The Last Kremer Prize

by submission
August 15th, 2007

Author : J. S. Kachelries

The Gossamer Comet hung motionless 10 meters beyond the Folkestone Colony’s outermost habitation “wheel.” The Gossamer Comet was a one-man “human-powered” spacecraft that was about to attempt to win the last unclaimed Kremer Prize, a £100,000 award for the first person to “fly” unaided, in less than twelve hours, between any two of the 247 space colonies in geostationary orbit.

Generally, all of the attempts to make the human-powered crossing involved Newton’s third law. Contestants would typically launch massive projectiles using a human compressed spring in one direction, and the ship would move in the opposite direction at a velocity proportional to the mass of the projectiles and the ship. Alternatively, contestants would use a hand pump to pressurize a liquid, and release it like a rocket exhaust. The big problem, however, was achieving the correct trajectory. In orbit, there were complicating factors. If the ship moves retrograde (opposite to the direction of Earth’s rotation) its orbital velocity decreases. This means that it is no longer in geostationary orbit, and it starts to “fall” perceptibly toward the Earth. Consequently, after traveling several hundred kilometers, it misses the target low. Some intrepid designers added multidirectional “guidance” capability to their ships. But all those craft ended up rotating helplessly out of control (the rules prohibited gyroscopes on the ship). In over twenty years of trying, nobody had been able to “thread the needle” (i.e., achieve the correct angle and velocity to dock successfully with an adjacent space colony).

But today, Allen Bryan, a 25-year-old graduate student in Physics, had a plan to improve his odds. He had spent months preparing for this attempt. Seconds after he was notified that the twelve-hour time limit had begun, he exited a hatch and clipped a tether line to his spacesuit. He then began turning a winch that caused a circular hull plate to move inside his ship. He climbed into the newly created cavity, and satisfied that he was aimed correctly, released the preloaded spring. As shocked onlookers watched, Bryan launched his body at an angle slightly outboard of the Gris-Nez Station, which was 358 kilometers “behind” the Folkestone. Of course, his more massive ship moved slowly in the opposite direction. Bryan had meticulously controlled the mass of the ship, the tether line, and his own mass. As he flew on a trajectory outboard of the Gris-Nez, he began to drop toward the Earth because of his retrograde motion. His plan was to overshoot the Gris-Nez, but cross its orbit five to ten kilometers on the far side. After eight hours of flight, the 500-kilometer long Kevlar tether line had played out. Bryan was safely beyond, and below, the Gris-Nez, with his tether line “draped” across the outer wheel of the space station. Bryan began to feverishly crank the winch on his spacesuit to reel himself in. He continued to shorten the tether line until he lightly crashed into the Gris-Nez colony two hours later. Exhausted, he scrambled into an open cargo bay.

“Very clever, Mister Bryan,” said a member of the Royal Aerospace Society’s Human-Powered Spacecraft Rules Committee, “that technique significantly increased your margin of error. Very clever, indeed. However, the rules clearly stipulate that ‘the pilot and the ship’ must arrive at the space station to claim the £100,000 prize. I suggest, sir, that you get busy manually hauling in your ship. You only have two hours left on the clock.”