Space shuttle Discovery is back in the Vehicle Assembly Building

Space Shuttle Discovery
STS-124 Launch May 31,2008
External tank is bright orange
Photo credit: NASA

Space shuttle Discovery is back in the Vehicle Assembly Building (VAB this morning Tuesday December 22, 2010. There was a crawler problem that delayed move from Launch Pad 39A until late last night (10:48 p.m. EST).  The problem with the crawler was a sensor in the crawler level control system.

While in the Vehicle Assembly Building, the shuttle's external tank will be radiographed to look for cracks in all 108 stringers. Sensors from the recent tanking test will be removed and foam reapplied. A decision is expected next week (December 30)  by NASA project managers on a possible engineering modification to install stiffeners on 36 stringers in the external fuel tank.

Mike Moses, NASA Space Shuttle Program Launch Integration manager, said the results from the tanking test on December 17, 2010 looked good although it would take a few weeks to fully analyze them.

A launch attempt on November 5, 2010 was scrubbed a hydrogen leak was found on the Ground Umbilical Carrier Plate (GUCP) which is an attaching point between the external tank and a ventilation pipe for a  7 inch quick disconnect. Cracks in foam led to discovery of cracks in the tops of two stringers. Repairs were made. No leak at the GUCP was detected during the December 17 tanking test. The space shuttle external tank has a capacity of 535,000 gallons of liquid oxygen (LOX) and liquid hydrogen (LH2). Liquid oxygen is boiling point is 90.19 K (−297.33 °F, −182.96 °C). Liquid hydrogen boiling point is −252.87 °C (−423.17 °F, 20.28 K).

Space Shuttle Discovery in the Vehicle Assembly Building
December 22. 2010 after completing 3.4 mile roll back from Launch Pad 39A. Photo credit: NASA TV

Cutaway diagram of the space shuttle
external fuel tank showing the stringers

References:


http://www.nasa.gov/mission_pages/shuttle/main/tankingtest.html


http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=36289


http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts133/multimedia/gallery/gallery-index.html

http://www.nasa.gov/centers/marshall/multimedia/photogallery/photos/photogallery/shuttle/shuttle.html

http://www.nasa.gov/mission_pages/shuttle/main/

Cracked foam on external tank during fueling
operations  November 5, 2010 caused by cracking
in top of two of 108 vertical stringersPhoto credit: NASA
 cracks were on two of the 108 stringers

Tank repairs to the GUCPPhoto credit: NASA

Removing vent line at the GUCP during external tank repair
Photo credit: NASA

Removing vent line at the GUCP during external tank repair
Photo credit: NASA

External Fuel Tank with sensors attached 

for tanking test on December 17, 2010.

Photo credit: NASA