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| An image of Europa taken by Galileo in the late 1990's. The brown streaks suggest the presence of a sub-surface ocean because contaminant (claimed to include sea salt) have mixed with the icy surface to create the "dirty ice." http://cseligman.com/text/moons/europa.htm |
The Galileo mission piqued scientists’ curiosity about this moon, and a mission to Europa is expected to launch in the 2020’s. This mission, the Europa Clipper, will perform 45 flybys at various altitudes, from 1700 miles to 16 miles above the surface. Its goal is to take high-resolution pictures of the surface to determine its composition, and use an ice-penetrating radar to search for sub-surface waters. A thermal emission imaging system will survey the surface in search of any recent eruptions of warmer water, and other instruments will search for evidence of water and tiny particles in the moon’s atmosphere. This flyby approach will obviate the need to drill through layers of ice to find possible signs of life.
Why is drilling currently not an ideal approach? It is not definite that there is an ocean below the surface. It is possible that drilling before fully understanding Europa will be a waste of time, resources, and money. Also, the surface of the moon is exposed to extreme radiation from Jupiter’s radiation belts. A drilling machine or spacecraft will need a vast amount of radiation protection, which will make the craft heavy and thus expensive to transport. The flyby approach will decrease the amount of protection needed because the Europa Clipper will only be close to Jupiter during a small portion of its orbit.
On the other hand, if the Europa Clipper discovers strong evidence that suggests Europa has a sub-surface ocean that may be habitable for people or other lifeforms, a drill will be necessary to reach the habitable area. The amount of radiation on the surface is enough to cause severe illness or death after a single day’s exposure, but the thick, icy crust is thought to be able to shield the ocean from the radiation on the surface. While the Europa Clipper is not designed to search for life, a future mission would need to be designed to determine if Europa is already inhabited. It is uncertain now whether Europa is suitable to house life, but the Europa Clipper mission hopes to reveal if the ability is present.
