IF-MOS trade-off study: Concerns and questions
During this study, the following concerns and questions about the MOS and IFS design concepts have arisen.
MOS-specific
- A micro-mirror or shutter array in the NGST focal plane will act as a diffraction grating. The ultimate fate of the diffracted light may have an adverse effect on the level of parasitic light within the instrument. How can this be predicted and controlled?
- How will the MOS background subtraction actually be done: from the object slitlets themselves or from separate apertures (or both)?
- What are the costs, in thermal dissipation and reliability, of the necessary mechanisms?
- What are the failure modes of the MMA/MSA?
- Will the target acquisition requirements preclude parallel observations?
IFS-specific
- Is a spectral resolution of R = 150 too low for doing the 'wide field' parts of the DRM?
- What are the sources of parasitic light expected for the image-sliced IFS?
- What are the costs, in thermal dissipation and achievability, of the large detector array required for the LR mode??
- What is the expected degradation to the prism transmission after 10 years in the L2 radiation environment?
General
- How realistic is it to assume that the optical throughputs of the two types of spectrograph are similar?
- Which device gives the optimum performance for a single, faint source - galaxy and unresolved?
Modified by Bob Fosbury on July 20, 1999.
For more information, please send mail to Bob Fosbury.