Figure A

Seen here before being shipped from the U.K. to the U.S., the Lunar Thermal Mapper (LTM) is one of two instruments that will be carried by NASA's Lunar Trailblazer. Launching in 2023, the small spacecraft – measuring only about 11 feet (3.5 meters) wide with its solar panels fully deployed – will also carry the High-resolution Volatiles and Minerals Moon Mapper (HVM³). The two instruments will work together to help detect and map water on the Moon's surface to determine its abundance, location, form, and how and why it varies by location and time.

In February 2023, LTM completed qualification for flight and calibration at the University of Oxford in England. The instrument will provide maps of lunar surface temperature from about minus 261 degrees Fahrenheit (minus 163 degrees Celsius) to 261 F (127 C) using four broad-band infrared channels covering wavelengths from 6.25 to 100 micrometers. The instrument also has 11 narrower infrared channels that are sensitive enough to detect and map small variations in the composition of silicate minerals that make up the rocks and soils of the Moon's surface.

The instrument is shown here wrapped with a multilayer insulation blanket to assist with thermal control. Not covered by insulation is LTM's single "eye" – a scan mirror that can pivot down to look at the Moon's surface or outward into space for calibration purposes. The scan mirror collects a line of pixels at a time to form an image via the motion of the spacecraft.

Figure A shows LTM, without the blanket, being mounted in the test calibration and vacuum chamber at the University of Oxford. During vacuum testing the instrument viewed external targets that varied in temperature between minus 261 F (minus 163 C) and 243 F (117 C) so that it could be calibrated. The alignment, spectral, and radiometric (temperature) accuracy of LTM was checked both before and after the instrument was tested via vibration and cycling through thermal environments identical to what it will experience during launch and operation in lunar orbit.

With these tests complete, the instrument was packed and shipped for integration with the Lunar Trailblazer spacecraft at Lockheed Martin Space in Colorado.

Lunar Trailblazer was selected to be part of NASA's SIMPLEx (Small Innovative Missions for Planetary Exploration) program in 2019. The mission is led by Caltech in Pasadena, California, and managed by JPL. The Lunar Thermal Mapper instrument is funded by the UK Space Agency and is a collaboration between the University of Oxford, University of Durham (UK), and the University of Central Florida, with assistance from STFC RAL Space, UK.

For more information about Lunar Trailblazer's mission:
https://trailblazer.caltech.edu