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General => General Technical Chat => Topic started by: Homer J Simpson on November 02, 2016, 11:52:35 pm

Title: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: Homer J Simpson on November 02, 2016, 11:52:35 pm


http://www.space.com/34593-james-webb-space-telescope-complete-2018-launch.html (http://www.space.com/34593-james-webb-space-telescope-complete-2018-launch.html)

Wiki

https://en.wikipedia.org/wiki/James_Webb_Space_Telescope (https://en.wikipedia.org/wiki/James_Webb_Space_Telescope)
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: JoeN on November 03, 2016, 05:24:49 am
"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.
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: EEVblog on November 03, 2016, 07:43:12 am
Did they get the mirror right?
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: Refrigerator on November 03, 2016, 01:10:33 pm
let's hope this one doesn't blow up while fueling.
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: David Hess on November 03, 2016, 07:27:22 pm
Did they get the mirror right?

We will see after they launch.
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: Sal Ammoniac on November 03, 2016, 08:20:25 pm
Did they get the mirror right?

Won'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.
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: Homer J Simpson on November 03, 2016, 10:55:57 pm


For NASA's Hubble Successor, Failure Isn't an Option

http://www.space.com/34610-james-webb-space-telescope-hubble-repair-mission-astronomy.html (http://www.space.com/34610-james-webb-space-telescope-hubble-repair-mission-astronomy.html)
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: T3sl4co1l on November 03, 2016, 11:52:45 pm
So excited about this!

Tim
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: tautech on November 04, 2016, 12:02:59 am
So excited about this!

Tim
Did you have some hand in it Tim ?
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: T3sl4co1l on November 04, 2016, 06:25:21 am
So excited about this!

Tim
Did you have some hand in it Tim ?

I wish; the pictures it will give, in bands never seen before, will be magnificent though.  All goes well of course. :)

Tim
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: rstofer on November 04, 2016, 03:15:43 pm
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.

Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: JacquesBBB on November 04, 2016, 03:41:05 pm
One of the key mission of   JWST  will be to make spectroscopy of  extrasolar planet atmospheres. It will be the best instrument
for 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 transit
their central star.
 
Title: Re: World's Largest Space Telescope Is Complete, Expected to Launch in 2018
Post by: SeanB on November 04, 2016, 07:40:26 pm
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.