The Hubble-Shuttle Linkage and the Future of Space-Based Astronomy

Abstract

When NASA Administrator Sean O’Keefe announced the cancellation of Servicing Mission 4 (SM4) of the Hubble Space Telescope (HST), scientists and politicians were outraged. A decision that could shorten the lifetime of this enormously successful observatory initially seems difficult to justify. However, a close examination of the history of the HST and its linkage to the Space Shuttle reveals that the decision was the right one for the future of both space-based astronomy and human spaceflight. By avoiding the pitfalls of connecting these two separate enterprises, NASA will be better able to implement the Vision for Space Exploration. Using Hubble as a case study, this paper demonstrates from a programmatic and a scientific perspective the weaknesses inherent in linking space-based astronomy to human spaceflight. Although the four servicing missions conducted so far have greatly augmented the scientific value of the HST, the telescope has encountered numerous setbacks because of its dependence on the Shuttle. Furthermore, with or without the SM4 upgrades made, Hubble will not survive long enough to serve as an adequate complement to the James Webb Space Telescope (JWST). A Next-generation Hubble Space Telescope (NHST) will be needed when the JWST’s planned five-year mission ends in 2016. The cancellation of SM4 could spur the development of such a telescope. Even if efforts to service Hubble robotically are not fully successful before the telescope goes dark, robotic servicing capabilities will have been developed for the NHST and other future space telescopes. The cancellation of Hubble Servicing Mission 4 signifies the end of an unnecessary linkage between human spaceflight and space-based astronomy. By removing this dependency as soon as possible, NASA will be able to reserve the costs and risks associated with human spaceflight for those activities for which humans are best suited – the exploration and development of the inner solar system.