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NASA’s is slated to return astronauts to the Moon no sooner than April 2026. Astronauts were last on the Moon in 1972 during the .

Artemis II will utilize NASA’s , which is an extremely powerful rocket that will enable human space exploration beyond Earth’s atmosphere. The crew of four will travel in an , which the agency launched around the Moon and successfully returned during the .

But before Artemis II, NASA will send two missions to scout the surface of the lunar south pole for resources that could sustain human space travel and enable new scientific discoveries.

are interested in data from Lunar Trailblazer, one of these two scouting missions. The data from this mission will how water forms and behaves on rocky planets and moons.

Starting with scientific exploration

, or the Polar Resources Ice Mining Experiment, will be mounted on a lunar lander. It’s scheduled for launch in January 2025.

Aboard the lander are two instruments: , TRIDENT, and the , MSOLO. TRIDENT will dig down up to 3 feet (1 meter) and extract samples of lunar soil, and MSOLO will evaluate the soil’s chemical composition and water content.

Joining the lunar mining experiment is Lunar Trailblazer, a satellite launching on the same .

Think of this setup as a multimillion-dollar satellite , or a rideshare where multiple missions share a rocket and minimize fuel usage while escaping Earth’s gravitational pull.

, is the principal investigator of Lunar Trailblazer and is leading an operating team of . Trailblazer is a NASA .

These missions intend to provide practical operations experience at a lower cost. Each SIMPLEx mission is capped at a budget of US$55 million – Trailblazer is slightly over budget at $80 million. Even over budget, this mission will cost around a quarter of a typical robotic mission from . Discovery Program missions typically cost around $300 million, with a maximum budget of $500 million.

Building small but mighty satellites

Decades of research and development into , or , opened the possibility for Trailblazer. SmallSats take highly specific measurements and complement data sourced from other instruments.

Multiple SmallSats working together in a constellation can take various measurements simultaneously for a high-resolution view of the Earth’s or Moon’s surface.

SIMPLEx missions can use these SmallSats. Because they’re small and more affordable, they allow researchers to study questions that come with a . Lunar Trailblazer, for example, uses to keep the cost down.

These low-cost, high-risk experimental missions may help geologists further understand the origin of the solar system, as well as what it’s made of and how it has changed over time. Lunar Trailblazer will focus specifically on mapping the Moon.

A brief timeline of water discoveries on the Moon

Scientists have long been fascinated by the surface of our closest celestial neighbor, the Moon. As early as the mid-17th century, astronomers mischaracterized ancient volcanic eruptions as , derived from the Latin word for “seas.”

Nearly two centuries later, astronomer suggested that the Moon had no atmosphere. This led him to conclude the Moon could not have water on its surface, as that water would vaporize.

However, in the 1990s, NASA’s detected water on the Moon. Clementine was the first mission to completely map the surface of the Moon, including the lunar poles. This data within on the Moon in low resolution.

Scientists’ first water detection prompted further exploration. NASA launched the in 1998 and the in 2009. The India Space Research Organization launched its with the , M3, instrument in 2008. M3, although not designed to detected liquid water, unexpectedly did find it in sunlit areas on the Moon.

These missions collectively provided maps showing how – minerals containing water molecules in their chemical makeup – and ice water are distributed on the lunar surface, particularly in the cold, dark, permanently shadowed regions.

Novel mission, novel science

But how does the temperature and physical state of water on the Moon change from variations in sunlight and crater shadows?

Lunar Trailblazer will host , the , LTM, and an evolution of the M3 instrument, the , HVM3.

The LTM instrument will map surface temperature, while the HVM3 will measure how lunar rocks absorb light. These measurements will allow it to detect and distinguish between water in liquid and ice forms.

In tandem, these instruments will provide thermal and chemical measurements of hydrous lunar rock. They’ll measure water during , which is about 29.5 Earth days, to try to show how the chemical composition of water varies depending on the time of day and where it is on the Moon.

will tell researchers what phase – solid or liquid – the water is found in.

Scientific significance and what’s next

There are three leading theories for where lunar water came from. It could be water that’s been stored inside the Moon since its formation, . Some geologic processes may have allowed it to slowly escape to the surface over time.

Or, the water may have that collided with the lunar surface. It may even have been with , which is a stream of particles that comes from the Sun.

Lunar Trailblazer may shed light on these theories and help researchers make progress on several other big science questions, including how and whether future astronauts will be able to use it.