What Is William Shatner Doing in a NASA Promo About 'Seven Minutes of Terror'?

NASA's most ambitious and expensive Mars mission yet depends on the safe arrival of the Curiosity rover on the red planet late Sunday.

It won't be easy. The complicated touchdown NASA designed for the Curiosity rover is so risky it's been described as "seven minutes of terror" - the time it takes to go from 13,000 mph to a complete stop.

(Related: Are You Curious About the New $2.5 Billion Mars Rover Set to Launch This Weekend)

Scientists and engineers will be waiting anxiously 154 million miles away as the spacecraft plunges through Mars' thin atmosphere, and in a new twist, attempts to slowly lower the rover to the bottom of a crater with cables.

If it succeeds, a video camera aboard the rover will have captured the most dramatic minutes for the first filming of a landing on another planet.

In the mean time though, NASA has called upon those familiar with spacecraft -- at least the Hollywood kind -- to narrate how the landing should go. William Shatner and Will Wheaton, both of whom appeared on Star Trek, talk about Curiosity in this NASA videos.

Watch Shatner's promotion video:

Here is Wheaton's:

Curiosity was launched in November and has been making its way to Mars ever since. The project cost has cost $2.5 billion thus far.

During its two-year exploration, the plutonium-powered Curiosity will climb the lower mountain flanks to probe the deposits. As sophisticated as the rover is, it cannot search for life. Instead, it carries a toolbox including a power drill, rock-zapping laser and mobile chemistry lab to sniff for organic compounds, considered the chemical building blocks of life. It also has cameras to take panoramic photos.

The Associated Press contributed to this report.

(H/T: Popular Science)