Wednesday, December 22, 2010
In the hopes of performing new x-ray scans on the back side of the external tank, technicians moved space shuttle Discovery from her launch pad overnight to the vehicle assembly building.
The 3.4 mile rollback from launch pad 39-A to the massive assembly building began Tuesday night at 10:48 p.m. EST, following a one day delay due to a clearance issue with the crawler transporter.
It is the 1960's built crawler which travels underneath the space shuttle's launch platform and carries it to and from the launch pad at a speed of 1 m.p.h.
The combined stack of the space shuttle, mobile launcher platform and the crawler transporter weighs 17,501,000 pounds.
Discovery arrived back inside the building's high bay at 7:01 a.m. today, and will stay there until about January 14, the Johnson Space Center states.
This was the sixth time Discovery was hauled back to the assembly building from her launch pad, and only the 20th time in the space shuttle program.
Over the next three weeks, technicians will perform extensive x-ray inspections of the shuttle's rust-colored external fuel tank's inner tank area to check for cracks.
It is that region where several cracks were discovered following a November 5 launch scrub after cryogenic fuels began draining from the tank.
Discovery's fuel tank is loaded with 535,000 gallons of super cold liquid hydrogen and liquid oxygen on launch day. The fuels are stored inside two inner tanks and at launch they mix together to power the orbiter's three main engines during the first eight minutes of flight.
The inner tank, or middle region, has a total of eight panels around its diameter, and two 2-inch thick aluminum panels at the section where the forward solid rocket boosters attach.
The Nov. 5 cracks were located on two of the 108 twenty-one foot long aluminum brackets known as stringers, and later were repaired at the launch pad.
Several panels could not be reached from at the launch pad to be x-rayed. Engineers will x-ray scan all 108 stringers and reapply new insulation once the tests are complete.
Crews will also remove several sensors from the external tank which were installed for a Dec. 17 fueling test.
The fueling of Discovery tank last Friday was to check if additional cracks would occur as the super cold fuels left; and to check an unrelated repaired bracket panel for leaking gaseous hydrogen which was the root cause of the launch scrub.
NASA managers are aiming to launch Discovery no earlier than February 3, however several at Kennedy have told this aerospace journalist that a slip of one week is likely.
Once underway, Discovery and her crew of six will fly up to the International Space Station for one week. The STS-133 mission is designed to add a new module for storage to the complex and deliver fresh supplies for the crew of two Americans, three Russians and one Italian.
Piloting Discovery on her 39th and final flight will be former Chamblee, Georgia resident Colonel Eric Boe.
Boe grew up in Atlanta and graduated from Henderson High School in 1983.
Boe's thoughts of growing up in metro Atlanta are many, "I remember, just getting started, being involved... very involved with sports in school and also a lot of other activities".
A veteran of a 2008 shuttle flight, Boe still keeps in touch with his connections in the area, "I still talk to friends back home in Atlanta", the Georgia Tech graduate said.