"NASA should take no actions that would preclude a space shuttle servicing mission" to extend the life of the Hubble Space Telescope, an independent panel told the space agency on July 13. This was one of the interim recommendations of a National Research Council (NRC) committee tasked with evaluating the feasibility, risks, and comparative benefits of a servicing mission to extend and enhance the scientific life of the telescope, either by space shuttle or by some robotic or ground-based alternative. The committee urges NASA to "commit to" some form of servicing mission to the Hubble, which it calls "arguably the most important telescope in history." Additionally, it concludes that the findings of the Columbia Accident Investigation Board (CAIB) do not preclude a possible servicing mission by astronauts using the space shuttle.
The Hubble was launched in 1990, with a planned 15-year mission life. It has been repaired or upgraded four times, and NASA's current plans call for it to be robotically de-orbited in 2013. After the Columbia tragedy, the grounding of the space shuttle fleet, and the report by the CAIB, NASA Administrator Sean O'Keefe decided for safety reasons to cancel future shuttle servicing flights to the Hubble. The next servicing mission, planned for 2006, would have replaced batteries and gyroscopes and enhanced the Hubble's scientific capabilities, the committee's report says, "by allowing qualitatively new observations in two underexploited spectral regions." Outcry over the cancellation from scientists, Members of Congress, and the public, and calls for an independent assessment of the situation, ultimately led O'Keefe to ask for an NRC review of the options.
The NRC committee was charged with assessing the viability of a human servicing mission; evaluating possible robotic and ground-based servicing options; assessing the likelihood and impact of Hubble component failures; and providing a risk-benefit assessment of servicing options and whether any would be "worth the risks involved." The committee was also asked to consider "the practical implications of the limited time available for meaningful intervention." Recognizing that the potential for age-related instrument failure on the Hubble lends "some urgency" to the issue, the NRC committee issued its interim findings and recommendations in the form of a July 13 letter to O'Keefe from Committee Chairman Louis Lanzerotti.
A significant portion of the letter describes the telescope's "extraordinary" contributions to science. The committee finds that, with a servicing mission, the Hubble will continue to provide "compelling scientific returns." Therefore, it calls on NASA to commit to a servicing mission that would accomplish the same scientific instrument, battery and gyroscope replacements originally planned for the cancelled shuttle mission.
Secondly, the committee finds that a robotic servicing mission would involve a high level of "complexity, sophistication, and technology maturity," and notes that "there has been little time for NASA to evaluate and understand the technical and schedule limitations of robotic servicing." It urges NASA to immediately "take an active partnership role" in robotic space technology demonstration activities of other federal agencies.
While acknowledging that "there is risk to the astronaut crew in any human flight mission," the committee "concludes that a shuttle flight to the [Hubble] is not precluded by or inconsistent with the recommendations" of the CAIB and other advisory groups. The committee finds that "the key technical decision points for committing to a specific service scenario are at least a year in the future," but believes that "there would be little additional investment in time and resources required over the next year for NASA to keep open an option" of a crewed shuttle servicing mission. "Until the agency has completed a more comprehensive examination of the engineering and technology issues" of robotic and human servicing options, the report states, "NASA should take no actions that would preclude a space shuttle servicing mission."
The committee hopes that its interim report will "provide useful guidance to NASA that can be utilized during the time that the committee (as well as NASA) continues to investigate the servicing options in greater detail." It plans to finish drafting its final report by the end of summer or early fall. The committee's interim letter to O'Keefe can be viewed in pdf format at http://books.nap.edu/html/Hubble_Space_Telescope/letter_report.pdf.
Several Members of the House Science Committee issued statements commending the committee for its work so far. The Ranking Minority Member, Bart Gordon (D-TN), praised the committee for its "clear and timely guidance to NASA and Congress," and Chairman Sherwood Boehlert (R-NY) declared, "I wholeheartedly endorse its recommendations."
In his response to the letter, O'Keefe called the space telescope "a national treasure" and pledged to "keep options open to assure the best possible outcome." He noted that "the challenges of a robotic mission are under examination and we'll continue our exhaustive and aggressive efforts to assess innovative servicing options." While promising that "we're committed to doing everything possible to safely extend the scientific life of this valuable asset," he made no explicit reference to the committee's findings regarding a possible shuttle mission.