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Spacecraft propulsion

There are many different ways to accelerate spacecraft. Below is a summary of some of the more popular, proven technologies, followed by increasingly speculative methods.

Propulsion methods
MethodSpecific Impulse (seconds)Thrust (Newtons)Duration
Conventional propulsion methods
Solid rocket100-400103- 107minutes
Hybrid rocket150-420minutes
Monopropellant rocket100-3000.1-100millliseconds - minutes
Momentum wheel (attitude control only)n/a0.001-100indefinite
Bipropellant rocket100-4000.1-107minutes
Tripropellant rocket250-450minutes
Dual mode propulsion rocket
Air-augmented rocket500-600seconds-minutes
Liquid air cycle engine450seconds-minutes
Resistojet rocket 200-60010-2-10minutes
Arcjet rocket400-120010-2-10minutes
Hall effect thruster (HET)800-500010-3-10months
Ion thruster1500-800010-3-10months
FEEP (Field Emission Electric Propulsion)10000-1300010-6-10-3weeks
Magnetoplasmadynamic thruster (MPD)2000-10000100weeks
Pulsed plasma thruster (PPT)
Pulsed inductive thruster (PIT)500020months
Variable specific impulse magnetoplasma rocket (VASIMR)1000-3000040-1200days - months
Solar thermal rocket
Nuclear thermal rocket900105minutes
Nuclear electric rocketAs electric propulsion method used
Solar sailsN/A9 per km2 (at 1 AU)Indefinite
Mass driversN/AIndefiniteseconds
Tether propulsionN/A1-1012minutes
Technologies requiring more engineering development
Magnetic sailsN/AIndefiniteIndefinite
Mini-magnetospheric plasma propulsionN/AIndefiniteIndefinite
Gaseous fission reactor1000-2000103-106
Nuclear pulse propulsion (Orion drive)2000-100,000109-1012 half hour
Antimatter catalyzed nuclear pulse propulsion2000-40,000days-weeks
Nuclear salt-water rocket10,000103-107half hour
Beam-powered propulsionAs propulsion method powered by beam
Nuclear photonic rocket5x1061-105years
Biefeld-Brown effect (see also Lifter)N/A0.01-1 (currently)weeks, probably months
Significantly beyond current engineering
Fusion rocket
Bussard ramjet
Antimatter rocket
Redshift rocket
Requires new principles of physics
Alcubierre drive (Warp drive)Not Applicable
Differential sail
Disjunction drive
Diametric drive
Pitch drive
Bias drive
Time machines

Launch mechanisms

The launch of a spacecraft from the surface of a planet into space places special requirements on the methods of propulsion used. Generally speaking high thrust is of vital importance for launch, and many of the propulsion methods above do not provide sufficent thrust to be used in this capacity. Exhaust toxicity or other side effects can also have detrimental effects on the environment the spacecraft is launching from, ruling out other propulsion methods. Currently, only chemical rockets are used for the launch of spacecraft from Earth's surface.

One advantage that spacecraft have in launch is the availability of infrastructure on the ground to assist them. Proposed ground-assisted launch mechanisms include: