CAPE CANAVERAL, Fla. -- After replacing a critical space shuttle part, NASA began another launch countdown for Endeavour's long-delayed mission to map Earth.
Endeavour is scheduled to blast off at 12:30 p.m. Friday. This morning, shuttle weather officer Ed Priselac said there is an 80 percent chance of acceptable launch conditions, although crosswind could be a problem.
The 11-day mission -- to create the most complete and accurate topological map of Earth by using radar -- was scheduled for September but was delayed so NASA could fix damaged wiring in the shuttle.
A new launch date was set for Jan. 31, but a computer malfunction halted the countdown.
The faulty master events controller has since been replaced; engineers still don't know why it put out bad data. The controller is needed to send commands to ignite the two solid rocket boosters at liftoff and to later separate the boosters and external fuel tank from the shuttle.
On Tuesday, as the countdown began again, technicians discovered scuff marks on an electrical cable in the left booster. NASA test director Steve Altemus said the damage was confined to the outer layer of insulating tape and therefore of no concern.
Today, a Global Positioning System satellite receiver aboard Endeavour failed a routine test. Even if the receiver has to be replaced, it will not affect the countdown, Altemus said. The GPS receiver is needed to help pinpoint the orbital location of Endeavour and its radar antennas.