The ice-ball solution.
The Rapscallion edged closer and closer to the fringes of the Oort cloud. The ship had spent a great deal of time collecting ice boulders and chunks of frozen methane and cementing them together to build a shield around the ship. A small ice-world had been manufactured and the ship had applied its lasers to bore a hole, deep within the bitter cold shell. Here the ship had anchored itself and refroze the mantle around it to provide the protection that they would need to fly at 90% light speed through the oncoming blizzard of trillions of ice particles and rocks.
All the human crew were in suspended animation in stasis chambers while the running of the star-ship was left to Amos the A.I. (Artificial Mind over Ship) It had taken twenty years to get here from Saturn, where the majority of the ice mantle had been created. The fusion generator continued to apply the magnetic bottle that housed the anti-matter plasma and maintained the storage of the uranium pellets that combined, would furnish the drive. The long range scanners would sweep the way ahead and feedback the information to Amos so that adjustments could be made to the trajectory. This was to miss concentrations of the deep frozen rubble left over from when the solar system had finished the accretion into planets etc. Planetoids the size of Sedna were easily recognised and were quite rare. It was the rubble the size of pebbles that would wear down the defences and once the ice melted to show the metal underneath, the star-ship would disintegrate under the barrage.
Heavy duty lasers mounted in the ice constantly swept the area in front of the ship’s direction and turned the droplets into a gas that rapidly re-froze over the front of the ice-ball. These pulsed at a steady rate to help clear the way, but put a heavy drain on the fusion power-plant. Out here the sun was no more than a bright star and the way forwards was an inky black with next to no reflected light. Amos sent the signal back to Earth that would tell NASA that they were on their way, although it would take about 312 days to be received. By the time that the Rapscallion cleared the cloud, the signal would take twice that length of time, nearly two years. Even out here at 100Au the escape velocity of the sun’s gravitational pull would be 2,900 miles per hour. At that speed and to cross 90,000 Au (Astronomical Unit – distance from the Sun to the Earth – 93,000,000 miles!) the outside of the star-ship would still be constantly peppered by icy buckshot. At that speed the star-ship would take over 22million years to just clear the outer fringes of the Oort cloud. Sub-light speeds were needed or the very stars would extinguish themselves before they got there.
Amos’s mobile unit buckled up and the A.I. linked in to the fusion generator and began to project anti-matter from the magnetic bottle into the combustion chamber whilst feeding uranium pellets into the stream. A giant hand began to apply pressure to the star-ship and thrust began to build up. The vessel soon passed the Voyager one’s velocity of 39,000 miles per hour and would continue to accelerate, until the ship reached 90% light speed. The repeated concussion of millions of particles of super hard ice that had got through the laser barrage began to shake the ship with a harmonic vibration. The sheer mass of the ice world that contained the ship shielded them from annihilation. Every so often a larger piece would smash into the icy shield that was a mile thick and boil off as gas, instantly to refreeze, adding to the shield. By now, time had slowed down inside the star-ship, as the effects of relativity made itself shown. By the time the ship obtained 90% of the speed of light, for each day on board, two and a quarter days pass for an observer on Earth. As the ship approached 99% light-speed, hundreds of years had passed back on Earth while the Rapscallion had endured for several years in its own relativity bubble. Now the increased mass of the ship due to relativity would carry it through the ice fields by compressing the shield even more.
Amos compensated for this as he had been programmed to do and rode the shockwave that formed in front of the ship. The outer ice shell at -270C was as hard as carbon steel and was accepting the continual impacts of the ice rubble by continuing to add to the shell. Every time that the Rapscallion entered a relatively clear area the front of the ice-ball re-froze. It would be some time before the ship entered the halo of comets and ice particles about the star that the Kepler telescope had picked out as a harbouring a water world planet. Meanwhile all sperm and eggs would remain frozen in their liquid nitrogen capsules until Amos was satisfied that the conditions were right for the colony to begin on a new world and that would not be for several hundred years just yet. Until then the stasis chambers would continue to keep the crew in suspended animation until they were needed.
Should the planet be absolutely unsuitable they would return to the stasis chambers and leave Amos to carry on, as the mission was always going to be a one-way trip no matter what happened at their ultimate destination? The radio-active ruin that that was their home would receive their message after their departure, but never hear it. Rapscallion was the only Ark that humanity had launched towards the stars, carrying the hopes of Earth to be replanted in an alien soil. As the Oort Cloud was 100,000 Au thick, even at 90% light speed it would take the star-ship at least 1.5 years to clear it before Amos could increase the speed to 99% light-speed in the relatively empty space.
It would be a long voyage.