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Robots to the rescue for the ailing Hubble?

Space: A team at the University of Maryland, College Park has developed a robot called Ranger that could help extend the life of the imperiled orbiting telescope.

May 01, 2004|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Since 1980, a decade before he moved his lab to Maryland from the Massachusetts Institute of Technology, Akin and his colleagues have worked with NASA to develop robotic systems that could maintain satellites in orbit.

`A wonderful example'

Recent research at College Park suggests that more than $1 billion worth of commercial, military and scientific satellite "assets" are lost each year to premature breakdowns. "That is the market," Akin said. "Hubble is a wonderful example."

Because Hubble was designed to be repaired in orbit by astronauts, Akin used the telescope, and the experience of those who have worked on it, as the "gold standard" for his robot.

"If humans and robots could do the same tasks, you had a more robust system," he said. So Ranger evolved as a pair of highly dextrous arms with a varied set of interchangeable tools for "hands." And it's all sized to go where astronauts' hands and arms go.

The arms are atop a single flexible "leg" with a "head" equipped with a stereo camera.

In Akin's most optimistic assessment, Ranger would be mated to an upper-stage rocket platform called the Interim Control Module (ICM), developed by the Naval Research Laboratory in Washington.

A version of the ICM has reportedly proved itself in classified "black" missions for the military, Akin said.

A 6-ton Ranger-ICM package carrying batteries, gyros and new instruments for Hubble would be launched into orbit atop an Atlas or Delta rocket. The ICM would fly Ranger to Hubble and dock to its base, using the same mating hardware flown on the shuttle.

Guided by astronauts and engineers on the ground, Ranger would unfold itself, methodically open Hubble's access doors, then disconnect and replace the old hardware and instruments.

"It opens the doors and does it pretty much the way the astronaut does it," Akin said. It could also rotate the telescope, and reach every serviceable part.

Ranger could not remain attached to Hubble without interfering with the telescope's scientific work. So, after boosting the telescope to a higher orbit, it would fly some distance away, ready to return with additional spare parts if needed. When the time came, it could guide Hubble to a safe re-entry.

Akin conceded that Ranger, as a university project, lacks the redundant, "fail-safe" systems that aerospace companies are expected to provide. "But we have more than 1,000 hours on the robot, and it hasn't failed," he said. "It's really good hardware."

Akin calculates that NASA could fly the entire Ranger mission for $300 million or less. That's far less than the $500 million-plus cost of a shuttle servicing mission.

He said he knows of two other systems that are competitive with Ranger. One is a "humanoid" NASA robot with five-fingered hands. The other is the Special Purpose Dextrous Manipulator (SPDM), developed by a contractor for the Canadian Space Agency for use aboard the International Space Station.

SPDM is as close to being ready as Ranger is, Akin said. But he argues that the Canadian robot's "hands" might be too large for work on Hubble and that it lacks the flexibility of Ranger's interchangeable tools. "Sort of like doing repairs with wastebaskets for hands," he said.

At NASA headquarters, Moore said the agency is likely to issue a formal request for proposals next month, detailing its vision for a robotic Hubble rescue and soliciting competitive responses from the robot builders.

With preliminary findings from the Hubble assessment committee expected by late summer, he said, O'Keefe could be ready to make a go or no-go decision by the end of September.

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