Humans on Europa: A Plan for Colonies on the Icy Moon
By Don Lipper
Special to SPACE.com
posted: 07:00 am ET
06 June 2001
Forewarned is forearmed in science fact and science fiction when it comes to Jupiter's icy moon Europa. Frigid and ice-covered, Europa is believed to harbor a giant liquid ocean beneath its crusty arctic surface, a primordial sea whose tidal motions are driven by Jovian gravity and warmed by intense radiation given off by the giant planet.
Yet despite the planet's fearsome environment, members of the Artemis Society, a private venture dedicated establishing a permanent, self-supporting community on the Moon, also have set their sites on the creation of a human colony at Europa.
The group has planned almost everything from how to build communities in subsurface air pockets, to how to program the colonist’s digital watches. Some folks at NASA are skeptical.
"Europa is right in the middle of an incredibly deadly radiation belt around Jupiter," said Jet Propulsion Laboratory’s Rich Terrile, deputy project scientist for the Europa Orbiter. "A fairly well shielded human being on the surface of Europa, and even in the vicinity of Europa, would die in about 10 minutes. It would be like standing 30 feet (9 meters) away from the unshielded core of a 10-gigawatt nuclear reactor. It’s just where you really don’t want to be."
Don’t think that the radiation-absorbing ice will protect any intrepid explorers either. According to Terrile, "if you get beneath maybe 6 feet (2 meters) of ice you’ll be okay. But you’ve got to get to the surface and every 10 minutes is a lethal dose so you don’t have very much time."
The Artemis plan looks straight at the radiation problem and blinks. "For the purposes of our mission, we assume that it takes place in an era in which the engineering challenges of providing electromagnetic shielding have been mastered," says Peter Kokh, the primary author of the Europa plan.
Hiding in accelerators and under ice
Any chance deflector shields could protect the explorers? According to JPL's Terrile, "building these shielded ships is like being inside a VanDeGraph accelerator but these things don't work. You have to build these very, very high-charge gradients around you in order to deflect particles and there's no practical way to do that."
But recently Kokh has dreamed up an inspiringly simple solution for the radiation problem. "Callisto is outside the radiation zone," he says. "If you could start with a staging base where you jacket the ship with ice from Callisto, you could have either humans or robots mine the ice. That way you wouldn't have to spend all that fuel to get that shielding from the Earth."
As for how to survive on Europa's surface, "you just have to get under the ice fairly quickly," he says. "That's just an engineering detail."
Gravity and magnetic data collected by the NASA Galileo orbiter over the past five years have provided increasing evidence that an ocean exists underneath Europa's uniform 5- to 62-mile (10- to 100-kilometer) thick coat of ice. The possible ocean on Europa may contain more liquid water than all the oceans on Earth combined.
Magnetic studies have indicated that there must be a conducting layer in Europa. A salty ocean would fit the bill. Researchers hope to discover whether Europa is made up entirely of mushy ice or if it contains an ocean. Where there is water, there may be life.
No business plan yet
The Artemis Society's main business is making manned exploration a business with models for a profit private Moon mining operation. But a manned Europa mission presents a sky-high obstacle for the even the most wild eyed financier.
"We can't present a business plan. Economic reasons to justify exploration of the outer solar system may emerge but we just can't see it now," says Peter Kokh, the primary author of the Europa plan.
Some ideas Kokh and the Artemis Society have created, like the International Space Station's Transhab module and an underslung lunar lander, have shown up years later in NASA plans.
"That's fine, imitation is the sincerest form of flattery," says Kokh. "I don't care if anything gets attributed to me or not. I'm 63. I probably won't be seeing much of this happen. All I care about is getting my ideas in people's heads."
But if an expedition were launched tomorrow? "I'd give my left arm to go," he says. "The only requirement is that I could bring one of my dogs along."
Manned mission preferred to robotic
While the plan’s authors rely on probes for preliminary landing information, "the manned mission is the dog that wags the robotic tail, and any brainstorming of robotic missions without consideration of the needs of follow-up manned efforts would be so much irrelevant ivory tower scientific curiosity scratching."
For living on the Europan surface, the Artemis plan proposes a simple modular inflatable hangar (pictured below) covered with shredded ice that is solidified into a "self-sustaining igloo arch" by microwaves. Once the ice form is established, the inflatable form can then be deflated and moved down to the next section creating a surface network of connected tunnels and buildings.
Getting through the ice crust and into the ocean is accomplished by using a vertical cabin cylinder with a heated drill head in its prow. Inside this 10-foot (3-meter) diameter vehicle, spherical rotating rooms would be stacked one atop the other for the descent and then rotate horizontally fore and aft in submarine mode once through the ice. The vehicle would unspool a communications cable as it descended to maintain constant contact with the surface even if the melted water or slush slurry in the shaft above refroze, seizing the cable. Once through the crust, the sub would attach an antenna to the end of the cable.
Then the sub would roam free through the Europan ocean while maintaining wireless communications with the surface. As for how the submarine crew would get back up to the surface, "we did not discuss means of ascent."
Colonizing air pockets
The most speculative feature of the plan centers on "air pockets" under the ice, either naturally occurring through ongoing volcanic outgassing or artificially created via electrolysis of the ice. The plan suggests establishing an outpost either floating on the surface of the ocean or anchored in the lagoon of any outcropping island. If a suitable pressure-temperature ratio can be formulated, colonists could stroll inside a pressurized dome in their shirtsleeves with temperatures in the "balmy 50s."
The plan envisions a new Europan civilization bubbling up in such air pockets. "Individual outposts could be named after classical harbors of old: New Syracuse, New Carthage, New Tyre, New Alexandria, New Atlantis and so on."
The Europan empire builders are sanguine about their chances of occupying such high-priced real estate. "Maybe there are no such places, and all we have done is provide science fiction writers with a new class of venues for their stories."
Still nailing down that ocean
Although most planetary scientists are comfortable with the idea of an ocean at Europa, its existence still remains unproven. So Massachusetts Institute of Technology researchers plan to use acoustics to explore the Arctic Ocean and apply that work to the question of a vast liquid ocean under the ice blanketing Europa.
MIT researchers will report this week at a Chicago meeting of the Acoustical Society of America that they may be able to use a technique similar to ultrasound, the sonar navigation used by bats and dolphins, to gather information about Europa.
MIT ocean engineer Nicholas C. Makris said that implanting soda-can-sized sensors in Europa's icy exterior could provide researchers with information on the temperature and structure of the planet. Current sensor technology makes it possible to detect even tiny motions, and there is evidence that massive ice fractures on Europa's surface occur daily.
While such an experiment may be a decade or more away, this unconventional approach to planetary exploration would have to begin to be developed now, Makris said. An array of geophones on the icy surface could simultaneously localize discrete events such as fractures and determine the moon's ice-layer thickness as well as the thickness of a potential ocean layer.
Using sound to 'see'
Europa's numerous fractures and ridges, shown in Galileo images taken in the past five years, are believed to have formed in response to tidal deformations generated by the moon's slightly eccentric 85-hour orbit around Jupiter.
Inspired by evidence for these regularly occurring ice fractures, the MIT researchers propose probing Europa's interior by deploying an array of surface microphones that listen to naturally occurring sound. Knowledge of ice mechanics suggests that these propagating fractures would generate significant acoustic energy in the frequency range 0.1-100 hertz (Hz).
Studying the ice sounds would allow researchers to see if there was a connection between the moon's orbital period and the ice fractures, which occur on Europa once every 30 seconds.
Starting in the Arctic
MIT researchers led by Makris have used sound-based techniques to explore the Arctic Ocean. By inserting vibration-sensitive hydrophones in the water, researchers used ambient sound to listen for changes in noise levels. They found that noise levels increased when winds and currents put stresses on the ice.
"Noise levels are like a thermometer for stress on the ice," Makris said. "The ice is very sensitive and conducive to sound." Sound waves made by large fractures go through the ice and penetrate into the ocean.
These low-frequency sound waves, akin to those created by whales, get trapped and can propagate hundreds of miles (kilometers) through the water. Even if they can't be heard, instruments can pick up their vibrations from a distance.