Shuttle launch postponed third time: Nasa

The US space agency Saturday delayed the launch of the space shuttle Atlantis for a third consecutive day and announced plans to strengthen safety rules governing launches. Liftoff is now set for 3:21 pm (2021 GMT) Sunday, said Kennedy Space Center spokesman Allard Beutel.
Problems with fuel gauges on the shuttle's external tanks had forced Nasa to put off launches scheduled first on Thursday and then Friday. A Nasa meteorologist said that there is a 70 percent probability of favourable launch weather on Sunday.
"If we find that this proposal allow us to fly with an acceptable risk we'll try to launch Sunday," Wayne Hale, director of the shuttle program, told reporters. The problems with the gauges started on Thursday, when Atlantis's fuel tanks were being filled with hydrogen and liquid oxygen.
The monitors indicated that the tanks were empty when in fact they were full, a malfunction that under the rules of the National Aeronautics and Space Administration prevents a shuttle launch. Hale said three sensors had failed in a manner that did not allow Nasa to launch Atlantis. "We had this problem way back in March 2005," he added, pointing out that as a program manager he found this problem "extremely frustrating."
The new safety proposals, according to Hale, tighten up launch criteria and require that all four of the sensors be functioning well. They also call for use of new instrumentation to measure the voltage of the system, the manager said. Hale said Nasa engineers will gather for a meeting at 1:00 pm (1800 GMT) Saturday to evaluate chances for the planned launch.
He said technicians had already carried out a series of engineering tests, examined every piece of the system-the electronic box that interprets voltage readings coming from the sensor box, the sensors themselves and the wiring between all of the components.
"We believed we had solved this problems, quite frankly," Hale said. The Atlantis crew of seven is preparing for an 11-day mission to fly the European Columbus laboratory to the International Space Station, orbiting hundreds of miles above Earth.
The crew includes astronauts from France and Germany, joining the mission to add the European installation. Countries are developing the station as a possible future jumping-off point for deeper space exploration.
The current window of opportunity for a launch closes on Thursday. If Atlantis has to return to its hangar for repairs, the mission would be delayed until mid-January, said launch director Doug Lyons. This would disrupt the schedule of future trips to the space station, including one to deliver the next installation: the Japanese Kibo laboratory.