Not for nothing, but I heard that the biggest problem NASA is worried about is not the foam that has caused problems in recent years. It is apparently, as quooted from NewScientistSpace ^[1],

On Saturday morning, workers noticed a problem with a heater on one of the orbiter’s in-space thrusters, designated L5L. The thruster is one of 38 that the orbiter uses once it is in space to change orientation, particularly to inspect the heat shield and rendezvous and dock with the International Space Station.

The heater is used to keep the thruster propellant from freezing in space. But NASA discovered the thruster’s thermostat was not working. The thermostat showed temperatures around 27°C (80°F) – but it should have read over 38°C (100°F).

But there is still an issue with the foam:

During the 16 and 17 June Flight Readiness Review that determined the space shuttle Discovery’s launch date, NASA’s chief engineer and the manager of the agency’s safety office withheld their full approval of the launch until so-called ice/frost ramps on the external tank were fixed.

The 37 ice/frost ramps cover metal brackets on the outside of the fuel tank. NASA expects some of the manually-sprayed foam from these ramps to come off during launch, but officials do not expect the result to be catastrophic.

It is my hope that these problems do not cause a tragedy, as has happened twice with the shuttle. It is a half an hour until launch. I hold my breath in anticipation, hoping for the best.

I will be watching on NASA TV ^[2]. It will certainly be exciting. I wish I were in Florida to see the most spectacular fireworks display of the year live and in person. No, I take that back. I wish I worked for NASA, and was part of the shuttle program team.