The United States is offering to pay private companies to mine rocks and other resources on the moon. The U.S. space agency NASA published an official government listing for the mining proposal on September 10. NASA officials are asking interested companies to collect rocks, soil and other objects from the surface of the moon. The lunar materials would then be sold to the space agency. NASA administrator Jim Bridenstine says the project was created “for the purpose of demonstrating” that mined resources can be collected. He spoke at a conference organized by the Secure World Foundation, a space policy organization. The proposals would not involve private companies sending workers to the moon. Instead, NASA wants the businesses to provide robots to be launched into space by the space agency or private companies.