Countdown Resumes at T-2 hours
The launch team picked up the count to today’s launch again at the T-2 hour mark after a planned hold. The next step is to begin loading cryogenic – or super-cold – propellants into the Atlas V first stage and Centaur upper stage. Liquid oxygen with a temperature of minus-297 degrees will be pumped into the first stage where it will mix with kerosene inside the RD-180 engine during launch. The Centaur will be loaded with liquid oxygen and liquid hydrogen. LH2, as they call liquid hydrogen here, is one of the coldest materials known. Its temperature is minus-423 degrees. Absolute zero is considered about minus-459 degrees.
