NASA
engineers will remove parts of a suspect fuel tank connector for analysis and repair,
work that will likely further delay the planned January launch of the shuttle
Atlantis, the agency's shuttle chief said Thursday.
Space
shuttle program manager Wayne Hale told reporters that engineers will replace
external components of an oversized electrical socket on Atlantis' fuel tank before
setting a new launch date.
"This is
probably going to not allow us to fly on Jan. 10," Hale said in an afternoon
teleconference. "We're probably going to be a little bit after that."
A few extra
days, or possibly weeks, will be required to complete the troubleshooting work,
he added.
Atlantis' STS-122 construction
flight to the International Space Station (ISS) has been delayed since
December, when fuel gauge-like sensors failed standard
countdown tests during two separate launch attempts. The sensors are vital,
since they serve as a backup system to shut down a shuttle's three main engines
before their fuel supply runs out.
Engineers tracked
the intermittent glitch to a so-called "pass-through" connector that serves
as a bridge for electrical connections running from the interior of Atlantis'
fuel tank to the orbiter's aft-mounted avionics bay. The connector consists of
internal and external electrical sockets that plug into a central glass plate
with embedded metal pins.
"We believe
we are experiencing intermittent electrical system open circuits in this
arrangement," Hale said, adding that the glitch occurs only when Atlantis' fuel
tank is fueled with its super-chilled liquid hydrogen and liquid oxygen.
On
Saturday, engineers will remove the pass-through connector's central plug and
exterior wiring for additional tests in early January, Hale said.
"After the
first of the year, when we start getting the first of these lab reports in, we
will begin to have a handle on our no earlier than launch date," he added.
The leading
repair option under discussion is a soldering method that will fuse the
exterior electrical connections in the pass-through plug, which will avoid open
circuits caused by the movement of pins when the fuel tank is fueled. A similar
fix was used on Atlas-Centaur rockets when they experienced engine cutoff
sensor glitches, Hale said.
"We have a
high degree of confidence that that will solve our problems," he added.
Commanded
by veteran shuttle flyer Stephen Frick, Atlantis' seven-astronaut crew is
tasked with delivering the European Space Agency's Columbus laboratory to the
ISS during a planned 11-day mission. The spaceflight will be the first of possibly
six NASA shuttle flights slated for 2008.
"We're
taking this one step at a time," said Hale, adding that any changes to the 2008
shuttle flight schedule are secondary to fixing the current sensor glitch. "Obviously,
we'd like to fly as soon as it's practical and safe to do so."
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