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The James Webb Space Telescope and stuff


Streetwind

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1 minute ago, Xd the great said:

Well, will NASA be able to use the orion sls system to fix it if deployment goes wrong? In the future?

Probably not. 

I doubt that JWST is even designed to be serviced, unlike HST. Even if we could get out there, servicing it may not be possible.

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2 minutes ago, Bill Phil said:

Probably not. 

I doubt that JWST is even designed to be serviced, unlike HST. Even if we could get out there, servicing it may not be possible.

So no fixing in space? I thought with the materials and stuff, we can just take it apart and rebuild it out there.

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13 minutes ago, Xd the great said:

So no fixing in space? I thought with the materials and stuff, we can just take it apart and rebuild it out there.

Webb is going to be orbiting in the Earth-Sun L2 point, way beyond the range of any manned vehicle in service. A BFR could maybe capture it and bring it back to Earth for repairs, but by that point it might actually be easier to just launch a replacement (or ten) instead.

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34 minutes ago, Xd the great said:

So thats like 2 tines the distance between earth and moon?

More like 4 times.

As in, no human has even been that far from Earth.

56 minutes ago, Xd the great said:

So no fixing in space? I thought with the materials and stuff, we can just take it apart and rebuild it out there.

That would require much more money. It may be cheaper to just send another one, and if BFR works, you could probably send a bigger one for less.

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5 minutes ago, Bill Phil said:

That would require much more money. It may be cheaper to just send another one, and if BFR works, you could probably send a bigger one for less.

It not the sending part that is expensive.  It's the designing, building and testing of the telescope and sunshield where most of the money is spent.

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Just now, AVaughan said:

It not the sending part that is expensive.  It's the designing, building and testing of the telescope and sunshield where most of the money is spent.

Yeah, but BFR is much larger, allowing a potential successor to not use the fold-out method, and thus be much simpler in design, reducing cost significantly.

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21 minutes ago, Bill Phil said:

As in, no human has even been that far from Earth.

That would require much more money. It may be cheaper to just send another one, and if BFR works, you could probably send a bigger one for less.

Would it be feasible to send a remote controlled maintenance bot? No life support, no sacks of meat, no time limit, no need to plan for re-entry.

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4 minutes ago, HebaruSan said:

Would it be feasible to send a remote controlled maintenance bot? No life support, no sacks of meat, no time limit, no need to plan for re-entry.

Maybe. Although JWST isn't designed for maintenance, from what I can find. If it was, a remote maintenance probe might be a good idea.

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10 hours ago, tater said:

Repair not an option, not least because RCS alone would not be very good for it, even assuming you could get to it.

I don't even want to think about how much damage would a little bit of cold gas do to the sensitive instruments JWST has. Probably even an ion-based RCS would do more harm than the robot could do good to the telescope.

About that BFR telescope thing: not only it would be bigger but also simpler as the mirror could be cast in one piece instead of being all origami like JWST. It would be like HST 2.0 except probably even cheaper than that. That's what makes me so excited about the BFR. It makes so many things possible and available sooner.

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I heard that, even servicing not being planned, JWST has a docking ring

https://www.scientificamerican.com/article/is-the-james-webb-space-telescope-too-big-to-fail/

So it's not completely discarted by NASA the idea of maintenance. A robot could use RCS to dock "under" the sunshield and move around JWST using some sort of arms. That (maybe) would prevent RCS damaging the mirror or the instruments

 

EDIT: From the article

Quote

There are, however, modest efforts being made to make JWST “serviceable” like Hubble, according to Scott Willoughby, JWST’s program manager at Northrop Grumman Aerospace Systems in Redondo Beach, California. The aerospace firm is NASA’s prime contractor to develop and integrate JWST, and has been tasked with provisioning for a “launch vehicle interface ring” on the telescope that could be “grasped by something,” whether astronaut or remotely operated robot, Willoughby says. If a spacecraft were sent out to L2 to dock with JWST, it could then attempt repairs—or, if the observatory is well-functioning, simply top off its fuel tank to extend its life. But presently no money is budgeted for such heroics.

 

Edited by VaPaL
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So another year, and another billion dollars. yeesh.

How about a new paradigm of launching more, but cheaper experiments?

130 M$ FH launch, and an 800 M$ telescope, then make 10 of them.

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1 hour ago, tater said:

So another year, and another billion dollars. yeesh.

How about a new paradigm of launching more, but cheaper experiments?

130 M$ FH launch, and an 800 M$ telescope, then make 10 of them.

Yeah. That might be a better idea. 

Can't you take multiple telescopes and get similar results to a single large telescope?

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21 minutes ago, Bill Phil said:

Yeah. That might be a better idea. 

Can't you take multiple telescopes and get similar results to a single large telescope?

Yes, interferometry is possible for optical telescopes. For example, it is one of the nice features of the VLT. (cf. https://en.wikipedia.org/wiki/Interferometry)

However, even down here on Earth combining optical telescopes is incredibly hard (Guess why ESO is building the Extremely Large Telescope with its nearly 40m mirror?!). The biggest problem is the fact that you need to actually combine the light from the participating telescopes to a very high degree of precision, unlike for radio waves, for which computationally combining the data from multiple telescopes is enough (cf. Event Horizon Telescope).

So, I would say that it is incredibly unlikely that one could do the same thing as the JWST with multiple space telescopes, while reducing costs.

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42 minutes ago, Bill Phil said:

Yeah. That might be a better idea. 

Can't you take multiple telescopes and get similar results to a single large telescope?

Optical interferometry to make a synthetic aperture? Yeah, it could be done, though it might be pretty complex on orbit.

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15 minutes ago, tater said:

Ouch.

The slip, plus no slop.

So:

  • JWST has now surpassed SLS/Orion as the most bloated, delayed, and overpriced NASA program
  • Launch will not happen until 2022
  • JWST will probably launch on the last Ariane 5 or be moved to a different vehicle

 

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38 minutes ago, _Augustus_ said:

So:

  • JWST has now surpassed SLS/Orion as the most bloated, delayed, and overpriced NASA program

Since "overpriced" is relative to value, then possibly yes---except that JWST will actually do something useful assuming it works. SLS/Orion? I'm honestly unsure it ever has any return on investment at all.

Quote
  • Launch will not happen until 2022

It could still happen in 2021, but they have no margin of error for March. 2022 would not surprise me in the least.

Quote
  • JWST will probably launch on the last Ariane 5 or be moved to a different vehicle

 

Yep.

 

 

Quote

A wiring error caused workers to apply too much voltage to the spacecraft’s pressure transducers, severely damaging them. And during an acoustics test, which examines whether hardware can survive the loud sounds of launch, the fasteners designed to hold the sun shield together came loose. The incident scattered 70 bolts, and engineers scrambled to find them. They’re still looking for a few. “We’re really close to finding every one of the pieces,” Zerbuchen said.

https://www.theatlantic.com/science/archive/2018/06/nasa-james-webb-space-telescope-delay-human-error/563903/

Edited by tater
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3 hours ago, _Augustus_ said:

So:

  • JWST has now surpassed SLS/Orion as the most bloated, delayed, and overpriced NASA program
  • Launch will not happen until 2022
  • JWST will probably launch on the last Ariane 5 or be moved to a different vehicle

 

Hubble was delayed 7 years, 10 if we count the mirror mishap... by comparison 3 years or so isn't too bad. Of course, JWST is much more delayed than Hubble.

Also, some may consider the ISS (used to be Space Station Freedom) to be much more bloated and much more delayed...

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