JPL's mission page for SPHEREx says:
The mission will create a map of the entire sky in 96 different color bands, far exceeding the color resolution of previous all-sky maps.
Wikipedia's SPHEREx Spacecraft/telescope says:
The triple mirror telescope will have an aperture diameter of 20 centimeters with a 3.5° x 11° field of view and six 2k x 2k mercury cadmium telluride (HgCdTe) photodetector arrays.12, 8 Each 2K x 2K focal plane array is covered with a linear variable filter, providing narrow-band response with a band center that varies along one axis of the array. SPHEREx obtains spectra through multiple exposures, placing a given source at multiple positions in the field of view, where it is measured at multiple wavelengths by repointing the spacecraft.8
Question: How exactly does SPHEREx implement 96 spectral bands with a linear variable filter across its focal plane?
Does the telescope constantly rotate like GAIA and use fancy array readout techniques to produce the 96 discrete spectral bands in software?
Or does it move discretely such that nearby objects are actually recorded at slightly different central wavelengths since the filter is linear.
How does this work exactly?
It seems SPHEREx has adopted the KISS principle:
- Low-Risk Implementation
- No Moving Parts
- Single Observing Mode
- Large Technical & Scientific Margins
- Follows successful CIT/JPL mgt. model of NuSTAR