The design of a versatile dual-telescope thermal-infrared radiometer spanning the spectral wavelength range 8 to 200 µm, in five spectral pass bands, for outer planet fly-by missions is described. The dual-telescope design switches between a narrow-field-of-view and a wide-field-of-view to provide optimal spatial resolution images within a range of spacecraft encounters to the target. The switchable dual-field-of-view system uses an optical configuration based on the axial rotation of a source-select mirror along the optical axis. The optical design, spectral performance, radiometric accuracy, and retrieval estimates of the instrument are discussed. This is followed by an assessment of the surface coverage performance at various spatial resolutions by using the planned NASA Europa Mission 13-F7 fly-by trajectories as a case study.
The design of an advanced Net Flux Radiometer (NFR), for inclusion as a payload on a future Ice Giants Probe mission, is given. The Ice Giants NFR (IG-NFR) will measure the upward and downward radiation flux (hence net radiation flux), in seven spectral bands, spanning the range from solar to far infra-red wavelengths, each with a 5° Field-Of-View (FOV) and in five sequential view angles (±80°, ±45°, and 0°) as a function of altitude. IG-NFR measurements within either Uranus or Neptune's atmospheres, using dedicated spectral filter bands will help derive radiative heating and cooling profiles, and will significantly contribute to our understanding of the planet's atmospheric heat balance and structure, tropospheric 3-D flow, and compositions and opacities of the cloud layers. The IG-NFR uses an array of non-imaging Winston cones integrated to a matched thermopile detector Focal Plane Assembly (FPA), with individual bandpass filters, housed in a diamond windowed vacuum micro-vessel. The FPA thermopile detector signals are read out in parallel mode, amplified and processed by a multi-channel digitizer application specific integrated circuit (MCD ASIC) under field programmable gate array (FPGA) control. The vacuum micro-vessel rotates providing chopping between FOV's of upward and downward radiation fluxes. This unique design allows for small net flux measurements in the presence of large ambient fluxes and rapidly changing ambient temperatures during the Probe descent to ≥10 bar pressure.
the on-resistance of the switches themselves can be difficult to mitigate. Usually, the capacitors are switched. In SC cir-
A wide-band first-order voltage differentiation circuit relies on swirchedrapacitor (SC) techniques to yield an indication of slew direction. Fabricated in a 0.35um CMOS process using double poly capacitors, the circuit incorporates a regions. The circuit's sensitiviry is adjustable by varying the measurement time-interval along with the threshold voltages of the window comparator and offers advantages over con-V,,", window comparator to facilitaie deiecrion of infection VIN ventional differentiator schemes relying on resisiors and capacitors.Figure 1-1. Simplest form of circuit differentiation.
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