Color me pedantic, but... (Score 2, Interesting)

We'll need to find innovative new ways of shielding spacecraft from fraction-of-lightspeed interstellar rubbish if we're ever to spend much time outside our own magnetosphere...

I think you meant LARGE fraction of lightspeed interstellar rubbish. The spitballs my cubicle mate hurls at me are fraction-of-lightspeed rubbish. A very small fraction of lightspeed. Shielding requirements are minimal.

How, though, will we protect ourselves from the terrible secret of space?