AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

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ground, sea and air launches of Lightcraft to LEO with air launch occurring at either
subsonic or hypersonic speed.
Lightcraft Ground/Sea to Space Investigation
The current Air Force Lightcraft vehicle concept has been designed for not only placing
nanosats into LEO at low cost (Figure 14 ), but also for performing much of the nanosat
function as well. In this concept the precision optics system that focuses ground/sea­
based laser light into the Lightcraft's cowl area for propulsion is also used as a space
telescope for viewing military targets on Earth and in space. And structural panels on
the Lightcraft forebody are also used as solar panels that are unfurled in orbit for
generation of satellite power. Thus, the current Lightcraft's design allocates only 0.1 kg
of its 1.0 kg dry mass for exclusively nanosat functions. There is a military need for 1.0
kg to 2.0 kg nanosats with optical sensors for visual inspection of unknown objects in
space and on Earth.
Since conventional expendable rockets could conceivably be an alternative to laser­
powered Lightcraft for the rapid placement of military nanosats in LEO, a cursory
comparison of Lightcraft and conventional rockets was made by Froning and Davis [26]
to get some idea of their comparative costs. Hybrid rocket sizing and costing was
based upon tactical strategic missile sizing and costing information possessed by H. D.
Froning. This information related costs (in 1982 dollars) to rocket and payload
characteristics. Lightcraft sizing assumed a propellant mass fraction of 0.5 and 1.0 MW
of laser power per pound of payload (dry mass) placed into orbit. Costs for laser power
and refurbishment were based upon AFRL estimates (amortized over a fewer number of
flights). Although these Lightcraft and laser costs are higher (based upon much fewer
flights) than those of previous AFRL estimates, they are believed to be consistent with
the conventional rocket costs, and therefore applicable for relative cost comparisons.
More detailed future Lightcraft/conventional rocket designs and cost comparisons are,
of course, needed before a strong argument can be made for either design.
Shown in Table 2 is the estimated performance and weights (masses) for 3-stage
hybrid rocket launch vehicles and single-stage laser-powered launch vehicles that are
capable of placing nanosats of 1.0 kg, 5.0 kg, and 10 kg into LEO. And Table 3 shows
estimated costs for hybrid rockets and laser-powered Lightcraft assuming 100 flights
over a 10-year period. These estimated costs indicate that Lightcraft could boost
nanosats in the 2.0 kg to 5.0 kg range into LEO at about 1/l0th to 1/5th the cost of
expendable rockets. But Lightcraft cost superiority over conventional rockets is less
overwhelming for satellites that are significantly heavier. Thus Lightcraft appear
extremely attractive for satellite delivery missions only if Lightcraft dry masses,
including the satellites being carried, are less than about 5.0 kg.
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