Utilizing Excess Capacity of Current Launch Vehicles to Lift Secondary Payloads

Spacelift is a precious commodity that should never be wasted. Taking advantage of excess capacity on space launch vehicles is crucial to orbiting as many satellites as possible and is sometimes also the only path to orbit for many small and low-priority payloads. There have been many attempts to utilize this excess capacity over the years. Recent successes include the EELV secondary payload adapter (ESPA) and the manifesting of small secondary payloads on Minotaur and Falcon I launch vehicles. In most cases, the process of adding secondary payloads to an existing launch mission is problematic due to a variety of reasons including politics, funding, compatible requirements, and availability of crucial tools such as multi payload adapters. This paper will examine the factors that impact the development of multiple manifest launch missions. In particular it will identify the various types of secondary payloads that have been flown, outline the history of adapter development for smaller payloads, and identify the critical elements necessary to successfully manifest multiple satellites on one launch vehicle. Finally, this paper will outline a successful process to put small secondary payloads on all Minotaur launch vehicles and identify a growth path that others can follow to take advantage of excess launch capacity most efficiently.