Read The Sails of Tau Ceti for Free Online

directly. If they intend to stop inside the Solar System, they have to decelerate at something around one-thousandth of a standard gravity.”
    “That isn’t very much.”
    “More than enough to halt short of the sun. Remember, they’ve got one hell of a long distance to fall.”
    “If they’re slowing, they won’t arrive as quickly.”
    “True. We now estimate that the sail will reach us in five years rather than three-and-a-half. A precise figure will have to await a better estimate of their deceleration constant.”
    Tory had been reviewing the technology of electrostatic brakes ever since activating her implant. The idea had a surprisingly long history. An electrostatic brake was essentially a device for sweeping up hydrogen across a vast region of space and funneling it into a spacecraft’s path. In effect, the spacecraft would plow through an artificially enhanced solar wind. Every impact on the craft robbed it of momentum, causing it to slow.
    The literature contained dozens of proposals on how to accomplish the trick. All relied on the fact that there are some 100,000 hydrogen atoms per cubic meter even in deep interstellar space. Most used a tuned laser to ionize the hydrogen over a large region in front of the ship, and then attracted the ions with a powerful negative electrical charge. The electrical field acted as a giant invisible funnel that concentrated the interstellar gas onto a collecting device such as a light sail. If the surface of the sail was then negatively charged, the ions could be reflected back the way they had come before impact. Reflecting the ions allowed twice the momentum transfer of merely bombarding the sail, while protecting the sail’s surface from erosion at the same time.
    “Electrostatic brakes work well enough when a ship is moving at high speed,” Tory said, quoting from an encyclopedia article she had just scanned, “but their efficiency drops off drastically with reduced velocity.”
    “Once close to the sun, they’ll transition to light pressure braking,” Hunsacker replied.
    “I think not,” Pierce responded. He, too, had been busy with his implant. “Tory’s right. Electrostatic braking efficiency falls off rapidly as you slow. Even with optimistic assumptions for both electrostatic and light pressure, they would still be going too fast to stop by the time they reached the sun. They must be planning an aerobraking maneuver near the sun to finish the job. That is a ticklish thing. If they hit that soup too fast, the passengers will be turned to red mush.”
    “How do we know the mush would be red?” Ben asked. The question sounded like a joke and drew him a baleful look from Sadibayan. In truth, he had been completely serious.
    Tory felt a small shiver run up her spine. The aliens were using their light sail like a giant parachute. If they were to go into solar orbit, they would practically have to dive into the sun. Whoever had thought up this scheme must have been truly desperate. After a moment’s thought, however, she chuckled quietly to herself.
    Sadibayan turned his disapproving look from his aide to Tory. “What’s so funny?”
    “We are,” she replied. “Here we’re worried that they will fly too close to the sun and end up like Icarus. Yet, they launched from out of the heart of an exploding nova. I doubt they will be frightened by the prospect of diving headlong into our little star!”
    #
    “All right,” Pierce said after the technical discussion had gone on for nearly an hour, “now that we have all reviewed the new information, what do we do about it?”
    “Luna makes their announcement!”
    “I’m sorry, Miss Bronson,” Sadibayan said, “but that is not going to happen. My orders from Earth are that no mention will be made of this discovery for the time being.”
    “Why the hell not?” Pierce demanded.
    “We need time to study the implications of the situation. We don’t know how people will react.”
    “But that’s