How will the instrument performance depend on the on-orbit performance of the detectors (e.g. cosmic ray susceptibility)?
By virtue of being able to acquire spectra with the full bandpass of light impinging on the detector elements, an FTS is tolerant of detector performance degradation, both in terms of dark current and read noise. Furthermore, by taking a series of readouts to effectively monitor the apparent photo-current, large cosmic ray glitches can be removed on orbit. Also, because spectral information is derived from modulated light levels, the 1/f type of focal plane array glitch noise which is apparently very significant for instruments such as those on ISO, can be very significantly reduced. Using the observed ISO cosmic ray glitches as an example, the suppression of glitch noise by IFIRS could reasonably be expected to exceed an order of magnitude.
