Jupiter’s moon Europa is often referred to as a “waterworld,” and for good reason: a global ocean almost definitely exists below its outer icy crust, making it a primary focus of interest in the search for life elsewhere in the solar system. So far, most of the information we have about this fascinating moon has come from flybys of the Galileo and Voyager spacecraft; these missions have been invaluable, of course, although limited. If we want to learn more about what is going on below in the Europan ocean, it will require new spacecraft with the necessary instruments to carry out long-term studies. Budgets are tight for an orbiter or lander, but a newly proposed “clipper” mission may just fit the bill.
The Europa Clipper, which could launch by 2021, would make repeated flybys of Europa after a six-year journey. It would carry a wide variety of instruments, such as ice-penetrating radar, a topographical imager, a magnetometer, an infrared spectrometer, a neutral mass spectrometer, and a high-gain antenna. It would also do reconnaissance for a possible subsequent future lander mission. During a nominal 2.3-year mission, it would make dozens of flybys of the moon, even as close as 15 miles (25 kilometres) from the surface. It would immensely increase our knowledge of both Europa’s surface and interior.
Previously, another proposed Europa mission, the Jupiter Europa Orbiter (JEO), was the leading favorite and more ambitious in scope. As well as Europa, it would also study another Jupiter moon, Io, the most volcanically active place known in the solar system. It was ranked by the Planetary Science Decadal Survey as the second-highest priority large-scale mission—behind only a Mars sample-return mission. The price tag, however, was deemed to be too high, at $4.7 billion. It would need to be scaled down somehow, and kept within a $2 billion price cap, while keeping as many of the scientific objectives as possible. Thus, the Europa Clipper concept was born.
The new mission proposal was presented to NASA last month, with a very favorable response. According to mission proponent David Senske from the Jet Propulsion Laboratory, “We briefed [NASA] headquarters on Monday, and they responded very positively.” It’s not a done deal yet, but the outlook is promising.
What’s clear though, is that some type of return mission to Europa should be a high priority for NASA. Europa’s underground ocean is thought to contain more water than all of Earth’s oceans combined. So if you want to look for possible life, this is the kind of place to go—as well as similar moons such as Saturn’s Enceladus, which not only (likely) has a subsurface ocean or sea, it spews out huge water vapour geysers on a regular basis, like oversized versions of Yellowstone.
These alien oceans are thought to be similar to the ice-covered seas in Antarctica, as an earthly analog. Despite the cold and lack of sunlight, they are teeming with life. Could the same be true for waterworlds like Europa? The only way to know is to go there and find out. …
A good overview of the various Europa mission concepts is also available here: Clipper