Happy Lonely Birthday, Curiosity

The Curiosity rover turns 4 years old Friday on Mars. With no one else around, it has to sing "Happy Birthday" to itself.

Happy Lonely Birthday, Curiosity

Curiosity landed on Mars on Aug. 5, 2012. It's now four years old.

So it's singing "Happy Birthday" to itself, using tools designed to analyze samples of Mars' dirt.

SEE MORE: How NASA Brings Parts Of The Universe Home

There won't be a Martian birthday party. The current population of Mars is just two — robots.

Curiosity's nearest friend is Opportunity. It's on the other side of the planet.

This video includes clips and images from NASA.