The technical wizards behind last May’s fifth and ostensibly final servicing mission to NASA’s Hubble Space Telescope have been keeping busy planning an in-orbit satellite refueling demonstration that with a little luck — and support from the agency’s upper echelons — could be blazing an important trail by this time next year.
Engineers at NASA’s Goddard Space Flight Center are working to meet an end-of-the-year schedule for delivering 300 kilograms of experimental flight hardware to Cape Canaveral, Fla., for delivery to the international space station. The hardware consists of a mock satellite and the tools needed to demonstrate that controllers in Houston can command the space station’s specially equipped robotic arm to grapple and refuel a satellite with inert propellant to specified volume and pressure level. Astronauts onboard the space station will have no part in the experiment beyond that of passive observers.
Preparations for the demo, including building and testing the necessary hardware, are being led by the Space Servicing Capabilities Office established at Goddard last year to preserve the expertise NASA has built up through a half-dozen satellite repair missions, starting with a 1984 space shuttle mission to retrieve and repair the ailing Solar Maximum Mission spacecraft.
The engineer in charge of that pioneering mission, Goddard’s Frank Cepollina, went on to lead the first Hubble repair mission in 1993 as well as three subsequent service calls to the popular telescope. Perhaps more significantly, it was Mr. Cepollina and his team of engineers who just a few years ago expended considerable brainpower — not to mention funding — figuring out how to repair Hubble without astronauts following NASA’s decision to cancel a shuttle mission that had been planned for that purpose. The team took the proposed robotic servicing mission through preliminary design review before NASA reversed course and reinstated the shuttle mission.
Today Mr. Cepollina runs the Space Servicing Capabilities Office as deputy associate director in the Space Servicing Capabilities Office at NASA Goddard Space Flight Center, where he continues to champion on-orbit satellite repair and refueling.
“The time for study is over,” Mr. Cepollina said at a NASA-sponsored satellite servicing workshop in Maryland in March. “We have now got to move forward.”
Moving forward, at this point, depends on Mr. Cepollina and his government-industry team finding a suitable launch to the space station for the demo hardware, which is designed to be mounted to an Express logistics pallet on the station’s exterior.
The ideal vehicle is the space shuttle. But with the experiment hardware not expected to be ready to leave Goddard until the end of the year, the only way Mr. Cepollina’s team will be able to hitch a shuttle ride is if at least one of the three remaining orbiter flights slips into 2011, or if the White House or Congress directs NASA to fly more shuttle missions. Under either scenario, making room for Mr. Cepollina’s payload should be treated as a high priority. After all, satellite servicing has at least as many near-term applications as the 135-kilogram humanlike helper robot that NASA is planning to launch to the space station this fall on the shuttle’s last scheduled flight.
Besides shuttle, relatively near-term options for getting the demo gear to the space station are Japan’s H-2 Transfer Vehicle and Space Exploration Technologies Corp.’s Dragon capsule, both of which offer the unpressurized flight accommodations the hardware needs.
But an even more pressing issue is funding.
Congress established Mr. Cepollina’s office with a $20 million earmark for 2009 and $50 million for 2010, money that has been used to build flight hardware and conduct ground-based tests.
NASA’s 2011 budget proposal currently before Congress is awash with technology money. Some of it should be used to finish and fly the space station-based satellite refueling demo and to allow Mr. Cepollina’s team to get started on the next step: showing that satellites operating 36,000 kilometers from Earth in geosynchronous orbit — the operating location of most communications spacecraft — also can be refueled and repaired.
By some estimates, operational satellites commonly forfeit two or three years of productive and potentially lucrative service life in order to preserve enough fuel to boost themselves into higher disposal orbits where they won’t pose a threat to other satellites.
The follow-on demo the Goddard group has in mind entails building and launching a robotic spacecraft to boost one or two failing geosynchronous satellites into graveyard orbits to prove the servicing craft’s rendezvous and grappling capability. Having demonstrated this, the craft could then be sent on to replenish the nearly empty tanks of an otherwise healthy spacecraft to extend its useful life.
Surely there’s a commercial operator — and perhaps the U.S. Defense Department as well — that has a satellite or two that fits the bill.