It may even be possible, using measurements collected by NASA’s upcoming Europa Clipper mission, to determine with precision how fast the ice cap must be rotating. When scientists compare images collected by the Europa Clipper with those previously captured by NASA’s Galileo and Voyager missions, they will be able to examine the location of ice surface features and potentially determine whether the position of the moon’s ice cap has changed over time.
For decades, planetary scientists have debated whether Europa’s icy shell might be rotating faster than its deep interior. But instead of tying it to the movement of the ocean, the researchers focused on an outside force: Jupiter. They theorized that as the gas giant’s gravity pulls on Europa, it also pulls on the moon’s shell, causing it to spin a little faster.
“For me, it was completely unexpected that what happens in the circulation of the ocean could be enough to affect the icy shell. It was a huge surprise,” said co-author and Europa Clipper Project Scientist Robert Pappalardo of JPL. “And the idea that the cracks and ridges we see on Europa’s surface could be tied to the circulation of the ocean below—geologists don’t usually think, ‘Maybe it’s the ocean that’s doing it.'”
Europa Clipper, now in its assembly, testing and launch operations phase at JPL, is set to launch in 2024. The spacecraft will begin orbiting Jupiter in 2030 and will use its suite of sophisticated instruments to collect scientific data, while it flies past the moon about 50 times. The mission aims to determine whether Europa, with its deep interior ocean, has conditions that could be suitable for life.