Two teams competing in the Google Lunar X Prize, a private moon-landing competition, say they've joined forces in an attempt to reach the lunar surface by the end of next year.

Hakuto, a Japanese team competing in Google's $30 million contest to put a private spacecraft on the moon's surface, has partnered with Pittsburgh-based Astrobotic with the goal of reaching the moon in the second half of 2016, the two teams announced.

The intention, they say, is to "piggyback" twin rovers being developed by Hakuto -- tagged "Moonraker" and "Tetris" -- on the "Griffin" moon lander being built by Astrobotic.

The lander will also carry Astrobotic's "Andy" rover, being created by Carnegie Mellon University.

Hakuto and Astrobotic have been competing with 16 other teams in the Google contest, which will see a $20 million grand prize go to the first outfit that can put a robotic rover on the lunar surface, have it travel a minimum of 500 meters (1,640 feet) and transmit high-definition video and still images back to Earth.

By creating a partnership, Astrobotic and Hakuto can split the cost of launching their lander/rovers combination to the moon on a SpaceX Falcon 9 rocket.

Astrobotic CEO John Thornton says he has spoken to around half the other teams in the competition to see it any of them want to join Astrobotic and Hakuto on the Falcon rocket.

There should be room aboard the rocket for the rovers of as many teams as might choose to join in the partnership, he said.

Once on the moon, all of the rovers would compete equally to win the Google prize, he said, challenging each other in a "Formula 1 race on the surface of the moon."

If not, then the Astrobotic and Hakuto teams would make it a two-man -- well, two-rover -- race, he said.

"We will be flying with Hakuto to the surface of the moon," Thornton said. "When we get to the surface, we will deploy our rover and deploy Hakuto's rover, and then, together, we will drive off as fast as possible to win the Google X Prize. It'll be a full-on race once we get there."

Under the rules of the Google competition, at least one team must have a launch scheduled by the end of 2015, and completion of the prize attempt must occur before Dec. 31, 2016.

"We are delighted that two of our teams have engaged in this partnership for their Google Lunar X Prize missions," said Andrew Barton, director of technical operation for the competition, explaining that stimulating new business ecosystems is one of the GLXP core goals.