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An artist's conception of the British Interplanetary Society design for Project Daedalus

Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible interstellar unmanned spacecraft.[1] A dozen scientists and engineers led by Alan Bond worked on the project, and settled on proposing a fusion rocket as its drive.

The design criteria had specified that the spacecraft had to use current or near-future technology and had to be able to reach its destination within a human lifetime (a flight time of 50 years was allocated). However, as noted above, it was not to be manned, being intended mainly as a scientific probe.

The target chosen was Barnard's Star, 5.9 light years away, which at the time was believed to possess at least one giant planet (the evidence on which this belief was based has since been discredited). However, the design was required to be flexible enough that it could be sent to any of a number of other target stars.

Project Daedalus is not considered feasible within the 21st century due to economic reasons.

Contents

Concept

Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 metric tons, including 50,000 tons of fuel and 500 tons of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of light speed (0.071 c), and then after it was jettisoned the second stage would fire for 1.8 years, bringing the spacecraft up to about 12% of light speed (0.12 c) before being shut down for a 46-year cruise period. Due to the extreme temperature range of operation required (from near absolute zero to 1,900 K) the engine bells and support structure would be made of beryllium, which retains strength even at cryogenic temperatures. A major stimulus for the project was Friedwardt Winterberg's fusion drive concept[2][1] for which he received the Hermann Oberth gold medal award. [3]

This velocity is well beyond the capabilities of chemical rockets, or even the type of nuclear pulse propulsion studied during Project Orion. Instead, Daedalus would be propelled by a fusion rocket using pellets of deuterium/helium-3 mix that would be ignited in the reaction chamber by inertial confinement using electron beams. 250 pellets would be detonated per second, and the resulting plasma would be directed by a magnetic nozzle. Due to the scarcity of helium-3 it was to be mined from the atmosphere of Jupiter via large hot-air balloon supported robotic factories over a 20 year period.

The second stage would have two 5-meter optical telescopes and two 20-meter radio telescopes. About 25 years after launch these telescopes would begin examining the area around Barnard's Star to learn more about any accompanying planets. This information would be sent back to Earth, using the 40-meter diameter second stage engine bell as a communications dish, and targets of interest would be selected. Since the spacecraft would not decelerate upon reaching Barnard's Star, Daedalus would carry 18 autonomous sub-probes that would be launched between 7.2 and 1.8 years before the main craft entered the target system. These sub-probes would be propelled by nuclear-powered ion drives and carry cameras, spectrometers, and other sensory equipment. They would fly past their targets, still travelling at 12% of the speed of light, and transmit their findings back to the Daedalus second stage mothership.

The ship's payload bay containing its sub-probes, telescopes, and other equipment would be protected from the interstellar medium during transit by a beryllium disk up to 7 mm thick and weighing up to 50 tonnes. This erosion shield would be made from beryllium due to its lightness and high latent heat of vaporisation. Larger obstacles that might be encountered while passing through the target system would be dispersed by an artificially generated cloud of particles, ejected by support vehicles called dust bugs, some 200 km ahead of the vehicle. The spacecraft would carry a number of robot "wardens" capable of autonomously repairing damage or malfunctions.

Daedalus specifications

  • Overall length: 190 meters
  • Propellant mass first stage: 46,000 metric tons
  • Propellant mass second stage: 4,000 metric tons
  • First stage empty mass: 1,690 metric tons
  • Second stage empty mass: 980 metric tons
  • Engine burn time first stage: 2.05 years
  • Engine burn time second stage: 1.76 years
  • Thrust first stage: 7,540,000 newtons
  • Thrust second stage: 663,000 newtons
  • Engine exhaust velocity: 10,000,000 m/s
  • Payload mass: 450 metric tons

Variants

A quantitative engineering analysis of a self-replicating variation on Project Daedalus was published in 1980 by Robert Freitas.[4] The non-replicating design was modified to include all subsystems necessary for self-replication, using the probe to deliver a "seed" factory with a mass of about 443 metric tonnes to a distant site, having the seed factory replicate many copies of itself there to increase its total manufacturing capacity, and then using the resulting automated industrial complex to construct more probes with a single seed factory on board each over a 1,000 year period. Each REPRO would mass over 10 million tons, mostly fuel needed to decelerate from 12% of lightspeed.

See also

References

  1. ^ a b Project Daedalus Study Group: A. Bond et al., Project Daedalus – The Final Report on the BIS Starship Study, JBIS Interstellar Studies, Supplement 1978
  2. ^ F. Winterberg, "Rocket propulsion by thermonuclear microbombs ignited with intense relativistic electron beams", Raumfahrtforschung 15, 208-217 (1971).
  3. ^ Winterberg is Hermann Oberth Gold Medalist,Physics Today, December 1979
  4. ^ Freitas, Robert A., Jr. (July 1980). "A Self-Reproducing Interstellar Probe". J. Brit. Interplanet. Soc. 33: 251–264. http://www.rfreitas.com/Astro/ReproJBISJuly1980.htm.  

External links

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