"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.
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