Launch Rehearsal Hits Some Snags

The space shuttle Discovery crew held a rehearsal Wednesday for a planned launch in July, but the practice run had problems that would have halted takeoff of the spacecraft.

Discovery is the first shuttle scheduled to fly since February 2003, when Columbia disintegrated on reentry, killing all seven astronauts aboard. Columbia’s wing was damaged during the launch by a falling piece of insulation foam.

Two issues surfaced during the test -- poor weather and a communications glitch with Air Force safety and tracking equipment that would have been required for an actual launch.

The exercise concluded with a scripted last-second cutoff of the shuttle’s main engines, a fail-safe mechanism designed to prevent an explosion should something go wrong.

The practice countdown was a routine test NASA conducts before each shuttle launch. Discovery was scheduled to be hauled back to the vehicle assembly building in Cape Canaveral for additional work.

Discovery was scheduled to launch in May or June, but last week managers decided to delay the mission until mid-July so engineers could work on the shuttle’s fuel tank.

Managers were debating whether to conduct a second test of the fuel tank before the shuttle was removed from the launch pad, NASA officials said.

An initial test last month revealed problems with sensors that monitor the amount of liquid hydrogen in the tank. The system includes four cutoff sensors, but two of the devices failed repeatedly during the test.

After the practice countdown, Discovery astronauts inspected the launch pad emergency evacuation system and discussed the exercise with managers.

As the launch team practiced flight preparations, photographers oversaw an upgraded network of 20 still and video cameras that will operate on launch day, NASA said.

Columbia accident investigators called for the cameras to give NASA a better view of the shuttle at takeoff.