SPITZER SPACE TELESCOPE

1. SPITZER SPACE TELESCOPE

3. The Rationale for Infrared Astronomy • reveal cool states of matter • explore the hidden Universe • provide access to many spectral features • probe the early life of the cosmos

4. WANT TO SEE... • Formation of Planets and Stars • Comets, Primordial Solar System • Planetary Debris Disks • Protostellar Winds • Brown Dwarf Surveys • Origin of Energetic Galaxies and Quasars • Spectra of Luminous Galaxies • Distribution of Matter and Galaxies • Deep 10 to 100 Micron Surveys • Galactic Halos and Missing Mass • Formation and Evolution of Galaxies • Protogalaxies

5. OVERVIEW • Recent History • Innovations Clever Choice of Orbit Cryogenic Architecture • Technology Telescope Multiple Instrument Chamber InfraRed Array Camera InfraRed Spectrograph Multiband Imaging Photometer Outer Shell • Final Notes

6. DE-EVOLUTION OF SPITZER

7. Innovations: Clever Choice of Orbit • An important breakthrough in the redesign of Spitzer was to abandon the idea of placing the observatory into Earth orbit and instead to insert it into an Earth-trailing heliocentric orbit.

8. Innovations: Clever Choice of Orbit • A consequential benefit of the solar orbit is that Spitzer will have a large instantaneous view of the celestial sky. ...the Observatory cannot point closer than 80 degrees in the direction of the Sun, in order to minimize the thermal heating of the telescope by solar radiation. …it cannot point more than 120 degrees away from the direction of the Sun, because of need to illuminate the solar panels and produce electricity to power the Observatory.

9. About a third of the sky will be instantaneously visible to Spitzer at any given time. • This broad window on the sky will simplify scheduling and operations of Spitzer, and will allow it to achieve very high astronomical observingefficiency.

10. Innovations: Cryogenic Architecture • Unlike IRAS and ISO, Spitzer adopts an innovative "warm-launch" cryogenic architecture • This innovative launch architecture, combined with 360 liters of liquid helium, yields an estimated mission lifetime of about 5 years • IRAS used 520 liters of cryogen during its 10-month mission and ISO used 2140 liters for to achieve a mission lifetime of nearly 2.5 years

11. Spitzer Technology Overview

12. The Cryo-Telescope Assembly, shown in blue, is cooled to within a few degrees above absolute zero with liquid helium. The warmer spacecraft, shown in red, is uncooled.

13. Spitzer's Telescope • a lightweight reflector of Ritchey-Chrétien (less than 50 kg ) • has an 85 cm diameter aperture • all of its parts, except for the mirror supports, are made of light-weight beryllium (because of its low heat capacity at very low temperatures ) • attached to the top of the vapor-cooled cryostat vacuum shell

15. Spitzer's Multiple Instrument Chamber • contains the cold parts of Spitzer's three science instruments, IRAC, IRS, and MIPS, as well as the pointing calibration reference sensor • built to be so tight that no light can get through it except that which is allowed to be detected directly by the instruments

16. Spitzer's Infrared Array Camera • provides imaging capabilities at near- and mid-infrared wavelengths • a four-channel camera that provides simultaneous 5.12 x 5.12 arcmin images at 3.6, 4.5, 5.8, and 8 microns • Each of the four detector arrays in the camera are 256 x 256 pixels in size • two short-wavelength channels are imaged by composite detectors made from indium and antimony • long-wavelength channels use silicon detectors that have been specially treated with arsenic

18. Spitzer's Infrared Spectrograph • provides both high- and low-resolution spectroscopy at mid-infrared wavelengths • has four separate modules: …a low-resolution, short-wavelength mode covering the 5.3-14 micron interval; …a high-resolution, short-wavelength mode covering 10-19.5 microns; …a low-resolution, long-wavelength mode for observations at 14-40 microns; …a high-resolution, long-wavelength mode for 19-37 microns • Each module has its own entrance slit to let infrared light in • shorter-wavelength silicon detectors are treated with arsenic; the longer-wavelength silicon detectors are treated with antimony

19. Spitzer's Multiband Imaging Photometer • has three detector arrays …a 128 x 128 array for imaging at 24 microns is composed of silicon, specially treated with arsenic …a 32 x 32 array for imaging at 70 microns …a 2 x 20 array for imaging at 160 microns both use germanium, treated with gallium • 32 x 32 array will also take spectra from 50 - 100 microns • MIPS field of view varies from about 5x5 arcmin at the shortest wavelength to about 0.5x5 arcmin at the longest wavelength

20. Spitzer's CTA Outer Shell • made up of: …a dust cover, outer shield (cooled by helium vapor) …thermal shields (which block radiation from space) …solar panels • shell keeps exterior heat from reaching the telescope and instuments by radiating it out into cold space

21. Lyman Spitzer, Jr. • one of the 20th century's great scientists • made major contributions in the areas of stellar dynamics, plasma physics, thermonuclear fusion, and space astronomy • was the first person to propose the idea of placing a large telescope in space and was the driving force behind the development of the Hubble Space Telescope.

25. The beginning of the end, Just long enough to keep you running,and why?Heaven only knows! The beginning, of the end,the beginning of the end, It's all a vicious circle and the race is run again.