NASA's
launch of the space shuttle Atlantis has slipped to late January, with a push
to early February likely, as engineers work to replace a faulty fuel tank
connector, a top official said Thursday.
John
Shannon, NASA's deputy shuttle program manager, said Atlantis will not fly
until Jan. 24 at the earliest, a two-week slip from an earlier
Jan. 10 target, to allow tests and modifications of a vital fuel tank
connector.
"Everything
has to go exactly right for us to make the 24th," Shannon told reporters.
More likely
launch targets are Feb. 2 or Feb. 7, which allows time for extra tests but no
major unexpected surprises, Shannon said.
Atlantis'
planned 11-day mission to deliver a new European
laboratory to the International Space Station (ISS) has been delayed
since early December, when vital fuel gauge-like sensors failed standard
countdown checks. Known as engine cutoff sensors, the fuel gauges serve as a
backup system to shutdown an orbiter's three main engines before its fuel
supply runs out.
NASA
tracked the glitch to a suspect
electrical connector near the bottom of Atlantis' 15-story external tank,
where sporadic open circuits may form as the tank is filled with its super-cold
liquid hydrogen propellant.
The
three-part connector consists of an interior electrical socket, a glass-and-metal
pin bridge and an exterior electrical socket that work together to transmit signals
from four liquid hydrogen fuel gauges to a computer aboard Atlantis.
Engineers
have already removed exterior portions of the electrical connector and will
replace it next week with a modified version with wires soldered directly to
their corresponding pins to avoid open circuits, NASA said.
"It's
fairly simple," said Shannon. "It's a fairly elegant change and we
feel very confident that, if the problem is where we think it is...that this will
solve that."
NASA
requires at least a five-week breather between shuttle launches, which pushes
the planned Feb. 14 launch of the Endeavour orbiter and the first part of Japan's massive Kibo
laboratory beyond its initial target, he added.
The space
agency also must not conflict with the planned ISS arrival of the unmanned
Russian Progress 28 cargo ship, which is currently slated to launch on Feb. 7.
"The hard
constraint today is not to have a shuttle docked while we're trying to dock a
Progress," said Mike Suffredini, NASA's ISS program manager.
Suffredini
added that ISS managers are also discussing when to add an extra spacewalk to
the chore list of the space station's Expedition 16 crew to replace a solar wing
motor.
Commanded by
veteran spaceflyer Stephen Frick, Atlantis' seven astronauts expect to install
the European Space Agency's Columbus laboratory and stage at least three
spacewalks slated for their shuttle mission.
"They
did get the holidays off. I think that was a good thing," Shannon said of
the shuttle astronauts. "They're, from all I can tell, very excited and
ready to go whenever the shuttle is."
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