Spitzer Technology Overview
The Spitzer Space Telescope consists of a 0.85-meter diameter telescope and three cryogenically-cooled science instruments which will perform imaging and spectroscopy in the 3 - 180 micron wavelength range. Since infrared is primarily heat radiation, detectors are most sensitive to infrared light when they are kept extremely cold. Using the latest in large-format detector arrays, Spitzer will be able to make observations that are more sensitive than any previous mission. While Spitzer's mission lifetime requirement remains 2.5 years, recent developments have brought a 5-year mission within reach. Spitzer launched on 25 August 2003.
The telescope is surrounded by an outer shell that radiates heat to cold space in the anti-Sun direction, and is shielded from the Sun by the solar panel assembly. Intermediate shields intercept heat from the solar panel and the spacecraft bus. The outer shell and inner, middle, and outer shields are vapor cooled, i.e., the cold helium vapor from the helium tank is used to carry away the heat from these structures.
The telescope is attached to the top of the vapor cooled cryostat shell. The telescope and cryostat shell are launched warm, and cool down once in orbit. The multiple instrument chamber (MIC) containing the science instruments is mounted directly to the helium tank in the cryostat shell.
The spacecraft bus contains the subsystems required for housekeeping and control engineering: telecommunications, reaction control, pointing control, command and data handling, and power. The star tracker and gyro package is mounted on the spacecraft bus. The main antenna is located at the rear of the spacecraft bus. Reaction control system thrusters are located on outriggers from the spacecraft bus.
The three science instruments each consist of a cold assembly mounted in the cryostat, and warm electronics mounted on the spacecraft bus.