The X Prize Foundation announced Thursday the name of eight of the nine competitors in this year's Northrop Grumman Lunar Lander Challenge to be held this October during the Wirefly X Prize Cup and Holloman Air and Space Expo.

The number of teams competing for the $2 million purse increased from four teams to nine. Sponsored by NASA's Centennial Challenges Program, the event is designed to accelerate commercial development of technology that can ferry cargo and humans between the Moon's surface and lunar orbit.

"We are excited by the number of teams competing this year and their overall level of sophistication," Peter H. Diamandis, Chairman and CEO of the X Prize Foundation said in a statement. "We fully expect to award the $2 million purse this year in what will prove to be an exhilarating showdown between a number of very qualified teams."

The 2007 Wirefly X PRIZE Cup and Holloman Air and Space Expo will be held October 27-28 at Holloman Air Force Base in Alamogordo, NM.

Teams participating in the competition are:

• Acuity Technologies,  Menlo  Park,  CA: Led by Robert Clark, who founded the company in 1992, they previously designed Unmanned Aerial Vehicles for the Department of Defense.

• Armadillo Aerospace,  Mesquite,  TX: The only team to fly a vehicle in last year's challenge with the vehicle Pixel, the company is led by John Carmack, founder of id Software.

• BonNova, Tarzana, CA: Allen Newcomb, an engineer who was part of the SpaceShipOne team that won the Ansari X PRIZE, helms this group.

• Masten Space Systems, Mojave, CA: Masten Space Systems is currently working on launching tethered flights and now sells what they have dubbed "SodaSats", the opportunity to launch and recover very small payloads for only $99.

• Micro-Space, Denver, CO: The Micro-Space team, along with Armadillo Aerospace, is one of two Ansari X PRIZE to compete.

• Paragon Labs,  Denver,  CO: Kevin Sagis, founder of Paragon is leading a 16-member team to create the Volkon vehicle.

• SpeedUp, Laramie and Chugwater, WY: Led by Robert Steinke, a former employee of NASA.s Jet Propulsion Lab, SpeedUp plan to use a non-propellant engine.

• Unreasonable Rocket, Solana Beach, CA: The father-son team of Paul T. Breed and Paul A. Breed are building their vehicles in a garage for under $200,000.

The ninth team requested to remain confidential, lending an air of controversy to the announcement. Space bloggers have surmised the ninth team is Amazon.com founder Jeff Bezos' Blue Origin, but sources told SPACE.com that information was wrong.

Their confidentiality period ends 60 days before the start of the competition at which time the X Prize Foundation will announce the team's name.

For further information about the teams vying for the $2 million prize purse, visit http://ngllc.xprize.org

• Complete Coverage: WireFly X Prize Cup
• Special Report: The New Space Race