While Curiosity is definitely loaded up with some of the most high-tech instruments ever made to investigate the surface of Mars, it also carries one very low-tech instrument: a sundial, which can be used to determine the position of the Sun in the sky and the season on Mars — just like they do here on Earth. Curiosity’s sundial also has a message inscribed upon it, a message that likely won’t be read by anyone for a very long time — just how long is entirely up to us.

What is it? Find out here.