Sunday, February 06, 2011
BBC has a great page here on three proposed ways to spend about a billion euros on upcoming space missions, and the article asks the reader which of the three would be best. The answer to me is quite obvious. The three are:
1) a 20-metre telescope that will be able to see the edge of black holes
2) a trio of satellites that will be able to see ripples in space-time left by the moment of creation itself
3) two satellites (one built by NASA) that would go to Ganymede and Europa
#3 is the obvious choice. Numbers 1 and 2 would be great to have if the budget were three times the size, but neither of them appeal to people that are not already intensely interested in space. Nor do they tell us anything about the locations closest to us in our own solar system. The Ganymede/Europa mission also has a particular importance in understanding planetary moons around gas giants, which we desperately need to know more about as by the time the mission is launched it is very likely that we will know about moons orbiting gas giants in the habitable zones of other stars and the more we know about our own the more we can guess at the conditions there.
Europa and Ganymede have been seen close up before:
but in order to truly understand them we need to view them over long periods of time and in a predictable manner. Flybys are by nature quite random events - the distance from the moon can be controlled to a certain extent but the timing of the flyby cannot, and there's no guarantee that a portion of a moon photographed last time will be visible the next time around. In order to understand the oceans underneath them we need to be able to view the entire surface over and over again.
The pdf explaining the join mission can be seen here. Unfortunately the European side of the mission would be using solar power instead of nuclear, but besides that it is ideal.
Edit: reading the pdf, getting to Jupiter via a Venus (and Earth twice) flyby is another plus. Galileo went to Jupiter in the same way, and also took six years (1989 to 1995). At the time of launch it felt like Galileo would never get there.
Edit 2: even better news, the orbiter will also spend some time (a bit over a year) in between orbiting Jupiter and transferring to Ganymede in a pseudo-orbit around Callisto. Io will be given some attention too but Callisto is especially important in that it is the only Galilean moon that humans could inhabit. The others are far too irradiated for humans to survive.