The moon is not bone dry, scientists now know. But how many drops of water will thirsty astronauts find? No one knows for sure.

A robotic NASA spacecraft called Lunar Trailblazer, which launched Wednesday night from Kennedy Space Center in Florida, is aiming to provide a detailed map from orbit of the abundance, distribution and form of water across the moon.

Lunar Trailblazer tagged along for the ride to space on the same SpaceX Falcon 9 rocket as Athena, a commercial lunar lander built by Intuitive Machines of Houston, which will deploy a NASA instrument to drill in the moon and sniff for water vapors.

Athena will study one spot on the moon. Lunar Trailblazer will provide a global picture of water on the moon.

“That’s another exciting thing for us as we get more science into space with one launch,” Nicola Fox, the associate administrator for NASA’s science mission directorate, said during a news conference before the launch.

Less than an hour after liftoff, Lunar Trailblazer and Athena went their separate ways. Athena is taking a direct path to the moon, with landing scheduled for March 6, while Lunar Trailblazer set off on a meandering but fuel-efficient journey that will take four months to reach its destination. After it enters orbit, the spacecraft will make observations for at least two years.