Space shuttle Atlantis launch scrubbed

Space shuttle Atlantis on the launch pad this morning. [Getty Images]

CAPE CANAVERAL -- Today's scheduled launch of the space shuttle Atlantis has been scrubbed because of malfunctioning sensors in a fuel tank. NASA hopes to try again tomorrow.

The fuel sensors are important because they would let mission control know if the space shuttle is running out of fuel prematurely while launching.

If the shuttle were to run out of fuel during the eight-minute trip into space it could conceivably cause the space shuttle's main engines to blow up.

NASA officials said they will meet this afternoon to decide whether to try launching at 4:09 p.m. Friday. In the meantime, workers are examining the giant external fuel tank and poring over data.

NASA scrubbed today's launch because two fuel sensors weren’t working properly. The sensors are an important safeguard – they help make sure the shuttle’s three main engines don’t shut down too soon or too late, either of which could create a disaster.

Even if the problem cannot be fixed in time for a launch on Friday, NASA officials say they believe they will be able to try again within the coming week.

“We really are confident that we can work our way through this and get a few launch attempts in this window,’’ said Launch Director Doug Lyons.

In this flight, Atlantis is scheduled to carry a new European-built laboratory to the International Space Station. The lab, called Columbus, will be removed from the shuttle and attached to the station.

Engineers discovered the problem during a routine test this morning. In the test, two of four sensors acted as though the shuttle’s large tank of super-cold hydrogen fuel was “full,” when they should have read “empty.’’

If Atlantis prematurely ran out of fuel as it shot through the atmosphere, NASA fears the shuttle’s three main engines might explode. That’s what makes accurate readings important.

If the sensors falsely read “empty’’ during the eight-minute launch into space, that could force NASA to unnecessarily abort the trip, and make astronauts land Atlantis back at the Kennedy Space Center or in Europe. That kind of abort procedure has never been used in the shuttle’s more than 100 flights.

On the other hand, if fuel sensors gave a false reading in the opposite way – indicating the tank was full when it really was empty – that could lead the engines to run out of fuel while operating, and possibly, explode.

NASA has been wrestling with malfunctioning fuel sensors off and on since the 2005 flight of Discovery, the first space shuttle launch since the fatal 2003 break-up of the shuttle Columbia.

Although the sensors have at times given false readings in the past, NASA has not always been able to pinpoint why.

--Curtis Krueger, Times staff writer