NASA has granted a research team from the University of Arizona $500,000 to develop robots able to mine, excavate and even build simple structures on the Moon's surface.
Environment officials and campaigners have called for a global moratorium on deep-sea mining and on issuing new exploration contracts unless marine ecosystems can be effectively protected.
Coal mining is more commonly criticised by environmentalists for polluting air and water, degrading landscapes and fuelling climate change than for creating new wildlife habitats.