Timeline for Why are eclipses of the James Webb by the Earth or Moon not permitted during the mission?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Nov 27, 2022 at 16:41 | vote | accept | Woody | ||
| Jan 13, 2022 at 16:37 | comment | added | Woody | The question asks why eclipses (partial or total) are not permitted during the entire mission. Unfurling solar panels only happens once, shortly after launch. If the batteries have the capacity to unfurl panels, surely they have the capacity to survive a partial lunar eclipse in halo orbit ? As the quote says, disallowing eclipses has a mission design restraint "cost", but scant "benefit". | |
| Dec 26, 2021 at 14:49 | comment | added | Freddo411 | The easiest way to avoid running out of power is to avoid eclipses? How about sizing the battery to handle these short duration events? Sure, it's an engineering trade off, but it's really weird to not address this option. | |
| Dec 4, 2021 at 9:20 | comment | added | Ng Ph | true. Also li-ion batteries do not like sub-zero temperatures. So, the decision to disallow eclipse is a wise and well-justified, IMO. I think I have understood the general strategy in designing the JWST orbit: they did not start from an "ideal halo" template. This is because the achievable orbit is very dependent of the date and time of launch, as it is explained in a paper by Brown et. al. (2015). See comments after space.stackexchange.com/questions/56043/… | |
| Dec 3, 2021 at 23:46 | comment | added | David Hammen | @NgPh In addition to the above, this document was from 2006. That would have given NASA over a decade to refine the JWST operations concepts. What that decade wouldn't have given NASA was the ability to allow eclipse crossings. Once that decision had been made to disallow eclipses, the sizing of the batteries was pretty much set in stone. | |
| Dec 3, 2021 at 23:13 | comment | added | David Hammen | @NgPh Halo orbits are a subclass of Lissajous orbits. | |
| Dec 3, 2021 at 21:31 | comment | added | Ng Ph | At the end of the same paragraph that you cited from the linked Mission Operations Concept document, it can be read "A L2 Lissajous orbit with a semi-major axis of 800,000 km has been selected". Do we have to conclude that JWST orbit is not necessarily a halo orbit? | |
| Dec 3, 2021 at 19:30 | history | answered | David Hammen | CC BY-SA 4.0 |