With new batteries, gyroscopes and a pair of new science instruments, astronomers hope to extend the 14-year-old Hubble’s life through 2013.
In mid-January, when National Aeronautics and Space Administration administrator Sean O’Keefe declared plans for a fifth space shuttle-led repair mission too risky, the agency scrambled to satisfy Hubble’s outraged supporters in Congress, the science community and the public.
robonexus robotSo NASA Hubble managers turned to MD Robotics, a suburban Toronto company that began the development of the shuttle’s robot arm nearly 30 years ago. Most recently, the company developed the space station’s 57-foot-long mobile construction crane.
As O’Keefe weighed the risks of mounting a mid-2006 shuttle mission to Hubble in the aftermath of last year’s loss of the shuttle Columbia, MD Robotic’s Special Purpose Dextrous Manipulator - also known as Dextre - was awaiting launch to the space station in 2007. Now, it could be headed to Hubble in 2007 instead.
A leggy device that resembles a giant mechanical spider, Dextre was developed as an orbital handyman able to be fitted to the end of the space station’s construction crane. Among its expected duties is the changing of failed external electronics components, tasks that would otherwise require repairs by spacewalking astronauts.
Because the Hubble requirements are remarkably similar, NASA announced last month that Dextre is the leading candidate to save a telescope that - unless it’s repaired - likely won’t survive past 2008.
“There is not enough time to do a research and development project to do the (Hubble) mission,” said Paul Cooper, MD Robotics vice president for research and development. “NASA’s only real choice was to poll industry. There was only one company that had already built, designed and flight qualified a robot with the capabilities of doing the tasks, and that was Dextre.”
NASA considered other robotic devices - including one being built at NASA’s Johnson Space Center - but Dextre’s advanced development and the flight-proven history of its robotic siblings on the shuttle and station gave it an edge, according to Al Diaz, NASA’s associate administrator for space science. Work on Dextre began seven years ago.
“I think the conclusion we reached is the special-purpose dextrous manipulator is probably closest to being able to be ready in time,” Diaz recently said.
In ground tests using a Hubble mockup at NASA’s Goddard Space Flight Center in Maryland, Dextre has demonstrated an ability to disconnect and reconnect power cables and remove and replace science instruments.
During a repair mission, Dextre would be operated by an astronaut or an engineer posted at a control console at Goddard, which serves as Hubble’s Mission Control.
Critical Hurdles Ahead
But before NASA can launch a robotic repair mission, it has several significant hurdles to clear:
- A government-funded think tank to assess the robotic strategy’s chances of success. A final report from the National Research Council will be issued in late October, but the research council has already urged O’Keefe to not rule out repairs by a space shuttle crew.
- White House must persuade lawmakers to amend NASA’s 2005 budget by at least $ 1 billion to accommodate the cost of a Hubble repair mission.
- The robotic repair effort must pass NASA’s so-called “critical design review.” The test is planned for sometime next summer.
While the Canadian hardware has an impressive record of success, Dextre and the complex procedures required for the Hubble tasks have not been demonstrated in space, experts said. Until they are, NASA runs the risk of an expensive failure, said Jerry Grey, science and technical director for the American Institute of Aeronautics and Astronautics.
For now, the robotic overhaul would require the launch of an unmanned rocket equipped with two modules and the electronic equipment needed for an automated rendezvous with the 360-mile-high telescope. The repair spacecraft would maneuver alongside the orbiting telescope. Responding to commands from a ground control team, the craft would reach out and carefully grab the Hubble using a robot arm.
The mechanical limb, also developed by MD Robotics, would link the telescope and the repair spacecraft for the repair session that likely would take several weeks.
Dextre’s most difficult task could be installing a science instrument that would require it to open a large bay in the tail of the telescope.
Though the robot has successfully demonstrated the task in a ground simulation, spacewalking shuttle astronauts have wrestled with closing those doors in the past.
Among the other candidates for the Hubble task was Johnson Space Center’s Robonaut. The human-like mechanical device will serve as Dextre’s understudy. It could be used on future space shuttle test flights or could join future human explorers bound for the moon or Mars.
Though it lacks Dextre’s spaceflight heritage, Robonaut recently demonstrated the ability to use a power tool in response to voice commands and can climb along the outside of a spacecraft by grasping hand rails.
“While I can’t go back in time, I can go forward and make sure that five to 10 years from now, we have a robot that has matured to the point that we can answer whatever the next call is,” said Rob Ambrose, manager of the Robonaut project. “Who knows what it will be?”
Copyright 2004 The Houston Chronicle Publishing Company
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