If you assume an interstellar spacecraft of 100 m in diameter traveling to the nearest star - that ship would plow through 3 x 10^20 m^3 of interstellar space. At 0.5 c the energy release of such a spaceship encountering a piece of space "dust" weighing (~0.01g) becomes significant. Only one such impact would be enough to cause severe spacecraft damage given the kinetic energy involved (150,000 Joules). This collision would explode like a pinpoint bomb (30 g of TNT - one half the charge in a hand grenade).
So, what are the chances of such a space ship encountering such a interstellar grain of dust in traveling to the nearest star?
