Glenn D. Allred

Wide-Field Infrared Explorer (WIRE) instrument description: focal planes, optics, and electronics

An elegantly simple cryogenic instrument has been proposed to measure far infrared radiation from starburst galaxies. The experiment-known as WIRE- employs a Cassegrain telescope with diamond-turned mirrors to provide a light- weight optical system for photon collection. A dichroic beamsplitter and filter separate the light into two broad, well-defined bands of interest. Two 128- X 128-pixel arsenic-doped silicon focal plane arrays spatially sample the incoming photons. These arrays feature exceptionally low dark current and low read noise, which allows the coaddition of thousands of images. The entire optical section and focal plane arrays are cooled to 12 Kelvin and 7.5 Kelvin, respectively, by a two-stage, solid-hydrogen cryostat. An uncomplicated electronics package provides some on-board coaddition of images, accepts the simple command required by the WIRE instrument, and interfaces the data signals to the SMEX spacecraft for telemetry to the ground.

Applying An Interferometer Spectrometer Aboard The Space Shuttle With A Payload Specialist In The Control Loop

A cryogenic interferometer/spectrometer (FTIR) has been developed at Utah State University as part of the CIRRIS-1A experiment for flight aboard the space shuttle. The inter-ferometer has been configured to optimize its operation by a payload specialist who may not have experience with interferometry but has had payload-specific training. CIRRIS-lA incorporates an automatic sequencer which can be used to operate pre-planned measurement routines. However, a command and monitor panel in the orbiter allows the payload specialist to select which measurement routines control the experiment; it also displays system and subsystem monitor values on its CRT display. The specialist can actuate various internal calibration sources and monitor interferometer performance by viewing the resulting waveforms on a video monitor. An automatic alignment system is provided in case the interferometer needs to be realigned during flight. Detailed operational procedures have been developed to guide the specialist through planned measurement and malfunction procedures and will be flown as part of the payload flight data file to allow in-flight anomalies to be resolved with minimal aid from the ground.