A decision-making framework to determine the value of on-orbit servicing compared to replacement of space telescopes

Abstract

The Hubble Space Telescope has demonstrated that on-orbit servicing can provide significant benefits for scientific space programs. Specifically, servicing missions can replace failed components to keep spacecraft operational, and can upgrade onboard components to improve spacecraft performance. Hubble was able to capture these benefits because it was designed to be serviceable; however, many other programs have excluded serviceability from the design due to cost considerations. Often, the value of serviceability cannot be quantitatively justified. This thesis develops a framework to determine the value of including serviceability in a space telescope. Various principles to evaluate serviceability are proposed throughout the literature, and this thesis incorporates three main principles to construct the framework. First, the costs and benefits of servicing are separated so that the "cost" of servicing is expressed as the maximum price the customer is willing to pay. Second, the value of serviceability will be determined by comparing a telescope servicing program to a telescope replacement program. Third, the value of flexibility provided by servicing is analyzed by a Monte-Carlo simulation and decision rule analysis. A case study was performed to demonstrate how the framework is used, using representative data from Hubble. For a simple space telescope, the case study calculated the increase in science return gained by servicing and the maximum price for servicing missions. The case study illustrated an important trade between science return and risk of telescope downtime. Finally, the principles and techniques used in this framework are more generally applicable to non-revenue generating spacecraft.