October 23, 2012
HUNTSVILLE, Ala. — Work underway at NASA’s Goddard Space Flight Center on ways to service satellites in Earth orbit can help keep exploration crews alive much deeper into the Solar System, according to a manager of the effort.
Addressing the Wernher von Braun Memorial Symposium, sponsored by the National Astronautical Society, Deputy Project Manager Ben Reed of Goddard’s Satellite Servicing Capabilities Office said the same kind of work pioneered on the Hubble Space Telescope can give deep-space human-exploration vehicles the level of reliability needed for missions to near-Earth objects and eventually Mars.
“I think that paradigm is going to serve us well as we expand into the Solar System, using servicing as a technique for that high system reliability,” he told the gathering in Huntsville, Ala., last week.
Goddard’s Robotic Refueling Mission, an external testbed delivered to the International Space Station (ISS) by the final space shuttle mission last year, and extensive ground testing of related satellite-servicing systems, is advancing the technology readiness level in all of the areas that would be needed for underway inspection, maintenance and repair of a spacecraft that has moved past the second Earth-Moon Lagrangian point (EML2).
Beyond EML2, Earth-based teleoperation is impractical because of the time lag in command signals, Reed says. But robots teleoperated from inside a deep-space vehicle, or operating autonomously, could conduct inspections, servicing and repairs to stretch vehicle reliability without complex multiple redundancy.
Goddard’s goal is to mature the technologies needed for on-orbit satellite refueling in the geostationary orbit where valuable telecommunications satellites reside. But while NASA wants to turn that technology over to the private sector for commercial operations, it also can use it on human exploration missions.
Specific technologies under development are dexterous robotic manipulators; high-speed, radiation-hard, onboard processors; propellant storage and transfer; autonomous rendezvous; robotic arms, and advanced tools to manipulate the subject spacecraft and its components. Also in the mix are free-flying “inspectors,” like the “Spheres” software testbeds already at work inside the ISS that can image the outside of deep-space vehicles for damage.
“Forget the location; they’re all going to require the same common set of tasks,” Reed says.
One possible use for the technology would be the robotic assembly of a 30-meter telescope at the Sun-Earth L2 (SEL2) point, where the James Webb Space Telescope is scheduled to be deployed after a 2018 launch. The basic elements could be sent to SEL2 first, and autonomously assemble themselves into the basic telescope structure. The final assembly work could be conducted by a human crew arriving later with a deep-space habitat, with subsequent Hubble-like servicing missions possible.