NASA decided to scrap plans to service the Hubble Space Telescope without giving its engineers the chance they had been promised to show whether a pathbreaking mission to do the job with a robot handyman is feasible.
NASA's Mark Borkowski, program manager for the Hubble Robotic Servicing Mission, said yesterday that a March 21 "preliminary design review" intended to present the robotic mission design will now deal almost exclusively with plans to de-orbit Hubble so it will eventually fall harmlessly into the sea.
The decision to deny Goddard Space Flight Center engineers a chance to roll out their plan prompted incredulity even among those most skeptical about the feasibility of robotic servicing. It also promises to reignite debate over the fate of the telescope, an international icon for most of the 15 years it has been aloft.
"They're being stopped prematurely," said Joseph H. Rothenberg, the robotics expert from the National Academies of Science board, which late last year deemed "very low" the chances of a successful robotic servicing mission. "The Hubble is such an important asset that NASA should give it every chance."
Canceling the robotic mission was the latest, and perhaps fatal, shift in Hubble's fortunes, followed avidly by astronomy buffs as NASA decided a year ago to scrub a space shuttle servicing mission, then adopted robotic servicing as an alternative.
Without new financing, however, NASA's latest change of heart appears to leave Hubble fated to die in orbit around 2008, when its gyroscopes will wear out.
The Hubble design team is "very let down," Goddard Director Edward J. Weiler acknowledged in a telephone interview. "They felt they had a pretty good chance of pulling this robotic mission off. I share that opinion."
NASA Administrator Sean O'Keefe announced the long-rumored demise of robotic servicing Monday during presentation of the agency's 2006 budget request. He cited the National Academies of Science report as the principal reason:
The academies "view it as highly unlikely given the expense of the task and the effort necessary as well as their view [that] even if we could do it, we probably could not [do it] in . . . time," O'Keefe told reporters. He said the position has left "an incredibly difficult hill to climb to demonstrate the contrary."
But several federal government sources, some of whom spoke on the condition of anonymity because their views contrast with those of superiors, said the main reason to derail the plan was its estimated cost -- $1 billion to $2 billion by 2007 to replace the gyros.
"There's no question that fiscal constraints are part of the problem," said David Goldston, chief of staff of the House Science Committee, which held a hearing on Hubble last week. He noted that a de-orbiting mission would cost about $500 million. It could be spread over eight or nine years because the spacecraft would not need to arrive in time to save the gyros, which the telescope uses to point accurately at the targets it observes.
The sources also noted that a servicing visit by the space shuttle -- recommended by the academies -- would mean an extra flight for an orbiter fleet committed to finishing construction of the international space station by 2010 as the first step in implementing President Bush's initiative to explore the moon and Mars.
Controversy over Hubble arose a year ago when O'Keefe announced that NASA was canceling a shuttle servicing mission to Hubble because it was too risky for astronauts after the 2003 Columbia disaster.
Shuttle astronauts have serviced Hubble three times since it was put into orbit in 1990. They added new instruments, made repairs and did maintenance that ensured a steady stream of spectacular images and science.
O'Keefe's announcement triggered an uproar, but he has stood by his shuttle decision. He reaffirmed it Monday even as he prepared to leave the agency -- probably next week -- to become chancellor of Louisiana State University, in Baton Rouge.
But as 2004 progressed, enthusiasm grew within NASA for a robotic servicing mission composed of the de-orbit module, a grappling arm to seize the telescope during docking, a module to carry spare parts and tools, and a Canadian-built robot known as Dextre.
NASA let a $330.6 million contract to Lockheed Martin for the de-orbit module and a $154 million contract to MDA Space Missions of Brampton, Ontario, for Dextre and the grappling arm. By November, Goddard engineers had become convinced that Dextre could do the required maintenance jobs and instrument swaps. The preliminary design review next month was to have been the first test of the concept.
MDA Space Missions Vice President Paul Cooper noted in a telephone interview that Dextre, designed for the space station, is built and ready to go to space, and "if you're going to do a [Hubble] de-orbit anyway, why not take a shot at fixing it?"
But Rothenberg, a former NASA associate administrator for spaceflight, said Dextre "is not the problem." Goddard must put together all elements of the mission, and although the academies' study did not think this could be done quickly enough, the engineers "need an opportunity" to prove the contrary, he said.