In all things there must be balance, said my physics prof to me, And in the days of sailing ships, the ballast was the key, Some sand and garbage in the bilge are all you need at sea, But things work slightly differently when you turn in zero-gee. The ballast must be accurate to ten places, maybe more, Whether you are dodging asteroids or just going to the store. When the spaceships first used ballast, they tried everything in sight, And inert materials at first worked out all right, But when spaceships first went past light-speed, the laws of physics changed, Gravitation pulled unequally, several ships were... rearranged. They finally discovered that the ballast must float free, To go where it's most needed -- so the ballast now is me. I tried to be a Space Marine, but they wouldn't let me go, My vision was myopic, my reflexes way too... slow, And all my dreams of Space Marines and interstellar fame Were dashed to Hell by defects in my undernourished frame, But still I made it into space, although my job is dull, For now I serve as ballast sealed up inside the hull. Now inert, unliving ballast will not do the job -- instead, They've got me in a Kevlar jumpsuit, pockets lined with lead, The hyperdrive computer says where we'll need extra ma**, We accelerate to F.T.L. and inertia kicks my a**, I bounce around between the seams, grabbing anything at hand, Like a plane whose one wing tears and falls, the ballast wants to land.