Talk:Spitzer Space Telescope

Spitzer for sale

The National Aeronautics and Space Administration's (NASA) Science Mission Directorate (SMD) is seeking information from parties who are interested in operating the Spitzer Space Telescope using non-NASA funding, including defining and executing a Spitzer science program, beyond the timeframe of the NASA-funded mission.

Layout Question

I can't seem to get the image size right on the artist's concept in the box. Can anyone help out with this? It's filling my whole screen on the article page, but the image I uploaded, [[Image:Sirtf 09 2002.jpg]] is only 250x180 pix. --zandperl 03:35, 24 Feb 2004 (UTC)

Instrumentation

Does anyone know more about the instruments on Spitzer, much like the Hubble Space Telescope page has? --zandperl 00:58, 18 Mar 2004 (UTC)

See 2nd para of Don Barry comment a few below - Rod57 (talk) 15:40, 13 March 2021 (UTC)

MIPS 160 micron array is actually a 2x20 array. See http://mips.as.arizona.edu/mipspage/instrument_f.html for full description of MIPS instrumentation. --AmberRobot 09:47, 14 Aug 2004 (CST)

NO plain and simple —Preceding unsigned comment added by 80.2.143.42 (talk) 16:36, 12 October 2009 (UTC)

Orbit

From what I can infer, the Spitzer orbit is not truly at L5, but is attracted toward L5. I believe L5 itself is rather dirty, and may not be well suited for an observatory. The only authoritative orbit detail says it is moving away from the earth at 0.1AU per year:

http://www.spitzer.caltech.edu/about/orbit.shtml

I added a bit more text to describe this, but did not delete the reference to L5 in the table. 04:16, 28 May 2004‎ 12.64.126.134

As Spitzer's orbit is heliocentric, changed "Satellite of:" in infobox from Earth to Sun. Harperska 21:32, 23 December 2006 (UTC)

Comments by Don Barry

To the commentator above -- Spitzer's orbit is not taking it towards an Earth resonance point; it truly is a heliocentric orbit which lags Earth's by about 1/60 orbit per year, i.e. in 60 years (the synodic period of the two) it will catch up to Earth again.

There is no propulsion capability on the spacecraft other than a quite limited dry-nitrogen system intended for occasional angular momentum dumps off the reaction wheels, so there was no intent to "aim" it anywhere except in a low-precision trajectory. The spacecraft radio antenna is not steerable, so pointing in the daily data dumps is done by slewing the entire telescope -- eventually the orbit will move so far from Earth so that this maneuver would require spilling sunlight over the shielding solar panels onto the telescope itself -- this will not take place until several years after cryogen exhaustion and effective end of mission, however.

To the commentator far above -- Spitzer contains three "instrument packages", designated IRAC (infrared array camera) built by Harvard, consisting of four 256x256 detectors sampling 3.6, 4.5, 5.8, and 8.0 microns (http://cfa-www.harvard.edu/cfa/oir/Research/irac/firstpage.html), the MIPS (multiband imaging photometer) package built by the University of Arizona, consisting of a 128x128 24 micron camera, a 32x32 70 micron camera, and a 2x20 160 micron camera (http://mips.as.arizona.edu/MIPS/Home.html) and the IRS (InfraRed Spectrograph) package built by Cornell, consisting of four spectrometers, two low resolution (resolution of roughly R=100, 5-15, 15-38 microns), and two high resolution (R=600, 10-20, 19-37 microns) modules. The low resolution modules are long slit instruments providing spatial as well as spectral resolution. Currently, as of February 2006, about 50% of the requested observing time is for spectroscopic observations.

Don Barry, Spitzer Space Telescope IRS Instrument Team, Cornell University

01:54, 2 March 2006‎ 24.59.116.16 

Anyone object to splitting Dons comment between the two sections he's responding to ? Should be easier to read - It might make future archiving easier too - Rod57 (talk) 16:04, 17 May 2017 (UTC)

Challenger Disaster

Challenger disaster? Isn't it supposed to be Columbia? I mean, the SST was launched after 2000, no?

The planning for the Spitzer Space Telescope took decades. At one point, it was called the Shuttle Infrared Telescope Facility, and it was supposed to operate in the cargo bay of the Space Shuttle. If my memory serves me right, a decision was made prior to the 1986 Challenger disaster to make the telescope free-flying, although I recall seeing nothing about whether it would be launched from the Space Shuttle or on its own rocket. By the time the 2003 Columbia disaster occurred, Spitzer was being prepared to launch on a Delta II rocket. I don't recall that the Columbia disaster had any impact on the launch or the program. George J. Bendo 08:44, 22 June 2006 (UTC)

f/12

"The primary mirror is 85 cm in diameter, f/12 and made of beryllium and cooled to 5.5 K." In this case, what does f/12 mean? I think that should be clarified/linked. --Eyrian 12:44, 20 March 2006 (UTC)

I added a short explanation. 193.171.121.30 18:48, 20 March 2006 (UTC)

My guess is that it is the "effective focal ratio" since it is a RC design. mcsew2k 71.189.241.42 12:26, 13 November 2007 (UTC)

If Eyrian had done some research on focal lengths, he would not have asked us. — Preceding unsigned comment added by Explodingstar (talk • contribs) 09:37, 30 August 2014 (UTC)

Collecting Area

A circle of 85 cm diameter has got an area of no more than 0.57 m², and part of it is occluded by the secondary mirror. Therefore the 2.3 m² collecting area was wrong. I changed it to 0.5 m², but this is only a guess because I don't know the exact size of the secondary mirror. 193.171.121.30 18:48, 20 March 2006 (UTC)

Requested move

Spitzer space telescope → Spitzer Space Telescope – {It's the propor name} copied from the entry on the WP:RM page

Done. —Nightstallion (?) ^{Seen this already?} 22:28, 26 March 2006 (UTC)

HD 209458 b

"As one of its most noteworthy observations, in 2005, SST became the first to directly capture the light from extrasolar planets; the "hot Jupiter" planets HD 209458b and TrES-1 respectively."

Would it be possible to find one of these images and include in the article? I looked, and couldn't find them at NASA's site, or the Spitzer site hosted at Caltech. --Eyrian 10:05, 18 June 2006 (UTC)

The wording in the article may be somewhat misleading and I am planning to change it. The Spitzer did indeed directly capture the light from the planets, but it did not (and could not) resolve that light into an actual image.Kevin Nelson 13:06, 30 August 2006 (UTC)

Pixelage

Is the camera resolution not far too low? --maxrspct in the mud 00:34, 25 June 2006 (UTC)

Not sure which instrument you mean, but the numbers in the "Instrument" section are correct. It gets more and more difficult to build detector arrays at longer wavelengths. At 160µm for example, each pixel is a little chunk of Ge, about 1 mm³, which must be held individually in a tiny vice and squeezed to around half its shatter stress, then lined up, in two rows of twenty, the rows spaced one pixel-width apart to allow room for the vices, and then kept at about 6 K in liquid He. To make a complete filled image, one must move the field of view a little and take another exposure to supply the missing row of pixels. Also, the optical resolution gets worse in proportion as the wavelength gets longer (for the telescope's 85 cm primary mirror). The pixels at each wavelength are sized with that in mind, being no smaller than necessary to match the optical response. Wwheaton (talk) 23:58, 28 June 2008 (UTC)

I made an edit/deleted text

While reading this article I found this text was added: "Spitzer is a kid in my school who likes penis penis penis penis penis and more penis. And takes it up the butt :[" and I made the deletion. —Preceding unsigned comment added by 162.119.64.119 (talk) 18:38, 5 October 2007 (UTC)

No need to ask or remark about this sort of thing. It happens constantly; just revert and leave a comment in the edit summary (for the page history), as seems appropriate. Wwheaton (talk) 00:02, 29 June 2008 (UTC)

Total cost of Spitzer at launch

I read the statement that the cost of Spitzer was $800M but the SpaceflightNow article cited claims only $670M. It is also not clear if it is the cost of just the payload or including the cost of launching it. Is that the $130M difference?

mcsew2k 71.189.241.42 12:20, 13 November 2007 (UTC)

Minor edits

Removed "In keeping with NASA tradition, " from before "The telescope was renamed after successful demonstration of operation, on December 18, 2003."

I don't believe this is a NASA tradition; I don't recall Hubble having a different name before launch. The James Webb Space Telescope was renamed from NGST a long way ahead of launch. The only other example I can think of is MAP being renamed WMAP, but even that was a modification of the name rather than a rename.

If I'm wrong I'm sure someone will put it back.

The *Japanese* certainly do rename their satellites once they are up in orbit and working.

AdamW (talk) 16:43, 22 August 2008 (UTC)

This has been a well-established NASA tradition, though not universally followed. The Explorer program satellites often got names after launch, and the Small Astronomy Satellite series (themselves Explorers), SAS-1, SAS-2, and SAS-3, was an early example; SAS-1 was renamed Uhuru after launch in 1970. The Orbiting Solar Observatory (OSO) series were given letter designations before launch, and numbered after; eg, OSO H became OSO 7 in 1971. Similarly HEAO A, B, & C became HEAO 1, Einstein Observatory, and HEAO 3 respectively. In earlier times only especially successful missions got proper names, like Einstein. HST was originally the LST, the "Large Space Telescope", Compton Gamma-Ray Observatory was just GRO, Chandra was AXAF, and Spitzer was SIRTF. Naming a mission before a successful launch is unusual. The idea seemingly has been not to honor failed missions with official names. Wwheaton (talk) 01:28, 10 October 2008 (UTC)

Removed (SST) as telescope acronym. When Spitzer got its name, the mandate from NASA HQ was specifically that it was NEVER to be referred to as "SST" because of potential confusion with Supersonic_transport (the supersonic planes which, at that point, had been recently decommissioned). If you look on the Spitzer public and science sites, you will only find "Spitzer" as an abbreviation, never SST. Mharbut (talk) 19:01, 19 August 2020 (UTC)

Changed "first images taken by Spitzer" to "first released images." There were a large number of initial observations from which images were selected the nicest to be used in press releases.Mharbut (talk) 19:25, 26 August 2020 (UTC)

Added some references to observatory and instrument scientific and technical information

I just added a bunch of references to the Spitzer Science Center's (SSC) web sites at Caltech (IPAC), mostly intended for astronomers and other scientists, but with much more extensive and reliable information than the various media references we mainly have. The main shortcoming of these is that the links are liable to change a bit from time to time. The most reliable permanent information is of course in the science archival literature, but that is not so easily available to most people who are not connected to a university or other professional institution. However, digging up these archival references and putting them in is a chore that needs to be done as the Spitzer Project begins to wind down, what with liquid He exhaustion, etc. There was an issue of the Astrophysical Journal ("ApJ", Supplement series) devoted to Spitzer, issued a year or so after launch that had much of the basic information, which has mostly not changed since. (I should note that even the ApJ web sites seem to have changed now that the University of Chicago Press is no longer the publisher of the ApJ, since the Institute of Physics (IoP) took over that contract.) Anyhow, I will try to dig out and add that ref to the article asap if someone else does not beat me to it. (WP:COI note: I have been at the IPAC SSC, working on MIPS, for the past several years.) Wwheaton (talk) 06:09, 5 October 2009 (UTC)

Nitrogen exhaustion

Is nitrogen exhaustion likely to be what ends the warm mission ?
How much nitrogen is left and how long is it likely to last ? - Rod57 (talk) 13:08, 21 June 2011 (UTC)

Is that what will end the mission? Its not clear when the mission will end. Ottawakismet (talk) 02:56, 30 May 2013 (UTC)

Which channels can still be used

Article says only the 3.6u and 4.5u of IRAC are now in use, but recent image released by NASA June 2011 says it uses IRAC 3.6 and 8.0, and MIPS 24u. Which is correct, or is the 24u image years old ? - Rod57 (talk) 13:23, 21 June 2011 (UTC)

Let's make a Good article!

Hello. I thought, that we can bring this article to a good article status. Let's take this challenge! FriyMan ^talk 08:42, 27 February 2017 (UTC)

Attitude and pointing control

Would be nice to find refs to describe how it daily turns to earth to send data, keeps the sun shade to the sun, and turns to astronomical targets. What direction is the fixed communication dish pointing ? Maybe its directly away from its viewing direction ? How fast can it slew ? Is it restricted to targets in the plane tangential to its orbit - if so it might have to wait 6 months to view some targets. How are its sensing gyros holding up ? and its reaction wheels ? Have they found any new ways to unload the reaction wheels without using nitrogen gas (hard without movable solar panels?) ? - Rod57 (talk) 15:42, 17 May 2017 (UTC)

End of life - costs - future communications

[1] says it costs $14 m pa to operate, and after about 2020 it will be further from earth and hard or impossible to communicate with. - Could mention ? - Rod57 (talk) 13:38, 30 May 2019 (UTC)

Animation of Spitzer's Orbit Relative to Earth

This animated gif is very misleading and probably shouldn't be in this article. While the coordinates with respect to Earth may be technically correct, the gif feeds into a massive misconception that Spitzer orbits Earth, which it doesn't. Spitzer orbits the Sun like Earth does; it just slowly trails away from Earth with time. The following video explains several different infrared telescopes including Spitzer (2:00 to about 9:30 is relevant to this discussion): Crash Course in IR missions.

To be really clear, “Earth is stationary” doesn't mean just “fixed in its orbit” but also “fixed in its diurnal rotation”. So it really is *really* fixed in this animation, and it’s mind-bending to understand what is actually plotted. Upon seeing this, too many people will just assume that Spitzer orbits Earth, which isn’t correct. Mharbut (talk) 18:21, 26 August 2020 (UTC)

Yes - the animation is confusing and unhelpful. Can't we just say how many degrees Spitzer falls behind Earth each year ? A plot of annual relative position around Earths orbit would be nice ? - Rod57 (talk) 13:03, 27 December 2021 (UTC)

No mention of the attempt to observe 'omuamua

Spitzer's failure to see 'Oumuamua seemed to eliminate some possible sizes and material combinations. Surely significant - especially that Spitzer was used so near to its retirement ? What was the 2nd choice telescope for IR observations ? - Rod57 (talk) 15:34, 13 March 2021 (UTC)

Not the 3rd IR mission

The Widefield InfraRed Explorer (WIRE) was launched in 1999. It's cryogen leaked on launch so it never did any specialist IR work, but the wording at the moment is not correct, because Spitzer was the 4th to *launch* if WIRE is included. — Preceding unsigned comment added by 74.123.252.42 (talk) 04:20, 14 March 2024 (UTC)