by Kristen Dahlgren
NASA was forced to scrub Thursday's planned launch of the space shuttle Atlantis when some faulty fuel sensors were noticed in the shuttle's external fuel tank.
Atlantis was on the launch pad and the skies were clear when a problem with some sensors stopped the shuttle in its tracks.
NASA was fueling the giant external fuel tank when engineers noticed the sensor failure and scrubbed the launch.
Those sensors play a vital back-up role in shutting down the main engines, a malfunction could lead to a premature engine shutdown
Flight director, Doug Lyons said, "It is a redundant system, but something that is critical to fly."
It's a problem NASA has seen before.
In the first launch after the Columbia disaster, sensors failed and the launch had to be delayed for more than a month.
So like they did then, engineers are now inspecting the sensors and the wiring.
This time they hope they can troubleshoot the problem on the launch pad and try again Friday.
"We've got to do some additional engineering anyalysis and evaluation," said Lyons.
NASA is anxious to get Atlantis on its way as it tries to keep up an ambitious construction schedule for the International Space Station.
When it does launch, Atlantis will be carrying the new Columbus module a school bus sized European laboratory the shuttle will leave behind at the ISS.
"Launching Columbus, attaching it to the ISS, operating it around the clock, Europe will become a senior partner in human spaceflight," said European Astronaut Hans Schlegel.
But spaceflight, it seems is never a sure thing and engineers must now figure out the problem with those faulty sensors to get Atlantis off the ground.
This launch window is only a week-long.