Technicians Load Discovery's PRSD for Flight

Liquid oxygen and liquid hydrogen will be loaded into Discovery's Power Reactant Storage and Distribution system today as the countdown for the STS-133 mission continues. Discovery is to lift off Thursday, Feb. 24, at 4:50 p.m. EST.

The system, known by its initials PRSD, holds the chemicals for use in the shuttle's three fuel cells to produce electricity in space. The oxygen is also used to pressurize the shuttle's crew cabin. The combination of hydrogen and oxygen in the fuel cells produces a beneficial byproduct for the shuttle: water. Shuttle crews visiting the International Space Station routinely fill up bags with the water for use by station residents.

The same two chemicals, liquid oxygen and liquid hydrogen, are used by the space shuttle main engines at liftoff, but the propellants for that job go into the 15-story-tall external fuel tank and are not loaded until launch day.

STS-133 Commander Steve Lindsey and Pilot Eric Boe will practice landing approaches at the Shuttle Landing Facility in shuttle training aircraft, a Gulfstream II jet modified to simulate a shuttle's cockpit, motion and handling qualities. The rest of the crew will conduct a review of orbiter ingress procedures. A countdown status briefing will air on NASA TV at 10 a.m.

This article was sponsored by Forensic Science Books.