Dyson calculated that the properties of available materials limited the velocity transferred by each explosion to ~30 meters per second independent of the size and nature of the explosion. The limitation is then set by the capacity of shock absorbers to transfer momentum from the impulsively accelerated pusher plate to the smoothly accelerated vehicle. In order to improve on this performance while reducing size and cost, Dyson also considered an alternative momentum limited pusher plate design where an ablation coating of the exposed surface is substituted to get rid of the excess heat. It would then take on the order of 1000 years for the energy-limited heat sink Orion design to reach Alpha Centauri. 100 seconds would be required to allow the copper to radiatively cool before the next explosion. Dyson estimated that if the exposed surface consisted of copper with a thickness of 1 mm, then the diameter and mass of the hemispherical pusher plate would have to be 20 kilometers and 5 million metric tons, respectively. The more conservative energy limited pusher plate design simply had to absorb all the thermal energy of each impinging explosion (4×10^15 joules, half of which would be absorbed by the pusher plate) without melting. To estimate the upper and lower limits of what could be done using contemporary technology (in 1968), Dyson considered two starship designs. His conclusions were simple: the debris velocity of fusion explosions was probably in the 3000–30,000 km/s range and the reflecting geometry of Orion’s hemispherical pusher plate would reduce that range to 750–15,000 km/s. Dyson moved away from the use of fission bombs and considered the use of one megaton deuterium fusion explosions instead. Technical aspects of Interplanetary and Interstellar Project Orion Designsįreeman Dyson had a 5 page “Interstellar Transport”ĭyson retained the concept of large nuclear explosions. Should they continue? Also there’s been a murder on the ship, which never happened before. Should they turn around and go back to Earth, which they’ve lost touch with? So they have no idea of what Earth even looks like now. And there are a lot of conflicts going on. It’s their children, their children’s children, who are going to get to where they’re going. A lot of the people who started on this ship have died. Essentially the ship is like a time capsule, another civilization that continued for 50 years parallel to our civilization.” Blum added that “the people on the ship, only some of their children, but most of their grandchildren, are the only people who are going to arrive at this new world. About the starship he said that “it feels like a cruise ship. He was terrified that they were turning it into a Death Star”. Levens pointed out that Kennedy squashed the development of Orion soon after Bay of Pigs as the military began equipping the spaceship with weapons. It was inspired by the Orion military project under JFK.
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