NASA Secondary Payload Plans, Policies and Requirements

Whenever there is excess launch vehicle capacity on either the Space Shuttle or an expendable launch vehicle (ELV), a logical spinoff is to carry a secondary or piggyback payload and provide a relatively low-cost flight opportunity for small satellites, instruments or experiments. NASA typically deploys moderate to large spacecraft as primary payloads on either the Space Shuttle or ELV's in support of the Agency’s scientific, planetary and technology objectives. NASA has flown over a dozen piggyback payloads on the Delta rocket in the past. The Small Expendable Deployment System (SEDS) experiment, originally baselined for launch on the Shuttle, is currently planned as the first in a series of small NASA space experiments launched as a piggyback on an ELV. Small research and commercial payload owners have a variety of ways to access space: on a dedicated small ELV, as a secondary payload on the Space Shuttle, or as a piggyback payload on an ELV. This paper provides an overview of the secondary flight opportunities available today along with an overview of NASA's secondary payload plans, policies and requirements. NASA's initiative to act as a clearinghouse for small payload launch requirements is also presented.