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NASA Unveils Hubble's Successor
dalutong writes "BBC News has an article detailing NASA's replacement for the much-loved Hubble telescope. The $4.5 billion telescope will be placed in orbit 1.5 million km from Earth and will be almost three times the size of the Hubble. It is set to launch in 2013. They also plan to service the Hubble in 2008."
Its going to be nearly a million miles away, so its out of reach for any repair mission (for the forseable future anyway.)
JWST will provide diffraction-limited images at 2 micron. It will have imaging and spectrographic capabilities in the near and mid-IR -- everything from 6000AA out to 27micron with the mid-IR imager and spectrograph (MIRI). StSci has a JWST primer online here (pdf link).
While difficult, its much cheaper and easier to get hubble-style resolution in the optical range from ground.
Dont forget that "hugely expensive" for a ground telescope is compareable to "dirt-cheap" for a space-based one.
All 4 of the VLT telescopes were (IIRC) cheaper than a single hubble service mission. And OWL should be compareable to a modern space-telescope, too, for a fraction of the price (dont forget: its a tradeoff: better seeing vs "have to design a mirrror that can withstand the acceleraion and fits the launch vehicle).
Also, i think the huge bias on that single octave of electromagnetic radiation is out of proportion.
There arent even that many useful lines in it
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
As radiation travels from distant stars and passes through obstacles, gravitational lensing, dust clouds, etc., it loses energy and thus frequency eventually turning radiation from the gamma/x-ray spectrum into visible light then into infrared light. This new telescope will help us by giving us insights to some of the conditions that would be found very early on in the universe. Hubble and other similar land-based telescopes can't give us that insight because of not showing the infrared, the oldest information.
cb_is_cool knows where his towel is.
..."JWST is named after James E Webb, Nasa Administrator during the Apollo lunar exploration era; he served from 1961 to 1968."
To add more evidence. Look, wikipedia!
http://en.wikipedia.org/wiki/James_Edwin_Webb
To 1-up wikipedia. Look, NASA!
http://www.jwst.nasa.gov/whois.html
The man whose name NASA has chosen to bestow upon the successor to the Hubble Space Telescope is most commonly linked to the Apollo moon program, not to science. Yet, many believe that James E. Webb, who ran the fledgling space agency from February 1961 to October 1968, did more for science than perhaps any other government official and that it is only fitting that the Next Generation Space Telescope would be named after him.
The imaging will be near infrared with particular capability near 2 microns, but the 5 micron capability is alos of interest. There is also a smaller camera working from 5 to 27 microns. This is mid-infrared. The resolution of this instrument will not be so good because of the longer wavelength. The Keck Telescope can get better image quality. But what it will have is spectroscopic capability and much greater sensitivity. We've gotten quite alot of milage out of the much smaller Spitzer Space Telescope using it's 5--30 micron spectrograph. This new instrument should really open things up, allowing us to analyse stars in galaxies as they were when the universe was 12 billion years younger. All telescopes can be considered time machines, but this one is made to see some of the very first stars. You can read more about it here: http://www.stsci.edu/jwst/instruments/.s -selling-solar.html
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Rent solar power: http://mdsolar.blogspot.com/2007/01/slashdot-user
Also wrong. Try this one.
I knew it was pretty big, but it wasn't until I saw a picture of the mockup with people next to it that I realized just how big it was. Suddenly you understand why it's a segmented mirror and lot's of folding pieces.
The captcha is spectrum...how fitting.
I recall that the Orion program which is currently under development will have the capability to do the job. It is slated to replace the shuttle and also have the ability to reach the moon. One of the goals was to be able to do a service mission of the JWT far far away. More info here. http://www.nasa.gov/mission_pages/constellation/ma in/index.html/
Geometry.
Earth only has 12000km diameter. Sun has 1.4 million km diameter.
For earth to give shade, it would have to be closer than AU*(r_earth/r_sun), which is much closer than the lagrange point.
Simply put: you would get a dark spot on the sun, but no complete cover.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
First, the Sun is larger than the Earth, there is no permanently shaded point at L2. Second, the telescope will not actually be parked at L2, it will be in a halo orbit around L2. Third, it would be rather silly to park a solar powered vehicle in the shade, doncha think?
Thus, the need for the sunshade.
The point of sending something to L2 is that it is still permanently close enough to Earth to make high bandwidth communications easy, while it is far enough from Earth to have an unobstructed view of nearly the entire sky. Additionally, L2 requires comparably mild propulsive resources to reach and to maintain position near.
Ground based telescopes are good only for light that is not filtered by the atmosphere. There is a whole lot of spectrum outside it. The JWST targets the infra-red wavelengths, which would be much harder to do with an atmosphere above it
http://www.dieblinkenlights.com
FWIW, you can say "far side of the moon" next time to avoid confusion and pedants. That's what I do now.
Actually, the far side of the moon is getting serious consideration for construction of a very sensitive radio telescope after (if) the Constellation program gets rolling. Radio telescopes are for the most part too big to place in orbit realistically, and on earth they contend with the large amounts of background noise we generate. On the far side of the moon there would be 1500 km of rock blocking all that noise, and the 28.5 day rotational period would give a fixed antenna longer to study individual targets than for example, the Arecibo observatory on earth.