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man on the moon
2003-Jul-15, 12:07 AM
Hubble II (http://www.msnbc.com/news/937144.asp?0bl=-0)

wedgebert
2003-Jul-15, 01:49 AM
See, this is why we need a lunar colony/outpost. You could build a mirror on the moon using lunar silicon and whatnot. Then you could build it much larger since you have lower gravity and you'd have no problem seeing how it reacted to the extreme cold of space since it's already there.

Plus you could throw a few dozen more telescopes up on the lunar surface itself and either have a look at a variety of different targets or use them as a giant array to create a telescope with a huge effective mirror size.

ToSeek
2003-Jul-15, 02:23 AM
I don't think the Moon would be a good location for this telescope - one of the reasons it's at L2 is to keep it in Earth's shadow, where it will be very, very cold. The Moon would only work for that about half the time.

wedgebert
2003-Jul-15, 03:41 AM
I don't think the Moon would be a good location for this telescope - one of the reasons it's at L2 is to keep it in Earth's shadow, where it will be very, very cold. The Moon would only work for that about half the time.

Actually, the James Webb Space Telescope (JWST) will most likely be placed at the L2 point, but just outside the ecliptic plane. This means it will be in direct sunlight all the time. The JWST will employ a sunshield to keep the telescope itself out of sunlight.

Anyways, I wasn't expecting the lunar telescopes to have the same resolution in the IR range as the JWST. They would make excellent visible light gatherers and while in lunar night they could work in the IR as well.

The main point of using the moon was to BUILD the mirrors there, then send them into space. Assuming that structural integrity (and thus gravity) is the limiting factor in mirror construction, the moon could build a telescope six times as large. The JWST is going to use a 6 meter mirror, imagine if it had a 36 meter mirror.

Plus, you can use arrays of telescopes to increase the resolution of your images. We do this with radio telescopes already, but it's harder to do it with telescopes in the visual and IR range because of space considerations. Those telescopes are usually on a mountain where the air is thinner and there's less light pollution. A lunar array could be easily built because there's no atmosphere to distort and absorb what you're looking at or to scatter light from nearby sources into your mirror either. Thus you could just pick a spot and plop down a few dozen mirrors, link them together and start looking around.

Kaptain K
2003-Jul-15, 10:52 AM
Plus, you can use arrays of telescopes to increase the resolution of your images. We do this with radio telescopes already, but it's harder to do it with telescopes in the visual and IR range because of space considerations.
The difficulty with optical interferometers is that the spacing of the instruments must be stable to within a fraction of a wavelength. This is much easier in the radio bands were the wavelenth is in meters or centimeters. The wave length of light is less than one micron (millionth of a meter).

WHarris
2003-Jul-15, 11:45 AM
Interferometers aren't easy to build, but there are a few being tested and used for observations.

The Very Large Telescope Interferometer (http://www.eso.org/projects/vlti/) uses 4 1.8 meter mirrors.

The Keck Interferometer (http://planetquest.jpl.nasa.gov/Keck/keck_index.html) uses 2 10 meter telescopes. (Holy cow!)

And heres another one being developed:NPOI (http://ftp.nofs.navy.mil/projects/npoi/)

Manchurian Taikonaut
2005-Feb-03, 08:34 AM
more here on the James Webb Space Telescope, this is NASA's promissory note to the future: The James Webb Space Telescope (JWST) will push the cosmological envelope, letting astronomers delve deeper and further back in time to better understand the origins of the Universe


The JWST is the successor to the NASA/ESA Hubble Space Telescope and, with a six-metre mirror, it will be almost three times the size of Hubble.

JWST will have a primary mirror with a diameter of six metres - at least twice that of Hubble's - giving it much more light-gathering capability.

Packing a six-metre telescope into a small rocket with a diameter of five metres has been described by JWST scientists as 'a bit like designing a ship in a bottle'



Peering deeper into the Universe than Hubble, the increased light-collecting power of JWST should unveil an important but previously unobserved epoch of galaxy formation. It will stare through dust to witness the birth of stars and planetary systems similar to our own.
In putting JWST to work, scientists hope to shed light on such intriguing questions as dark matter - that mysterious, non-luminous matter, whose existence is suggested because of the effects of its gravity on the rotation rate of galaxies and the presence of clusters of galaxies

The James Webb Space Telescope is a packaged deal. That is, once lobbed into space -- likely by Europe's Ariane 5 booster -- the observatory unfurls into a final configuration.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33138

http://www.ballaerospace.com/jwst.html

:D