The Lucy spacecraft has wide solar arrays that are folded up for launch. It will then deploy them once in space.

At what moment of the Lucy mission (2021) will its solar arrays be deployed? As soon as it is in space?

  • $\begingroup$ looking forward to a followup question about what Lucy will do for power beforehand; do they still deliver some power folded, or will it launch with batteries fully charged, or will it be in low power mode, or... hopefully worded better than that though :-) $\endgroup$
    – uhoh
    Oct 6, 2021 at 0:37
  • 1
    $\begingroup$ @uhoh I've learned from Kerbal Space Program -- not the most authoritative source, I'm aware -- that the process of running a rocket provides an opportunity to generate electricity during launch, so I'd guess the batteries are fully charged upon reaching orbit. $\endgroup$ Oct 6, 2021 at 13:35
  • $\begingroup$ You'd think they'd make sure they were fully charged before they set off. I know I do with the leisure batteries in my campervan, even though the alternator charges them en-route... ;-) $\endgroup$ Oct 6, 2021 at 19:41
  • $\begingroup$ @GilesBennett I don't know if it applies to payloads like this, but there are some launch providers that have strict rules on stored energy in satellites, those include chemical (e.g. pyrotechnics) mechanical (springs), magnetic and electric (batteries). This is mostly for the cubesat launch market so may not apply here, but it's not a given that batteries are always launched fully charged. $\endgroup$
    – uhoh
    Oct 6, 2021 at 20:03
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    $\begingroup$ @uhoh Very interesting, thank you! $\endgroup$ Oct 6, 2021 at 20:15

1 Answer 1


One hour after launch.

"At about one hour after the spacecraft launches, the solar panels will need to deploy flawlessly in order to assure that we have enough energy to power the spacecraft throughout the mission,” said Principal Investigator Hal Levison of the Southwest Institute in Boulder, Colorado. “These 20 minutes will determine if the rest of the 12 year mission will be an success. Mars landers have their seven minutes of terror, we have this.”

Source: https://www.nasa.gov/feature/goddard/2021/nasa-lucy-stretches-its-wings-in-successful-solar-panel-deployment-test


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