NASA engineers have taken a successful first step in showing they could service the Hubble Space Telescope using only robots, implicitly challenging NASA headquarters' insistence that Hubble will have to be abandoned because the controversial $470 million mission is too expensive and too difficult.
In an unpublished March 28 letter marking the end of a "preliminary design review" of the robotic proposal, review chairman Dennis B. Dillman, a NASA engineer, complimented Goddard Space Flight Center's Hubble team for an "extremely successful" presentation. "Congratulations are due for reaching this milestone in such [a] short time," the letter said, urging "robust support" in "resources and staffing" for the Hubble team.
NASA is planning to stop servicing the Hubble Space Telescope, but engineers have begun to show that a servicing mission could be unmanned.
The letter was completely at odds with the Bush administration's determination to abandon the mission, and the Hubble controversy seemed certain to come up during Senate confirmation hearings today on President Bush's nomination of Johns Hopkins University physicist and engineer Michael D. Griffin to become NASA administrator.
NASA's Mark Borkowski, the headquarters program manager for the Hubble Robotic Servicing Mission, said yesterday that the agency did not intend to let a robotic servicing mission proceed and had allowed the preliminary design review to go forward "because the folks [at Goddard] asked for the opportunity."
He also said some of the design work could prove useful in plans to send a spacecraft to dock with the telescope and eventually steer it into the ocean when it wears out. This project is regarded as essential to ensure that the Hubble does not come down in a populated area and will also give NASA new technology to allow unmanned spacecraft to rendezvous in space, useful in Bush's initiative to promote human spaceflight to the moon and Mars.
It was not clear whether the Goddard team or the reviewers intended to proceed with the robotic servicing project. Neither Dillman nor other members of the review panel or the Goddard team responded yesterday to requests to discuss Hubble's future.
The Hubble dispute arose more than a year ago when former NASA administrator Sean O'Keefe canceled the telescope's fourth space shuttle servicing mission, saying it was too risky after the Columbia tragedy.
Hubble, put in orbit in 1990, has produced a steady flow of spectacular images of the heavens for more than a decade, but without another servicing mission, the telescope can operate only until its gyroscopes or batteries give out, probably sometime after 2007.
O'Keefe's decision prompted an outpouring of protest, but by the middle of last year enthusiasm had kindled for a possible robotic servicing mission to be developed by Goddard and centered on the surprising skills of a Canadian-built stick-figure handyman known as "Dextre."
In early February, O'Keefe told Congress that the agency was abandoning the robotic mission, citing a National Academy of Sciences report that said the proposal was too difficult. "Even if we could do it, we probably could not do it in time," O'Keefe said.
Borkowski, in a telephone interview, acknowledged that "the president's budget reflected the decision" to abandon robotic servicing. Bush's "Vision for Space Exploration" has prompted funding cutbacks in several NASA programs.
Estimates from Goddard in February were that a robotic servicing and de-orbiting mission to Hubble would cost $1.364 billion, with the launch and de-orbiting spacecraft -- necessary with or without robotic servicing -- costing $894 million of that. Servicing itself would cost $470 million.
The preliminary design review took place at Goddard's labs in Greenbelt March 21 to 24. The reviewers were mostly from NASA centers across the country.
The Goddard engineers' efforts were "considered successful by the review team," Dillman's letter said. "The project . . . demonstrated that the proposed design meets requirements to proceed."
A successful "Critical Design Review," originally planned for September, would present the project's final design and start the clock running on spacecraft construction.
The reviewers called the project's staffing and organization "excellent" but cautioned that although "morale appears good, even in the face of uncertainty of the fate of this mission . . . a protracted decision on [robot servicing] versus de-orbit only will tend to erode morale."