# Dyson slingshot

Artwork of a binary pulsar such as might prove effective for a Dyson slingshot. Image credit: John Rowe Animation / Australia Telescope National Facility, CSIRO.

A Dyson slingshot is a technique proposed by Freeman Dyson for
accelerating a spacecraft to high speeds by using the gravitational field
of binary star systems in which the components are collapsed stars. Dyson
found that a ship dispatched towards a two-star system with a velocity *v* where the stars are rotating around each other with velocity *V* could perform a slingshot maneuver (see gravity
assist) and be flung out of the system with a velocity equal to to *v* + 2*V*. The final velocity that can be achieved depends critically
on the mass and orbital velocity of the paired stars. For example, two white
dwarf stars, each with a diameter of 20,000 km and a mass of one solar mass,
and with a combined orbital period of 100 seconds, could provide a departure
velocity of 0.009c (2,700 km/s). However, two neutron stars, each with a
diameter of 20 km and a mass of one solar mass, and with a combined orbital
period of 0.005 sec could provide a departure velocity of 0.27c (81,000
km/s).

### Reference

1. Dyson, Freeman J. "Gravitational Machines." [Submitted as prize essay
to Gravity Foundation, April 1962]. *Interstellar Communication*,
A. G. W. Cameron, Editor, New York: Benjamin Press, 1963, Chapter 12.