While NASA continues to revel in the victory of being offered $18.5 billion by the Obama administration to oversee space travels and technologies, its scientists at the Jet Propulsion Laboratory in Pasadena, CA, are gearing up to put finishing touches to the design of a robotic mission concept to Europa scheduled to be launched mid-2020s.
The europa is the fourth largest satellite of Jupiter, and it is covered with a smooth shell of frozen water. NASA chief financial officer David Radzanowski said the US space agency is requesting $30 million for preliminary studies into a mission to Europa for the year that begins Oct. 1. This is in addition to the $100 million Congress added to NASA’s budget to begin design work for a Europa mission last year.
The agency has been exploring Europa mission concepts for close to 15 years, considering the fact that many mission concepts are always inappropriate in size and cost, JPL senior research scientist Robert Pappalardo says, “we believe we have now found the one that is just right. We call this concept the Europa Clipper,” he said.
The Clipper concept will consist of a Jupiter-orbiting spacecraft that will make multiple flybys of the Jovian moon Europa over a 3-year period. The spacecraft will dive deep into Jupiter’s radiation belts to fly over Europa’s surface approximately 45 times during its primary mission.
NASA’s Cassini spacecraft, which is currently orbiting Saturn, has carried out similar flybys of moon Titan, constructing a comprehensive map of its surface and measuring the moon’s thick atmosphere. The Europa Clipper will be focused on Europa in an effort to understand its habitable potential.
It is believed that there is a vast sub-surface body of ocean beneath the thick icy crust of Europa – and this is possibly kept liquid by the tidal interactions with gases. It is thought that this ocean of water might be three times the volume of water on Earth; and since water means organic life, astrobiologists hypothesize that there might be signs of life in Europa’s waters.
“Europa’s ocean, to the best of our knowledge, isn’t that harsh of an environment,” said astrobiologist Kevin Hand, JPL’s Deputy Chief Scientist for Solar System Exploration, at a special JPL “Icy Worlds” media event on Monday.
While it is hypothesized that the depth of Europa’s ocean might be up to 100 km or 62 meters deep, the deepest part of the Pacific Ocean – the Mariana Trench, is only 11 km or 6.8 miles deep. And since some form of life has evolved in the cold, dark recesses of Mariana’s Trench where the sun cannot permeate, it is believed that some form of life might develop also in the depths of Europa’s ocean given the chemosynthesis that could occur from thermal vents.
Europa’s deep ocean owes its potential habitability to the moon’s size. It’s only the size and approximate mass of Earth’s moon and therefore has comparable gravity, ensuring ocean pressures are not too extreme for biology to evolve. It’s possible that, through the constant tidal heating of Europa’s core, the moon will also have hydrothermal vents spewing the heat and chemicals needed for Europan life.
“The radiation is stopped in the upper 10′s of centimeters to a meter” of icy crust, said Pappalardo, who is principal investigator for the Europa Clipper concept.
And while Europa is concluded to have liquid water, a heat source, and possible of recycling nutrients, JPL scientists note that they are not going to search for life with the proposed mission to the space body.
“The way we framed the Europa mission science objectives is not to specifically look for life, but to understand habitability; the ingredients for life,” said Hand. To search for life, argues Hand, a surface mission would be required, a technological feat that is currently out of our scope.