Title: The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) to Enable Temporally-Resolved Observations of Clouds and Precipitation on a Global Basis using 6U-Class Satellite Constellations
Presenting Author: Steven C. Reising
Organization: Colorado State University
Co-Author(s): Todd C. Gaier, Sharmila Padmanabhan, Boon H. Lim, Christian D. Kummerow, V. Chandrasekar, Cate Heneghan, Wesley Berg, Richard Schulte, C. Radhakrishnan, Shannon T. Brown, and Matthew Pallas

Abstract:
Global observations of clouds and precipitation are essential to improve monitoring and prediction of hurricanes, tropical cyclones and severe storms with substantial impacts on human life and property. To understand cloud and precipitation processes that lead to rain, snow, sleet and hail in a variety of climate environments, global observations with rapid revisit times are essential. To this end, sensors on geostationary satellites have substantially improved weather prediction by providing visible and infrared measurements with temporal resolution down to a few minutes. However, to improve understanding of cloud and ice processes leading to the onset of precipitation on a global basis requires fine time-resolution observations using millimeter-wave radiometry capable of penetrating into the storm to where precipitation begins. To address this critical observational need, microsatellite constellations enable rapid revisit times on a global basis for measurements of the radiative effects of scattering from cloud particles and hydrometeors. The Temporal Experiment for Storms and Tropical Systems (TEMPEST) mission is a proposed constellation consisting of identical 6U-class satellites with rapid, 3-6 minute temporal sampling, to observe cloud and precipitation processes over an individual storm cell's life cycle, including genesis, maturity and decay. The payload for each 6U-Class satellite is a five-frequency millimeter-wave radiometer (90-183 GHz) with the capability to remotely sense the interior of the cloud to observe microphysical changes in water and ice as precipitation begins and ice accumulates inside the storm. Such a 6U-class satellite constellation mission would enable the first global measurements of clouds and precipitation on the time scale of a few to a few tens of minutes and the corresponding single-storm cell spatial scale of a few hundred m to a few km. TEMPEST is planned to improve understanding of cloud and precipitation processes as well as helping to constrain one of the largest sources of uncertainty in cloud models. Such a mission is to provide critical information on temporal signatures of clouds and the onset of precipitation. For TEMPEST, 6U-class satellites are chosen to provide substantial margins on mass, power, satellite-to-ground communications and capability for microwave radiometer calibration. To demonstrate the feasibility of a constellation of 6U-class TEMPEST satellites, the TEMPEST Technology Demonstration (TEMPEST-D) mission is underway to raise the TRL of the instrument and key satellite systems from 6 to 9, as well as to demonstrate the observational capabilities required to achieve a full TEMPEST mission. The Level 1 requirements for the TEMPEST-D mission are to: (1) demonstrate precision inter-satellite calibration between TEMPEST-D and one other orbiting radiometer, i.e., NASA/JAXA's Global Precipitation Microwave Imager (GMI) or the Microwave Humidity Sounder (MHS) on NOAA and ESA/EUMETSAT operational satellites, measuring at similar frequencies; and (2) demonstrate orbital drag maneuvers to control altitude to 100 m or better, sufficient to achieve required temporal spacing in a constellation of 6U-Class satellites. TEMPEST-D is a partnership among Colorado State University (Lead Institution), NASA/Caltech Jet Propulsion Laboratory and Blue Canyon Technologies. The TEMPEST-D instrument has been demonstrated in the laboratory, vibration and thermal vacuum testing to be TRL 6. The instrument has been integrated into a 6U-Class spacecraft, successfully vibration and thermal vacuum tested and delivered to NanoRacks for launch integration on March 22, 2018. TEMPEST-D was selected by NASA CSLI and manifested for Orbital ATK-9 commercial resupply service to ISS, planned for launch in May 2018. NanoRacks will deploy TEMPEST-D into orbit within 1-3 months after arrival at ISS. The mission consists of a minimum of three months of technology demonstration from an initial orbit with 400-km altitude and 51.6 degrees inclination.