Space policy experts told U.S. Congress that NASA must consider alternatives to its current plan to return astronauts to the moon with the Artemis program.

Lunar Trailblazer, an orbiter that shared a launch on Wednesday with the commercial Athena lander, will help scientists understand where the moon’s water is, and what form it takes.

An illustration shows NASA’s Lunar Trailblazer approaching the moon as it enters its science orbit in this artist’s concept. The small satellite will orbit about 60 miles (100 kilometers) above the lunar surface,