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AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

U.S. Department of War · 2010-11-01 · 77 pages · text from the file's own layer

This Defense Intelligence Reference Document (DIA-08-1011-001), dated 1 November 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications program. It covers nanosatellite technologies, laser Lightcraft propulsion, a weapon mission selection study and a multi-megawatt laser study. The author recommends that the Department of Defense, working with NASA, bring laser Lightcraft propulsion research back to the United States and restart the Air Force X-50LR test flight program.

From the source:Release of 2026-09-18 Incident: 11/1/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines laser-propelled “Lightcraft” as a possible low-cost method to launch very small satellites into low Earth orbit by using a remote high-energy laser to supply most of the propulsion energy rather than relying entirely on onboard energy sources. The report combines a survey of nanosatellite trends with a review of “Lightcraft” propulsion concepts, vehicle design, beam-control requirements, and mission studies, and argues that the most promising application is the launch of nano- or pico-satellites, especially Earth- and space-observing payloads of a few kilograms or less. It presents the concept as potentially much cheaper than conventional multistage rockets for very small payloads, while also noting significant practical constraints including strict beam-riding geometry, atmospheric losses, demanding pointing and adaptive-optics requirements, and heavy dependence on large ground-, sea-, or air-based laser infrastructure. Overall, the document presents laser “Lightcraft” as a technically plausible launch concept whose attractiveness depends on whether the supporting laser and beam-control system can be made reliable and economical at operational scale.

UNCLASSIFIED/;'POR: OPPICIAE USE 014Lf
• 11 = 1: this is the conversion efficiency of laser rocket propellant-thrust-jet KE into
vehicle KE, in which the propellant/laser is designed so that the rocket thrust-jet
velocity is equal to the vehicle velocity throughout the mission, i.e., the laser
rocket has variable lsp "" 100 seconds at beginning of mission to 1000 seconds at
end of mission;
• ap = 0. 5: a is efficiency of laser energy absorption and p is efficiency of
conversion of propellant internal energy into thrust-jet KE;
• y = 0.7: this is the atmospheric transmission efficiency;
• Eiaser = 750 MJ.
These numbers multiplied together give a vehicle KE = 262.5 MJ in LEO. If the effective
change in velocity (~v) required to get to LEO is 10 km/sec (8 km/sec orbital velocity +
1 km/sec for gravity + 1 km/sec for drag loss), then 1 kg in LEO has SO MJ of energy
investment and a 5.25 kg payload in LEO has 262.5 MJ of energy investment.
The 60 kg/sec mass flow requirement of the 3: 1 N2/CO2 lasing gases means that a
mass flow of 15 kg/sec of CO2 and 45 kg/sec of N2 is required. For the 300 seconds of
thrust we will therefore need 4.5 tons of CO2 and 13.5 tons of N2 gases (we are
neglecting the tiny amount of H2) to launch a payload to LEO. Liquid CO2 costs $100
per ton and liquid N2 costs $154 per ton. The total lasing gas cost is therefore $450 for
the liquid CO2 and $2,079 for the liquid N2. Adding these two gas fuel costs to the $104
cost of the required electrical energy gives a total of $2,633 to launch a 5.25 kg
payload to LEO. This result represents a cost of $501 per kg of payload (or $228 per
pound) launched to LEO, which is 44 times lower than the oft-quoted standard space
launch industry cost of $10,000 per pound for conventional chemical propulsion rockets
systems.
However, this cost figure needs to be slightly adjusted to account for other factors. If
we use the N2/CO2 gases at a temperature of 217 Kin the laser, then we will have to
boil the liquid CO2 and the liquid N2 with additional heating of the gaseous N2. Boiling
4.5 tons of liquid CO2 at 217 K requires 1,175 MJ of energy, boiling 13.5 tons of liquid
N2 at 77 K requires 2,683 MJ of energy, and heating the 13.5 tons of gaseous N2 from
77 K to 217 K requires 1,890 MJ of energy. Therefore, the additional energy required
to prepare the laser gases is 5,748 MJ (= 1,175 MJ + 2,683 MJ + 1,890 MJ), which
represents an additional electricity cost of $160. Adding this additional energy cost to
the previous total of $2,633 gives a final total cost of $2,793 to launch a 5.25 kg
payload to LEO. This new final result represents a cost of $532 per kg of payload (or
$241 per pound) launched to LEO, which is 41 times lower than the space launch
industry cost of $10,000 per pound for conventional chemical propulsion rockets. Note
that this final cost estimate excludes the operations, life-cycle, and maintenance costs
that are listed in Table 1, which were based on the use of a bulk solid-state laser.
UNCLASSIFIED'I i'FAA: 061i1Clali.k W&& 8PtLY
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 77 pages are in the text index: search them above, or from the library's search.