Can anyone claim the red planet or natural resources on asteroids? Business leaders and legal experts say the question has become more than philosophical as a growing number of firms, often backed by capital and technology from Silicon Valley, have set their sights on the resources of outer space asteroids and Mars.

The company will launch its first robotic probe mission to scout asteroids for resource deposits in 2020, said Planetary Resources' chief executive Chris Lewicki.

Lewicki is not planning on bringing those water resources back to Earth; he wants market them in space, creating a "gas station" for other exploration missions.

This clause could prove tricky for private firms who want to mine on asteroids or Mars, said Haqq-Misra, including Planetary Resources and SpaceX, the private rocket ship company run by tech billionaire Elon Musk.

Under the United Nations' Law of the Sea Convention countries have exclusive rights to exploit natural resources within around 322 km of their coast line, but ships and planes from other nations can freely pass through the waters.

This could be a template for space resource rights, where companies have exclusive economic rights in a given area around their landing point, but not ownership over an entire asteroid or planet, lawyers said.

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