If there's one place in the solar system where we’re likely to find extraterrestrial life, it’s Europa. The Jovian moon is covered in ice, almost certainly has liquid water oceans underneath, and tidal forces from Jupiter drive geologic activity to keep everything warm.
Considering that finding aliens (even if they’re just microbes) would be (or will be) one of the most profound discoveries that anyone has ever made, ever, it’s a little weird that we’ve managed to send a few dozen spacecraft to Mars, and not a single one to Europa. NASA has had Europa missions scrapped over and over by budget cuts, but it now looks as though the agency will be putting a “Europa Clipper” mission together starting later this year. NASA won’t be incorporating a lander into the Clipper, but they've asked the European Space Agency if they’re interested in sending one along for the ride.We could be looking at the very first Europa landing attempt.
NASA’s Europa Clipper would launch in the early 2020s and head straight for Jupiter, spending about eight years in transit. On arrival, rather than try to orbit Europa, the Clipper would loop into a fancy orbit around Jupiter that it would swing it past Europa as many as 45 times, giving us an excellent look at the moon (from altitudes as low as 25 kilometers) over the course of several years, or until Jupiter's radiation fries the Clipper to a crisp.
Since NASA doesn’t have the budget for the fancy life-detecting robotic lander/submarine that we all want, they've asked ESA if the agency wants to send its lander along for the ride. NASA might be a little wary of sending a lander if they're fans of Arthur C. Clarke (and I’m sure they are), but besides budgetary constraints, ESA also already has some experience dropping probes onto the moons of gas giants.
Ten years ago, ESA’s Cassini spacecraft launched a small probe called Huygens toward Titan, one of the moons of Saturn. Even though Huygens wasn’t really intended to be a lander, but more of an atmospheric probe, it managed to survive entry into Titan’s atmosphere, descent, and a touchdown on the surface, where it continued to send back data for an hour and a half, despite an expected design life of just a few minutes.
Specifically, NASA has asked ESA to consider a surface lander or even a surface penetrator for the Europa mission. For its part, ESA seems open to the idea, especially since they’re already planning to launch their own JUpiter ICy moons Explorer (JUICE) mission to study Europa, Ganymede, and Callisto in 2022.
The next step is for ESA to decide whether it wants to be involved in the Clipper mission, and if so, what exactly its involvement will consist of. NASA expects to make some sort of announcement regarding the science payload of the Europa Clipper within the next few weeks, and final instrument selection will (hopefully) happen by next year.
Evan Ackerman is a senior editor at IEEE Spectrum. Since 2007, he has written over 6,000 articles on robotics and technology. He has a degree in Martian geology and is excellent at playing bagpipes.