In the recent past, much of the search for extraterrestrial life has been focused on Mars. Mars is not the only possible candidate for life in our solar system, and some scientists believe it might not even be the most likely. Although the other planets seem hostile to life as we know it, their moons are a different story. One moon in particular has garnered much attention from scientists in recent months.
In early March, NASA announced its plans for an upcoming mission to Europa, an icy member of Jupiter’s small moon army. Besides Earth, Europa may be the only place in our solar system with access to the three basic ingredients of life as we know it: water, organic compounds, and an energy source. Covered by a layer of ice kilometers thick, this moon is believed to house a massive subterranean ocean beneath its icy mantle. On the surface of its frozen exterior, clay minerals have been discovered, likely delivered by comets or asteroids. These extraterrestrial rocks often contain organic materials like amino acids as well. To complete the trio, the underground ocean is likely kept in liquid form by tidal forces, which could lead to volcanic activity and the exciting possibility of hydrothermal vents, or “black smokers,” in the deep sea.
“We may have black smokers like we do on Earth,” Richard Leveille, a planetary scientist at the Canadian Space Agency and a visiting scholar at McGill, told The Daily. Far from the reach of sunlight, black smokers, or deep-sea vents, line the ocean floor, erupting heated water laced with dissolved chemicals. On Earth, they’re teeming with primordial organisms that derive energy from the reactive chemicals the vents release. Some scientists even believe that life could have originated in these deep-sea vents; however, it is speculation that they exist on Europa. In their absence, there are other possible energy sources available, including accelerated particles from Jupiter’s magnetic field, and of course, the Sun.
The idea of life existing in such an extreme, icy environment may seem like something out of science fiction, but such cryophiles, or ice-loving organisms, aren’t limited to fantasy. They can be observed here on Earth. Jay Nadeau, a professor in McGill’s biomedical engineering department, will soon be studying bacteria that swim beneath sea ice, an environment most would believe to be inhospitable to life – but one that likely mimics conditions on Europa.
Complex life has been observed thriving under these thick sheets of ice as well. Earlier this year, a new species of sea anemone was discovered within Antarctica’s Ross Ice Shelf, clung onto the ice with its tentacles extending into the freezing waters below. Worms, crustaceans, and fish that swim upside down have also been found living in these extreme environments. The existence of such cryophilic organisms lends hope to scientists for the upcoming mission to Europa.
Currently, the details of the mission itself are unknown. One idea that is generating much hype among scientists is the Europa Clipper, a spacecraft that would enter in to Jupiter’s orbit and make multiple flybys of Europa, studying its icy surface and the possible ocean beneath. Given the radiation surrounding Jupiter and its distance from Earth, the craft would have to be well-shielded and would likely take six years to arrive. If launched according to schedule, in the early 2020s, then it would reach Jupiter around 2030.
Although scientists are eager to sample this icy moon, it’s unlikely to occur on this mission. The Clipper will mainly function as a scout for a future landing party. Yet, recent observations suggest that a craft wouldn’t even have to land to take a sample of Europa’s makeup.
Late last year, scientists observed plumes of water 200 kilometers high erupting from Europa’s southern pole as the moon reached its furthest point of orbit from Jupiter. A spacecraft could easily fly through these geysers and collect samples of water without even having to land; however, this method, while simple and cost-effective, may be limiting, says Leveille. “You’d get a snapshot of what’s going on underneath, but it wouldn’t be the same as drilling into the ice and having a submarine swim around there.” We’re probably still a few decades off from such a project, but perhaps we’ll have a camera beneath the ice within our lifetimes.