Plans are afoot to explore one of the biggest moons in our solar system, and one of the best places to seek extra-Earth life.
“ALL THESE WORLDS ARE YOURS — EXCEPT EUROPA. ATTEMPT NO LANDINGS THERE.” So read the ominous message from the monolith aliens in Arthur C. Clarke’s “2010: Odyssey Two.” Humans were ordered to stay away from Europa so we wouldn’t interfere with the aquatic life evolving deep beneath the thick ice sheet covering Jupiter’s sixth moon.
While Europa was discovered in 1610 by Galileo, the satellite has become a focal point among scientists in the last few decades, with some speculating that Jupiter’s tidal forces could be heating the moon internally, providing a warm undersea environment hospitable to life. These hypotheses have been bolstered by flyby data from the Galileo and Voyager spacecraft, making Europa one of the leading candidates for finding extraterrestrial life in the solar system.While Europa may, for these reasons, seem an obvious choice for sending surface landers and other kinds of probes, it poses more technical obstacles than a big rock like Mars or even other interesting moons like Saturn’s Titan. The problem is that Europa is covered with an ice sheet, and no one knows exactly how thick it is. Current estimates range from a few hundred feet to 20 miles, with most geologists opting toward the latter. It might be impossible for a lander to dig that far, but fortunately there may also be cracks and fissures where water actually reaches the surface. We could learn a great deal even if we can’t reach the subsurface ocean — if it exists.
The European Space Agency has a mission planned for 2022 called the Jupiter Icy Moon Explorer (JUICE), which should enter the Jovian system sometime in 2030. It’s not a lander, nor is it specific to Europa, but it is intended to image the moons Ganymede and Callisto as well. It’s an exciting mission and we will undoubtedly learn a great deal. But with decade long construction times and six to eight years of travel time, we should be sending several probes at once, based on the best information we have now. Landing on Europa should be a priority.
Such a mission is in the planning stages at NASA, though it hasn’t been funded yet. The mission would call for two identical landers, each weighing about 800 pounds. Both robots would use a mass spectrometer, seismometers and several specialized cameras to study Europa’s icy crust. The mass spectrometer would be able to detect organic chemicals if they exist, while the cameras and seismometers would gather data on the moon’s geology. The mission would give valuable data on Europa’s ability to support life along with information regarding the thickness of its ice sheet, which will be critical for designing a lander capable of tunneling. The soonest this mission could be launched is 2020, with a six-year travel time.
With such long lead times and inevitable funding issues, it looks like we won’t know if life exists on Europa for another few decades.
If Europans are there, they’ve probably been there for countless eons, so another 30 years won’t matter. They’ll still be waiting for us, below the ice.