magnemoe Posted December 20, 2021 Share Posted December 20, 2021 4 hours ago, tater said: As @sevenperforce said, Progress has been doing this for decades, so it was clearly a possibility. My guess is that refueling MIR and later ISS is much easier than an fragile and exposed space telescope out at L2. Is lifetime limit because of fuel limits very relevant as it is it likely to break for other reasons first. Quote Link to comment Share on other sites More sharing options...
Codraroll Posted December 20, 2021 Share Posted December 20, 2021 If we're being properly optimistic, we could hope that by the time JWST reaches the end of its lifespan, it will be a matter of a routine Starship flight to go out there and refurbish it. Popping in a new tank of hydrazine, inserting some new sensors, improving comms, all that jazz. Or maybe just installing a new telescope entirely and taking JWST down to be exhibited in a museum. Quote Link to comment Share on other sites More sharing options...
Beccab Posted December 20, 2021 Share Posted December 20, 2021 4 minutes ago, Codraroll said: If we're being properly optimistic, we could hope that by the time JWST reaches the end of its lifespan, it will be a matter of a routine Starship flight to go out there and refurbish it. Popping in a new tank of hydrazine, inserting some new sensors, improving comms, all that jazz. Or maybe just installing a new telescope entirely and taking JWST down to be exhibited in a museum. Docking itself may be a problem, JWST with the sunshield deployed is extremely fragile. The vibrations during docking would be a problem Quote Link to comment Share on other sites More sharing options...
cubinator Posted December 20, 2021 Share Posted December 20, 2021 From what I understand, the gases emitted by spacecraft maneuvering nearby would dirty the mirror. Hubble could close itself up while this was happening, James Webb cannot. Quote Link to comment Share on other sites More sharing options...
tater Posted December 20, 2021 Share Posted December 20, 2021 1 hour ago, magnemoe said: My guess is that refueling MIR and later ISS is much easier than an fragile and exposed space telescope out at L2. Is lifetime limit because of fuel limits very relevant as it is it likely to break for other reasons first. Still, it was not an impossible notion. I think minus the cost overruns maybe it mattered less—that's really the problem with these incredibly expensive flagship projects, throwing in the kitchen sink makes more and more sense because it's so ^%R&ing expensive. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted December 20, 2021 Share Posted December 20, 2021 I wish I remembered enough from my undergraduate optics class to calculate the size of the largest possible telescope that could fit inside a custom Starship. Hubble's primary mirror is 2.4 meters with a gross area of 4.52 m2. Webb's primary mirror is 6.5 meters with a gross area of 26.8 m2. A 9-meter telescope would have a gross area of 63.6 m2, more than double that of JWST, but if you tilted it sideways inside the Starship payload bay it could be oval-shaped and thus even larger. This would result in some aberration but nothing that couldn't be corrected. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted December 20, 2021 Share Posted December 20, 2021 21 minutes ago, sevenperforce said: I wish I remembered enough from my undergraduate optics class to calculate the size of the largest possible telescope that could fit inside a custom Starship. Hubble's primary mirror is 2.4 meters with a gross area of 4.52 m2. Webb's primary mirror is 6.5 meters with a gross area of 26.8 m2. A 9-meter telescope would have a gross area of 63.6 m2, more than double that of JWST, but if you tilted it sideways inside the Starship payload bay it could be oval-shaped and thus even larger. This would result in some aberration but nothing that couldn't be corrected. Say 8 meter diameter or a bit larger as inside diameter is smaller and you will want an margin. Don't think I would keep it inside the spaceship however unless it was for testing. Having it free flying would let you target much more easy and without using fuel. Would obviously make it easy to service. probably have the rear part an as an large torus who let you access the rear of the telescope trough an hatch or gateway then you put it in maintenance mode. You would not be so concerned saving some hundred kg after all. 3 hours ago, Beccab said: Docking itself may be a problem, JWST with the sunshield deployed is extremely fragile. The vibrations during docking would be a problem One idea who some is working on for communication satellites as contract is signed is to have an control satellite grabbing it and then take over station keeping and perhaps even reaction wheels. For web this would probably be more to have the secondary wheels doing the grunt works of pointing and saturated the web wheels who is probably needed for fine control. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted December 20, 2021 Share Posted December 20, 2021 I don’t think the deployment sequence has been posted yet… Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted December 21, 2021 Share Posted December 21, 2021 Quote Link to comment Share on other sites More sharing options...
Gargamel Posted December 21, 2021 Share Posted December 21, 2021 Not even NASA knows Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted December 21, 2021 Share Posted December 21, 2021 OM*G- This will be the best or worst timing ever depending on what happens. Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted December 21, 2021 Share Posted December 21, 2021 That’s 420 Am my, I would have just left for work. But it’s also Christmas Morning, so I’ll be sawing logs instead. Hopefully that’ll be one more present in the morning Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted December 22, 2021 Share Posted December 22, 2021 56 minutes ago, StrandedonEarth said: 420 Nice. Quote Link to comment Share on other sites More sharing options...
grawl Posted December 23, 2021 Share Posted December 23, 2021 I'll blame it on Santa's sleigh if anything happens . Quote Link to comment Share on other sites More sharing options...
Shpaget Posted December 23, 2021 Share Posted December 23, 2021 They have a nice press kit: https://www.arianespace.com/wp-content/uploads/2021/12/VA256-launchkit-EN.pdf From it Quote The journey of the telescope in detail: On the third day, the heat shield will begin to deploy. On the eleventh day, the secondary mirror will begin positioning. Between the 13th and 14th day, the primary mirror, comprising 18 hexagonal segments and measuring 6.5 meters in diameter, will be assembled. The telescope is slated to arrive at its final destination, 1.5 million kilometers from Earth, approximately 29 days after launch. Am I reading this correctly? Does this mean they'll start to unfold the mirrors before it gets to L2? Quote Link to comment Share on other sites More sharing options...
VaPaL Posted December 23, 2021 Share Posted December 23, 2021 1 hour ago, Shpaget said: Am I reading this correctly? Does this mean they'll start to unfold the mirrors before it gets to L2? Yes, you can see an animation of the deployment with a graph showing its position here: Quote Link to comment Share on other sites More sharing options...
Shpaget Posted December 23, 2021 Share Posted December 23, 2021 Thanks! Hope the mirror is figured significantly better then in the video, though. Quote Link to comment Share on other sites More sharing options...
Pthigrivi Posted December 23, 2021 Share Posted December 23, 2021 Honestly I'm so stressed out by this. I cant watch. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted December 23, 2021 Share Posted December 23, 2021 8 minutes ago, Pthigrivi said: Honestly I'm so stressed out by this. I cant watch. My 11 y.o. daughter tells me I'm not allowed to interrupt XMass to watch. "They'll have it on video, Daaaaad." Quote Link to comment Share on other sites More sharing options...
Pthigrivi Posted December 23, 2021 Share Posted December 23, 2021 12 minutes ago, JoeSchmuckatelli said: My 11 y.o. daughter tells me I'm not allowed to interrupt XMass to watch. "They'll have it on video, Daaaaad." Oh, sacrifices of family life. Anyway they'll probably delay it again. Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted December 23, 2021 Share Posted December 23, 2021 1 hour ago, JoeSchmuckatelli said: My 11 y.o. daughter tells me I'm not allowed to interrupt XMass to watch. "They'll have it on video, Daaaaad." You tell Her that watching Webb launch is your Christmas gift. Also rollout is complete: It feels almost like a dream seeing this finally happen, and on Christmas day, the timing is amazing...or horrible depending on what happens. If this thing fails NASA is going on the governments naughty list for a good decade or two at least. Quote Link to comment Share on other sites More sharing options...
SunlitZelkova Posted December 24, 2021 Share Posted December 24, 2021 Those wishing for success of JWST should be happy the launched got delayed so long. Remember the Nightmare Before Christmas? Quote Link to comment Share on other sites More sharing options...
Admiral Fluffy Posted December 24, 2021 Share Posted December 24, 2021 (edited) Nearly 21 hours until launch. JWST launch countdown Edited December 24, 2021 by Admiral Fluffy Launch Countdown! Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted December 24, 2021 Share Posted December 24, 2021 "Pucker Factor 4, Mr Sulu!" Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted December 24, 2021 Share Posted December 24, 2021 1 hour ago, Admiral Fluffy said: Nearly 21 hours until launch. JWST launch countdown Sir, I think I'm scared. I'm sorry sir, I've tried to keep things together but it's just....It's....I can't do this anymore, it's just so hard...it's been so long, we can't fail now X( Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.