes’ release triggers for the capsule. That resulted in the smaller chute, called a drogue, to fire in the wrong order.

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The smaller chute was supposed to deploy at an altitude of about 100,000 feet so it could slow the capsule for about five minutes before it hit 10,000 feet and the main parachute took over. Instead, a signal at 100,000 feet cut the smaller chute free before it was released. That meant that when the capsule hit 9,000 feet, the smaller chute deployed and immediately flew away since its retention cord was already severed.

NASA said the main parachute deployed as expected, and that it was sturdy enough to sufficiently slow down the capsule on its own. The agency said there was no negative impact due to the parachute problems.

The primary cause for the mishap was confusing labels in the design plans. NASA said the word “main” was used inconsistently between the device that sends the electric signals, and the device that receives the signals. On the signal side, “main” meant the main parachute. But on the receiver side “main,” it meant the pyrotechnic that pops off the canister cover and deploys the smaller chute.

When engineers connected the two mains, it shuffled the order of the parachute deployment actions.

But no harm, no foul. And with the asteroid sample safely back on Earth, scientists can now begin research to see just how much of a role crashing asteroids played in laying the foundations for life on Earth.


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