Here's why it says 'Don't Panic' on the dashboard of the car Elon Musk just shot toward Mars

SpaceX

The view of earth from Musk's roadster

• SpaceX has launched Falcon Heavy, the most powerful rocket the company has ever built.
• The rocket lifted off Tuesday from a historic Apollo-era launchpad at Kennedy Space Center in Florida, where Business Insider is on the ground.
• Musk put his Tesla Roadster on top as a test payload.
• The car is bound for Mars orbit.

SpaceX launched its Falcon Heavy rocket - the company's biggest yet - into space on Tuesday. It's carrying Elon Musk's own midnight-cherry red Tesla Roadster out to Mars orbit. 

Soon after the launch, Musk tweeted out a live feed of the car, and its driver - a dummy named Starman (after the David Bowie song) - with Earth in the background. It's not the only pop culture reference in this car. 

Right in the middle of the car, on the center screen, are the words "Don't Panic." It's a reference to "The Hitchhiker's Guide to the Galaxy," the 1979 book that was first in a series by Douglas Adams about an accidental space traveler named Arthur Dent. In the story, the Guide itself has the words "Don't Panic" on its cover.

Musk, who first read "The Hitchhiker's Guide" as a teenager, has said that he loves the book. In a 2015 interview he said the spaceship from the book was his favorite from science fiction. 

"I'd have to say [my favorite] would be the one in 'The Hitchhiker's Guide to the Galaxy' that's powered by the improbability drive," Musk said.

Watch the livestream of Starman and the roadster here: