Project Selections for SLI-T 19
6 Projects Awarded Under the Sustainable Land Imaging – Technology Program
08/03/2020 NASA’s Science Mission Directorate, NASA Headquarters, Washington, DC, has selected proposals for the Sustainable Land Imaging-Technology Program in support of the Earth Science Division (ESD).
The goals of the SLI-T program are to research, develop, and demonstrate new measurement technologies that improve upon the Nation’s current land imaging capabilities while at the same time reducing the overall program cost for future Sustainable Land Imaging measurements.
The SLI-T solicitation was targeted to technology development activities aimed specifically at: (1) demonstrating improved, innovative, full-instrument concepts for potential infusion into the architecture and design of missions beyond Landsat-10; and (2) development and technical maturation at the component and/or breadboard-level of technologies that have long-term potential to significantly improve future land imaging instruments and systems through substantial architecture changes. The ESD has selected 6 out of a total of 12 received proposals in response to this solicitation. The first-year funding for these investigations is approximately seven million dollars.
Super Uncooled Multi-Band Radiometer Sensor (SUMRS)
Philip Ely/DRS Network & Imaging Systems, LLC
Leonardo DRS is pleased to provide a proposal for a Super Uncooled Multiband Radiometer Sensor (SUMRS) in response to the Sustained Landsat Imaging Technology (SLIT) RFP. DRS’ offering builds upon the successful ESTO IIP MURI instrument which demonstrated that an uncooled bolometer based instrument is capable of meeting existing Landsat TIR performance expectations and is mature enough for use. Our MURI instrument used existing high TRL bolometers. Our proposed SUMRS instrument seeks to maximize TIR capability and performance through exploiting the latest developments in uncooled technology and advances in metafilters. We propose to demonstrate these improvements in an airborne demonstration similar to our successful MURI IIP program. The proposed SUMRS instrument will provide temporal/spatial simultaneous imaging in 6 spectral bands at 30m GSD from a 705km orbit and sensitivity better than the SLIT RMA requirements and current LANDSAT 8/9 TIRS instruments. The low SWAP of the Uncooled Radiometer design, by eliminating the cryocooler typically needed for LWIR FPAs, make it ideal for use on a small satellite platform to allow for launch of a constellation of small satellites to facilitate higher frequency revisits.
Our proposed SUMRS instrument leverages the MURI IIP proven piezo back-scan mechanism to allow for frame stacking of up to 14 frames. The primary technology advancements included in the proposed SUMRS instrument are:
- Bolometer arrays with 10 μm pixels (reduced from MURI’s 17 μm) and the introduction of DRS’ super uncooled bolometer technology for better GSD and higher sensitivity at lower SWAP. Super-uncooled bolometer arrays will provide improved sensitivity by modifying the ROIC to operate with continuous bias rather than pulsed bias, implementing higher resistance bolometers to allow for continuous bias operation, thermal mass reduction of the bolometer combined with increased thermal isolation of the bolometer material by utilizing higher thermal resistance bolometer leg materials.
- Larger format 2,100 x 2,000 element bolometer arrays with 10μm pixels to hold all 6 spectral bands on a single FPA thereby improving band to band registration and,
- Meta-surface filters that split the color bands such that the vertical FOV is imaged simultaneously in all 6 color bands. This simultaneity will allow for true simultaneous image capture in all six bands, eliminating the color to color latency seen in butcher block filter approach.
Incorporation of these technologies will enable a 30m GSD from the Landsat orbit using a small wide field of view 235mm EFL f/1 lens. This is 2X better than the GSD requested in the SLIT RMA requirements. This gives the science community options for analysis: use the data at full 30m resolution or aggregate up to 60m resolution. The aggregated 60m data will be more sensitive and have better RER. The lower 30m GSD can facilitate improving co-registration with the reflective bands as requested in the SLIT RMA. This five year Super Uncooled Multiband Radiometer Sensor (SUMRS) instrument program will start with the development of the SUMRS Instrument Concept Design and a SFPA ROIC trade study and detailed design through PDR in the initial year. In the second year the SFPA ROIC design and wafer fabrication, and the Meta-surface Filter design will be completed. In year three the SFPA ROIC wafers will be characterization tested. Also in year three the SFPA Bolometer design and the SFPA bolometer package design will be completed and the first bolometer lot will be processed and characterization testing. In year four the SFPA bolometers will be packaged and tested. Also during year four the SUMRS Flight Instrument Design will be completed and hardware delivered, to support the Flight Instrument integration and Airborne Demonstration of the SUMRS Instrument in the fifth and final year. Our SUMRS instrument will provide a next generation TIR capability meeting or exceeding the SLIT RMA.
Land Calibration Satellite – Breadboard
Geir Kvaran/Ball Aerospace & Technologies Corporation
The Land Imaging Community continues to demonstrate the value of improved sensor performance, with higher spatial resolution, temporal coverage, more spectral bands, and improved radiometry enabling broader science investigations and supporting increased societal benefits. The Community is pivoting toward increasing temporal coverage through data fusion from a constellation of sensors, including international and commercial assets – each with diverse strengths and weaknesses. However, integrating data from other, less capable sensors, has been more challenging, as the Community wrestles with instrument-induced data artifacts.
The LandCalSat Breadboard (LCS-B) project demonstrates a path to space for LandCalSat (LCS): a mission that would provide the cross-calibration and validation capability required to knit together this future Land Imaging Constellation. LCS-B focuses on the key technical challenges to providing an on-orbit reference instrument – specifically, differences in spatial and spectral performance between disparate platforms, such as Sentinel-2, Planet, and Landsat-8. Characterization uncertainties in spatial and spectral performance have a large impact on radiometric cross-calibration. While the Land Imaging Community recognizes the impact in comparing spectral performance and the need to effectively subsample spectrally, the impact of varying spatial performance on cross-calibration is less well-understood and has a greater impact, posing a challenge to successful radiometric cross-calibration between sensors and direct comparison to ground-based vicarious calibration sites. The LCS-B has a three year period of performance and would raise the TRL from 3 to 5.
The primary goals of the spaceborne LCS are to provide a single sensor that has appropriate resolution both spatially and spectrally and bridges the spatial resolution gap between low resolution, radiometrically calibrated observations designed for climate applications and higher-resolution Land Imaging sensors. LCS leverages Ball Aerospace’s expertise in design and characterization of Land Imaging sensors, high spatial resolution imagers, and imaging spectroscopy.
TransCal – An Innovative, Highly Accurate, Transmissive Radiometric Calibration Approach
Nathan Leisso/Ball Aerospace & Technologies Corporation
TransCal is an innovative calibration approach using Polymer Dispersed Liquid Crystal (PDLC) material to continue the precise solar diffuser based radiometric calibration used extensively in the Landsat program, while significantly reducing the size and complexity of the calibration subsystem. An essential aspect underlying the utility of the long-term Landsat data record is extensive pre-launch sensor characterization and on-orbit calibration. To improve on current earth remote sensing capabilities, the Sustainable Land Imaging-Technology (SLI-T) 2019 program aims to reduce resources needed (e.g., cost, size, volume, and mass) for the next generation SLI instruments, while meeting or exceeding the current Land Imaging capabilities, with emphasis on improved temporal, spatial, and spectral resolution. TransCal meets this objective of reducing sensor Size, Weight, and Power (SWaP) while maintaining critical radiometric performance.
PDLC material is composed of liquid crystal (LC) micro-droplets encased in a transparent polymer matrix. The orientation of the LC molecules defines the optical, electrical, magnetic, and mechanical properties. In its nominal state, each LC micro-droplet is randomly aligned, resulting in a high degree of optical scattering and creating an opaque, diffuse PDLC material. The LC molecules orientation may be controlled through weak electric or magnetic fields. To accomplish this, the PDLC material is typically flanked by thin conductive layers of Indium Tin Oxide (ITO). This enables the application of a local electric field which preferentially orientates the LC molecules across all droplets and renders the PDLC optic transparent.
The objectives of the TransCal program are to develop a TransCal PDLC optic and to fully characterize this optic as a reversible, highly accurate solar diffuser permanently located in the optical path of a future sensor. Full characterization will include spectral transmittance, Bidirectional Transmittance Distribution Function, and the transmitted wavefront. The temporal stability and radiation testing will verify its applicability for space flight instrumentation. Finally, the on-orbit imaging and calibration performance will be modeled and verified with an operational sensor such as the Compact Hyperspectral Prism Spectrometer (CHPS). To achieve this, we propose a two-year-long program beginning at TRL 2 and exiting at TRL 4.
Improved Radiometric Calibration of Land Imaging Systems (IRIS)
The Improved Radiometric calibration of future land Imaging Systems (IRIS) project addresses a key SLI program objective by developing and demonstrating technology to reduce risk, cost, size, volume, mass, and development time for next generation SLI instruments, while meeting or exceeding current land imaging program capabilities. IRIS addresses this SLI objective in two different, but complementary ways. The first way involves designing and building an ultra-compact, full RMA spectrum (0.4-2.3 micron and 6-13 micron) end-to-end calibration source and testing this source with the existing NASA ESTO Advanced Technology Land Imaging Spectroradiometer (ATLIS) free form reflective triplet telescope and VNIR FPA along with SWIR and uncooled TIR FPAs acquired as part of the proposed work. The NASA ESTO ATLIS project demonstrated that an advanced technology land imager with 160x less volume and 16x less mass than the Landsat 8 (L8) Operational Land Imager (OLI) meets L8 and RMA 2019 VSWIR requirements. IRIS extends ATLIS by reducing volume of the onboard calibration assembly, occupying roughly a third of the OLI volume, by 90% using an innovative, full-spectrum Jones source. IRIS will demonstrate a functionally complete full-spectrum prototype land imager with much reduced size and mass by verifying calibration performance across the full RMA spectral range and full imager field of view by comparison with well-understood NIST traceable full aperture laboratory sources. The second way involves in-flight absolute solar radiometric calibration of L8 OLI onboard lamp assemblies based on Raytheon’s patented Specular Array Calibration (SPARC) method. SPARC uses spherical convex mirrors to create a collection of “solar stars” with identical spectra and well-defined radiometric properties directly traceable to the exoatmospheric solar spectral constant. SPARC site observations provide in-flight absolute calibration and sensor image quality validation achieved at a high level of repeatability and accuracy. Labsphere is developing a global network of fully automated commercial SPARC sites called FLARE, for improving in-flight calibration of space-based imagers. The proposed work involves imaging the FLARE beta site on Mauna Loa using L8 OLI. FLARE observations occur nearly simultaneously with active onboard calibration lamp measurements to enable the first direct in-flight absolute solar radiometric calibration of an onboard lamp assembly.The proposed research, if successful, supports SLI objectives by demonstrating that absolute radiometric calibration of an onboard lamp source or other onboard source such as the IRIS VSWIR calibration subassembly can provide absolute calibration meeting or exceeding requirements independent of an onboard solar diffuser over the full mission lifetime. In addition, FLARE site imaging of the point sources created by the mirrors provides point spread function and other image quality data.
Versatile Computational Pixel Infrared Land Imager
David Ting/Jet Propulsion Laboratory
We propose to develop a revolutionary infrared focal plane array based on a computational pixel digital readout integrated circuit (D-ROIC) and a type-II superlattice (T2SL) dual-band unipolar barrier infrared detector (BIRD) capable of spectral coverage from the near infrared to the very long wavelength infrared. Focal plane arrays (FPAs) based on T2SL BIRD technology have consistently demonstrated high uniformity and operability, as well as excellent performance and cost-effectiveness. The D-ROIC with computational pixel imager (CPI) technology has large effective well depth and in-pixel processing power for building disruptive new capabilities into the pixel and onto the focal plane. The combination of T2SL-BIRD and CPI D-ROIC technologies will result in infrared imaging FPAs with higher operating temperature, wide spectral coverage, large ground swath/resolution, and exceptional versatility to enable striking improvements in observational capability and operational efficiency for land imaging.
Reduced Envelope Multispectral Infrared Radiometer (REMIR)
Michael Veto/Ball Aerospace & Technologies Corporation
The Reduced Envelope Multispectral Infrared Radiometer (REMIR) is the next step in meeting the five thermal infrared band requirements for beyond Landsat 10 by leveraging NASA and Ball investments in new detectors, innovative calibration subsystems, and a scanning approach that enables significant reductions in size, weight, and power (SWaP) compared to the existing Landsat architecture. Through the course of this Advanced Technology Demonstration (ATD), we will design and build a single, full spectral range (VIS-TIR) instrument suite for airborne verification of the Reference Mission Architecture (RMA) 2019’s thermal infrared requirements. This approach will validate the use of an uncooled microbolometer focal plane array (FPA) with image motion control (IMC) and coadding of step-stare frames using Ball’s Wide-Angle Steering Mirror (WASM) as a viable solution. Specifically, we will integrate a commercially available uncooled microbolometer FPA into the existing Reduced Envelope Multispectral Instrument (REMI) suite to offer a robust airborne demonstration platform and verify the ability of uncooled microbolometer FPA’s, meeting the following RMA performance characteristics: Noise Equivalent Delta Temperature (NEDT), spatial resolution, edge response, and calibration requirements. REMIR’s scan mechanism approach, successfully demonstrated on REMI for the VNIR-SWIR, enables this proposed uncooled microbolometer FPA solution. During operation, REMIR dynamically compensates for thermal background sensitivity, temperature gradient effects, and calibration uncertainty using the Compact Infrared Radiometer in Space (CIRiS) calibration system approach that employs two internal carbon nanotube blackbody calibration sources. The REMIR concept has an entrance TRL of 3 and uses low risk components with high TRL. The airborne REMI instrument, a NASA-Ball Sustained Land Imaging Technology 2015, has a TRL of 6; CIRiS, a NASA-Ball In-Space Validation of Earth Science Technologies (InVest) 2015, is currently in on-orbit commissioning, maturing to a TRL of 7. By leveraging test equipment and hardware in-house at Ball Aerospace, we can comfortably demonstrate the advantages of CIRiS for SLI-T and its incorporation into REMI, bringing the REMIR system to TRL 6, while maintaining the planned cost and schedule during this four -year build and test program. The REMIR architecture readily supports the addition of TIR band capability, in an architecture that maintains continuity of on-orbit Landsat requirements with a sustainable and reliable solution to meet the desired enhancements for Landsat 11. REMIR is sustainable in its simple uncooled microbolometer FPA approach, maintains continuity through consistency of people and facilities used on previous SLI programs, and is reliable through reusing previous high TRL NASA-Ball technologies and offering a low-cost and SWaP solution for reproducibility for constellation architectures. This SLI-T program strongly leverages a mentorship approach, pairing highly experienced Co-I’s and Collaborators with younger PI and Co-I’s. This approach allows younger key personnel to devote appropriate attention to the project, while benefitting from the instrument development and project management experience of more experienced personnel to ensure the future continuity of the Landsat program. Given the level of experience of the principals and a robust mentorship model, this SLI-T will be a low-risk, productive endeavor.