Lunar Trailblazer blasts off to map water on the moon

Once in orbit, the spacecraft -- weighing 200kg and about the size of a washing machine- will map the surface temperature and composition of the lunar surface 12 times a day, at a resolution of 50 metres. Using cutting-edge instruments, it will examine features including the permanently shadowed craters at the Moon's South Pole, which could contain significant quantities (potentially 600 million metric tons) of water ice. This could be used in various ways, from purifying it as drinking water to processing it for fuel and breathable oxygen for future human Moon landings.

One of the two principal instruments, the Lunar Thermal Mapper (LTM), was constructed by researchers in the Planetary Experiments Group at the University of Oxford's Department of Physics. This will measure the surface temperature and the various minerals that make up the lunar landscape, to help confirm the presence and location of water. The instrument will work in tandem with NASA/JPL's High-resolution Volatiles and Minerals Moon Mapper (HVM3) to produce the most detailed maps of water on the Moon's surface to date. (Further details on how the instruments work below)

Lunar Trailblazer was selected by NASA's Small Innovative Missions for Planetary Exploration (SIMPLEx) program in 2019, which provides opportunities for low-cost science spacecraft to ride-share with selected primary missions. The spacecraft will launch as a secondary payload on a planned lunar lander mission led by Intuitive Machines, effectively hitchhiking on the larger spacecraft, which will attempt a soft landing on the Moon. If the launch at NASA's Kennedy Space Center, Florida, goes smoothly, the first images from the LTM should arrive back on earth within three days.

Since the spacecraft has a relatively small engine, its planned trajectory will use the gravity of the Sun, Earth, and Moon to guide it to the final orbit -- a technique called low-energy transfer. The momentum provided by the rocket booster will propel the spacecraft past the Moon and into deep space before it is pulled back by gravity. The spacecraft will then use small thruster bursts to slowly correct its orbit until it is about 60 miles (100 kilometers) above the Moon's surface. In all, Lunar Trailblazer should take between four and seven months to arrive in its final orbit.

The LTM was constructed by the Planetary Experiments Group at the University of Oxford's Department of Physics, with £3.1 million funding from the UK Space Agency and the Department for Science, Innovation and Technology (DSIT). For the group, building the LTM is the latest achievement in a 50-year history of developing components for spaceflight and infrared thermal mapping cameras, including for missions to Mars, Saturn, and the Moon. With the LTM's components being produced by various UK academic institutes and companies (details below), this collective effort highlights the nation's leading role in space exploration and scientific research.

Professor Neil Bowles, Instrument Scientist for LTM at the University of Oxford's Department of Physics, said:

"The Lunar Thermal Mapper was designed, built and tested here in Oxford and the launch is an important moment for the whole of our team. The measurements of temperature will help confirm the presence of the water signal in HVM3's measurements and the two instruments will work together to map the composition of the Moon, showing us details that have only been hinted at previously."

The mission could also reveal why the Moon has water in the first place. Possible reasons include comets and 'wet asteroids' crashing into the Moon; ancient volcanic eruptions disgorging water vapor from the Moon's interior; or hydrogen within the solar wind combining with oxygen on the Moon. Lunar Trailblazer's findings will shed light on which hypothesis is more likely.

Lauren Taylor, Major Projects Lead from The UK Space Agency said:

"The UK Space Agency is thrilled to be a part of NASA's Lunar Trailblazer mission. Our work with the University of Oxford to develop the Lunar Thermal Mapper showcases the UK's leading role in space exploration and scientific research.

"This mission will provide invaluable data on the Moon's water resources, supporting future human missions and enhancing our understanding of the lunar environment."

Further detail on how the Lunar Thermal Mapper works:

The two instruments on the Lunar Trailblazer spacecraft -- the Lunar Thermal Mapper (LTM) and High-resolution Volatiles and Minerals Moon Mapper (HVM3) will work in tandem to generate high-resolution maps of the Moon's water to help determine the Moon's water cycle.

The Oxford-built LTM will use four broadband infrared channels to measure the temperature of the lunar surface ranging from approximately -163°C to 127°C. The instrument will also use eleven narrow infrared channels to map small variations in the composition of silicate minerals that make up the rocks and soils of the Moon's surface. This will provide more information about what the lunar surface is made of and where water may potentially be found.

Meanwhile, the HVM3 (built by NASA's Jet Propulsion Laboratory and funded by NASA) will detect and map the form, abundance, and locations of water over the lunar landscape by measuring spectral fingerprints (wavelengths of reflected sunlight). The temperature of the surface being measured affects the apparent strength of the absorption signal of water, therefore the HVM3 spectral data will be calibrated using the temperature measurements recorded at the same time by the LTM.

By mapping the Moon day and night, Lunar Trailblazer will be able to detect whether the amount of water changes on this airless body, for instance, by transforming into a gas as the surface heats up, or accumulating like frost in the shadowed regions as the surface cools down. The mission will help answer key questions such as whether water molecules might be locked up inside lunar rock, or if the permanently shadowed craters at the lunar poles hold significant quantities of water ice.