How engineers solved the Lucy spacecraft’s solar panel problem
NASA’s Lucy spacecraft had a rocky start to the mission, with a deployment issue affecting its solar power system – but thankfully engineers were able to fix the problem. Now, NASA has shared more information about how members of Lucy’s team worked to troubleshoot and resolve the issue from Earth and the craft flew through space.
Lucy launched in October 2021, with its two circular solar panels folded to fit inside the rocket’s fairing. Once in space shortly after launch, Lucy had to deploy both arrays to collect solar energy that would power the craft on its long journey to the Trojan asteroids, located in Jupiter’s orbit. One array deployed as expected, however, the other did not fully deploy. The rows were supposed to unfold like the hands of a clock and lock into place, but one of them only unfolded halfway and did not lock.
The good news was that the craft produced enough power to sustain itself even with the array partially deployed. However, when not locked in place, the array was not energized, making it fragile, and it was feared that future maneuvering forces might shake or damage the array. Lucy’s team, made up of engineers and scientists from NASA, Lockheed Martian, Northrop Grumman and the Southwest Research Institute (SwRI), set to work figuring out what she 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, Lucy’s principal investigator at SwRI, said in a statement. “Fortunately, the spacecraft was where it was supposed to be, nominally functioning and, most importantly, safe. We had time.
The team discovered that the problem had been caused by a lanyard, which was pulled by a motor to pull the array into its round shape. Something seemed to have snagged the cord and prevented the board from fully opening. They were faced with a choice: leave the craft as it was, currently healthy but potentially risking problems in the future, or use the extra force of a standby engine to pull the tether harder.
“Each path had an element of risk to achieve the basic science goals,” said Barry Noakes, Lockheed Martin’s chief deep space exploration engineer. “A big part of our effort was to identify proactive actions that mitigate risk in both scenarios.”
After modeling the risks of each option using test footage and a replica of the craft here on Earth, the team decided to attempt to solve the problem. It took several tweaking and tugging sessions on the lanyard in May and June of this year, but eventually the network was almost fully rolled out. It’s still not locked in place, but it has deployed between 353 and 357 degrees out of 360 degrees, which is stable enough for the craft to complete its mission.
Lucy is now continuing her long journey, scheduled to arrive at Les Troyens in 2027.