NASA’s Lucy mission – set to explore a group of asteroids trailing behind and in front of Jupiter’s orbit – hit a snag recently when one of its solar panels failed to unfold. On Thursday, the Lucy team announced that it would perform two maneuvers to fully unroll its solar panels.
The Lucy mission will study the crumbs left over from the early Solar System and need to reach Jupiter’s orbit, where two gravitational rifts have collected them. Operating further from the Sun requires large solar panels to capture the waning sunlight for energy, so Lucy was equipped with two peeper-like solar wings.
Shortly after the launch in October 2021, NASA officials noticed something was wrong with one of the solar panels. Their readings were unusual, and staff soon realized that the cord surrounding a solar panel had not fully retracted, blocking sunlight from reaching the panels. An engineering model suggests that when retracting, “the cord may not have wound onto the spool as intended,” NASA reported a month after launch.
According to NASA officials, the defective matrix is between 75% and 95% implanted.
The space agency has been monitoring the situation for the past half year, and on April 18 it decided on a plan that it hopes will address the issue.
They will take two steps over the next few months to see if the solar panel can be fully deployed.
The first will take place on May 9, when they will try to pull back some of the cord in a quick maneuver. The team anticipates that this single operation will not be enough, so they are planning a second array deployment task for a month later, which will hopefully successfully crash the solar array. The month between each task will give teams time to analyze how best to perform the second maneuver.
“The solar panel is designed with a primary and a backup motor winding to provide an additional layer of reliability for deploying mission-critical solar panels. Lucy’s engineers will take advantage of this redundancy by using both engines simultaneously to generate higher torque than used on launch day. Ground tests show that this additional torque may be enough to pull the growling cord the remaining distance needed to lock,” NASA officials shared in a mission update published last Thursday.
So far, the issue has not affected the mission very severely. “This solar panel is generating almost the expected power when compared to the fully deployed wing. That energy level is enough to keep the spacecraft healthy and running,” NASA officials shared three days after launch.
Having fully charged batteries is important. Lucy is heading to Jupiter at a speed of approximately 108,000 km/h to study Trojan asteroids, peculiar rocks significantly different from those found between the orbits of Mars and Jupiter in the Asteroid Belt.
Trojans are remnants of the Solar System’s formation that were placed in orbit around Jupiter and thus avoided being ejected into deep space. The Trojans are trapped in two gravitationally stable points called Lagrange Point 4 and Lagrange Point 5, created by the interaction of the Sun and Jupiter.
Lucy will study seven asteroids over 12 years, so having fully operational batteries will be critical. The team also hopes that if the lanyard cannot be retracted and the solar panel has to remain as it is, the main engine burns will not mess with the solar panel.
Lucy will hit her first target in 2025, an Asteroid Belt object nicknamed Donaldjohanson. After the encounter with this asteroid, the spacecraft will continue towards the group of Trojans residing in front of Jupiter, aiming for an arrival in 2027. After that, a maneuver will take it back to the inner Solar System to use Earth for gravitational assistance. in 2031, only to return for a second Trojan trip in 2033 towards the asteroids on the right.
The mission is named after the three-million-year-old hominid fossil discovered in Ethiopia in 1974. Donaldjohanson is named after Lucy’s discoverer. “Lucy” is an homage to origins science and likely a reference to the Beatles song that inspired the fossil’s name, “Lucy in the Sky with Diamonds”. Hal Levison, Lucy’s principal investigator, has compared Trojans to jewels for their “immense scientific value”.