Elon Musk is always one for a nice surprise.

Just after SpaceX launched the first flight of its Falcon Heavy rocket on Tuesday, lofting a red Tesla Roadster to deep space, Musk revealed a little secret hidden within the cosmic car.

Musk posted a photo on Instagram displaying a message for any space-faring civilization that may come across the car in the future. The words "made on Earth by humans" are printed on the Tesla's circuit board.

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The Tesla also comes equipped with a dashboard message reading "don't panic," and a dummy driver named "Starman" who will fly through the solar system in the Tesla for millions, if not billions, of years to come.

This is far from the first time humans have sent a signpost of our existence out into the universe.

NASA's two Voyager spacecraft are each carrying a Golden Record, which includes the sounds of Earth as well as a map that explains where we are in space.

Basically, Starman is in good company.

The Falcon Heavy — SpaceX's most powerful rocket ever — took flight at 3:45 p.m. ET from Kennedy Space Center.

The huge rocket is basically three Falcon 9 rockets strapped together and can bring heavy payloads to distant parts of space like the moon or Mars.

The key to the Falcon Heavy's success will be its reusability. SpaceX hopes to bring back the rocket's three first-stage boosters to Earth after launch, meaning they can use them again for later flights.

The two side boosters made it back to the landing zones at Kennedy, but SpaceX has yet to reveal the fate of the third booster, which was expected to land on a drone ship in the Atlantic Ocean.