NASA halts efforts to fully deploy Lucy solar panel

WASHINGTON – NASA is halting efforts, at least until the end of next year, to try to fully deploy a solar array on the Lucy spacecraft, citing diminishing returns as the spacecraft moves away from the sun.

In a statement quietly posted on NASA’s website on January 19, the agency said the last attempt to lock one of two solar arrays on Lucy, more than a month earlier, failed to complete deployment of the circular array and lock it into place. This effort, NASA said, “produced only slight movement in the solar panel.”

The mission has been working on fully deploying the solar array since shortly after launch in October 2021. While one of the arrays, 7.3 meters in diameter, unfolded and locked into place as designed, the other did not. Engineers spent months diagnosing the problem, concluding a loss in tension in a cord used to deploy the array prevented it from fully deploying and locking into place.

NASA has played down the issue, noting that engineers believe the array is almost fully deployed and appears to be stable. That was based on the array’s performance during a gravity-assisted flyby of Earth on October 16, when it passed less than 400 kilometers above Earth, through the thin upper atmosphere, without a problem.

However, spacecraft controllers have attempted since that flyby to try to complete the array’s deployment and lock into place. One test on Nov. 7 “deployed the wing incrementally forward,” NASA said, but controllers also noticed a slight vibration in the array, which engineers concluded was the result of an interaction between the engine and the structural modes of the array.

After adjusting the engine, NASA tried again on December 13, but noticed that propulsion had “diminished to minimal levels,” which engineers concluded was due to the falling temperatures as Lucy moves further from the Sun.

“NASA’s Lucy mission team has decided to suspend further solar panel deployment activities,” the agency said in its latest statement. “The team determined that operating the mission with the solar array in its current unlocked state carries an acceptable level of risk, and further deployment activities are unlikely to be beneficial at this time.”

The agency has not ruled out another attempt to lock the array, but not before the spacecraft makes its next close approach to Earth in late 2024, warming it up enough to make progress more likely. These plans will also depend on the stability of the array during the first maneuver of the spacecraft’s main engine in February 2024.

Even if the array does not fully deploy and lock, NASA said the array, 98% deployed, can generate enough power for the spacecraft to complete its mission, flying past a main belt asteroid and seven Trojan asteroids at Jupiter’s distance from the Sun. These flybys will take place between 2025 and 2033.

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