A new law clears U.S. companies to own what they mine from asteroids and other celestial bodies, ending a legal quandary that had overshadowed technical and financial issues facing the startups, industry officials said on Tuesday.

The Commercial Space Launch Competitiveness Act, signed by President Barack Obama last week, includes provisions that authorize and promote exploration and recovery of space resources by U.S. citizens, although no one can claim ownership of a celestial body.

"It's not unlike fishing vessels in international waters," said Bob Richards, chief executive of Moon Express, a lunar transportation and mining company.