How Engineers Fixed Lucy’s Solar Array Problem

NASA’s Lucy spacecraft has had a turbulent start to its mission, with a deployment issue affecting its solar power system—but thankfully, engineers have been able to address that problem. Now, NASA has shared more information about how members of Lucy’s team are working to explore and solve the problem from Earth and race the craft through space.

Lucy’s solar powered journey continues

The Lucy was launched in October 2021, with the two circuit solar arrays folded to fit inside the rocket’s hull. Once in space shortly after launch, Lucy had to deploy the two arrays to collect solar energy that would power the craft on its long journey to the Trojan asteroids located in Jupiter’s orbit. One set was published as expected, however, the other was not fully published. The arrays were supposed to open like a clockwise and lock in place, but one of them was only partially deployed and not locked.

The good news was that the craft was generating enough power to sustain itself even with the array only partially deployed. However, when the array is not held in place, it does not undergo tension making it flimsy, and there have been concerns that future maneuvering forces could shake or damage the array. Lucy’s team, made up of engineers and scientists from NASA, Lockheed Martin, Northrop Grumman, and the Southwest Research Institute (SwRI), set out to see 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,” Hal Levison, principal investigator for Lucy from SwRI, said in a statement. “Fortunately, the spacecraft was where it was supposed to be, nominally operating, and most importantly, it was safe. We had time.”

The team discovered that the problem was caused by a rope being pulled by a motor to pull the array into its circular shape. It looks like something has caused the cord to malfunction and prevented the array from opening completely. They faced a choice: leave the vehicle as it is, currently healthy but potentially risking problems in the future, or use extra power from a spare engine to pull the rope more aggressively.

“Each trajectory carries some element of risk to achieve basic science goals,” said Barry Knox, chief engineer for deep space exploration at Lockheed Martin. “A large part of our effort has been to identify proactive measures that mitigate risks in either scenario.”

After modeling the risks of each option using test footage and a replica of the vehicle here on Earth, the team decided to try to fix the problem. It took several sessions of rope tweaking during May and June of this year, but in the end, the matrix rolled out almost completely. It’s still not bolted into place, but has sprung between 353 and 357 degrees out of 360 degrees, which is stable enough for the vehicle to perform its mission.

Lucy is now continuing her long journey, set to reach the Trojans in 2027.

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