It's not exactly a Mountie in a red coat, but the most-likely rescuer for the imperiled Hubble Space Telescope does appear to be a Canadian - a gawky robot named Dextre.
NASA officials said yesterday that Dextre - formally the Special Purpose Dextrous Manipulator - has demonstrated to engineers at the Goddard Space Flight Center in Greenbelt that it's fully capable of replacing Hubble's failing hardware and installing two new scientific instruments.
Unless an engineering showstopper emerges between now and a critical decision point next summer - or Congress denies the funding - Dextre could ride to Hubble's rescue sometime in 2007 or 2008. That's when scientists think critical components on the telescope could begin to fail.
"It has the ability to do as much as we think is necessary to do most of the jobs we've recognized need to be done," said Al Diaz, associate administrator of NASA's science mission directorate.
MD Robotics, the Toronto-based company that also developed robot arms for the space shuttles, expressed full confidence in Dextre - a headless, 6-foot-6-inch trunk with 11-foot arms. "Basically we're taking a flight-qualified design and generating a copy of it. So it's ready to roll," said Paul Cooper, the company's vice president for business development.
With engineers getting the go-ahead to design a robotic mission, the option of sending astronauts on a space shuttle to fix and upgrade Hubble appears clinically dead.
Diaz insisted the space agency is still complying with a recommendation from a National Academies science panel that NASA "do nothing to preclude" a manned repair mission. But he conceded that "there is no work that is being directed to actively pursue that."
Diaz refused to confirm news reports Monday quoting NASA Administrator Sean O'Keefe as estimating the mission's cost at $1 billion to $1.6 billion - a figure certain to catch Congress's eye. "I don't recall him saying that, and I'm not going to speculate about it," Diaz said.
NASA has issued no official cost estimate for a robotic expedition to Hubble. Diaz said that won't happen until the plan is fully developed and NASA completes consultations with the Bush administration and with Congress.
Shuttle mission canceled
Hubble's fate became the focus of a national debate in January when O'Keefe announced he was canceling a planned shuttle servicing mission in 2006. He cited astronaut safety concerns expressed by a panel that investigated the Columbia shuttle disaster.
Astronauts assigned to that servicing mission were to replace worn-out batteries and gyroscopes needed to keep the observatory alive. They were also to install two new scientific instruments that have already been built at a cost to NASA of $167 million.
An outcry from astronomers, some lawmakers in Washington and Hubble's other fans eventually led O'Keefe to consider other options. In the spring, he asked engineers to study the feasibility of a robotic rescue mission. They in turn called for ideas from the space industry and from academia. The results have been so positive that O'Keefe urged engineers at Goddard on Monday to press toward a final "go or no-go" decision next summer.
Designing and building a robotic rescue mission will not be easy, Diaz said. "But he [O'Keefe] told the team that if it wasn't complex or difficult it might not be the kind of thing NASA ought to be doing."
There's not much time, either. If Hubble's batteries aren't changed within 3 1/2 years, Diaz said, they're likely to fail, crippling the observatory.
Two other robotic candidates for the job - NASA's own Robonaut and the University of Maryland's Ranger system - were judged to be insufficiently developed to tackle the job on such short notice.
That's where Dextre came in. Developed for the Canadian Space Agency, its task was to serve as the business end of a "Mobile Servicing System" to be mounted on the International Space Station.
NASA wants to attach the original Dextre to a mobile platform on the space station's main truss. By moving it up and down the rails, astronauts can reach out to key electronics boxes and replace them without a risky space walk.
Dextre is in a clean room near Toronto awaiting a shuttle ride to the space station. That mission was scheduled to blast off in 2005, but the Columbia accident in 2003 has postponed the flight until at least 2007.
NASA believes that a near-duplicate - mounted at the end of a slender, 39-foot grapple arm that can reach any spot on Hubble - could be built quickly to service the telescope.
While other manufacturers submitted robotic servicing proposals to NASA last month, Diaz said the space agency has indicated that it will seek a "sole source" procurement contract with the Canadian firm that built Dextre.
Cooper said a full-scale, Earth-bound version of Dextre has undergone extensive testing since late April on a detailed Hubble mockup in Goddard's "clean room."