Spitzer Liquid He |
Spitzer Liquid He |
Oct 14 2005, 05:01 AM
Post
#1
|
|
Member Group: Members Posts: 356 Joined: 12-March 05 Member No.: 190 |
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.
|
|
|
Nov 12 2005, 02:48 AM
Post
#2
|
|
Member Group: Members Posts: 356 Joined: 12-March 05 Member No.: 190 |
QUOTE (hendric @ Nov 10 2005, 10:29 PM) 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. |
|
|
Dec 5 2005, 05:15 PM
Post
#3
|
|
Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
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 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
|
|
Jan 16 2006, 08:23 PM
Post
#4
|
|
Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0511358 From: William T. Reach [view email] Date (v1): Fri, 11 Nov 2005 16:32:59 GMT (59kb) Date (revised v2): Thu, 17 Nov 2005 07:43:56 GMT (0kb,I) Date (revised v3): Thu, 17 Nov 2005 21:57:35 GMT (0kb,I) Date (revised v4): Fri, 13 Jan 2006 18:04:39 GMT (59kb) The Dust cloud around the White Dwarf G 29-38 Authors: William T. Reach, Marc J. Kuchner, Ted von Hippel, Adam Burrows, Fergal Mullally, Mukremin Kilic, D. E. Winget Comments: accepted for publication in the Astrophysical Journal Letters Journal-ref: 2005, Astrophysical Journal Letters, volume 635, page L161 We present new observations of the white dwarf G 29-38 with the camera (4.5 and 8 microns), photometer (24 microns), and spectrograph (5.5-14 microns) of the Spitzer Space Telescope. This star has an exceptionally large infrared excess amounting to 3% of the bolometric luminosity. The spectral energy distribution has a continuum peak around 4.5 micros and a 9-11 micron emission feature 1.25 times brighter than the continuum. A mixture of amorphous olivine and a small amount of forsterite in an emitting region 1-5 Rsun from the star can reproduce the shape of the 9-11 micron feature. The spectral energy distribution also appears to require amorphous carbon to explain the hot continuum. Our new measurements support the idea that a relatively recent disruption of a comet or asteroid created the cloud. http://arxiv.org/abs/astro-ph/0511358 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
|
|
Jan 24 2006, 07:15 PM
Post
#5
|
|
Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0601495 From: Patrice Bouchet J.. [view email] Date: Mon, 23 Jan 2006 01:45:09 GMT (761kb) SN 1987A After 18 Years: Mid-Infrared GEMINI and SPITZER Observations of the Remnant Authors: Patrice Bouchet, Eli Dwek, I. John Danziger, Richard G. Arendt, I. James M. De Buizer, Sangwook Park, Nicholas B. Suntzeff, Robert P. Kirshner, Peter Challis Comments: 23 pages; 3 tables; 12 figures (Fig.2, Fig.4, and Fig.7 missing because too big; Fig.14 is provisory); submitted to ApJ January 2006 We present high resolution 11.7 and 18.3um mid-IR images of SN 1987A obtained on day 6526 with T-ReCS attached to the Gemini telescope. The 11.7um flux has increased significantly since our last observations on day 6067. The images clearly show that all the emission arises from the equatorial ring (ER). Spectra obtained with Spitzer, on day 6184 with MIPS at 24um, on day 6130 with IRAC in the 3.6-8um region, and on day 6190 with IRS in the 12-37um region show that the emission consists of thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is ~166K, and the emitting dust mass is ~2.6 x 10-6 Msun. Lines of [Ne II]12.82um and [Ne III]15.56um are clearly present, as well as a weak [Si II]34.8um line. We also detect two lines near 26um which we tentatively ascribe to [Fe II]25.99um and [O IV]25.91um. Comparison of the Gemini 11.7um image with X-ray images from Chandra, UV-optical images from HST, and radio synchrotron images obtained by the ATCA show generally good correlation of the images across all wavelengths. Because of the limited resolution of the mid-IR images we cannot uniquely determine the location or heating mechanism of the dust giving rise to the emission. The dust could be collisionally heated by the X-ray emitting plasma, providing a unique diagnostic of plasma conditions. Alternatively, the dust could be radiatively heated in the dense UV-optical knots that are overrun by the advancing supernova blast wave. In either case the dust-to-gas mass ratio in the circumstellar medium around the supernova is significantly lower than that in the general ISM of the LMC, suggesting either a low condensation efficiency in the wind of the progenitor star, or the efficient destruction of the dust by the SN blast wave. http://arxiv.org/abs/astro-ph/0601495 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
|
|
Lo-Fi Version | Time is now: 6th June 2024 - 02:33 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |