A SpaceX "Starman" is aboard the company's new rocket that's set to make its launch debut from Florida.
SpaceX chief executive Elon Musk revealed pictures of the surprise dummy passenger today.
Test flights usually carry steel or concrete for cargo, or mundane experiments — nothing valuable in case the rocket blows up.
But aboard the Falcon Heavy for Tuesday's demo is Musk's red Tesla Roadster. A figure is in the driver's seat, with the right hand on the wheel and the left arm resting on the convertible's door.
Starman, as Musk calls the passenger, is wearing a white-and-black-trimmed spacesuit and helmet. It's the same outfit real astronauts will wear when riding SpaceX rockets from Florida a year or so from now, bound for the International Space Station.
Musk, who also runs the electric car company Tesla, is sending his Roadster into a long solar orbit stretching out to Mars.
Last week, the Federal Aviation Administration officially licensed the flight from Kennedy Space Centre. The Falcon Heavy, at liftoff, will be the world's most powerful rocket currently in operation.
A David Bowie fan, Musk has promised via Twitter to have the car soundtrack playing Space Oddity. Starman is the title of a Bowie song from 1972. That's three years after the late rocker penned Ground Control to Major Tom for Space Oddity.
"There's a Starman waiting in the sky," goes Bowie's Starman.
If the flight succeeds, Musk's Starman should cruise around the sun for a billion years.