S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...

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New Approaches in Advanced Propulsion: Solar-Thermal Rockets
Schematic of Solar-Thermal
Propulsion
reflector
FUEL
(Courtesy of SNECMA)
Heat exchanger
thrust
chamber
Possible application for future orbit
transfer vehicles
Concept: Solar energy is concentrated on a
heat exchanger by using mirrors or lenses.
E.g. liquid hydrogen propellant is passed
through a heat exchanger, reaching very high
temperatures up to 2500 K, before expanding
through a nozzle.
By this, solar-thermal rockets make use of the
limitless power of the sun to produce relatively
high thrust, F, with high exhaust velocities, ve:
- F = 5 to 10 N continuous for 70 kW
(solar power)
- ve ≈ 8000 m/s
Basic engineering problems limit thrust levels
due to limit in heat transfer from heat
exchanger to propellant.
In addition, the deployment and steering of
large mirrors to collect and focus the solar
energy presents an operational challenge.
Status: Several concepts for solar-thermal
propulsion systems have been proposed,
however, so far none have been tested.