20 December 2005
The Lockheed Martin team plans to look for potential problems in a fuel tank on the Atlas 5 rocket, but first it must be drained of the kerosene-type fuel and then purged, spokeswoman Julie Andrews said Monday.
The purge will take several days and will coincide with a planned holiday break, she said.
The New Horizons spacecraft, whose launch from Cape Canaveral slipped from Jan. 11 to Jan. 17, is under a time crunch. If it flies by Jan. 28, it gets to Pluto in 2015, several years faster, with a gravity assist and bonus data from Jupiter.
However, it could launch through Feb. 14 and arrive later. Or, the probe could fly in 2007 and reach Pluto as late as 2020.
Engineers don't necessarily think there's a problem with this Atlas 5 rocket, the first to employ five solid rocket boosters.
Structural testing of another tank in September, designed to test the five-booster Atlas configuration, tried to push the test tank to its limit after several pressure cycles. It failed, Andrews said.
The New Horizons tank will fly at far less than the pressure at which the test tank failed, she said, and previously was inspected. Because it has been fueled recently in a dress rehearsal, however, engineers want to examine it.
"They're looking for anything inside the tank that might point to some structural integrity problem," Andrews said.
The testing in January will take a couple of days. Analysis will follow. "Everybody is quite confident that we'll find nothing," Andrews said.
The Jan. 17 launch date is a target but isn't firm, NASA spokesman George Diller said. "They're still mapping out a schedule for all of this," he said.
The spacecraft, the first to explore Pluto and its "twin planet," the moon Charon, carries a plutonium power source. The generator will keep the instruments warm and functioning as New Horizons speeds away from the sun.
The craft was mated to the Atlas 5 on Saturday.
Officials said Monday they wanted to ensure the rocket is safe to launch.
"We're being prudent and taking all measures to make sure it's ready, and we won't launch until it is," said Andy Dantzler, director of NASA's solar system division.
The success of the mission will be measured by what the spacecraft gets at Pluto, not when, said principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colo.
"We'll fly it when we're ready," he said, "and then we'll make some history."
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