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Interesting! I didn't know the telescope started to unfold en route to L2. I thought it would start unfolding after reaching L2. Are there any significant accel

Interesting! I didn't know the telescope started to unfold en route to L2. I thought it would start unfolding after reaching L2. Are there any significant acceleration events needed to enter L2, one that might add stress to the unfolded sections?

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IntrepidWorm 5y ago
I would assume these are well known concerns to the Webb team: if they are planning to begin unpacking prior to reaching L2, it must be because the forces involved with finalizing the orbit are well within the tolerances of the fully expanded craft. They would not risk damage to the telescope if the processes involved weren't already rigorously tested and safe. There's a lot of eyes and quite a lot of money riding on this project.
- aero-glide2 5y ago
  Okay that doesn't really answer the question
krisoft 5y ago
“A trajectory can be fashioned so that JWST ‘falls into orbit’ about L2 rather than having to forcibly inject itself into a set orbit using its propulsion subsystem; this saves propellant and makes for simpler orbit maintenance.” Quote from the JWST’s user documentation: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-orbit https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-o... So no significant acceleration event is expected as they enter an orbit around L2. Furthermore they will have to keep doing orbit maintenance burns every 21 day while there, so they must have designed the structure with that in mind.
- krisoft 5y ago
  Found an even better source! https://ntrs.nasa.gov/api/citations/20140008868/downloads/20140008868.pdf https://ntrs.nasa.gov/api/citations/20140008868/downloads/20... This paper discussed the Monte Carlo method they implemented to plan and control the orbital insertion. At page 16 they discuss nominal burn times. The MCC-2 burn has an associated deltaV of 0.712m/s. (That is the first of many burns which happen in the unfolded state) Of course the real value will depend on how accurate the previous burns happens to be, but it provides a rough estimate of what we can expect.
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- mcdonje 5y ago
  I wonder how many years worth of fuel they have to maintain orbit, and what happens when orbit fails. Does it settle into the L point instead of orbiting it? Does it fly off?
  - zardo 5y ago
    It's like a hilltop, without propellent to keep it near L2 it will roll off into solar orbit.
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IntrepidWorm 5y ago

I would assume these are well known concerns to the Webb team: if they are planning to begin unpacking prior to reaching L2, it must be because the forces involved with finalizing the orbit are well within the tolerances of the fully expanded craft. They would not risk damage to the telescope if the processes involved weren't already rigorously tested and safe. There's a lot of eyes and quite a lot of money riding on this project.

aero-glide2 5y ago
Okay that doesn't really answer the question

krisoft 5y ago

“A trajectory can be fashioned so that JWST ‘falls into orbit’ about L2 rather than having to forcibly inject itself into a set orbit using its propulsion subsystem; this saves propellant and makes for simpler orbit maintenance.” Quote from the JWST’s user documentation: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-orbit https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-o... So no significant acceleration event is expected as they enter an orbit around L2. Furthermore they will have to keep doing orbit maintenance burns every 21 day while there, so they must have designed the structure with that in mind.

krisoft 5y ago
Found an even better source! https://ntrs.nasa.gov/api/citations/20140008868/downloads/20140008868.pdf https://ntrs.nasa.gov/api/citations/20140008868/downloads/20... This paper discussed the Monte Carlo method they implemented to plan and control the orbital insertion. At page 16 they discuss nominal burn times. The MCC-2 burn has an associated deltaV of 0.712m/s. (That is the first of many burns which happen in the unfolded state) Of course the real value will depend on how accurate the previous burns happens to be, but it provides a rough estimate of what we can expect.
- deleted 5y ago
  [deleted]
mcdonje 5y ago
I wonder how many years worth of fuel they have to maintain orbit, and what happens when orbit fails. Does it settle into the L point instead of orbiting it? Does it fly off?
- zardo 5y ago
  It's like a hilltop, without propellent to keep it near L2 it will roll off into solar orbit.

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