Why Nasa’s Europa mission has people excited
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Version 0 of 1. Europa is a tantalising place orbiting the giant planet of Jupiter. Extraordinary images from the twin Voyager spacecraft in 1979 showed that Europa’s surface was cracked in places, with what looked like ice floes in others. This sparked the possibility that beneath that icy crust could be an ocean. Magnetic field data and further investigation by the Galileo spacecraft in the 1990s seemed to confirm this. And where there is water on Earth, there is life. Could the same be true at Europa? On Tuesday, the White House presented Congress with a request to give Nasa enough money to fund a concerted planning phase for a mission to go to Europa. The American space agency has been quietly working on concepts for a Europa mission for the last 15 years. It received a big funding boost specifically for a Europa mission planning last year but this new money is being seen as a real commitment. The mission concept that Nasa will develop is called the Europa Clipper. It will not orbit the icy moon. Instead it will orbit Jupiter and make a series of 45 flybys. In this sense it is similar to Nasa’s Cassini mission which is repeatedly flying past Saturn’s large moon Titan. The reason for this is that the radiation field near Europa is intense and would play havoc with a permanently stationed spacecraft’s electronics. Flybys mean the spacecraft can zip in and out. Despite some of the headlines about the mission, Europa Clipper will not be looking for life. To do that it would have to land, penetrate the ice and sample the water in the ocean. This is technologically too demanding at present. Instead, the mission’s website says: it would investigate whether the icy moon could harbor conditions suitable for life. In practice this mean probing the sub-surface ocean with radar, and analysing the chemical composition of the surface ice with onboard instruments. At present, Nasa is receiving hundreds of millions of dollars to make their plans. To fully fund the mission would require around $2bn (£1.3bn). If the mission stays the course – and Nasa does have a habit of cancelling them – it would most likely launch in the mid-2020s. By that time, Esa should already be on its way with its own mission. Aimed to launch in 2022, the Jupiter Icy Moons Explorer (Juice) was chosen by Esa in 2012. According to its website: The mission will tour the giant planet to explore its atmosphere, magnetosphere and tenuous set of rings and will characterise the icy moons Ganymede, Europa and Callisto. Detailed investigations of Ganymede will be performed when JUICE enters into orbit around it – the first time any icy moon has been orbited by a spacecraft. During its lifetime, the mission will give us an unrivalled and in-depth understanding of the Jovian system and of these moons. Clearly Europa is on this list and that could be good or bad for Nasa’s slightly later mission. Either Juice can be used as a fore-runner to hone the Europa Clipper’s objectives, or it can be seen as a rival. Nasa is already funding instruments on Juice. Let us hope that a spirit of cooperation between the agencies and scientists prevails. Working together, Juice and Europa Clipper could be spectacular planetary missions. Stuart Clark is the author of The Sky’s Dark Labyrinth (Polygon). |