NASA delays shuttle launch till at least Monday

By Michael Christie and Deborah Zabarenko

CAPE CANAVERAL, Fla. (Reuters) – NASA on Wednesday delayed
the launch of shuttle Discovery until next week at the
earliest, postponing its first human space flight since the
2003 Columbia disaster due to a problem with a fuel sensor.

“We will not be able to fly today,” said NASA launch
commentator George Diller. “There are a lot of long faces in
the control room.”

NASA Administrator Michael Griffin said the earliest date
for another launch attempt would be next Monday.

“It’s not possible to launch tomorrow,” Griffin said.

Discovery was fueled and ready with the astronauts strapped
in their seats for a planned launch at 3:51 p.m. EDT (1951 GMT)
when the problem with the liquid hydrogen fuel sensor occurred
at 1:32 p.m. (1732 GMT). The sensor is one of four that detects
fuel levels when the tank is nearly empty.

In the event of a launch, a sensor malfunction could
conceivably cause the main engines to switch off prematurely.

NASA called a news briefing for later on Wednesday to give
more information on the problem.

NASA has until July 31 to launch Discovery. After that it
will have to delay until Sept. 9, when the International Space
Station again comes into the right position for a shuttle
rendezvous after a daylight liftoff.

Discovery’s mission is the first shuttle flight since the
Feb. 1, 2003, Columbia disaster, when seven astronauts died as
their spacecraft disintegrated over Texas.

COMPLEX SYSTEM

“It is a complex system. Every little part counts,” said
astronaut David Wolf during Wednesday’s broadcast mission
commentary. NASA had problems with the sensors during a fueling
test in April but Griffin said Wednesday’s malfunction was
unrelated.

The problem was the third technical issue to crop up since
Tuesday.

A faulty heater delayed the fueling of the external tank
with liquid hydrogen and liquid oxygen by more than an hour on
Wednesday, and on Tuesday, a falling window cover damaged two
heat-resistant tiles near the shuttle’s tail.

The weather had also threatened to prevent the launch, said
NASA weather officer 1st Lt. Mindy Chavez, because of a 60
percent chance that thunderstorms would occur nearby.

In 2003, falling foam knocked a hole in Columbia’s wing at
liftoff, and superheated gases ate into the breach 16 days
later when the spacecraft re-entered Earth’s atmosphere for
landing, causing the craft to disintegrate.

Discovery’s main mission is to test new safety measures
introduced after the Columbia accident, and it will also
deliver much-needed supplies and equipment to the space
station.

The station’s construction has been stalled since the
remaining three-shuttle fleet was grounded after Columbia broke
apart.

Discovery’s flight heralds the last chapter for the shuttle
fleet, which is set to be retired in 2010 after about 20
construction flights to the station.

The shuttle’s resumption of flight and its eventual
retirement will also mark the first step in NASA’s new vision
of returning to the moon, and of heading to Mars and beyond
when the U.S. space agency replaces the shuttle with a new
generation of spacecraft.

(Additional reporting by Irene Klotz)