Alternate History

Prometheus-class (An Orion Future)

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Prometheus-class is name of first type of nuclear pulse spacecrafts in the world. It was developed by USA at early 1960's and used nearly 20 years with little changes, because it was the biggest Orion ship that could be launched by chemical rocket (and bigger is better in Orions).

Technical information


Standard nuclear propulsion bomb.

  • First launch: 19.3.1965
  • Empty mass: 780 t
  • Full mass: 1300 t
  • Ship height: 37 m
  • Ship diameter: 24,5 m
  • Bomb mass: from 360 to 300 kg
  • Bomb yield: from 40 to 30 tons of TNT
  • Number of bombs: 1500 or less
  • Speed from each bomb: 15 m/s
  • Max. acceleration: 1.6 g
  • Specific impulse: 40 Km/s
  • Payload to escape velocity: 250 t
  • Payload to Moon and back: 150 t
  • DeltaV: 20 Km/s with minimum payload
  • Launch cost: 48 000 000 $*

(* = Cost at 1960's. About 370 millions in today's money.)

Prometheus-class spaceships used big, conventional, reusable rockets as the first stage. They had following characteristics:

  • Empty mass: 590 t
  • Full mass: 3950 t
  • Thrust: 144 MN
  • Engines: 9xRocketdyne F-2
  • Crew: 2
  • Fuel: LOX + RP-1
  • DeltaV: 3 Km/s with full payload


At launch first stage pulled spaceship 100 seconds with 3 g acceleration. When stage was out of fuel, it was dropped and landed back to earth. Ship used its own engines until it was 310 kilometers above ground and had speed of 2.5 Km/s. Then EMP's from explosions become too big and craft flew freely about 800 Km, until it was high enough and could use nuclear pulses again.


Because launches took off near North Magnetic Pole, most fallout particles floated to space and only small amounts to earth. It is estimated that every ten launches of Prometheus-class spaceships caused one fatal cancer in earth. EMP's were problems, too. Some people even claim that every launch broke electronics costing many millions. On the other hand, at 60's or 70's computers and satellites weren't very vulnerable to EMP. Explosions within magnetosphere flooded van Allen belts with free electrons. Because the launch site was near they magnetic pole, this wasn't big problem. Charged particles were cleaned from space with long, magnetic cables.

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