Propulsion

Space propulsion engines are very different from thrusting engines designed to boost an object out of a planetary gravity well. They must be more efficient, must not require large quanties of expendable supplies (either fuel or thrusting material) and must be able to operate continually.

Thrusters:

  • Chemical thrusters currently used in satellite spacecraft don’t offer enough efficiency to be primary propulsion drives in space.
  • Thermal exhaust is an extension of chemical thrusters, but uses some form of plasma reaction or nuclear reaction to heat the propellent. This is an improvement on the chemical thruster but not by much and is probably not a viable space propulsion technology.
  • Ion thrusters accelerate ions through an electromagnetic field to provide thrust. These drives offer much lower thrust levels but much higher efficiency and can operate continuously.

Solar Sails

Making solar sails a viable propulsion system will depend on developments in material science that produce very thin and strong films that can be deployed across a wide area in order to produce enough “pull”. Materials that meet these criteria are very close to becoming a functional possibility.

Beamed Core Engine
Antimatter annihilation produces a beam of particles as high velocity exhaust. While this is a theoretical idea, primarily limited by our ability to produce antimatter, recent advances in that area offer great promise.

Spaceflight Propulsion

The 20th century saw the beginnings of space exploration, which was enabled by the development of new and powerful rocket propulsion systems that could lift heavy payloads into space, and give such payloads the ability to control themselves once they were in space. The development of spaceflight propulsion systems continues in the 21st century, with new technologies that offer improved capabilities. This document provides an overview of spaceflight propulsion systems.

Engage the antimatter drive – [newscientist.com]

Another possibility is to cruise through space on a sailing ship: make a reflective sail, unfurl it in space, and it will get nudged along by photons streaming out from the sun. This creates a slow but steady acceleration that can eventually add up to some serious travelling. According to engineers at US space research company Pioneer Astronautics, it’s possible to make a solar sail that could propel a craft to around 1 per cent of the speed of light. The key, they suggest, is to use a mesh of metal-coated carbon nanotubes. The ultra-lightweight sail this creates, just nanometres thick, could pass close to the sun after launch without melting. The intense illumination, as well as extra acceleration from the sun’s gravity, could boost the sail to speeds of over 3000 kilometres per second.

A Penning trap or similar storage device would act as the fuel tank of any antimatter-powered spaceship. There would be various ways you might use the energy it liberates, but the technique that seems best suited to high-speed interstellar travel is the “beamed core” engine. The basic idea is to trickle antiprotons into a reaction chamber where they meet matter containing normal protons. As they annihilate each other, they release high-energy charged particles which are focused with magnets and beamed out of the back.

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