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Quick fix for Hubble to be tested; new data unit to be sent aloft next year
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An upbeat NASA management team today said that some tinkering with data transmission channels from ground controllers might get Hubble science images streaming back within a couple of weeks. But for the long term and "redundancy," the 18-year-old telescope needs a new primary data controller, said Ed Weiler, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington.
The unit, shown here, stopped functioning over the weekend. Although neither Hubble nor its orbit is at risk, the balky data unit effectively stopped the transmission of Hubble observations back to Earth.
Side A of the unit shut down with no warning, said Preston Burch, Hubble manager at NASA's Goddard Space Flight Center in Greenbelt, Md. But there's a Side B, and engineers are working on a plan to get that side up and running.
The transition to Side B operations is complex. It requires that five other modules used in managing data also be switched to their B-side systems. The B-sides of these modules last were activated during ground tests in the late 1980’s and/or early 1990, prior to launch.
If the Side B fix works, some NASA instruments will be able to ship their observations back home, Weiler said. If all goes well, Hubble observations may only be lost for about two weeks.
Long term, however, the problem has put a hold on the STS-125 mission that had been scheduled to be launched on Oct. 14. The seven-member crew of Atlantis had a hefty schedule of multiple Hubble tasks over an intensive schedule of five spacewalks.
Now, something new will be added--when the Atlantis mission flies next year. Given the NASA desire to have redundancy--meaning more than one operational resource--and the fact that this Hubble mission is the final one for the telescope, managers decided to ship up a spare unit from the ground.
But before that happens, engineers must test the spare extensively, and the astronauts must undergo further training to learn how to install the new unit, along with their other tasks. The delay in the Atlantis mission leaves managers juggling schedules to get one launch pad ready to be reconfigured for the new Ares program. They must also ensure that there's another shuttle on standby in case an Atlantis rescue mission is needed during the difficult and dangerous spacewalks.
The addition of the new unit won't cause a weight problem for the orbiter, managers said. There's space available on the payload pallets. Most likely, a spot on a pallet called the "mule" will be used, and the weight of the unit will be swapped out with tail ballast weight.
Hubble "is the great american comeback story. Hubble has a history of coming back, " Weiler said.
After some hair-raising launch countdown stops, Hubble got off the ground aboard Discovery on the STS-31 flight, launched April 24, 1990. Since the Hubble telescope and mission had been in work since 1977, the rejoicing was great--until the first pictures were beamed back.
Hubble had rotten vision. The primary mirror had been ground wrong, a condition called " "spherical aberration." In 1993, the crew of the STS-61 mission, one of the most complex and demanding shuttle missions of that era,, installed a new lens and performed other Hubble upgrade tasks.
And then the universe opened to man, as Hubble began almost two decades of streaming back images that have not only shown astounding beauty, but have enlarged our understanding of how galaxies are born, die, and expand.
So far, the STS-125 mission has kept up with Hubble's history of being somewhat of a cosmic drama queen. Tropical storms, pad problems, and now the onboard Hubble data controller problems have caused launch delays and challenges for the team.
"We'll find a way....and we'll leave Hubble as healthy as we can after the next mission," Weiler said. Scientists estimate that after the newly-rescheduled 2009 servicing mission--with the date still to be set-- Hubble will easily be able to provide another "five to 10 years" of observations, according to Weiler.
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