By last August, engineers at MDRobotics had completed much of the testing on Dextre that NASA required. But the space agency wasn’t ready to give them the green light until it heard from a National Research Council (NRC) panel it had commissioned to evaluate the risks and costs of a servicing mission to Hubble.
The panel’s final report, released last December, more or less concluded that it was impossible for robotic technology to be developed in time to save the Hubble. The committee, which included robotics experts, Nobel-Prize-winning astronomers, and veteran astronauts, relied in part on an exhaustive evaluation done by the Aerospace Corporation, a federally funded R&D think tank based in El Segundo, California. That study concluded it would take five and a half years to ready a robotic mission—nearly double what it would take to prepare a shuttle mission, and longer than the telescope’s predicted remaining lifetime.
As a result, NASA killed the Hubble robotic servicing option outright—and, for that matter, a shuttle servicing mission as well. The decision to scrap the telescope angered astronomers, and was a blow to ambitious roboticists like Akin, who’d hoped to prove their stuff by rescuing one of NASA’s most prized possessions. But Akin and others are philosophical, and say that not getting a crack at servicing Hubble is only a short-term setback. They believe that as we extend our reach farther into the Solar System, robots undoubtedly will handle many repair and servicing tasks, help assemble spacecraft in orbit, and even build outposts on the moon and Mars. “We see [robotic] capability being required for future space missions anywhere,” says Dan King, director of robotics at MDRobotics.
In fact, some of the teams that proposed robots to fix Hubble are already pursuing technologies far more sophisticated than those imagined for the Hubble mission. At the Johnson Space Center in Houston, for example, engineers recently added a seven-jointed leg to their humanoid space robot Robonaut. With its new appendage, Robonaut can simulate climbing in zero G. It features a built-in CPU, five-fingered hands, and more than 150 sensors. Project engineers claim that it has dexterity comparable to that of a gloved astronaut and better range of motion. “Robonaut could light birthday candles on my kid’s cake,” quips former project manager Rob Ambrose.
“Humans in space will want to have excellent tools, and some of these will surely be robotic,” says Rud Moe, who manages the Hubble servicing missions at Goddard. “In other cases, the robots will serve very well where humans don’t dare to go—or can’t go.”
After outfitting ourselves in lab smocks, donning white shower caps, and inexplicably jumping up and down on a blue floor mat (I later learn it’s to discharge static), Paul Cooper, vice president of business development and R&D for MDRobotics, takes me inside the company’s 18,000-square-foot clean room. Three enormous Canadian flags hang from the rafters. “Don’t touch anything,” says Cooper, reminding me that even the slightest bit of static could short out one of the many electronic components carefully positioned on lab benches around the room.
The 3,600-pound Dextre robot is toward the back, where it’s suspended from a block-and-tackle rig that allows engineers to evaluate its performance in simulated zero gravity. “Repairing Hubble is such a noble mission, crossing the boundary of science and reaching into the public interest,” gushes Cooper, who stubbornly maintains that a robotic servicing mission would have been a viable option. “It’s not just some pie-in-the-sky design idea. Dextre really exists. And it has already been built and tested for the ISS.”
In Congressional hearings last Frebruary, members of the House Committee on Science questioned Cooper about the risks outlined in the NRC report—things like the time lag in robotically executing commands from Earth, and the feasibility of latching onto Hubble, which lacks a docking interface. Cooper pointed out that before a Hubble servicing flight would take place, other space missions would solve these technical challenges. Two such missions were launched this spring—NASA’s Demonstration of Autonomous Rendezvous Technology (DART) and the Air Force-sponsored XSS-11. Both were designed to prove that one spacecraft could meet up with another in orbit and work in close proximity, safely, with no human supervision.
“By the time we launch [Dextre],” Cooper argued in his testimony, “there’s going to be nothing left for us to do but actually go up there and do the mission, because everything we could possibly think of will have been covered by that point.” But DART had only mixed success, getting close to its target but then actually bumping into it.
Last summer, when robot rescue was still a possibility, astronauts and technicians at Goddard practiced maneuvers with Dextre on a life-size replica of the Hubble. The tests even simulated a two-second delay in Dextre’s response to human commands radioed from Earth. Cooper plays me a video from the Goddard shakedown that shows Dextre opening and closing panel doors on the Hubble mockup, twisting bolts, and yanking out power cords. Before Dextre can begin each task, it must switch the tool affixed to its “end-effector.” The device is similar to a dentist’s multi-tool driver: Dextre can swap out the heads—one for turning a screw, another for clamping onto a cable, a third for rotating a knob or opening a latch.