Spitzer Space Telescope: Dark Current and Total Noise Prediction for InSb Detector Arrays in the Infrared Array Camera (IRAC) for the Post-Cryogen Era

During the expected 5+ years of operation, the Spitzer Space Telescope is and will continue to produce outstanding infrared images and spectra, and greatly further scientific understanding of our universe. The Spitzer Space Telescope’s instruments are cryogenically cooled to achieve low dark current and low noise. After the cryogens are exhausted, the Spitzer Space Telescope will only be cooled by passively radiating into space. The detector arrays in the IRAC instrument are expected to equilibrate at approximately 30K. The two shortest wavelength channels (3.6 and 4.5 micron) employ InSb detector arrays and are expected to function and perform with only a modest degradation in sensitivity. Thus, an extended mission is possible for Spitzer. We present the predicted dark current, noise, quantum efficiency and image residuals for the 3.6 and 4.5 micron IRAC channels in the post-cryogen era.