This story was updated on August 16 to reflect a change in the time line for winning the grand prize and the addition of "milestone" prizes.

For five teams racing to reach the moon, it’s March 2018 or bust.

In January, X Prize and Google announced that just five of 33 initial teams have secured an elusive—yet essential—launch contract, which means they have rides on rockets that will send them toward the moon, and so they are able to vie for the coveted Google Lunar XPRIZE.

Now, it’s down to a literal photo finish between Moon Express, SpaceIL, Team Indus, Synergy Moon, and Hakuto.

To win the prize, one of these five finalists must successfully complete its mission to the moon by March 31, 2018. To reach completion, a moon rover needs to land, explore 1,640 feet of terrain, and beam images back to Earth, or at least $20 million in prize money could disappear like a villain’s dreams of gold.

The runner-up will snare $5 million, with an additional $5 million set aside for notable achievements, such as traveling more than three miles on the surface, finding evidence for liquid water, or enduring the harsh lunar night. Teams can also win up to $4.75 million in "milestone" prizes for orbiting the moon, entering a descent trajectory, and proving that its robot landed softly on the surface, as opposed to crashing.

It’s the type of competition that’s meant to inspire daring innovations among non-governmental entities. In 2004, a reusable spaceship capable of carrying passengers into microgravity won a similar X Prize. Called SpaceShipOne, it formed the foundation of Virgin Galactic’s suborbital spaceflight endeavor.

The Lunar X Prize is backed by Google, and with each of the five finalists now officially holding a one-way ticket to space, the race is on. So load those spacecraft into the starting gates, fire up those engines, and let’s get this show on the road.

View Images SpaceIL of Israel will launch a hopper-style spacecraft to the moon in its Lunar X Prize attempt. Illustration courtesy Google Lunar XPrize

SpaceIL (Israel)

SpaceIL secured its ticket to space in October 2015, and it’s planning on hitching a ride aboard one of SpaceX’s Falcon 9 rockets, which returned to flight on January 14. The SpaceIL craft, which is funded by a U.S. casino mogul, will be “small and smart,” capable of landing in one spot and hopping to a second site 1,640 feet away.

Moon Express (United States)

Based in Florida, Moon Express was the second company to be awarded a launch contract. If all goes well, a startup called Rocket Labs will send the Moon Express spacecraft to the moon later this year. Whether it wins or not, Moon Express intends to continue developing the ability to mine the moon for rare metals and other resources that could be useful here on Earth.

Team Indus (India)

Team Indus is shooting for the moon with a little help from the country’s Indian Space Research Organization, which successfully sent a spacecraft into orbit around Mars in 2014. It’s not yet entirely clear what the Team Indus rover will do once it gets to the moon, but rumors suggest that various teams are competing for space on the robot, which could do something as exotic and essential as making beer on the lunar surface.

Hakuto (Japan)

This team’s dual spacecraft will likely be sharing a ride on the Team Indus rocket. Ideally, their two-wheeled rover, called Tetris, will be tethered to a four-wheeled rover named Moonraker, and together the pair will explore one of the openings into lava tubes tucked beneath the moon’s dusty face.

Synergy Moon (International)