Space exploration has long been about reaching far off destinations but now there is a race to exploit new frontiers by mining their minerals.

Google has offered a $20m grand prize to the first privately-funded company to land a robot on the moon and explore the surface by moving at least 500 metres and send high definition video back to Earth by 2015.

A second-placed team stands to win $5m for completing the same mission, with bonus prizes for travelling more than 5km, finding water and discovering any traces of man's past on the moon, such as the Apollo site.

Alastair Leithead visited the test laboratory of Moon Express, one of 25 companies vying to win the prize.

This piece is part of the What If? season imagining what the future might hold.