James Webb Space Telescope runs one last dress rehearsal for its massive golden mirrors before heading to launchpad ESA, CSA and NASA's James Webb Telescope opened its giant primary mirror one last time on Earth ahead of being packed up for long awaited launch later this year. The 6.5m structure, comprised of 18 hexagonal mirrors, was commanded from the Northrop Grumman testing control room in California to expand and lock itself into place …
The Hubble and the James Webb have about the same ability to resolve details. The James Webb is much larger, but it also uses much longer wavelengths of light (infra red) which cancels out that advantage as far as resolution is concerned. Obviously the James Webb is better than Hubble in many ways ... but resolving details is not one of them.
Let's wait until it works before commenting on the engineering. There are just so many ways for it to fail. I can see SpaceX offering to run a repair or replenishment mission.
The Moon orbits the Earth at an average distance of about 384,400 km (238,900 miles).
The distance earth to the Earth-Sun L2 point, where the James Webb Space Telescope will be deployed, is roughly 400x the distance to the moon, at about 151.1 million km (For perspective Mars at its closest to Earth is about 62 million kilometers or ~38.6 million miles).
It took just over 3 days for Apollo 11 to travel from earths orbit to orbit the moon.
So with the above in mind I do not see SpaceX doing any repairs or replenishment missions.
Hubble is in a low earth orbit at about 547 kilometers (340 miles) above Earth, about 300,000 times closer to earth than the James Webb Space Telescope when deployed.
There were 5 services done in total, unless SpaceX is going to do service missions with autonomous machines, I just do not see them happening.
STS-61 was a 11 day mission - 5 days working on Hubble.
STS-82 was a 10 day mission - 5 days working on Hubble.
STS-103 was an 8 day mission - 3 days working on Hubble.
STS-109 was a 11 day mission - 5 days working on Hubble.
STS-125 was a 13 day mission - 5 days working on Hubble.
You've slipped a couple of decimals, AC. Try 1.5 million km.
It's still a long way beyond LEO, and your point more or less stands, but a little critical thinking should have suggested that 150 million km was a rather large distance in this context.
Why the hell would we send Meatbags to do this?
Would make more sense to send an unmanned satellite tender. Lighter, more efficient, an no need to even set it up for a return trip. And the trip out can be slower and efficient. That said, it all depends on what the failures that need to be addressed are.
The big question would be is it cheaper to fix or to build a new one. Considering it's history of delays and cost overruns, repair may it it's only hope if there is a failure, as we probably won't get to build a new one for a while unless we get a few years of science out of it to showcase what we are missing.
Hubble was the same way to some degree, that once it started operating at capacity, it was clear that it was worth the money pretty quick, that sold the public on the follow on projects like Spitzer and the JWST. Hopefully the launch goes off without a hitch and the thing holds together though. It would be nice to have the "Too big to fail" part of this in the rear-view for a while.
Dragon wouldn't be doing any servicing missions, if nothing else it hasn't the delta V to do it. But an appropriately configured Starship - or even SLS/Orion would be capable of doing so. It might be a better use for the latter in fact.
There were various extended range options for the Orbiter considered like doubling up on the SRB's but they never made it off the page. Perhaps for the best.
SpaceX is planning to take hordes of people to Mars. If they can do that, making it to the Earth-Sun L2 point and back to refill the liquid helium is a short trip. I'm not thinking Falcon 9 here but Starship. ("Not the local bulk cruisers mind you, I'm talking about the big Corellian ships now.") Obviously NASA didn't consider anything like this capability would exist in the foreseeable future (especially given that James Webb was supposed to launch in 2007) but hopefully they're wrong and Starship works.
When this was being planned back in the 90s the favourite design was a cheap lightweighted 6m conventional mirror, to be launched on the relatively new Ariane 5 with a bulged out fairing
Then after a change of government it had to be launched on a freedom rocket (instead of a cheese eating surrender rocket) which involved the complex folding design. This took so long and cost so much they had to find european partners who contributed the Ariane 5 launch
The concern since is whether it will be ready before Ariane 5 is retired
The launch complex is based around a specific model. If Guiana was upgraded to Ariane 6 it may not be possible to assemble and launch a 5, even if you can find one sitting around in the back of the cupboard.
The worry was that if JWST was delayed for another 5-10 years there wouldn't be an Ariane 5 for it and re-engineering for a new launch vehicle would be a massive task
The problem is that there are very specific things taken into account when designing a spacecraft for the launch vehicle it's going to ride on. The acceleration profile, launch vehicle vibration profiles and frequency content, sound pressure levels inside the fairing, assembly process and mounting point accessibility, available payload integration tooling and equipment, exact fairing load profile, ground power bus connections, vehicle bus connections, temperature profiles on the ground during payload integration, rollout to the pad, launch prep and during launch, and probably a million more things I don't know about and most people would never think about.
You can't just plonk JWST onto a Falcon 9 and call it good even if it could fit (which it can't since JWST requires the 5m fairing of the Ariane 5m, while F9 has 4.6m fairings). On top of that you'd need a massive additional dead weight below the telescope since JWST is so light compared to the normal payload weight of F9 that it would accelerate too fast and rip the telescope to pieces. Nor is the F9 second stage really rated to get payloads into the required orbit.
On top of that you'd need a massive additional dead weight
How heavy? Perhaps if it is quantified in meaningful units that we can all understand here...
https://www.theregister.com/Design/page/reg-standards-converter.html
...how many adult badgers?
Arianespace acknowledged that “post-flight analyses conducted on two recent Ariane 5 launches have indicated the occurrence of a less than fully nominal separation of the fairing, however with no adverse impact on the Ariane 5 flights in question.”
https://spacenews.com/ariane-5-issue-could-delay-jwst/
fairing separation...
see above:
https://forums.theregister.com/forum/all/2021/05/13/james_webb_last_checks/#c_4257407
I'm sure I am not the only one, but if a nobody like me is actually feeling nerves about this launch and deployment, I can't even begin to imagine the stress that all the engineering and launch teams must be under right now.
I can only doff my hat in respect for the sheer boffinry and cleverness going on right now. My mind boggles.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
