There is an interesting piece of news from the space exploration and planetary science community today (actually it was yesterday, but the news came out today), with the launch of the JUICE mission. This is a planetary probe that will spend the next eight years traveling through space to the planet Jupiter, where it will then explore three of the ice moons there before settling into a long term orbit of Ganymede. Although JUICE is not equipped with life detecting experiments, these three moons are among the best hope of finding alien life in our own Solar system and thus this is perhaps one of the most interesting missions in many years.

This mission is part of the European Space Agency's ongoing work to explore the planets of our Solar system. The JUICE spacecraft was launched with an Ariane 5 rocket from Europe's Spaceport in Kourou, French Guiana, one day later than originally planned due to bad weather conditions. (Even astronomers with multibillion dollar budgets have to deal with bad weather conditions!)

After its eight year long journey, it will be exploring the three Jovian moons, Callisto, Europa, and especially Ganymede. These moons are comparable in size to the Earth (they are actually slightly smaller, but relative to Jupiter they are comparable), but the most interesting detail is that they quite likely contain liquid water oceans. They are each covered in a thick crust of ice, but previous observations combined with theoretical models strongly suggest that each has some mechanism of internal heating that is causing deep oceans to form and remain fluid in the region between the (presumed) solid core and the icy crust above.

And this is of particular interest to astronomers and to scientists in general, because on our own planet it was the large oceans that caused life to first form. Even in our present era, most of the life on Earth exists within some form of liquid water, or relies on liquid water for its continued existence. Therefore finding large bodies of liquid water on a moon that has properties comparable to the Earth would be a major step towards understanding the basic elements needed to form life. And of course, the proverbial holy grail of space exploration, any of these three icy moons could eventually be found to actually contain some form of extraterrestrial life!

Unfortunately those studies are still well into the future. At present we do not have the technology necessary to send JUICE directly to Jupiter, and so it must take a very long route to get there. Next year it will be allowed to enter an unstable orbit around the Earth and the moon, which will 'slingshot' it towards Venus. About a year later it will swing around Venus and accelerate towards the Earth again, where it will be accelerated again in 2026 and 2029. Each of these steps is necessary to accelerate the probe to the high speed necessary to make its final two year journey to Jupiter, where it will arrive in the year 2031.

As JUICE approaches Jupiter, it will spend approximately six months using ten of its sensors to take photographs and collect data on the Jovian system, before performing a closer study of Jupiter for several months. Once that stage is completed, it will be moved into orbit around Europa, while also performing fly-by missions of Callisto. Approximately three years later it will then enter its final orbit around Ganymede, where it will remain for as long as the probe remains viable.

At this point it seems like a long way into the future, but in twelve years we should have some amazing new images and data on Jupiter itself and on three of its most interesting moons. It will also be the first time in history that mankind has placed a probe into orbit around a moon of another planet. And perhaps it will also be the first indications of a world that is habitable and capable of supporting complex life such as our own.

And the mission starts today!