Key points from article :
Japan’s space agency said it had discovered an enormous cave beneath the lunar surface that could be turned into an exploration base for astronauts.
Using a radar sounder system the orbiter initially found an opening 50 metres wide and 50 metres deep, prompting speculation that there could be a larger hollow.
The chasm, 50km long and 100 metres wide, appears to be structurally sound and its rocks may contain ice or water deposits that could be turned into fuel.
The discovery will boost plans by several countries to send astronauts to the moon almost half a century after the Apollo 11 mission.
