Historical research guide · 0350 · 2010

DIRD Laser Lightcraft Nanosatellites

DIA / AAWSAP contractor

In one minute

Fly a spacecraft on a beam of light and you leave the engine on the ground. That is the proposal the Defense Intelligence Agency set out in November 2010, and the striking part is that it had already flown. At White Sands, a 10-kilowatt pulsed carbon-dioxide laser lifted an acorn-shaped aluminium craft — 10 centimetres across, 20 to 40 grams, no fuel aboard at all — in free vertical flight, and the report records 68 metres, against the 12.5 metres Robert Goddard’s first liquid rocket managed in 1926. The mechanism is a polished parabolic underside that concentrates kilojoule pulses, 25 times a second, into a ring inside the craft’s shroud, where the air breaks down into a plasma at 10,000 to 30,000 kelvin and detonates. Below Mach 5 the reaction mass is simply free air. The report then sizes the orbital version: a 10-megawatt ground laser, an 8-kilogram craft, four kilograms into low orbit, and launch costs two to three orders of magnitude below today’s.

Connection

This is chapter 9’s glowing, hovering, disc-bodied craft produced deliberately and in the open literature — a luminous plasma ring struck out of ordinary air by a focused beam, lifting a vehicle that carries no fuel and rides the beam. It gives chapter 1 a measured, repeated flight record rather than an argument, and it hands chapter 13 the shape of the transition it keeps describing: the heavy half of a launch system stays on the ground, and what flies is almost all payload.

From the source

It has flown. At the White Sands Missile Range High Energy Laser Systems Test Facility, the U.S. Army’s 10 kilowatt Pulsed Laser Vulnerability Test System carbon-dioxide laser lifted a Lightcraft in the first passively controlled vertical free flight of a beam-propelled object — 43 metres in 2-second gyroscopically stabilised free flights, then horizontal guide-wire flights of 121.9 metres lasting 10 to 20 seconds, with Leik Myrabo reporting vertical flights reaching 68 metres. The vehicle is 10 centimetres in diameter, 20 to 40 grams, machined from a solid block of 6061-T6 aluminium, and carries absolutely no fuel on board; five different designs have been flight-tested. Goddard’s first liquid-propellant rocket reached 12.5 metres after a 2.5 second burn in March 1926.Chapter 2, History of the Lightcraft Technology Demonstration Program, pp. 13-17
The engine is a ring of plasma struck out of the air. A parabolic afterbody mirror concentrates 18-microsecond kilojoule pulses, arriving 25 times a second, into an annular focus inside the craft’s shroud; the intensity is high enough that atmospheric breakdown occurs and the inlet air bursts into a highly luminous plasma at 10,000 to 30,000 kelvin, producing a superheated shock wave with instantaneous pressures reaching tens of atmospheres, which a lip around the circumference expands like a plug nozzle into thrust. The craft flies airbreathing to Mach 5 and 30 kilometres, then switches to laser thermal rocket mode on onboard propellant.Chapter 2, opening and Lightcraft Nanosatellite Configuration, pp. 11-12, 17-18
The performance case rests on what is not carried. The system is single-stage-to-orbit and completely reusable; the reaction mass in the atmospheric phase is free air, so almost no onboard propellant is needed except for final ascent and orbital manoeuvring; the vehicle specific impulse is essentially infinite, several thousand seconds in rocket mode; payload mass fractions are 50 to 95 per cent; and the majority of the system mass required to launch a payload to orbit is left on the ground as beam generators and their electrical power sources. Estimated launch costs are 20 to 600 dollars per kilogram of payload — two to three orders of magnitude below the level of the day — at a beam power requirement of 0.1 to 1 megawatt per kilogram of vehicle mass.Chapter 2, Summary of Technical Performance and Benefits, pp. 17-18
The orbital vehicle is sized. With the selected ground-based laser — 1.62 micrometre wavelength, 10 megawatts radiated, 10 metre aperture — Froning and Davis obtain a Lightcraft takeoff mass of 8 kilograms carrying 4 kilograms of propellant, placing roughly 4 kilograms into orbit, with airframe, propulsion and control masses of 0.63, 0.46 and 0.45 kilograms and a 30 per cent contingency. Because the propellant fraction is about half the takeoff mass, the resulting takeoff masses are roughly 45, 80 and 360 times smaller than a conventional rocket’s for placing 10, 5 and 1 kilograms into low Earth orbit.Chapter 2, Lightcraft Nanosatellite Configuration, pp. 19-20
The whole programme turns on one number: laser wavelength, and the beam power available at that wavelength. Captured power is extremely sensitive to wavelength, with 75 to 99 per cent of radiated power lost to thermal blooming, turbulence, extinction and diffraction over the roughly 500 kilometre slant range at cut-off. The wavelength that suffers least, 1.62 micrometres, belongs to the tunable free-electron laser, whose beam power stood at about 20 kilowatts — so a 500-fold increase is required to reach the 10 megawatts a 10-kilogram-class Lightcraft needs. The report names the path to watch: Navy 100 kilowatt free-electron laser designs proposed for prototyping in 2011 and 2012, scaling to 1 megawatt per unit, then beam-combined.Chapter 2, pp. 21-24, Figures 10 to 13
The report ends with a recommendation rather than a summary. The Air Force Research Laboratory concluded its laser Lightcraft propulsion programme at Edwards Air Force Base in 2005 before an orbital launch was demonstrated; the Air Force Office of Scientific Research is now funding the Brazilian Air Force’s hypersonic shock tunnel study of laser Lightcraft propulsion in collaboration with Leik Myrabo’s group at Rensselaer Polytechnic Institute. The author recommends that the Department of Defense, with NASA, return laser Lightcraft research to the United States and restart the space launch flight demonstration of the X-50LR Lightcraft originally proposed by Frank Mead.Chapter 5: Conclusion, pp. 69-70

The way in

https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_27-DIRD_Laser_Lightcraft_Nanosatellites.pdf

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

Defense Intelligence Reference Document, Defense Futures. DIA-08-1011-001, 01 November 2010 (IcOD: 30 August 2010), stated on its title page as one in a series of advanced technology reports produced in FY 2010 under the Defense Intelligence Agency Advanced Aerospace Weapon System Applications (AAWSA) Program. Released under FOIA and published by The Black Vault. AUTHOR. Withheld under FOIA exemption (b)(6). The report is written in the first person about the Froning and Davis Air Force study, cites that study as its principal source throughout, carries a private communication from Leik Myrabo, and closes with a personal recommendation to the Department of Defense — internal evidence that the author is Eric W. Davis, recorded here as an inference and not as an attribution. TEXT. The complete report runs about 30,000 words across five chapters. Reproduced below: the Summary, the overview and propulsion sections of Chapter 1, the whole of Chapter 2 (the laser Lightcraft propulsion content), the findings and mission conclusions of Chapter 3, the opening of Chapter 4 with the multi-megawatt laser design outline, and the whole of Chapter 5. The remaining nanosatellite subsystem specifications in Chapter 1, the detailed ballistic-missile-defence analysis and the swarm mission catalogue in Chapter 3, the laser hardware specifications and beam-control survey in Chapter 4, the five tables, and the thirty-five numbered references are omitted for length; the complete text is at the source. The document carries a copyright warning against further dissemination of its photographs, so the thirty-six figures are not reproduced; the captions that carry technical content are kept. Greek letters, exponents and inequality signs lost or mangled in the scan are restored and written out in words so the page renders.

How to cite it

DIA / AAWSAP contractor (2010) DIRD Laser Lightcraft Nanosatellites https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_27-DIRD_Laser_Lightcraft_Nanosatellites.pdf

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