Search giant Google is offering a $30m prize pot to private firms that land a robot rover on the Moon.
More cash will be given for snaps of old equipment left on the Moon
The competition to send a robot craft to the Moon is being run with the X-Prize Foundation.
To claim the cash, any craft reaching the lunar surface must perform a series of tasks such as shoot video and roam for specific distances.
Firms interested in trying for the prize have until the end of 2012 to mount their Moonshot.
In a statement announcing the competition, Google and the X-Prize Foundation said it had been created in a bid to stimulate research into low-cost robotic exploration of space.
The top prize of $20m will be given to the private firm that soft lands a rover on the Moon which then completes a series of objectives.
These include roaming the lunar surface for at least 500m and gathering a specific set of images, video and data.
A prize of $5m will be given to the second firm that manages to reach the Moon with a rover that roams the surface and shoots some pictures.
Google said it would give bonuses of $5m if the rovers complete other objectives such as travelling further on the Moon, taking pictures of Apollo hardware, finding water-ice and surviving the freezing lunar night.
Rovers taking part must be fitted with high-definition video and still cameras.
"We are confident that teams from around the world will help develop new robotic and virtual presence technology, which will dramatically reduce the cost of space exploration," said Dr Peter Diamandis, chairman of the X-Prize Foundation in a statement.
The prize will be on offer until 2012. After that a smaller sum of $15m will be offered and, if the cash goes unclaimed, the competition will end in 2014.
Sending a robot rover to the Moon is a formidable task - involving far greater hurdles than the first X-Prize competition. Indeed, sending any sort of craft to the Moon would normally require the funding support of national or international space agencies.
The rocket plane SpaceShipOne claimed the Ansari X-Prize
The prize is the third offered and administered by the X-Prize Foundation.
The first was run to encourage private space travel. The $10m (£4.9m) Ansari-sponsored prize was won in October 2005 when the SpaceShipOne rocket plane climbed to an altitude of 100km twice inside seven days.
In October 2006, the X-Prize Foundation created the $10m Archon X-Prize for Genomics, which will be given to the first private research group to sequence 100 human genomes in 10 days.