NASA is developing the RASSOR mining robot to collect soil on the moon or Mars so it can be processed into rocket fuel, breathable air and other commodities. Source YouTube/NASA

NASA is shifting its focus from exploration to excavation with a prototype moon-mining robot.

Known as RASSOR, the experimental digging device is a prototype for a fleet of machines that NASA hopes to soon start sending to the Moon.

RASSOR is short for Regolith Advanced Surface Systems Operations Robot.

It is a small but sturdy robot intended to be compact enough to launch into space but reliable enough to work all day, every day, for years.

It is a 76cm tall, 45kg machine is a combination of whirling digging blades and caterpillar tracks designed to burrow into soil.

NASA's goal is to create a robot that will survive for several years on the harsh lunar surface.

To do this, it will need to be part of a robotic team suppling ice containing soil to a "mothership" lunar lander which will separate water from the detritus to make fuel and breathable air.

"This has been kind of the dream, the mission they gear this around," a RASSOR team engineer said.

The machine digs through a series of rotating bucket drums at its front and rear.

"The staggered shallow scoops shave the soil a bit at a time rather than scoop large chunks of it all at once, the way bulldozers do on Earth," NASA says.

The robotic diggers are no slouches.

It will be able to speed over the Moon's surface at 20 metres per second, leaving the likes of the Mars Curiosity probe in its dust.

It will also be required to work up to 16 hours a day, seven days a week, 365 days a year for five years.

There will be no smoko breaks.