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You thought Hubble was good...

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URL: http://forum.justflight.com/forum_posts.asp?TID=6898
Printed Date: 27 Apr 2024 at 11:26am


Topic: You thought Hubble was good...
Posted By: MartinW
Subject: You thought Hubble was good...
Date Posted: 02 May 2009 at 10:53am
...well the James Webb is going to be a cracker!
 
http://news.bbc.co.uk/1/hi/sci/tech/8029270.stm - http://news.bbc.co.uk/1/hi/sci/tech/8029270.stm
 
Quote

The most distant cosmic explosion ever recorded would have made a fascinating target for the James Webb Space Telescope (JWST), according to scientists now building the successor to the Hubble Space Telescope.

The cataclysmic detonation reported this week is the most far-flung object in the Universe yet seen.

BBC R4: THE NEW GALILEOS
Mirror%20model%20%28Nasa%29

http://www.bbc.co.uk/programmes/b00k29vv - Listen again to the scientists and engineers working on JWST

It was a class of celestial object known as a gamma-ray blast. At a distance of 13 billion light-years away, the blast was so remote that today's telescopes were stretched to their limits in revealing much information about it.

Nasa's James Webb is designed with the purpose of imaging and studying this realm of the cosmos - and beyond - in extraordinary detail.

It is scheduled for launch in 2013.

To see so far, the observatory will be the space agency's largest and most technically challenging telescope mission to date.

Its primary mirror is 6.5m (21ft) across - close to three times wider than Hubble's.

 
Herschel%20%28BBC%29
Hubble views some near-infrared wavelengths. James Webb will seek longer wavelengths
 


Replies:
Posted By: FSaddict
Date Posted: 02 May 2009 at 11:02am
Hubble would have been better if it's mirror hadn't been out by a few nanometers (it couldn't focus properly and images appeared fuzzy) but clearly this will be better anyway.

Posted By: VulcanB2
Date Posted: 02 May 2009 at 2:41pm
I'll wait until it is in orbit and the first images are in.

Best regards,
Vulcan.

Posted By: MartinW
Date Posted: 02 May 2009 at 6:00pm
Originally posted by FSaddict FSaddict wrote:

Hubble would have been better if it's mirror hadn't been out by a few nanometers (it couldn't focus properly and images appeared fuzzy) but clearly this will be better anyway.
 
No, the defect in the Hubble mirror was corrected by a  shuttle mission. They fitted corrective optics, specs if you like. Do't think there's any evidence that it was in some way a lesser telescope after the fix. On the contrary, the images returned have been exemplary.

Posted By: FSaddict
Date Posted: 02 May 2009 at 9:00pm
Originally posted by MartinW MartinW wrote:

Originally posted by FSaddict FSaddict wrote:

Hubble would have been better if it's mirror hadn't been out by a few nanometers (it couldn't focus properly and images appeared fuzzy) but clearly this will be better anyway.
 
No, the defect in the Hubble mirror was corrected by a  shuttle mission. They fitted corrective optics, specs if you like.


Oops didn't know that Wacko

Posted By: VulcanB2
Date Posted: 03 May 2009 at 2:31pm
Originally posted by MartinW MartinW wrote:

Originally posted by FSaddict FSaddict wrote:

Hubble would have been better if it's mirror hadn't been out by a few nanometers (it couldn't focus properly and images appeared fuzzy) but clearly this will be better anyway.
 
No, the defect in the Hubble mirror was corrected by a  shuttle mission. They fitted corrective optics, specs if you like. Do't think there's any evidence that it was in some way a lesser telescope after the fix. On the contrary, the images returned have been exemplary.

They're on the fence over this. They were saying that correction is not as good as the optics being correct in the first place, but it is close enough.

Best regards,
Vulcan.

Posted By: MartinW
Date Posted: 03 May 2009 at 7:39pm

I think with the fix or any fix, it can never be 100% as good as a perfect mirror in the first instance. I would imagine there has to be some losses as a result of the extra lens elements. But as you say, hardly enough to make a difference.

 

When you see the images the Hubble has provided, including the amazing deep field shots of what we assumed was an empty patch of space, the long exposure revealing countless galaxies that were previously invisible, it brings it home to you how successful the device has been.


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