World's Largest Space Telescope Is Complete, Expected to Launch in 2018 - Page 1
Forum section: electronics / general

author: Homer J Simpson
author_rank: Super Contributor
timestamp: November 02, 2016, 11:52:35 pm
content: http://www.space.com/34593-james-webb-space-telescope-complete-2018-launch.htmlWikihttps://en.wikipedia.org/wiki/James_Webb_Space_Telescope

author: JoeN
author_rank: Frequent Contributor
timestamp: November 03, 2016, 05:24:49 am
content: "The observatory attaches to the Ariane 5 rocket via a launch vehicle adapter ring which could be used by a future spacecraft to grapple the observatory to attempt to fix gross deployment problems. However, the telescope itself is not serviceable, and astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope."What I don't get is why we aren't at the point now where these deep space objects can be set up in advance for robotic servicing. For Hubble we could send people to work on it. For JWST we can't. But either way, wouldn't it be possible to set up some very precise mount points and fiducial marks so it might be feasible to send a robotic service mission that can literally remove panels, non-working parts and boards, and replace them, maybe without any human intervention? I know that is "high tech" even for where we are now, but it seems to me that we are pretty close to being able to do exactly this. Putting the mount points and fiducial marks on the deep-space satellite now even if it takes 10 years before we can use them would be a good idea.

author: EEVblog
author_rank: Unknown
timestamp: November 03, 2016, 07:43:12 am
content: Did they get the mirror right?

author: Refrigerator
author_rank: Super Contributor
timestamp: November 03, 2016, 01:10:33 pm
content: let's hope this one doesn't blow up while fueling.

author: David Hess
author_rank: Super Contributor
timestamp: November 03, 2016, 07:27:22 pm
content: Quote from: EEVblog on November 03, 2016, 07:43:12 amWe will see after they launch.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: November 03, 2016, 08:20:25 pm
content: Quote from: EEVblog on November 03, 2016, 07:43:12 amWon't matter as much as with the Hubble. The Hubble has a one-piece mirror, whereas the Webb has an 18-segment mirror and the individual segments are movable to optimize focus.

author: Homer J Simpson
author_rank: Super Contributor
timestamp: November 03, 2016, 10:55:57 pm
content: For NASA's Hubble Successor, Failure Isn't an Optionhttp://www.space.com/34610-james-webb-space-telescope-hubble-repair-mission-astronomy.html

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 03, 2016, 11:52:45 pm
content: So excited about this!Tim

author: tautech
author_rank: Super Contributor
timestamp: November 04, 2016, 12:02:59 am
content: Quote from: T3sl4co1l on November 03, 2016, 11:52:45 pmDid you have some hand in it Tim ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 04, 2016, 06:25:21 am
content: Quote from: tautech on November 04, 2016, 12:02:59 amI wish; the pictures it will give, in bands never seen before, will be magnificent though. All goes well of course.Tim

author: rstofer
author_rank: Super Contributor
timestamp: November 04, 2016, 03:15:43 pm
content: The telescope seems to have a short life expectancy. They're estimating just 5 years and it only carries 10 years of fuel. There's probably no point in arranging for robotic maintenance, just pretend it's a toaster and throw it out after a few years. Impacts from space debris may be a factor.The Hubbel telescope has been working for 25 years, give or take.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: November 04, 2016, 03:41:05 pm
content: One of the key mission of JWST will be to make spectroscopy of extrasolar planet atmospheres. It will be the best instrumentfor doing so.The ultimate goal being to detect an atmosphere with some signature of life, like O2 or O3.But even before that, the goal is to better characterize the atmosphere of exoplanets around the brightest stars.The technique could be the spectroscopy of transits, which provide at present the best data, but only for planets that transittheir central star.

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2016, 07:40:26 pm
content: Problem with making it serviceable is that introduces the most unreliable space rated parts, which are connectors, hinges and latches. Connectors are well known to cold weld together with time, or go intermittent with long vibration, hinges and latches will vacuum weld into one position if not moved regularly, and will wear with regular use as there is no real long term lubricant that works in a vacuum.The USSR solved the problem somewhat by simply putting every major electronic part in a hermetic housing, and filling it with a low pressure gas fill from a tank of compressed gas so there was a pressure inside to cool and move heat, plus provide the ability to use lubricant for things like tape drives and film cameras. They still had issues with motors outside though.