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Based on When will Lucy deploy its solar panels?, I learned that Lucy will unfold its solar arrays 1 hour after launch. How will it be powered during this hour? Does it have batteries that are charged before launch?

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    $\begingroup$ You accepted an unsourced educated guess instantly. That's your choice but why not wait a bit to see if an answer based on authoritative sources is added? $\endgroup$
    – uhoh
    Commented Oct 8, 2021 at 8:56
  • $\begingroup$ Realistically, what else could it be, but a battery? However, I agree that unsourced answers are of little value. $\endgroup$ Commented Oct 8, 2021 at 11:55

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A space probe like Lucy should be able to recover from an accidental misalignment of the solar cells to the sun. Such a misalignment may be caused by software errors or transient hardware errors.

To do a realignment after an emergency, the space probe needs an intermediate power source, a charged battery. The same battery may be used for the first hour after launch before unfolding the solar cells. Of course the battery should be charged again when solar power is available.

On Sept. 18, propulsion engineers finished filling Lucy’s fuel tanks with approximately 1,600 pounds (725 kilograms) of liquid hydrazine and liquid oxygen, which make up 40% of the mass of the spacecraft. The fuel will be used for precise maneuvers that will propel Lucy to its asteroid destinations on schedule, while the solar arrays – each the width of a school bus – will recharge the batteries that will power spacecraft instruments.

Source: https://www.scientiststudy.com/2021/09/nasas-lucy-mission-prepares-for-launch.html

So there is in fact a rechargeable battery in Lucy.

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  • $\begingroup$ Possible true but zero supporting sources. $\endgroup$
    – uhoh
    Commented Oct 8, 2021 at 8:54
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    $\begingroup$ @uhoh I hope you are happy with the single source. $\endgroup$
    – Uwe
    Commented Oct 8, 2021 at 13:58
  • $\begingroup$ How does the quoted source support the idea that LUCY will be launched with the battery charged? It doesn't actually say that anywhere. I think we can all guess that that's the case, but we should still keep an eye out for something, though it may not be easy to find. $\endgroup$
    – uhoh
    Commented Oct 8, 2021 at 14:15
  • $\begingroup$ @uhoh Launching Lucy with a fully discharged battery would be very strange. The difference of the mass of a discharged and a charged battery is so small, it could not be measured. Launching with an empty battery does not make sense. $\endgroup$
    – Uwe
    Commented Oct 8, 2021 at 17:29
  • $\begingroup$ I'm sure we'd all assume it was launched fully charged. While there are rules about stored energy for cubesat launchers, since Lucy has lots of fuel already they obviously don't apply here. It's just that in Stack Exchange answers we strive to support assertions with sources. $\endgroup$
    – uhoh
    Commented Oct 8, 2021 at 22:22

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