Since the final Apollo mission in 1972, the moon has been undisturbed by human footsteps. But that may soon change.

NASA plans to send astronauts back to the moon this decade in a series of spaceflights called the Artemis program. The first planned launch — a test flight with no crew members aboard — is set to take place Saturday, after an earlier attempt was scrubbed because of a technical problem. Eventually, though no earlier than 2025, NASA will send astronauts for a weeklong stay near the moon’s south pole. The crew will include the first woman and the first person of color to walk on the moon, NASA said.

Instead of crew members, the first Artemis mission will carry into space three mannequins named Helga, Zohar and Commander Moonikin Campos. Helga and Zohar contain plastic models of radiation-sensitive organs, such as the uterus and the lungs, so that scientists can study how radiation in space may affect future astronauts.

The three mannequins will travel inside a spacecraft called Orion, specially designed to protect human crew members and experiments in space.

Orion will launch into space atop the Space Launch System, a new rocket that stands 322 feet tall and weighs almost 6 million pounds. The Space Launch System that will be used in Artemis I is one of the most powerful rockets ever built by NASA, and can send a payload of almost 60,000 pounds to the moon.

Artemis II, the second mission, will carry four astronauts around the moon and back to Earth. The crew’s trip will take them about 4,600 miles above the far side of the moon. Depending on the position of the moon during the mission, this could be the greatest distance into the solar system that astronauts have ever traveled.

In Artemis III, astronauts will land a SpaceX Starship near the moon’s south pole while Orion waits in lunar orbit. The polar region is home to mysterious, permanently shadowed craters that have not seen sunlight in billions of years. The chemicals frozen inside could help scientists understand more about the history of the moon and the solar system.

If the Artemis III mission succeeds, NASA plans to regularly send crews to the moon. Its plans include a lunar base camp and an outpost spacecraft called Gateway stationed in lunar orbit.

This article originally appeared in The New York Times.