Low-Cost Launch of Payloads to Low Earth Orbit

Abstract

CRITICAL factor for the viability of a sustained human presence in space is launch cost. The exploration vision brings a heavy lift requirement for thousands of metric tons of propellant and hardware to establish, resupply, and expand moon and Mars bases. Because the basis for the exploration effort is guided by budget limitations, it is expected that the development of off-planet infrastructure will be chiefly driven by launch dollars per kilogram. High launch costs have a multiple budgetary impact. With present heavy lift technology, launch costs are in the range of $6000‐ $20,000/kg. Because high launch costs severely constrain system mass, ultralightweight reliable structures and payloads must be developed at high cost. Consequently, budget limits and high launch cost determine the scale of the entire exploration effort. Cost Model An empirical cost model described here predicts that launch costs can be sharply reduced by employing existing aerospace technology. The genesis of the cost model is the observation that the operating cost of high-power systems is not dictated by delivered energy but by peak system power. Electric utilities, for example, charge residential customers in energy units of kilowatt hours, but charge high-peak-power customers for the transmission lines and switching costs dictated by maximum-peak-power load. We have applied this paradigm to aerospace vehicles for which operating cost and performance data are available, 1 as plotted in Fig. 1. The plotted cost for fixed-wing aircraft is based on the operating cost for maximum load carried to maximum range. For boosters, operating cost is based on launch cost to low Earth orbit. The operating power for aircraft is taken for cruise conditions, where power is equal to drag multipled by cruise velocity. Operating power for boosters is taken as peak power for vacuum conditions, where power in terms of vacuum thrust and exhaust velocity is P = (1/2)( TU e)vac.