It's a big time at NASA. Scientific probes are sailing through our solar system, gathering legions of data and amazing photographs. Rovers are crawling all over intriguing extraterrestrial bodies, boring little holes into their surfaces and gathering samples.
When we bring humans to Mars, what sort of flag will we plant in the dirt? The question has relevance for many reasons. First, it will likely be a multinational mission -- unlike the American-led Apollo moon missions of the 1960s
Will we just point the ship towards any star and commit these resources to a random journey and outcome, or will we know a LOT about where we are going before the fuel is loaded? Most of us will agree that the latter case for such an expensive "one off" mission is more likely.
Listen up folks: it's time to stop screwing around and find out what's happening on Jupiter's moon Europa -- right now. Seriously, we managed to land a robot on a comet late last year... so what's the hold up? Let's go! Everybody in the van!
Navigation requires a reference frame. We need reference frames to tell us where we are with respect to other objects and we need reference frames to tell us how we are oriented with respect to other objects. There is no single universal frame that is used for all operations.
Imagine looking up and seeing a ring of little pearls in the sky that are human habitats, or knowing there are trees growing on the Moon and the first human babies are being born on Mars who will call it their Home.