BRUCE BUCKINGHAM: Good morning from the Kennedy Space Center in Florida. This is Space Shuttle Discovery's Launch Control.
The countdown for the launch of Discovery on mission STS-(121) is continuing on schedule this morning.
Launch is scheduled to occur at about 2:38 p.m. Eastern time, and our launch opportunity window extends for about five minutes.
This is our third launch attempt in four days. The first two attempts were scrubbed due to lightning and thick clouds.
Much better chances of being able to launch today than we had last Saturday and Sunday on our first two attempts.
Again, everything continues to run on schedule as we count down toward our targeted liftoff time at about 2:38 p.m.
There is one technical issue that the launch team is currently looking at. This is something that just arose over the past few minutes,
and it appears to be a situation with the circuit breakers that control all the heaters on the shuttle's booster joints.
Apparently, we lost our backup capability and we would like to have full redundancy for that capability.
The system is functional at this time and we could fly as is. However, to maintain a full redundancy,
we're looking at sending a team out to the launch pad, to the mobile launcher platform where this
circuit breaker panel is, and replacing that circuit breaker.
So we'll be pulling a team together shortly and preparing them and prepping them on what exactly needs to be done to replace this
100-amp circuit breaker that controls and commands all of our primary heaters on our,
on both of our solid rocket boosters, the segment joints on both of the boosters.
So that will be something that we will be tracking over the next little while as the team is pulled together.
This is something that has been practiced and planned for. The, the so-called "red" crew that we will be sending out will be minimal,
just two, perhaps three individuals that go out and do this work. They go out, get access to that specific panel in
the mobile launcher platform, replace that circuit breaker and then immediately leave the area.
Other than that, everything's going quite well this morning. The tanking operations to load the external tank with over 500,000 gallons
of liquid propellants that are used by the shuttle's three main engines lasted about three hours, finishing up at about 7:28 this morning.
With two hours, four minutes remaining in our scheduled built-in hold, at T-3 hours and holding, this is Shuttle Launch Control.