Mark Greenman

Preflight Assessment of the Cross-track Infrared Sounder (CrIS) Performance

The Cross-track Infrared Sounder (CrIS) is a part of the Crosstrack Infrared and Microwave Sounding Suite (CrIMSS) that will be used to produce accurate temperature, water vapor, and pressure profiles on the NPOESS Preparatory Project (NPP) and upcoming Joint Polar Satellite System (JPSS) operational missions. The NPP CrIS flight model has completed sensor qualification, characterization, and calibration and is now integrated with the NPP spacecraft in preparation for the launch. This paper reviews the CrIS performance during thermal vacuum tests, including the spacecraft integration test, and provides a comparison to the AIRS and IASI heritage sensors that it builds upon. The CrIS system consists of the instrument itself and ground-based scientific algorithms. The data reported in this paper was processed with the latest version of the CrIS science sensor data record (SDR) algorithm and thus reflects the performance of the CrIS SDR system. This paper includes the key test results for Noise Equivalent Differential Noise (NEdN), Radiometric Performance, and Spectral Accuracy. The CrIS sensor performance is outstanding and will meet the mission needs for the NPP /JPSS mission. NEdN is one of the key performance tests for the CrIS sensor. The overall NEdN performance for the CrIS in the LWIR, MWIR and SWIR spectral bands is excellent and is comparable or exceeds NEdN performance of AIRS and IASI. Also discussed is the Principal Component Analysis (PCA) approach developed to estimate contribution of random and spectrally correlated noise components to the total NEDN.

Measurement results from flight measurements with the hyperspectral imaging polarimeter

The Space Dynamics Laboratory at Utah State University has built and flown an airborne infrared Hyperspectral Imaging Polarimeter (HIP) as a proof-of-principle sensor for a satellite-based polarimeter. This paper briefly reviews the instrument design that was presented in previous SPIE papers1,2, details the changes and improvements made between the 1998 and 1999 measurements, and presents measurement data from the flights. Measurement data from a series of flights in 1998 indicated the need for wider-band measurements than could be made with our ferroelectric liquid crystal polarimeter design. For this reason, the existing sensor was modified to use a rotating wire-grid polarization filter. The reasons for this choice, equipment design, and measurement equations will be given. A short description of the 1999 flights aboard FISTA3 (Flying Infrared Signatures Technology Aircraft), an Air Force KC-135 based at Edwards Air Force Base will be given, as well as a small sample of the four-dimensional data set will be presented.

Calibration of the Hyperspectral Imaging Polarimeter

Abstract not available.

Algorithms for calibration and point-source extraction for a LWIR space-based sensor

The Midcourse Space Experiment (MSX) satellite is scheduled for launch in early 1996. The Spatial Infrared Imaging Telescope (SPIRIT) III sensor, the primary instrument of MSX, covers the spectrum from the midwave infrared to the longwave infrared. The SPIRIT III instrument is cryogenically cooled and consists of an interferometer and a five-band scanning radiometer with a spatial resolution of 90 (mu) rad. This paper describes the unique algorithms and software implementation developed to support the SPIRIT III radiometer. The algorithms for converting raw radiometer counts to calibrated counts and then to engineering units are described. The standard process (raw counts to corrected counts) consists of dark offset correction, linearity correction, integration mode normalization, non-uniformity correction, field of regard non-uniformity correction, and bad pixel processing. The algorithm to convert corrected counts to point source engineering units consist of pixel position tagging (non-uniform grid), color coalignment, distortion correction, background subtraction, correction for spacecraft attitude, and position and amplitude determination. The algorithms implemented in the software must produce goniometric estimates to within 5 (mu) rad (0.05 pixel) and radiometric results to within 1 percent. The results of the algorithms are demonstrated in this paper.

Calibration and validation on-orbit plan of the NPOESS Crosstrack Infrared Sounder (CRIS)

Calibration and validation of sensors is important for understanding how a sensor operates during its mission and shows the level of measurements that can be expected. The calibration is an on-going process throughout the mission but is most critical when the complete system comes together and during its initial stage after reaching orbit. Careful planning is required to accurately and efficiently collect data that characterizes the sensors response, process the data in a timely manner to generate results that are useful to mission science, apply the results for processing algorithms, and have a process for improvement as additional information about the sensor becomes available. This paper describes the calibration and validation plan of early on-orbit operations of the Cross-track Infrared Sounder (CrIS). The CrIS sensor is currently integrated on the NPP spacecraft that is scheduled to launch in October 2011.

MKV carrier vehicle sensor calibration

The Multiple Kill Vehicle (MKV) system, which is being developed by the US Missile Defense Agency (MDA), is a midcourse payload that includes a carrier vehicle and a number of small kill vehicles. During the mission, the carrier vehicle dispenses the kill vehicles to address a complex threat environment and directs each kill vehicle toward the intercept point for its assigned threat object. As part of the long range carrier vehicle sensor development strategy, MDA and project leaders have developed a pathfinder sensor and are in the process of developing two subsequent demonstration sensors to provide proof of concept and to demonstrate technology. To increase the probability of successful development of the sensor system, detailed calibration measurements have been included as part of the sensor development. A detailed sensor calibration can provide a thorough understanding of sensor operation and performance, verifying that the sensor can meet the mission requirements. This approach to instrument knowledge will help ensure the program success and reduce cost and schedule risks. The Space Dynamics Laboratory at Utah State University (SDL) completed a calibration test campaign for the pathfinder sensor in April 2008. Similar calibration efforts are planned in 2009 for the two demonstration sensors. This paper provides an overview of calibration benefits, requirements, approach, facility, measurements, and preliminary results of the pathfinder calibration.

Utilizing UV and visible sensors on micro-satellites to demonstrate target acquisition and tracking

The Distributed Sensing Experiment (DSE) program is a technology demonstration of target acquisition, tracking, and three-dimensional track development using a constellation of three micro satellites. DSE will demonstrate how micro satellites, working singly and as a group, can observe test-missile boost and ballistic-flight events. The overarching program objective is to demonstrate a means of fusing measurements from multiple sensors into a composite track. To perform this demonstration, each DSE micro satellite will acquire and track a target, determine a two-dimensional direction and movement rate for each, communicate observations to other DSE satellites, determine a three-dimensional target position and velocity, and relay this information to ground systems. A key design parameter of the program is incorporating commercial off-the-shelf (COTS) hardware and software to reduce risk and control costs, while maintaining performance. Having completed a successful Critical Design Review, the program is currently in fabrication, integration, and test phase. The constellation of satellites is scheduled for launch in CY2009. This paper describes the status and capabilities of the UV and visible sensor payloads, as well as the algorithms and software being developed to achieve the DSE mission.

Resampling algorithm for the Spatial Infrared Imaging Telescope (SPIRIT III) Fourier transform spectrometer

The Spatial Infrared Imaging Telescope (SPIRIT III) is the primary sensor aboard the Midcourse Space Experiment (MSX), which was launched 24 April 1996. SPIRIT III included a Fourier transform spectrometer that collected terrestrial and celestial background phenomenology data for the Ballistic Missile Defense Organization (BMDO). This spectrometer used a helium-neon reference laser to measure the optical path difference (OPD) in the spectrometer and to command the analog-to-digital conversion of the infrared detector signals, thereby ensuring the data were sampled at precise increments of OPD. Spectrometer data must be sampled at accurate increments of OPD to optimize the spectral resolution and spectral position of the transformed spectra. Unfortunately, a failure in the power supply preregulator at the MSX spacecraft/SPIRIT III interface early in the mission forced the spectrometer to be operated without the reference laser until a failure investigation was completed. During this time data were collected in a backup mode that used an electronic clock to sample the data. These data were sampled evenly in time, and because the scan velocity varied, at nonuniform increments of OPD. The scan velocity profile depended on scan direction and scan length, and varied over time, greatly degrading the spectral resolution and spectral and radiometric accuracy of the measurements. The Convert software used to process the SPIRIT III data was modified to resample the clock-sampled data at even increments of OPD, using scan velocity profiles determined from ground and on-orbit data, greatly improving the quality of the clock-sampled data. This paper presents the resampling algorithm, the characterization of the scan velocity profiles, and the results of applying the resampling algorithm to on-orbit data.