Spitzer Liquid He Options

[deglr6328]

How much cryogen does Spitzer have remaining in its dewar? Do they know, or are they just waiting to see a temperature rise after complete boil-off? Can't find much info on the website.

[deglr6328]

Will Spitzer be useful once the Helium runs out?

That's an interesting thought. If it ends up equilibrating at 30-40K after He boiloff I could imagine it still getting some useful data from the shorter wavelength IRAC sensors at ~3-5 microns. I should think that the noise wouldn't be too high to prevent some imaging in that band. hmmm. But then this is barely above the range of the Hubble NICMOS and you'd have the question of whether or not it would be economically worth it. (well, assuming that Hubble is still operating of course)

What I don't get is if it has such an incredibly low boiloff rate to begin with (something like a few milliliters per hour) why wouldn't they look at attaching something like this to reliquefy some of the helium? I would think that even with a modest investment in power from larger solar arrays (say.... 1 KW) you could easily double the mission lifetime by reducing the boiloff rate, if not eliminating it completely.

[ljk4-1]

Spitzer Space Telescope article in December, 2005 issue of National Geographic Magazine.

There's a lot hiding in the universe's dark corners. Interstellar dust clouds and inky stretches of deep space can appear dull to ordinary telescopes. But to a car-size telescope 26 million miles (42 million kilometers) from Earth, they are alive with light—infrared light, or heat rays. Since its launch in August 2003, says Robert Kennicutt, an astronomer at the University of Arizona, NASA's Spitzer Space Telescope "has opened up half the universe to us."

In the process, it has exposed cosmic birthplaces. Stars take shape in clouds of gas and dust, and planets emerge in disks of debris around new stars. Early galaxies are also swathed in dust. Little visible light gets out, but these objects still emit heat—and infrared.

http://www7.nationalgeographic.com/ngm/051...ure5/index.html