Compact Thermal Imager (CTI) for Atmospheric Remote Sensing

Wu, Dong L.; Jennings, Donald E.; Choi, K. K.; Jhabvala, M.; Limbacher, James A.; Flatley, Thomas W.; Kim, Kyu‐Myong; La, A.; Salawitch, R. J.; Oman, Luke D.; Gong, Jie; Holmes, Thomas; Morton, Douglas C.; Hewagama, T.; Swap, R. J.

doi:10.3390/rs13224578

Cited by 4 publications

(5 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a technology demonstration program, CTI did not have a dedicated processing infrastructure to convert the recorded images into calibrated products for direct use in quantitative investigations. However, procedures for flattening and calibrating the raw image counts to radiance have been developed and detailed in several papers (Jennings et al., 2022; Wu et al., 2021). A flat‐field correction accounts for vignetting (Wu et al., 2021), in which the background count is removed, and the remainder is divided by the FOV response function.…”

Section: Methodsmentioning

confidence: 99%

“…However, procedures for flattening and calibrating the raw image counts to radiance have been developed and detailed in several papers (Jennings et al., 2022; Wu et al., 2021). A flat‐field correction accounts for vignetting (Wu et al., 2021), in which the background count is removed, and the remainder is divided by the FOV response function. A median filter is applied for each scene to despeckle the resulting image.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

On‐Orbit Spatial Performance Characterization for Thermal Infrared Imagers of Landsat 7, 8, and 9, ECOSTRESS and CTI

Holmes,

Poulter,

McCorkel

et al. 2024

JGR Biogeosciences

Self Cite

View full text Add to dashboard Cite

In this analysis of the spatial resolving power of thermal imagery products we focus on four satellite instruments that are used in research and applications, for example, to monitor land surface temperature and derive evapotranspiration. These are thermal imagers on Landsat 7, Landsat 8, and Landsat 9, as well as the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS). We compiled sets of close‐in‐time, day‐time images of bridges surrounded by open water bodies, captured by each of the satellite imagers during cloud‐free moments. Where possible, we also included some images captured by the Compact Thermal Imager (CTI), a technology demonstrator that was co‐located with ECOSTRESS on the International Space Station in 2019. Bridges were found to provide a sufficient thermal contrast with the water surface to quantify the line‐spread function of satellite‐based thermal products. The full‐width‐at‐half‐max of a gaussian beam model fitted to this transect quantifies the on‐orbit spatial resolution of different imagers. The results show some loss of spatial resolving power in the final product delivered to end‐users as compared to the at‐sensor characterization of spatial resolution. For Landsat 7, 8, and 9, the spatial resolution of the thermal bands is 1.5 times the ground sampling distance of 60 and 100 m respectively. For the ECOSTRESS the difference is up to twice the sampling distance of 78 by 69 m2. Since spatial resolution is a main driver for instrument design it is important to understand and communicate this discrepancy between pre‐flight design parameters and the characteristics of the surface imagery delivered to the user community. The goal of this research is to facilitate an improved fusion of current and future satellite observations into harmonized products with superior temporal and spatial characteristics.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

On‐Orbit Spatial Performance Characterization for Thermal Infrared Imagers of Landsat 7, 8, and 9, ECOSTRESS and CTI

Holmes,

Poulter,

McCorkel

et al. 2024

JGR Biogeosciences

Self Cite

View full text Add to dashboard Cite

show abstract

“…During that time, IR detector capabilities have been greatly advanced in terms of sensitivity, spectral coverage, and less active cooling demand through the use of new materials (e.g., [38,39]). GSFC has been developing an IR detector system which utilizes these advances [40,41], as well as a next generation version of the SIDECAR ASIC (instrument data processor) utilized by OSIRIS Rex, ACADIA [42,43,44,45]. Although this Compact Thermal Imager (CTI) was developed initially for astronomical applications [42], the CTI has already been modified for Earth-orbiting applications [43,44,45], as well as for lunar surface applications as the Compact Lunar Hydration and Mineralogical Explorer (CLuHME) [46], with the incorporation of a compact cryocooler.…”

Section: Next Generation Detector Assembly Optics and Calibrationmentioning

confidence: 99%

“…GSFC has been developing an IR detector system which utilizes these advances [40,41], as well as a next generation version of the SIDECAR ASIC (instrument data processor) utilized by OSIRIS Rex, ACADIA [42,43,44,45]. Although this Compact Thermal Imager (CTI) was developed initially for astronomical applications [42], the CTI has already been modified for Earth-orbiting applications [43,44,45], as well as for lunar surface applications as the Compact Lunar Hydration and Mineralogical Explorer (CLuHME) [46], with the incorporation of a compact cryocooler. The detector system is a large format Type II InAs/GaSb strained super lattice (SLS), utilizing thin layers of Group III-IV semiconductor material, a FLIR ROIC (ReadOut Integrated Circuit) [47].…”

Section: Next Generation Detector Assembly Optics and Calibrationmentioning

confidence: 99%

Next generation compact IR spectrometers for the Moon

Clark,

Hewagama,

Brambora

et al. 2023

CubeSats, SmallSats, and Hosted Payloads for Remote Sensing VII

View full text Add to dashboard Cite

Our understanding of the origin, movement, and storage of water on the Moon remains largely unconstrained. Measurements of water absorption features over the same swaths as a function of time of day from a nearly polar orbit, the science goal proposed for the BIRCHES (Broadband InfraRed Compact High-resolution Exploration Spectrometer) payload designed and built for the Lunar Ice Cube orbiter, was intended to provide such essential constraints. BIRCHES was a compact version of OVIRS (Origins Spectral Interpretation Resource Identification Security Regolith Explorer Visible InfraRed Spectrometer) plus a compact cryocooler. IR spectrometer capabilities have been greatly advanced, since its selection in 2015 for the NASA NEXT STEP program, in terms of sensitivity, spectral coverage, and less active cooling demand as exemplified by the NASA GSFC Compact Thermal Imager (CTI), which utilizes a Type II SLS (Strained Super Lattice) combined with the ACADIA processor, follow on to the OVIRS SIDECAR (System Image, Digitizing, Enhancing, Controlling, And Retrieving) ASIC. Although initially developed for astronomical applications, the CTI has, with the addition of a cryocooler, already been modified for lunar surface applications. The 'Next generation' orbital mission and surface package concepts discussed here would utilize advanced versions of BIRCHES, of comparable mass, power and volume but with superior performance, and would likely be significantly more robust and 'roomy', due to availability of high-performance thermal protection components and a larger 12U platform. A compact textual camera and internal calibration source would thus be added.

show abstract

“…This goal was met for this instrument but beyond the technology qualification the CTI was an operational dual-band IR imager on the ISS capturing over 15 million images during 2019 [2]. This was an entirely unexpected and surprising outcome that yielded an enormous amount of earth imagery and specifically images of wildfires across the globe in two electrically selectable IR bands: 3.3-5.4µm and 7.8-10.2µm [3,4]. The SLS detector in the CTI was a 320x256 format array with 30µm pixels hybridized to a FLIR ISC0903 ROIC [5].…”

Section: Introductionmentioning

confidence: 99%

Dual and multi-spectral band SLS infrared camera systems

Jhabvala

Jennings

Turck

et al. 2023

Image Sensing Technologies: Materials, Devices, Systems, and Applications X

View full text Add to dashboard Cite

Based on the recent success of our strained-layer superlattice (SLS)-based infrared (IR) camera that performed Earth imaging from the International Space Station (ISS) in 2019 we have built, what we consider, to be the next generation multi-band SLS imaging system. The Compact Thermal Imager (CTI) was installed on the Robotic Refueling Mission 3 (RRM3) and attached to the exterior of the ISS. From this location we were able to capture 15 million images of a multitude of fires around the globe in 2019. This unexpected trove of data initiated quite a bit of scientific interest to further utilize this imaging capability but would include features to more precisely monitor terrestrial fires and other surface phenomena. To this end, we developed a technique to install specific bandpass filters directly onto the SLS detector hybrid assembly. Utilizing this technique we have built a CTI-2 camera system with two filters, 4 and 11µm, and have made a second detector assembly with six filter bands from 4-12µm. This second system will also be used to supplement Landsat remote imaging monitoring approximate land surface temperatures, monitor evapotranspiration, sea ice and glacier dynamics. The CTI-2 camera is based on a 1,024x1,024 (1kx1k) format SLS detector hybridized to a FLIR ISC0404 readout integrated circuit (ROIC). The six band SLS focal plane array is based on the 640x512 FLIR ISC 9803 ROIC. This camera system is based on the Landsat 8 and 9 Thermal IR Sensors (TIRS) instrument and one of its purposes is to perform ground truthing for the Landsat 8/9 data at higher spectral resolution. Both Landsat TIRS instruments are dual band thermal IR sensors centered on 11 and 12µm (each with about a 1µm bandpass). Both of our SLS systems utilize a Ricor K548 cryocooler. To streamline costs and development time we used commercial optics and both commercial and custom NASA electronic components. A primary feature of these camera systems is the incorporation of specific filters to collect fire data at ~3.9µm and thermal data at ~11µm. The CTI-2 instrument is designed for 37 m /pixel spatial resolution from 410km orbit (ISS orbit). In this paper, we will present the design and performance of the focal plane, optics, electronics and mechanical structure of the dual-band CTI-2 and the focal plane performance of the six-band focal plane.

show abstract

Compact Thermal Imager (CTI) for Atmospheric Remote Sensing

Cited by 4 publications

References 34 publications

On‐Orbit Spatial Performance Characterization for Thermal Infrared Imagers of Landsat 7, 8, and 9, ECOSTRESS and CTI

On‐Orbit Spatial Performance Characterization for Thermal Infrared Imagers of Landsat 7, 8, and 9, ECOSTRESS and CTI

Next generation compact IR spectrometers for the Moon

Dual and multi-spectral band SLS infrared camera systems

Contact Info

Product

Resources

About