D. C. Reuter

Simulation of Image Performance Characteristics of the Landsat Data Continuity Mission (LDCM) Thermal Infrared Sensor (TIRS)

The next Landsat satellite, which is scheduled for launch in early 2013, will carry two instruments: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Significant design changes over previous Landsat instruments have been made to these sensors to potentially enhance the quality of Landsat image data. TIRS, which is the focus of this study, is a dual-band instrument that uses a push-broom style architecture to collect data. To help understand the impact of design trades during instrument build, an effort was initiated to model TIRS imagery. The Digital Imaging and Remote Sensing Image Generation (DIRSIG) tool was used to produce synthetic on-orbit TIRS data with detailed radiometric, geometric, and digital image characteristics. This work presents several studies that used DIRSIG simulated TIRS data to test the impact of engineering performance data on image quality in an effort to determine if the image data meet specifications or, in the event that they do not, to determine if the resulting image data are still acceptable.

Landsat and Thermal Infrared Imaging

The purpose of this chapter is to describe the collection of thermal images by Landsat sensors already on orbit and to introduce a new Landsat thermal sensor. The chapter describes the Landsat 4 and 5 thematic mapper (TM) and Landsat 7 enhanced thematic mapper plus (ETM+) sensors, the calibration of their thermal bands, and the design and prelaunch calibration of the new thermal infrared sensor (TIRS). The TIRS will be launched in February 2013 on the Landsat Data Continuity Mission (LDCM) satellite, which will be renamed to Landsat 8 after it reaches orbit. Continuity of the data record has always been a priority for the Landsat project. The TIRS will extend the unique Landsat thermal data archive begun in 1978 that supports, among other applications, water resource management in the western United States and global agricultural monitoring studies. The TIRS also introduces improved technology and data quality, both of which are discussed in the chapter.

Landsat 9 Thermal Infrared Sensor 2 pre-launch characterization: initial imaging and spectral performance results.

The Thermal Infrared Sensor-2 (TIRS-2) aboard Landsat 9 will continue Landsat’s four decade-long legacy of providing moderate resolution thermal imagery from low earth orbit (at 705 km) for environmental applications. Like the Thermal Infrared Sensor aboard Landsat 8, it is a pushbroom sensor with a cross-track field of view of 15° and provides two spectral channels at 10.8 and 12 μm. To ensure radiometric, spatial, and spectral performance, a comprehensive pre-launch testing program is being conducted at NASA Goddard Space Flight Center at the component, subsystem, and instrument level. This paper will focus on the results from the subsystem level testing where the instrument is almost completely assembled. This phase of testing is specifically designed to assess imaging performance including focus and stray light rejection, but is also used to provide a preliminary assessments of spatial and spectral performance. The calibration ground support equipment provides a flexible blackbody illumination source and optics to conduct these tests. The spectral response test setup has its own illumination source outside the chamber that propagates through the calibration ground support equipment in an optical configuration designed for this purpose. This test configuration with the calibration ground support equipment and TIRS-2 subsystem in the thermal vacuum chamber enables a large range of illumination angles for stray light measurements. The results show that TIRS-2 performance is expected to meet all of its performance requirements with few waivers and deviations.

Imaging and spectral performance of the New Horizons Ralph instrument during the 2015 Pluto encounter (Conference Presentation)

The Ralph instrument on the New Horizons mission consists of a telescope that feeds two focal planes: the Multi-spectral Visible Imaging Camera (MVIC), a visible, near-IR imager and the Linear Etalon Imaging Spectral Array (LEISA), a short-wavelength IR spectral imager. During the encounter with the Pluto system in 2015, Ralph operated as expected collecting numerous high spatial resolution images of the main components of the system, Pluto and Charon, as well as the four much smaller objects Hydra, Kerberos, Nix and Styx. New Horizons, launched on January 19, 2006, is the first mission to explore Kuiper Belt Objects (KBOs).