WASHINGTON — Leaders of NASA’s Lucy asteroid mission are increasingly confident that the mission can continue as planned even if ongoing efforts to fully deploy and latch a solar array don’t succeed.
Engineers have been studying for months one of two circular solar arrays that did not fully deploy and latch into place after the spacecraft’s launch in October 2021. They concluded that a lanyard used to pull open the solar array lost tension during the deployment process, causing the lanyard to wrap around the motor shaft.
On May 9, controllers issued commands to run both the primary and backup motors for the solar array deployment process simultaneously, hoping that a harder pull would be sufficient to restore tension in the lanyard and continue deployment of the array. The spacecraft similarly ran both motors three times since then.
“That’s allowing us to make significant process towards latch, but we’re not latched yet,” Hal Levison, principal investigator for Lucy at the Southwest Research Institute, said in a presentation at a meeting of NASA’s Small Bodies Assessment Group June 8. “We are seeing significant tensioning of the array.”
That tensioning, he said, is a positive sign even though the array has not latched into place. “It makes it likely that, even if we don’t get the thing latched, we’ll be able to fly the mission as-is,” he said, noting the array, in its current configuration, is generating more than 90% of its planned power.
The mission is preparing for an Earth gravity-assist flyby in October, when the spacecraft will pass about 350 kilometers above the Earth. After a second Earth flyby in 2024, Lucy will go past an asteroid in the main belt in 2025, then several Trojan asteroids in a cluster leading Jupiter in orbit around the sun in 2027 and 2028. A third Earth flyby in 2030 will set up encounters with two Trojan asteroids in a separate cluster trailing Jupiter in 2033.
To set up the October flyby, Lucy performed a trajectory correction maneuver June 7, NASA said in a June 8 blog post. The maneuver is the first of several planned before the October flyby.