Dr. Robert V. Leslie Profile

Dr. Robert V. Leslie

at MIT Lincoln Lab

SPIE Involvement:

Author

Publications (7)

Proceedings Article | 20 October 2023 Presentation

Advances in small-satellite systems for high-resolution atmospheric sensing: TROPICS and CREWSR

W. Blackwell, A. Cunningham, M. Diliberto, S. Donnelly, J. Eshbaugh, C. Kataria, V. Leslie, W. Moulder, N. Zorn

Proceedings Volume 12729, 1272904 (2023) https://doi.org/10.1117/12.2675043

KEYWORDS: Atmospheric sensing, Radiometry, Satellites, Reflection, Temporal resolution, Radar, Prototyping, Ice, Absorption, Troposphere

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Two new systems are described to improve present capabilities for high-resolution atmospheric sensing from small satellite platforms. The NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission will significantly improve temporal resolution, and the NASA Configurable Reflectarray for Electronic Wideband Scanning Radiometry (CREWSR) instrument prototype will lead to significantly improved spatial resolution. TROPICS will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate of approximately 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. The TROPICS constellation mission comprises four 3U CubeSats (5.4 kg each) in two low-Earth orbital planes. Each CubeSat will host a high-performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. The four NASA TROPICS CubeSat constellation satellites were successfully launched into orbit on May 7 and May 25, 2023. The separate TROPICS Pathfinder mission launched on June 30, 2021, in advance of the TROPICS constellation mission, as a technology demonstration and risk reduction effort. CREWSR is a high-resolution, lightweight, low-power multiband (23, 31, and 50-58 GHz) radiometer with a deployable scanning reflectarray. It is envisioned to be fielded on an ESPA-class small satellite platform, whose stowed volume fits within 0.61m x 0.71m x 0.97m envelope. Once in orbit, the platform will deploy a large Reconfigurable Reflective Surface (RRS), as well as a multi-feed antenna connected to a multiband radiometer. These components allow for an electronically scanned beam for radiometric Earth observation. CREWSR would operate with a single, linear polarization, but fully polarimetric operation is also possible in principle. The reflectarray is also compatible with radar use, thus enabling wide-swath radar from a small satellite. This presentation will describe the on-orbit results over approximately two years for the successful TROPICS Pathfinder precursor mission and first light results from the TROPICS constellation mission and will overview the CREWSR design, prototype objectives, and recent laboratory measurement results.

Proceedings Article | 5 October 2023 Paper

On-orbit assessment of the NASA TROPICS mission

William Blackwell, Andrew Cunningham, Michael Diliberto, Shawn Donnelly, James Eshbaugh, R. Vincent Leslie, Nicholas Zorn

Proceedings Volume 12689, 1268903 (2023) https://doi.org/10.1117/12.2677316

KEYWORDS: Satellites, Radiometry, Space operations, Microwave radiation, Imaging systems, Temporal resolution, Environmental sensing

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The four NASA TROPICS Earth Venture (EVI-3) CubeSat constellation satellites were successfully launched into orbit on May 7 and May 25, 2023. TROPICS will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate of approximately 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. The TROPICS constellation mission comprises four 3U CubeSats (5.4 kg each) in two low-Earth orbital planes inclined at approximately 33 degrees with a 550-km altitude. Each CubeSat comprises a Blue Canyon Technologies bus and a high-performance radiometer payload to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. TROPICS spatial resolution and measurement sensitivity is comparable with current state-of-the-art observing platforms. Data is downlinked to the ground via the KSAT-Lite ground network with latencies better than one hour. NASA's Earth System Science Pathfinder (ESSP) Program Office approved the separate TROPICS Pathfinder mission, which launched on June 30, 2021, in advance of the TROPICS constellation mission as a technology demonstration and risk reduction effort. The TROPICS Pathfinder mission continues to yield excellent data over 24+ months of operation and has provided an opportunity to checkout and optimize all mission elements prior to the primary constellation mission. This paper describes the on-orbit results for the successful TROPICS Pathfinder precursor mission and the newly-commissioned TROPICS constellation mission.

Proceedings Article | 30 September 2022 Presentation + Paper

On-orbit results from the NASA TROPICS mission

William Blackwell, Andrew Cunningham, Michael Diliberto, Shawn Donnelly, James Eshbaugh, R. Vincent Leslie, Nicholas Zorn

Proceedings Volume 12236, 1223602 (2022) https://doi.org/10.1117/12.2633611

KEYWORDS: Satellites, Radiometry, Space operations, Microwave radiation, Imaging systems, Calibration, Temporal resolution, Sensors

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The NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. The TROPICS constellation mission comprises four 3U CubeSats (5.4 kg each) in three low-Earth orbital planes. Each CubeSat will host a high-performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. TROPICS spatial resolution and measurement sensitivity is comparable with current state-of-the-art observing platforms. Launches for the TROPICS constellation mission are expected in 2023 (the first launch of two of the original six CubeSats occurred on June 12, 2022 but did not successfully reach orbit). NASA’s Earth System Science Pathfinder (ESSP) Program Office approved the separate TROPICS Pathfinder mission, which launched on June 30, 2021, in advance of the TROPICS constellation mission as a technology demonstration and risk reduction effort. The TROPICS Pathfinder mission has provided an opportunity to checkout and optimize all mission elements prior to the primary constellation mission. This presentation will describe the on-orbit results for the successful TROPICS Pathfinder precursor mission and will highlight numerous technical innovations that have made the TROPICS mission possible and enabled new capabilities for future earth observing missions.

Proceedings Article | 9 October 2018 Paper

Calibration and validation of small satellite passive microwave radiometers: MicroMAS-2A and TROPICS

Angela Crews, W. Blackwell, R. Vincent Leslie, Michael Grant, Idahosa Osaretin, Michael DiLiberto, Adam Milstein, Kerri Cahoy

Proceedings Volume 10788, 107880Y (2018) https://doi.org/10.1117/12.2325757

KEYWORDS: Calibration, Microwave radiation, Radiometry, Satellites, Diodes, Sensors, Data modeling, Algorithm development, Atmospheric modeling

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Proceedings Article | 13 November 2010 Paper

Porting and testing NPOESS CrIMSS EDR algorithms

Xu Liu, Susan Kizer, Allen Larar, Daniel Zhou, William Smith, Chris Barnet, Murty Divakarla, Guang Guo, Bill Blackwell, Vincent Leslie, Laura Jairam, Karen St. Germain, Richard Lynch

Proceedings Volume 7857, 785705 (2010) https://doi.org/10.1117/12.869428

KEYWORDS: Satellites, Data modeling, Infrared radiation, Clouds, Apodization, Microwave radiation, Medium wave, Computing systems, C++, Fourier transforms

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Proceedings Article | 29 December 2008 Paper

On-orbit radiometric validation and field-of-view calibration of spaceborne microwave sounding instruments

William Blackwell, Laura Bickmeier, Laura Jairam, R. Vincent Leslie

Proceedings Volume 7154, 71540A (2008) https://doi.org/10.1117/12.804948

KEYWORDS: Satellites, Sensors, Calibration, Antennas, Microwave radiation, Space operations, Spectrometers, Atmospheric corrections, Radiometry, Video

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Two calibration/validation efforts planned for current and future spaceborne microwave sounding instruments will be presented. First, the NPOESS Aircraft Sounder Testbed-Microwave (NAST-M) airborne sensor is used to directly validate the microwave radiometers (AMSU and MHS) on several operational satellites. Comparison results for underflights of the Aqua, NOAA, and MetOp-A satellites will be shown. Second, a potential approach will be presented for on-orbit field-of-view (FOV) calibration of the Advanced Technology Microwave Sounder (ATMS). A variety of proposed spacecraft maneuvers that could facilitate the characterization of the radiometric boresight of all 22 ATMS channels will be discussed. Radiance observations from the NAST-M airborne sensor can be used to directly validate the radiometric performance of spaceborne sensors. NAST-M includes a total of four spectrometers, with three operating near the oxygen lines at 50-57, 118.75, and 424.76 GHz, and a fourth spectrometer centered on the water vapor absorption line at 183.31 GHz. All four feedhorns are co-located, have 3-dB (full-width at half-maximum) beamwidths of 7.5° (translating to 2.5-km nominal pixel diameter at nadir incidence), and are directed at a single mirror that scans cross-track beneath the aircraft with a nominal swath width of 100 km. We will present results for two recent validation efforts: 1) the Pacific THORpex (THe Observing-system Research and predictability experiment) Observing System Test (PTOST 2003, Honolulu, HI) and 2) the Joint Airborne IASI Validation Experiment (JAIVEx 2007, Houston, TX). Radiance differences between the NAST-M sensor and the Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sensor (MHS) were found to be less than 1K for most channels. Comparison results for ocean underflights of the Aqua, NOAA, and MetOp-A satellites are shown. We also present an approach for on-orbit FOV calibration of the ATMS satellite instrument using vicarious calibration sources with high spatial frequency content (the Earths limb, for example). The antenna beam is slowly swept across the target of interest and a constrained deconvolution approach is used to recover antenna pattern anomalies. Various proposed spacecraft maneuvers will be considered, with the intent to illustrate how each maneuver will help to identify and characterize possible FOV artifacts. Radiative transfer simulations that quantitatively assess the benefit of each satellite maneuver will also be presented.

Proceedings Article | 2 December 2008 Paper

Neural network microwave precipitation retrievals and modeling results

R. Vincent Leslie, William Blackwell, Laura Bickmeier, Laura Jairam

Proceedings Volume 7154, 715406 (2008) https://doi.org/10.1117/12.804815

KEYWORDS: Algorithm development, Microwave radiation, Sensors, Computer simulations, Terbium, Atmospheric modeling, Satellites, Radiative transfer, Neural networks, Clouds

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We describe a simulation methodology used to develop and validate precipitation retrieval algorithms for current and future passive microwave sounders with emphasis on the NPOESS (National Polar-orbiting Operational Environmental Satellite System) sensors. Precipitation algorithms are currently being developed for ATMS, MIS, and NAST-M. ATMS, like AMSU, will have channels near the oxygen bands throughout 50-60 GHz, the water vapor resonance band at 183.31 GHz, as well as several window channels. ATMS will offer improvements in radiometric and spatial resolution over the AMSU-A/B and MHS sensors currently flying on NASA (Aqua), NOAA (POES) and EUMETSAT (MetOp) satellites. The similarity of ATMS to AMSU-A/B will allow the AMSU-A/B precipitation algorithm developed by Chen and Staelin to be adapted for ATMS, and the improvements of ATMS over AMSU-A/B suggest that a superior precipitation retrieval algorithm can be developed for ATMS. Like the Chen and Staelin algorithm for AMSU-A/B, the algorithm for ATMS to be presented will also be based a statisticsbased approach involving extensive signal processing and neural network estimation in contrast to traditional physics-based approaches. One potential advantage of a neural-network-based algorithm is computational speed. The main difference in applying the Chen-Staelin method to ATMS will consist of using the output of the most up-to-date simulation methodology instead of the ground-based weather radar and earlier versions of the simulation methodology. We also present recent progress on the millimeter-wave radiance simulation methodology that is used to derive simulated global ground-truth data sets for the development of precipitation retrieval algorithms suitable for use on a global scale by spaceborne millimeter-wave spectrometers. The methodology utilizes the MM5 Cloud Resolving Model (CRM), at 1-km resolution, to generate atmospheric thermodynamic quantities (for example, humidity and hydrometeor profiles). These data are then input into a Radiative Transfer Algorithm (RTA) to simulate at-sensor millimeter-wave radiances at a variety of viewing geometries. The simulated radiances are filtered and resampled to match the sensor resolution and orientation.

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