Signs of ammonia on Pluto’s surface may hint at liquid water underground. (Credit: NASA/JHUAPL/SWRI)

The New Horizons spacecraft, which flew past Pluto in 2015, is still making new findings. Most recently, researchers used its data to find traces of ammonia on Pluto’s surface. Intriguingly, the ammonia lines up with a cracked region called Virgil Fossae, which has mounds of water ice and shows signs of past tectonic activity. Because ammonia is eventually destroyed in environments like Pluto