Padawanbater2
Well-Known Member
"What's going on here? Well for a long time Callisto was thought to be geologically dead as it is the most heavily cratered world in the solar system;
However, NASA's Galileo spacecraft in 2001 revealed mountains with caps of frost , as well as giant ice spires 80-100 metres high (330 feet)!
The Galileo spacecraft was intentionally sent on a collision course with Jupiter in 2003 so it wouldn't crash and contaminate any of the planet's moons, some of which might have life- Callisto, along with Europa and Ganymede, have underground liquid water oceans. So we haven't had any opportunity to see these spires again, and so we don't understand much about these spires. However we can guess their formation is almost certainly related to Callisto's atmosphere (yes, atmosphere, despite being thin its atmosphere is the third thickest of all the moons in the solar system) and sublimation of ice.
The next opportunity to study them again will be 2030, when ESA's JUICE spacecraft will do repeated flybys of Europa and Callisto and settle into orbit around Ganymede in 2033. However maybe we can convince the scientists on NASA's Europa mission to do at least one Callisto flyby when it arrives at Jupiter ~2025.
Statue of Liberty and Boeing 777 for scale"
