Several Praxair trucks carrying their loads of liquid oxygen, or LO2, have arrived at Launch Pad 39B at NASA's Kennedy Space Center in Florida. The trucks will offload LO2 slowly into a giant storage sphere located at the northwest corner of the pad to gradually chill it down from normal temperature to about negative 298 degrees Fahrenheit, during the first major integrated operation to prepare for the launch of the agency's Orion spacecraft atop the Space Launch System (SLS) rocket. The Ground Systems Development and Operations Program is overseeing upgrades and modifications to pad B to support the launch of the SLS and Orion spacecraft for Exploration Mission-1, deep space missions and NASA’s journey to Mars.