Nasa has outlined more details of its plans for a landing craft that will take humans to the lunar surface.
The plans call for an initial version of the lander to be built for landing on the Moon by 2024; it would then be followed by an enhanced version.
The news comes as work was completed on the Orion spacecraft that will fly around the Moon in 2021.
This mission, called Artemis-1, will pave the way for the first attempt to land since 1972.
The presolicitation notice to industry calls for proposals on an initial lander design capable of carrying two people down to the Moon’s South Pole in 2024.
Companies will then be given the option to develop an enhanced lander capable of carrying four astronauts to the lunar surface. It would also be able to stay for longer, including through the two-week lunar night.