Europa Clipper: NASA Investigates an Icy Ocean

Europa, one of Jupiter’s four biggest moons, appears to harbor a liquid ocean not far beneath its bright, icy surface. Is there life there? NASA plans to fly the Europa Clipper spacecraft to orbit Jupiter and, making frequent flybys of Europa, will study the satellite’s geology, composition, and subsurface ocean. Europa Clipper launched last October 14th, and will reach Jupiter in April of 2030. Learn about the mission, its scientific objectives, and the suite of sophisticated instruments it will employ in the decade to come.

Why is NASA going to Europa? While Europa is about the same size as Earth’s moon, the images from the Galileo spacecraft revealed a world that looks very different. The surface is covered, not with craters, but with long, linear features – cracks, and ridges, that can expand for thousands of kilometers across the surface. There are also disrupted areas of the surface, called chaos terrain, that look a little bit like icebergs. These are locations where pieces of the crust have been broken apart, rotated, and titled, and then froze into new positions. These features together, plus other evidence, leads us to believe that there is a large, global subsurface ocean on Europa. We know, from gravity and magnetic field measurements, there is a layer on the surface that is about 100 KM thick made up of solid ice and salty water. Below this, we know there is a rock mantle and a metallic core like on the Earth. We believe that Europa’s subsurface ocean layer has more water than all the Earth’s oceans combined. In the case of Europa, however, with a giant ocean of liquid water currently existing, this could presently support life. The subsurface ocean is possible due to Europa’s orbit around Jupiter. As Europa orbits around Jupiter, its distance around Jupiter varies over the course of its 3.5 day orbit. When Europa is closer to Jupiter, Jupiter’s strong gravity tugs on the surface and stretches it taller, creating a tidal bulge. When Europa is a bit further away, the gravitational pull is less, and this bulge goes down. It is this stretching and pulling that results in frictional heating. Scientists believe there is enough tidal heating to keep an ocean of water liquid beneath Europa’s surface over the age of the solar system. Join us in the New Year for our General Meeting presentation. Our presenter, Bill Higgins is a physicist and volunteer in NASA’s Solar System Ambassadors program. Bill has been a member of the Naperville Astronomical Association since 1989.