Aurora by Kim Stanley Robinson Read Free Book Online Page B

119 days. For most of that time the ship has been moving relative to the local background at approximately one-tenth the speed of light. Thus about 108 million kilometers per hour, or 30,000 kilometers per second. This velocity means the ship cannot run into anything substantial in the interstellar medium without catastrophic results (as has been demonstrated). The magnetic field clearing the space ahead of the ship as it progresses is therefore one of many identified criticalities in the ship’s successful long-term function. Every identified criticality in the ship was required to have at least one backup system, adding considerably to the ship’s overall mass. The two biome rings each contain 10 percent of the ship’s mass. The spine contains 4 percent. The remaining 76 percent of the mass consists of the fuel now being used to decelerate the ship as it approaches the Tau Ceti system. As every increase in the dry mass of the ship required a proportionally larger increase in the mass of fuel needed to slow the ship down on arrival, ship had to be as light as possible while still supporting its mission. Ship’s design thus based on solar system’s asteroid terraria, with asteroidal mass largely replaced by decelerant fuel. During most of the voyage, this fuel was deployed as cladding around the toruses and spine.
    The deceleration is being accomplished by the frequent rapid fusion explosion of small pellets of deuterium/helium 3 fuel in a rocket engine at the bow of the ship. These explosions exert a retarding force on the ship equivalent to .005 g. The deceleration will therefore be complete in just under twenty years.
    The presence of printers capable of manufacturing mostcomponent parts of the ship, and feedstocks large enough to supply multiple copies of every critical component, tended to reduce the ship’s designers’ apprehension of what a criticality really was. That only became apparent later.

    How to decide how to sequence information in a narrative account? Many elements in a complex situation are simultaneously relevant.
    An unsolvable problem: sentences linear, reality synchronous. Both however are temporal. Take one thing at a time, one after the next. Devise a prioritizing algorithm, if possible.

    Ship was accelerated toward where Tau Ceti would be at the time of ship’s arrival at it, meaning 170 years after launch. It might have been good to have the ability to adjust course en route, but ship in fact has very little of this. Ship was accelerated first by an electromagnetic “scissors field” off Titan, in which two strong magnetic fields held the ship between them, and when the fields were brought across each other, the ship was briefly projected at an accelerative force equivalent to ten g’s. Five human passengers died during this acceleration. After that a powerful laser beam originating near Saturn struck a capture plate at the stern of the ship’s spine, accelerating ship over sixty years to its full speed.
    The ship’s current deceleration has caused problems with which Devi is still dealing. Other problems will soon follow, resulting from the ship’s arrival in the Tau Ceti system.

    Devi: Ship! I said make it a narrative. Make an account. Tell the story.
    Ship: Trying.

    Tau Ceti is a G-type star, a solar analog but not a solar twin, with 78 percent of Sol’s mass, 55 percent of its luminosity, and 28 percent of its metallicity. It has a planetary system of ten planets. Planets B through F were discovered by telescope, G through K, much smaller, by probes passing through the system in 2476.
    Planet E’s orbit is .55 AU. It has a mass 3.58 times the mass of Earth, thus one of the informal class called “large Earth.” It has a single moon, which has .83 times the mass of Earth. E and E’s moon receive 1.7 times Earth’s insolation. This is considered within the inside border of the so-called habitable zone (meaning the zone where liquid H 2 O is common). Both planet and moon have