V-WiSHeS: Venus Wideband Submillimeter Heterodyne Spectrometer

SCIENCE GOALS AND OBJECTIVES We propose to build a low-SWaP engineering model of the Venus Wideband Submillimeter Heterodyne Spectrometer (V-WiSHeS), a high spectral resolution instrument optimized to remotely measure trace gases and continuum opacities in Venus’ middle atmosphere. V-WiSHeS will enable spatial and temporal profile measurements of wind, temperature, composition, and aerosol opacity, in both nadir and limb-sounding modes, to reveal the critical role of Venus’ middle atmosphere at altitudes spanning 60 to 150 km. With unprecedented wideband spectral coverage for submillimeter heterodyne planetary flight spectrometers, V-WiSHeS will cover 64 GHz of bandwidth between 529 and 600 GHz, with a spectral resolution as fine as 500 kHz (resolution 0.0000167 cm-1, R=1,000,000 at 557 GHz). These capabilities enable measurements of aerosol continuum opacity, thermal profiles, and isotopic abundances of the gases H2O, H217O, H218O, HDO, CO17O, CO18O, 13CO18O, 13CO17O, CO, 13CO, C18O, O3, OO17O, OO18O, O18O, H2S, H234S, H233S, H2SO4, ClO, 37ClO, H2O2, SO, SO2, 34SO2, OCS, O13CS, OC34S, OC33S, NO, and NO2.

The V-WiSHeS instrument is significantly leveraging our team’s previous MatISSE and DALI efforts. In our former MatISSE project, we matured subcomponents of a passive remote sensing planetary flight spectrometer called SELFI, the Submillimeter Enceladus Life Fundamentals Instrument. In our DALI effort, we incorporated – for the first time – broadband ASIC digital spectrometers into the design of the heterodyne spectrometer SSOLVE, the Submillimeter Solar Observation Lunar Volatiles Experiment. In this present effort, however, we will build on our SELFI and SSOLVE technologies, most notably by expanding the spectral coverage, while simultaneously reducing both mass and power.

METHODOLOGY We are developing a novel submillimeter planetary flight spectrometer that achieves both high spectral resolution and a groundbreaking 64 GHz of broadband spectral coverage in a low-power, low-mass, and compact instrument. Such an advancement is enabled in part by incorporating four Application-Specific Integrated Circuit (ASIC) spectrometers into the V-WiSHeS back-end, which are critically needed for their high-speed computational capacity. Moreover, we are able to simultaneously achieve wide spectral coverage by implementing an innovative time-multiplexed frequency switching scheme that utilizes four 4-GHz ASIC spectrometers to achieve a 16 GHz instantaneous bandwidth, in which we frequency switch four times to reconstruct 64-GHz of coverage (529 -- 561 GHz; 568 -- 600 GHz). At the end of this 3-year MatISSE project, our highly experienced team will deliver a TRL 6 instrument prototype to NASA, ready for a planetary flight mission opportunity.

RELEVANCE This proposed work is responsive to the stated objectives of the MatISSE program by advancing the development of V-WiSHeS, a planetary space flight remote sensing instrument with unprecedented spectral coverage for submillimeter heterodyne flight spectrometers. We will demonstrate that V-WiSHeS is an appealing instrument for a future Venus orbiter with its broad spectral coverage and high spectral resolution. V-WiSHeS provides numerous compelling science capabilities, which will help to unravel fundamental science questions at Venus (e.g., What do diverse climates such as Venus’ reveal about the vulnerability of Earth’s environment? What roles do the targeted trace gases play in Venus’ physical and chemical atmospheric environment?). V-WiSHeS will be an essential part of any orbiter mission to Venus including New Frontiers, Discovery, SIMPLeX, and SmallSat concepts. Beyond that of Venus, V-WiSHeS is applicable to numerous planetary targets such as Mars, Ceres, Jupiter, Io, Europa, Saturn, Titan, Enceladus, Uranus, Neptune, Triton, KBOs, and comets.