(ORDO NEWS) — On April 18, NASA made the decision to move forward with plans to complete the deployment of the stalled and unfixed solar array of the Lucy spacecraft.
The spacecraft is powered by two large solar arrays that were supposed to deploy and lock into place after launch. One of the fan-shaped arrays opened as planned, but the other one stopped short of completing its operation.
Through a combination of careful in-flight performance testing of the solar array and ground testing, Lucy engineers determined that the unclamped solar array was nearly fully open, opening about 345 out of 360 degrees and producing enough power for the spacecraft. However, the team is concerned about potential damage to the batteries if the spacecraft turns on the main engine.
After launching the apparatus, the batteries were opened using a small motor that winds a string attached to both ends of the folded solar array. The team estimates that between 50 and 100 cm of this lanyard (out of a total of about 740 cm) must be wound in order for the partially open solar array to lock into place.
The solar array has been designed with a primary and backup motor winding to provide an extra level of reliability for critical solar array deployments.
Lucy’s engineers will take advantage of this redundancy by running both engines at the same time to generate more torque than was used on launch day. Ground tests show that this extra torque can be enough to pull a hooked lace through the remaining distance needed to snap it into place.
The team is now preparing to complete the deployment of the solar array in two phases. The first stage, tentatively scheduled for May 9, is designed to retract most of the remaining lanyard and verify that flight results are consistent with ground tests.
This step will also strengthen the array of batteries, bringing them closer to a fully stretched state. Because the duration of this step is limited, there is little chance that the array will latch at this point.
If this stage does not go according to plan, then the second stage will continue to expand the array in order to fully commit.
The information obtained during the first stage will help to correct the second stage. The second phase is planned to take place a month after the first, which will give engineers enough time to analyze the data obtained during the first attempt.
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