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.

"They don't own the water ... but they have a right to put nets in the water and put the fish on the decks and once the fish are there, they own the fish," Richards said during an online panel discussion hosted by the Commercial Spaceflight Federation, an industry advocacy organization.

Extracting resources from celestial bodies is a volatile and contentious issue at the international level.

Gbenga Oduntan, a visiting professor from the University of Kent in Britain and an expert in international commercial law, said the law violates a number of treaties and international customary law. He called it "the most significant salvo that has been fired in the ideological battle over ownership of the cosmos," in an article published in online magazine The Conversation.

He calls the new law “a full frontal attack on settled principles of space law.” He adds that a U.N. effort, the 1979 Moon Treaty (PDF) bans signatories from conducting commercial mining until there is an international agreement covering the activity on planets and asteroids. It was signed by just nine countries, including France, but not the United States.

“It is important to remember that many spacefaring nations have national companies that engage in commercial space activities. They will definitely want to be part of the rule-making process,” said Joanne Gabrynowicz, a professor of space law at University of Mississippi.

A U.S. business executive said the new law does not provide a final word on the issues.

"I would caution anyone from popping the champagne quite yet," said Mike Gold, director of business operations for Bigelow Aerospace, a Nevada-based firm developing commercial space habitats. "This matter is rife with the opportunity for misperception and misunderstanding."

For Moon Express, which plans its first mission to the moon in 2017, and a handful of other companies, the new bill clears what has been a significant hurdle on the road to space.

The bill "gives a high comfort level for our investors and potential investors," said Peter Marquez, vice president with Planetary Resources, an asteroid mining startup whose backers include Google founders Larry Page and Eric Schmidt, as well as Virgin Group's Richard Branson.

"Every time we've had a discussion with investors or potential investors the discussion has not been about 'Is the technology doable?' The thing that gave them pause was, 'Can you actually protect my investment?" Marquez said.

Al Jazeera with Reuters