Competition might not be the mother of invention, but it certainly has inspired robotic innovation at Astrobotic Technology Inc.

The space-age robotics company in Oakland already has announced its intent to win the $20 million Google X Prize by being the first to send a mobile robot to the moon and beam back to Earth video images, possibly of the Apollo 11 landing site.

Now Astrobotic has announced that it will compete for a $500,000 prize from NASA with a robot it hopes will dig and dump the most simulated lunar dirt during a 30-minute workout.

The NASA Regolith Excavation Challenge, set for Oct. 17-18 at the NASA Ames Research Center in Silicon Valley, Calif., will help prepare the way for robots to construct durable landing pads on the moon, possibly with banks of moon dirt known as regolith piled around the pad to protect people, habitats and equipment from landings and blastoffs.

Robots also could cover human habitats with regolith to protect people from solar and cosmic galactic radiation and to dig trenches for electrical cables.

So digging robots will become important tools on the moon.

For now, NASA is projecting that humans will return to the moon as early as 2020. But robots could be sent there years earlier to prepare sites for human habitation.

The Astrobotic moon digger, developed in collaboration with Carnegie Mellon University's Robotics Institute, is a yard long and wide and stands 2 feet high. It has a laser scanner to measure distances inside the 13-by-13-foot competition area.

The robot uses a scraper to skim sand-like dirt into a hopper. Astrobotic President David Gump said the digger must climb a ramp then dump its load into a pit. The robot will be operated by a person but on a 4-second time delay to replicate the lag time in communications between the Earth and moon.

During the challenge, each robot must excavate at least 330 pounds of simulated moon dirt under lunar-like conditions with limited power and bandwidth. Last year's competition ended with no robot meeting minimum requirements.

Astrobotic did not compete last year.

In coming months, the moon digger will be refined during field trials in the "Regolith Simulant Testbed" that the California Space Authority, a co-host of the challenge, is providing to competing teams.

Astrobotic is led by William "Red" Whittaker, the noted CMU roboticist, who described his company's X Prize robot as a rolling TV studio designed to broadcast high-definition video back to Earth from the Apollo 11 site. If successful, the return trip to the site will be the first since the historic landing 40 years ago.