Space Shuttle: Discovery
Primary Payload: Permanent Multipurpose Module (PMM)
Launch Date: No earlier than Feb. 3, 2011
Launch Time: 1:34 a.m. EST
Launch Pad: 39A
Landing Site: Kennedy Space Center, Fla.
Mission Duration: 11 days
Inclination/Altitude: 51.6 degrees/122 nautical miles
A daylong test of space shuttle Discovery's external fuel tank took place Dec. 17 at NASA's Kennedy Space Center in Florida to help engineers evaluate the stringers that make up the ribbed portion of the tank. Two stringers cracked during fueling operations in November. That launch attempt was scrubbed after the ground umbilical carrier plate developed a leak.
The tanking test filled Discovery's 15-story-tall external fuel tank with more than 535,000 gallons of super-cold liquid oxygen and liquid hydrogen, the same propellants used to power the shuttle's three main engines. The liquid oxygen is at minus 297 degrees F and the liquid hydrogen is at minus 423 degrees F.
Technicians placed 39 strain gauges and 50 thermal sensors in the stringer areas of the tank to precisely measure the pressure on the stringers as the tank chills with the addition of the propellants. Typically, the tank's diameter shrinks by about an inch as it cools down.
Results of the test will not be known immediately. The data from the test will be analyzed at other NASA centers where small-scale tests of stringer material, design and construction will take place. Space Shuttle Program managers expect the information to give them a root cause for the cracking of the stringers and allow them to proceed toward the launch of Discovery on the STS-133 mission.
Teams plan to roll Discovery back into the Vehicle Assembly Building no earlier than Tuesday, Dec. 21, so technicians can scan the stringers on the back side of the external tank, the ones not facing the shuttle. Foam also will be reapplied after the sensors are removed from the tank.