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NASA has a plan to fix Lucy spacecraft’s solar array problem

NASA’s Lucy spacecraft has been traveling through space on its way to visit the Trojan asteroids since its launch in October last year, but the team has had to deal with an unexpected issue with its deployment.

The problem is with one of Lucy’s two solar arrays. These needed to be folded up for launch so the spacecraft could fit inside its launch vehicle, then they deployed once Lucy reached space. The arrays deployed by unfolding, fan-like, into two distinctive round shapes which should then have been latched into place.

Artist’s illustration of the Lucy concept.
Artist’s illustration of the Lucy mission. Southwest Research Institute

But one solar array failed to latch correctly after deployment on October 17, 2021. The array was almost completely deployed and was still capable of providing solar energy to the spacecraft, but it was not secured in place as it should have been. The mission team opted to continue with the craft entering cruise mode as planned because the combined two arrays were generating enough power for the mission to go ahead.

Now, though, NASA wants to try to lock the array in place once again. Engineers on the ground have been performing tests and looking at data from the spacecraft and have concluded that the array in question is open to 345 out of 360 degrees and is still producing enough power. But there are concerns that if and when the spacecraft fires its main engine, the unlocked solar array could be damaged.

In a recent update, NASA shared that on Monday, April 18, the team decided to go ahead with trying to fix the array into its proper place. To do that, they will work with the motor which controls the array deployment. “After launch, the arrays were opened by a small motor that reels in a lanyard attached to both ends of the folded solar array,” NASA writes. “The team estimates that 20 to 40 inches of this lanyard (out of approximately 290 inches total) remains to be retracted for the open array to latch.”

The array has both a primary and a backup motor for this deployment, so engineers will try to use both of these motors together to pull the lanyard through and allow the array to latch into place. Testing suggests that the additional torque from using both motors may be enough to tug the lanyard out of its snag.

Enacting this plan will require two steps. The first step, scheduled to begin in the week of May 9, is to pull the lanyard taut, which will allow the team to check that the spacecraft is in the same condition as the testing on the ground and will also help to strengthen the array. The second step, scheduled for a month after step one if everything goes well, will be to use the two motors to try to pull the array into place.

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