Thermal Emission Imaging System (THEMIS)

Thermal Emission Imaging System (THEMIS)
Name	Thermal Emission Imaging System
Acronym	THEMIS
Operator	Arizona State University / NASA
Mission	Mars Odyssey
Launch	2001-04-07
Spacecraft	2001 Mars Odyssey
Type	Imager
Spectral	Thermal infrared, Visible
Resolution	~100 m (thermal), ~18 m (visible)
Mass	~20 kg
Power	~30 W

Thermal Emission Imaging System (THEMIS) THEMIS is a multispectral imaging instrument aboard 2001 Mars Odyssey designed to map Martian surface composition and thermophysical properties in the thermal infrared and visible wavelengths. Developed by a team led at Arizona State University with contributions from NASA, THEMIS has provided high-resolution thermal maps used by researchers at institutions such as Jet Propulsion Laboratory, Smithsonian Institution, and Brown University. The instrument's data have informed missions including Mars Reconnaissance Orbiter, Mars Exploration Rover, Mars Science Laboratory, and InSight.

Overview

THEMIS was proposed in the late 1990s by scientists associated with Arizona State University, with flight selection under the NASA Discovery and Mars Surveyor program frameworks and formal integration into the 2001 Mars Odyssey payload. The instrument complements spectrometers like Mars Global Surveyor's TES and imagers such as Viking Orbiter cameras and Mars Reconnaissance Orbiter's HiRISE, enabling cross-comparison with datasets from Mars Express, Nozomi, and terrestrial facilities like Jet Propulsion Laboratory laboratories and Smithsonian Institution collections. THEMIS operations have been coordinated with teams at NASA Ames Research Center, Lockheed Martin, and international partners including European Space Agency investigators and researchers from University of Arizona and University of Colorado Boulder.

Instrument Design and Specifications

THEMIS comprises a multispectral thermal infrared radiometer and a visible-wavelength camera, employing detectors and optics supplied by contractors associated with Raytheon, Ball Aerospace, and university labs. The thermal channel uses ten longwave bands (approximately 6.8–14.9 μm) with nadir spatial resolution near 100 meters, facilitating mineralogical discrimination similar to instruments on Mars Global Surveyor and Mars Odyssey heritage sensors. The visible channel provides ~18 meter/pixel context images for geomorphic interpretation, supporting investigations analogous to those by Viking Orbiter and Mars Reconnaissance Orbiter instruments. Electronics, calibration blackbodies, and radiometric chains were designed in collaboration with teams at Jet Propulsion Laboratory, NASA Goddard Space Flight Center, and Arizona State University laboratories.

Scientific Objectives and Capabilities

Primary objectives included mapping surface thermophysical properties, identifying silicate and sulfate minerals, and constraining albedo and thermal inertia across regional to global scales. THEMIS data enable analyses of volcanic provinces like Tharsis, sedimentary basins such as Valles Marineris, and polar terrains near Amazonis Planitia and Hellas Planitia, complementing geologic context from missions like Mars Reconnaissance Orbiter and Mars Express. Capabilities extend to diurnal temperature mapping, aiding study of aeolian processes in regions like Gale Crater investigated by Curiosity of the Mars Science Laboratory mission, and stratigraphic mapping relevant to sites like Meridiani Planum explored by Opportunity.

Mission Operations and Data Processing

THEMIS operations were conducted from mission control centers at Arizona State University and coordinated with NASA flight operations for 2001 Mars Odyssey, with downlink scheduling using networks including Deep Space Network stations at Goldstone, Canberra, and Madrid. Raw telemetry underwent radiometric calibration, geometric correction, and mosaicking using software pipelines developed at Arizona State University and validated against instruments from Mars Global Surveyor and Mars Reconnaissance Orbiter. Data products, archived at Planetary Data System nodes and mirrored by institutions like US Geological Survey and Smithsonian Institution, include calibrated thermal brightness temperature maps, apparent thermal inertia maps, and visible context mosaics used by investigators at Brown University, University of Arizona, University of Washington, and international teams from University of Oxford and ETH Zurich.

Key Discoveries and Contributions

THEMIS contributed to identification of silica-rich deposits, detection of regional layered sediments, and mapping of volcanic and impact-related units across terrains such as Elysium Planitia and Isidis Planitia. Combined analyses with Mars Exploration Rover data enabled ground-truthing of orbital mineralogy at Gusev Crater and Meridiani Planum, while synergy with Mars Reconnaissance Orbiter's CRISM provided finer spectral constraints. THEMIS thermal inertia mapping refined understanding of sediment grain sizes in aeolian fields like Olympus Mons periphery and aided selection of landing sites for Phoenix and Mars Science Laboratory by teams at NASA Jet Propulsion Laboratory and Lockheed Martin.

Calibration and Validation

Calibration strategies relied on onboard blackbody references, cross-calibration with contemporaneous instruments such as Mars Global Surveyor's TES and terrestrial calibration facilities at Jet Propulsion Laboratory and NASA Ames Research Center. Validation campaigns included coordinated observations with Mars Odyssey radio science experiments and comparisons to in-situ thermal measurements from Mars Exploration Rover instruments and meteorological data from InSight and Phoenix. Long-term radiometric stability was monitored by teams at Arizona State University, NASA Goddard Space Flight Center, and international partners at European Space Agency affiliated laboratories.

Legacy and Impact on Planetary Science

THEMIS has left a lasting legacy by producing global thermal maps used across disciplines by researchers at institutions such as California Institute of Technology, Massachusetts Institute of Technology, University of Cambridge, University of Oxford, ETH Zurich, Imperial College London, University of California, Berkeley, Brown University, and Stanford University. Its datasets underpin studies in planetary volcanology, sedimentology, and landing site characterization, informing later missions including Mars Reconnaissance Orbiter, ExoMars, Mars 2020 (Perseverance), and proposals submitted to NASA and European Space Agency programs. THEMIS-trained methodologies influenced instrument design for thermal imagers on missions like Lunar Reconnaissance Orbiter and concept studies for Europa Clipper and mission concepts affiliated with Jet Propulsion Laboratory and Ames Research Center.

Category:Instruments aboard 2001 Mars Odyssey