System Requirements for Low-Earth-Orbit Launch Using Laser Propulsion

Lawrence, R. Jeffery; Zazworsky, Raymond M.; Monroe, David K.; Kare, Jordin T.

doi:10.13182/fst91-a11946924

Cited by 5 publications

(2 citation statements)

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“…A flight plan has been developed which is consistent with the requirements for the CW/HX laser-powered launch vehicle design. 13 The beam director must have a clear line-of-sight to the vehicle during the entire laser-powered ascent to orbit. Also, the angle between the beam and the local site zenith must be maintained at less than about 60 degrees, to assure that adaptive optics can adequately compensate for wavefront distortions.…”

Section: Flight Plan For a Cw/hx Vehiclementioning

confidence: 99%

<title>Fission-activated laser as primary power for CW laser propulsion</title>

Monroe¹

1994

SPIE Proceedings

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Recent advances in the development ofreactor-pumped lasers (RPL's) have stimulated renewed interest in the concept of laser-powered propulsion. This paper surveys a number oflaser propulsion concepts and identifies the ooe that is most promising from the standpoint ofpracticality. It is proposed that a ground-based FALCON (Fission-Activated Laser CONcept) RPL can provide primary power for this launch vehicle design. The laser-vehicle system could launch small payloads into low-earth orbit (LEO) with high repetition rates and at low costs per kilogram. For the favored design, thruster efficiencies are currently estimated to be about 50% with 80% being seen as a potentially realizable goal after further design refinements Laser launch system simulations indicate that, with a buy-in laser power of 10 MW, it will be possible to obtain specific impulses in the range of600 to 800 seconds and payload-to-power ratios of 1 to 3 kg/MW. RPL PROPULSION FOR LEO MISSIONSThe concept ofRPL-propulsion to LEO is illustrated in Figure 1. A ground-based laser (GBL) system is used to beam radiant power to an ascending launch vehicle. The laser beam is focused onto the launch vehicle's heat exchanger (HX) with the use ofa steerable beam director having a deformable mirror. The mirror has the capability ofpre-distorting the beam so as to compensate for wavefront distortions caused by atmospheric turbulence. Real-time control signals for the mirror are provided by an adaptive optics unit which uses a low-power laser beam to sense the degree ofturbulence and distortiorL With these corrections, the laser beam incident upon the vehicle's HX is nearly diffraction-limited.A number oflaser-powered propulsion system designs have been proposed during the last decades. Many ofthese are variations on the basic continuous-wave (CW) direct-heating thruster design, which will be described later.14 A more recent advance in 1aserwered vehicle design has been developed and promoted by J. T. Kare at Lawrence Livermore National g9-Iz The Kare design was used to obtain the performance parameters displayed in Figure 1.The design by Kare uses a CW laser source, a metallic HX and liquid-hydrogen propellant This so-called CW/HX launch vehicle can provide specific impulses of600 to 800 seconds, which is well above that Obtained with conventional chemical thrusters. The overall thruster efficiency is estimated to be about 50%, but it may be possible to achieve 80% efficiency after additional design refinements. The ratio ofdeliverable payload mass to laser power is about 1 to 3 kg/MW.913The GBL system design depicted in Figure 1 assumes a CW4aser power output of 10 MW, which is the estimated buy-in power for such systems. '3yl having masses in the range of 10 kg and greater are of importance, and have acquired the descriptive name "microsat". With a 10-MW laser it would be possible to cost-effectively deliver very large total payloads to LEO as sequences of small payloads having masses of about 10 kg and greater. System simulation results indicate that the Kare...

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Section: Flight Plan For a Cw/hx Vehiclementioning

confidence: 99%

<title>Fission-activated laser as primary power for CW laser propulsion</title>

Monroe¹

1994

SPIE Proceedings

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“…Occasional outages due to weather could be tolerated. An additional category for laser propulsion is launch from earth into orbit (Lawrence et al 1991). This application is more far term since it is calculated to require about a MW of laser beam for each kg put into low-earth orbit.…”

Section: Power-beaming Applications ¢mentioning

confidence: 99%

Power Beaming to Space Using a Nuclear Reactor-Pumped Laser

Lipinski¹,

Monroe²,

Pickard³

et al. 1994

AIP Conference Proceedings

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The present political and environmental climate may slow the inevitable direct utilization of nuclear power in space. In the meantime, there is another approach for using nuclear energy for space power. That approach is to let nuclear energy generate a laser beam in a ground-based nuclear reactor-pumped laser (RPL), and then beam the optical energy: into space. Potential space applications for a ground-based RPL include (1) illuminating geosynchronous communication satellites in the earth's shadow to exlend their lives, (2) beaming power to orbital transfer vehicles, (3) providing power (from earth) to a lunar base during the long lunar night, and (4) removing space debris. FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept that is being developed by the Department of Energy with Sandia National Laboratories as the lead laboratory. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 0.

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