Engineers investigating iffy solar array latch on NASA's Lucy as probe begins long journey to Trojan asteroids

Spacecraft otherwise stable and working well

NASA's Lucy is on its way to the Trojan asteroids, but engineers have already spotted a problem with one of the probe's 7.3-metre solar arrays.

The spacecraft was sent on its way from Cape Canaveral's Space Force Station's SLC-41 pad on Saturday atop an Atlas V rocket. The mission is set to last 12 years, over which the probe, dubbed "Lucy" (named for the fossilised skeleton of an early hominin ancestor), will fly past one main-belt asteroid and seven Trojan asteroids.

Lucy is now barrelling along at approximately 108,000kph and is due to swing past Earth in a year's time for a gravity assist. It sent its first signal to Earth just over an hour after launch and 30 minutes after unfurling its solar arrays.

Which is where things might not be going quite so well: while both arrays have deployed and are producing power to charge the spacecraft's batteries, one does not appear to have fully latched into place.

NASA’s #LucyMission is safe & stable. The two solar arrays have deployed, but one may not be fully latched. The team is analyzing data to determine next steps. This team has overcome many challenges already and I am confident they will prevail here as well https://t.co/8IYs8bJhKM pic.twitter.com/oICOA3ksre

— Thomas Zurbuchen (@Dr_ThomasZ) October 17, 2021

Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA, approved the mission in 2017.

The spacecraft is set to make its first Trojan asteroid encounter in 2027, in the swarm of asteroids ahead of Jupiter. After a third gravity assist from Earth in 2031 (a second will take place in 2024), it will reach the trailing swarm of Trojans in 2033.

Scientists reckon that the Trojan asteroids are leftover materials from the formation of the giant planets and could offer insights into how the solar system evolved. The asteroids share an orbit around the Sun with Jupiter.

The distances involved mean huge solar arrays are required to keep the probe's instruments running.

Lucy is not the first spacecraft to suffer power issues; a faulty connection on ESA's Mars Express reduced the power available from the probe's arrays. That mission has gone on to exceed all expectations.

The spacecraft has further checkouts ahead of it, although it is unclear if these will be postponed while engineers work on the latch issue. As well as insisting the spacecraft was stable and working well, NASA said: "The team is analyzing spacecraft data to understand the situation and determine next steps to achieve full deployment of the solar array." ®