The race to put the first private robot lander on the moon is heating up as a second company says it has secured a launch commitment for 2017 to pursue the $30 million Google Lunar X Prize.

Silicon Valley firm Moon Express, which plans to mine the moon for precious resources, has announced a contract with Rocket Lab to use that company's experimental Electron rocket to launch its MX-1E micro-lander to the moon, the X Prize Foundation confirmed.

"We are extremely proud to officially confirm receipt and verification of Moon Express's launch contract," said Bob Weiss, vice chairman and president of the X Prize Foundation.

Moon Express is up against an Israeli nonprofit group, SpaceIL, which certified its own launch plans in October.

SpaceIL has paid for a "rideshare" aboard a SpaceX Falcon 9 rocket for a scheduled September 2017 launch to send its "Sparrow" lander on the way to the moon.

Sixteen teams, including Moon Express and SpaceIL, remain in the Google Lunar X Prize competition, with groups from the U.S., India, Germany, Brazil and Chile competing.

Announced in 2007, the prize will go to the first group that lands a commercially-developed spacecraft on the moon that can robotically travel at least 500 yards across the lunar surface and return data, including high-resolution video, back to Earth.

The landers must be developed and built with private funding, and competitors are responsible for securing launch arrangements by the end of 2016.

Chanda Gonzales, senior director of the Google competition, says she can't estimate how many of the 16 teams in the running might submit launch contracts for certification by the deadline, but says, "I am hopeful that we'll have two, three or four teams."

The deadline for putting a lander on the moon and fulfilling the stated requirements is Dec. 31, 2017; the first team to do so will receive $20 million, while the second-place effort will bring $5 million.

Other cash prizes are on offer for teams that can achieve other scientific or technical goals, such as visiting an Apollo landing site once on the moon.

"At X Prize, we believe that the spirit of competition brings about breakthroughs that once seemed unimaginable or impossible, and so it thrills us to now have two Google Lunar X Prize teams with verified launch contracts attempting missions to the moon in 2017," says Gonzales.

"The new space race is truly on!"