Secondary and Hosted Payloads in the 2013 National Space Transportation Policy: A NASA Case Study

Abstract

Many spacecraft do not utilize the full capacity of the launch vehicle that places them in orbit. One concept for utilization of this unused launch vehicle capacity is the inclusion of secondary and/or hosted payloads (SHPs), possibly enabling low-cost access to space. Preliminary analysis shows that historically SHPs were infrequently used. The U.S. government's recently released National Space Transportation Policy mandates that agencies explore the use of SHPs to meet government requirements. NASA was identified as a sample agency where the impact of changing policy to follow the National Space Transportation Policy's guidelines could be assessed. In this article the potential of SHPs on NASA missions is examined by analyzing past launches and estimating the unused launch vehicle capacity. By evaluating the difference between the launch vehicle capacity and payload mass, the unused capacity was calculated. This simple method gives an upper bound and does not take into account many factors that would prevent the inclusion of SHPs. It was determined that 39,600 kg of payload capacity was unused on NASA missions between January 2006 and August 2013. The value of this capacity was calculated as $663 million by using methods from a previously published study of space transportation costs.