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The Epstein Drive is a modified Fusion Drive invented by Solomon Epstein Books • TV around 130 years ago, in approximately 2213 AD BXT. It enabled humanity to travel beyond Earth and the inner planets and colonize the asteroid belt and the outer planets.


The drive utilizes magnetic coil exhaust acceleration to increase drive efficiency, which enables spaceships to sustain thrust throughout the entire voyage. A ship fitted with the efficient Epstein drive is able to run the drive continuously for acceleration to its goal and then after flipping at about the halfway point is able to run the drive continuously during deceleration. Previous engine designs used propellant less efficiently and could not be run long enough to achieve the high velocities that the Epstein drive permitted.

Since its invention and up until the discovery of the Ring network, the Epstein drive remained the most advanced transportation technology humanity had access to.

Known models[]

Drive Details[]

Using the information available at Atomic Rockets website[1], the Epstein drive possesses the following performance characteristics (based upon the performance of Epstein's yacht):

  • Thrust: 1,000,000 N
  • Specific Impulse (isp): 1,100,000 seconds
  • Exhaust Velocity (ve): 11,000,000 m/second (~3.7% of light speed;1,109,232m/s)
  • Mass Flow Rate ( ): 0.09 kg/second
  • Thrust Power: 5.5 Terawatt
  • Engine's Thrust to Weight Ratio: ~140 [Citation needed]
  • Propellant mass fraction (yacht's mass fueled / mass empty): ~4

An alternative set of performance statistics has been suggested by the Tough SF website[2], based on the performance of the Rocinante on-screen:

  • Thrust: 6,370,000 N
  • Specific Impulse (isp): 1,927,000 seconds
  • Exhaust Velocity (ve): 18,900,000 m/second (6.8% of light speed)
  • Mass Flow Rate: 2.2 kg/second
  • Thrust Power: 60.2 Terawatt
  • Total power output: 96.8 Terawatt
  • Engine's Thrust to Weight Ratio: Presumably over 3 (The Roci has a dry TWR of 2.6)
  • Fusion type: D-He3 (1:2 mixture ratio)
  • Fusion pulse rate: "[what we see] can be achieved with as few as 10 pulses per second, or hundreds if possible"

This latter estimate would, for example, give a fully-fuelled Nauvoo with a Dv of 0.24c a mass ratio of around 34.


See also[]


External links[]