TABLE 1.1 Satellite Launch Characteristics Showing Satellite Type and Associated Orbits, Launchers, and Effective Average Launch Rates
|Satellite Type||Orbit Requirement||EELV Used||Average Annual Rate|
|Communications||GTO||Atlas V 531||0.64|
|Atlas V 501
Delta IV M
|Navigation||MEO||Atlas V 401||1.96|
|Missile warning||GTO SSO||Atlas V 411
Delta IV M
|Intelligence||LEO (high inclination)||Delta IV M+(4,2)||0.20|
|LEO (high inclination)||Delta IV H||0.29|
|LEO (high inclination)||Atlas V 541||0.20|
|HEO||Atlas V 551||0.29|
|Polar||Delta IV H||0.29|
|Polar||Atlas V 401||0.16|
|GTO||Delta IV M+(5,4)||0.50|
|GEO||Delta IV H||0.50|
|Average annual launch rate||8.00|
NOTE: EELV, Evolved Expendable Launch Vehicle; GEO, geosynchronous Earth orbit; GTO, geosynchronous transfer orbit; HEO, high Earth orbit; LEO, low Earth orbit; MEO, medium Earth orbit; SSO, Sun-synchronous orbit.
SOURCE: Air Force Space and Missile Systems Center, SMC Developmental Planning, “Reusable Booster System Costing,” presentation to the committee, February 15, 2012. Approved for Public Release.
lower launch costs, while maintaining the reliability achieved by EELVs, considering the average launch rate of only approximately eight per year distributed among the missions shown in Table 1.1.
The proposed RBS must accommodate the reliable and cost-effective delivery of the manifest in Table 1.1 via appropriate vehicle designs and ground infrastructure/operations capabilities. After analyses3 by the Air Force and the Aerospace Corporation, the RBS was proposed as an approach to meet overall launch requirements. The concept of operations (CONOPS) for the RBS is shown in Figure 1.1.
An essential feature of the RBS is that it uses reusable first stages and expendable upper stages. For reasons of operational efficiency and performance, the first stage would employ an oxygen-rich, staged-combustion (ORSC) cycle engine with liquid oxygen and kerosene-type propellants. The baseline expendable upper stage uses liquid hydrogen and oxygen propellants. A solid motor is added as a final stage to the expendable upper stage for the most energetic missions. As will be explained in Chapter 2, the staging velocity, where the first stage and second stage separate, is selected to minimize overall costs and maximize operational efficiency. This is unlike the usual selection criterion for fully expendable launch vehicles, which is to maximize delivered payload and is a critical characteristic of the RBS concept.
No alternatives to RBS-based launch approaches were presented to the committee; however, credible opportunities may soon be available that meet or exceed the Air Force goals for launches of EELV-class payloads. The U.S.
3 K.R. Hampsten and R.A. Hickman, Next Generation Air Force Spacelift, AIAA 2010-8723, paper presented at the AIAA Space 2012 Conference and Exposition, Anaheim, Calif., August 30-September 2, 2012. This meeting was unrestricted and open to the public.