It's been a long time coming, but NASA's new mission to Jupiter's moon Europa now has a formal name: Europa Clipper. The spacecraft, to be launched in the early 2020s, will conduct multiple close flybys of the moon, with the goal of determining just how habitable it actually is. With a global salty ocean just beneath its icy crust, Europa is thought to be one of the best places in the Solar System to search for possible alien life.
Europa Clipper would make a close flyby of the moon every couple weeks, using all of its science instruments to study both Europa's icy surface and the ocean beneath. As planned, Europa Clipper would conduct 40 to 45 flybys, during which the spacecraft would image the surface at high resolution and investigate its composition as well as study the structure of the interior and icy shell. The spacecraft will fly close to Europa's surface, at altitudes varying from 1,700 miles to 16 miles (2,700 kilometers to 25 kilometers).
"During each orbit, the spacecraft spends only a short time within the challenging radiation environment near Europa. It speeds past, gathers a huge amount of science data, then sails on out of there," said Robert Pappalardo, Europa Clipper project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.
While the existence of the ocean has been known about for some time now thanks to other earlier missions such as Voyager and Galileo, the actual conditions in that ocean are still unknown. There is evidence that it is salty, like Earth's oceans with heat/energy sources and active chemistry. Whether or not Europa's waters contain any form of biology is still the big question. It seems that the ocean is likely habitable by earthly standards, but Europa Clipper will be able to further define that.
As noted by Kevin Hand of the Jet Propulsion Laboratory (JPL), “As far as we can tell, Europa has the water, the elements and the energy needed to create a habitable world. If the origin of life involves some relatively easy processes, then it just might be there on Europa.”
The name Europa Clipper comes from the old clipper ships that sailed across Earth's oceans in the 19th century. They were streamlined, three-masted sailing vessels renowned for their grace and swiftness, an analogy to how the spacecraft will make repeated, sweeping close flybys of Europa.
Europa Lander Concept
Last month, the mission moved into the design phase. The mission successfully completed its Key Decision Point-B review on Feb. 15, 2017, which permitted the mission to move forward into its preliminary design phase, known as "Phase B," on Feb. 27. Phase B includes preliminary design work, while phases C and D include final design, spacecraft fabrication, assembly, testing, and launch.
NASA is also studying a Europa lander concept, which would have a small probe actually land on Europa's icy surface. This would follow the Europa Clipper flyby mission a few years later. The lander would be able to more directly search for evidence of life, including in material deposited on the surface from the water below (or in the ice itself) or possibly in plumes of water vapor erupting through cracks in the surface. Such plumes have been tentatively seen in images taken by the Hubble Space Telescope, but have not been confirmed yet.
Such a life-detection mission would be the first by NASA since the Viking landings on Mars in the 1970s. In the case of Mars, efforts to detect microbial life directly were abandoned after the mixed results from the two Viking landers, so there is still an element of caution with a Europa lander.
“What Viking taught us is that you don’t just jump in and look for life,” said Curt Niebur, a program scientist on both the Europa lander and flyby missions. “You need a general understanding of the environment in which you’re looking, because it can complicate things.”
As also stated in the report itself, “This mission would significantly advance our understanding of Europa as an ocean world, even in the absence of any definitive signs of life.”
“No singular measurement would provide sufficient evidence for the detection of life on Europa. Rather, the conclusion that evidence of life had been detected would require multiple lines of evidence, from different instruments…”
Europa Clipper will be NASA's first mission dedicated to Europa, hopefully to be followed by a lander. Next decade we may finally get closer to answering the question of whether life does or has ever existed on this fascinating ocean world.
More information about Europa and the Europa Clipper mission is available here.