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Beamed power to space vehicles
What is the maximum flux levels that can be beamed to space craft by
lasr or microwave? The specific application would be to beam power from a SSPS (power available: 5GW) to a space vehicle using an electric drive (e.g. VASIMR). The spacecraft would be descending from High Earth Orbit to swing by Earth, and the aim would be to give it the maximum boost whilst it passes Earth (for Gravity assist). My thinking is that microwaves are the way to go because: - They are more eficient than solar panels (even single wavelength panels) and therefore there is less waste heat to dump. - The wire mesh collector can be lighter than a solar array. Trying some numbers, if the collecting area were 1km2, or 10km2, what power could it collect? Could such a system approach chemical engines in terms of thrust? A later application would be to boost electric powered vehicles as they swing by the sun at some 600km/s. This would obviously involve transmitting power over much longer distances. |
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Beamed power to space vehicles
"Rodney Kelp" writes:
On that line wouldn't it be more feasable to slow a space craft down before reentering the atmosphere thereby eliminating the heating effect of reentry? Totally impractical --- It takes the same mass-ratio as putting the vehicle into orbit in the first place. It is not practical to have a single stage with a mass ratio greatly in excess of 10, and under those conditions, "Single-Stage To Orbit" is just barely marginal with known chemical propellants and materials, but "Single-Stage To Orbit And Back Again" is utterly hopeless, without advanced nuclear rockets that the EPA will _NEVER_ allow to fly in the Earth's atmosphere. Therefore, unless you have a propellant-dump in orbit and you are willing to launch 10 expendable propellant freighters for every vehicle you bring back, what you propose is simply not practical. -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' |
#4
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Beamed power to space vehicles
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