Advanced Net Flux Radiometer for the Ice Giants

Abstract

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 Uranus Multi-Experiment Radiometer for Haze and Clouds Characterization

“…Consequently, various instruments have been proposed in recent years for the descent probe of a prospective Ice Giant Mission. One such instrument is the Nef Flux Radiometer (Aslam et al 2020), which builds upon the legacy of the aforementioned NFR instrument from Galileo's mission. Its objective is to measure the atmospheric heat balance and structure, the three-dimensional flow in the troposphere, and the compositions and opacities of the cloud layers.…”

Scientific Exploration of Venus with Aerial Platforms

“…Measurements of the net flux of visible and infrared radiation are necessary for understanding the absorption of radiation in the cloud layer and its effect on atmospheric circulation. An advanced net flux radiometer developed for the outer planets [8] can be adapted for a 100-Earth-day mission in the Venus clouds Aerosol and Gas Mass Spectrometer (AGMS): Measurements of noble gases and their isotopes, as well as profiles of active species such as SO2, OCS, H2O & HCl, as a function of altitude, latitude, and time of day would be made by this experiment. A separator that isolates cloud droplets and aerosol particles from the ambient gas is needed to independently measure composition of both cloud and aerosol particles and of the gas, which surrounds them [9].…”

Parallel Computation of CRC-Code on an FPGA Platform for High Data Throughput

“…NASA Goddard Space Flight Center is currently working on several space based thermal radiometer concepts (e.g., [1,2]). One of these concepts is the Ice-Giants Net-flux Radiometer (IG-NFR) being developed for a future Uranus or Neptune probe mission [3].…”

“…The scientific integrity of IG-NFR relies on all seven spectral channels being data logged simultaneously (in parallel). Along with scientific data, there are also auxiliary data and thermal data to aid with understanding of the scientific data [2]. Here, we will use the IG-NFR as an example space-based instrument to demonstrate error check high data throughput using parallel computation of the CRC-code.…”