How engineers fixed Lucy spacecraft’s solar array issue

How engineers fixed Lucy spacecraft's solar array issue

NASA’s Lucy spacecraft has had a rough start to its mission, with an implementation problem affecting its solar power system — but luckily engineers were able to fix the problem. Now, NASA has shared more information about how members of the Lucy team have been working to troubleshoot and fix the problem from Earth and the spacecraft.

Lucy was launched in October 2021, with its two circular solar panels folded to fit inside the rocket fairing. Once in space, shortly after launch, Lucy would deploy the two arrays to collect the solar energy that would power the spacecraft on its long journey to the Trojan asteroids, which are in Jupiter’s orbit. One array was deployed as expected, the other not completely. The arrays were supposed to unfold like the hands of a clock and click into place, but one was only partially deployed and didn’t click into place.

The good news was that the craft was generating enough power to sustain itself even when the array was only partially deployed. However, when the array was not locked in place, it was not under tension, making it weak, and there were concerns that the forces of future maneuvering could shake or damage the array. The Lucy team, made up of engineers and scientists from NASA, Lockheed Martian, Northrop Grumman and the Southwest Research Institute (SwRI), set to work to find out what they could do.

“We have an incredibly talented team, but it was important to give them time to figure out what happened and how to move forward,” said Hal Levison, Lucy’s principal investigator at SwRI, in a statement. “Luckily, the spacecraft was where it needed to be, nominally functioning and – most importantly – safe. We had time.”

The team found that the problem was caused by a cord, which was pulled by a motor to pull the array into its round shape. Something seemed to have caught on the string and prevented the array from opening completely. They were faced with a choice: leave the craft as it was, currently healthy but could cause problems in the future, or use extra power from a spare motor to pull the rope tighter.

“Each path involved a certain amount of risk in achieving basic science objectives,” said Barry Noakes, chief engineer of deep space exploration at Lockheed Martin. “A big part of our effort has been to identify proactive actions that mitigate risk in both scenarios.”

After modeling the risks of each option using test images and a replica of the craft here on Earth, the team decided to try and solve the problem. Several sessions of tweaking and pulling the string were needed in May and June of this year, but eventually the array was almost fully deployed. It’s still not locked in place, but it’s deployed between 353 and 357 degrees of 360 degrees, which is stable enough for the craft to carry out its mission.

Lucy now continues his long journey, scheduled to arrive at the Trojans in 2027.

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