Shuttle Discovery is aiming to roll back out to Pad 39A on February 1, following what will be the completion of numerous “radius block” modifications to the circumferance of her External Tank (ET-137). NASA managers are also evaluating impacts to crew training – and potentially the launch date – following the injury sustained by STS-133’s Tim Kopra during a biking accident.
Engineers and technicians are methodically working their way around the LO2 Flange on the top of ET-137’s Intertank, removing foam, carrying out stringer work, followed by the reapplication of BX-265 foam.
With work on schedule, a preliminary timeline has been set out, with a target completion date for the modifications posted as January 27, which would allow for Discovery to rollout to 39A on February 1. Both dates hold some flexibility via contingecy days.
“OV-103 (STS-133) In the VAB HB1, continuing repair on the radius block mod; working panels 2, 3, 6, and 7. Targeting to be complete January 27,” noted the KSC Integration Manager on the latest Shuttle Standup/Integration report (L2). “The target rollout is February 1, which supports the launch date of February 24.”
With Discovery back into a pad flow for the latest launch attempt, managers will conduct a Delta Flight Readiness Review on February 10, updating the previous Space Shuttle Program (SSP) FRR at the Johnson Space Center (JSC), in preparation for the launch date-confirming Agency level FRR at the Kennedy Space Center (KSC) on February 18.
Work is continuing on ET-137 through most of the long weekend, prior to the teams taking a well deserved break on Monday.
“ET-137 Stringer Full Modification: Panel 3: Seven of the eight even-numbered stringers requiring modification are complete; the team is awaiting dispo on the oversized holes on Stinger 18. Once the even-numbered stinger modifications are complete, the team will transition to the odd-numbered stringers,” noted the latest NASA Test Director (NTD) report (L2).
“Panel 6: Stringer 6 doubler and radius block installation is in work and should complete today. The team is scheduled to complete installation/repairs of Stringer 11 today. Panel 7: Four of the 18 stringer modifications are complete; work continues on the even-numbered stringers.once complete, the team will transition to the odd-numbered.
“Work on Panels 1, 2, and 8 is progressing on a NIB basis to the work on Panels 3 and 7; the team is targeting Sunday to conduct final Foam spraying operations on Panels 3 & 7.
Weekend Work: ET-137 LO2 Flange Stringer modifications continue through 0600L on Monday morning when the team will observe the Martin Luther King Jr. holiday; operations resume at 0600L on Tuesday morning.”
Away from the Vehicle Assembly Building (VAB), engineers continue to look into the failure analysis, ensuring they have found all the root cause issues with the stringer material – which range from the observation of a “mottled” appearance on stringers that have reduced fracture toughness, through to assembly proceedures.
Such evaluations are taking place under the guidence of the ET-137 Intertank Crack/Repair/Modification TIM (Technical Interchange Meetings) at the Michoud Assembly Facility (MAF).
Integrated into the TIMs are results from the Subsystem Test Team, who are working with nine stringer test articles which are being prepared for testing with a fastener gun. This gun will be used to install radius blocks to test the “as modified” condition test articles per their test matrix, now that all their stringer test articles without radius blocks have completed testing.
STS-133 Specific Articles (click for numerous background content on the ET and relating to this article): http://www.nasaspaceflight.com/tag/sts-133/
Meanwhile, the Failure Analysis Team has performed the checkout of the compact fracture toughness and tensile test equipment for the ET-139 panel 7 stringer 7 tests. ET-139 is a part built spare tank located at MAF and may yet become part of the Space Launch System (SLS) test vehicle.
Some of the test stringer remnants from the Subsystems Test Team have been obtained and a cut plan is underway to gain tensile and fracture toughness samples.
Fractography analysis work is also continuing via their 3-D software system, which highlighted the mismatches that they have seen specifically in the ET-137 panel 6 cracked stringers data when compared to their models.
Over the weekend, NASA noted that STS-133 Spacewalker Tim Kopra was injured in a bike accident. Full details have not been revealed by NASA.
“STS-133 Mission Specialist Tim Kopra was injured Saturday in a bicycle accident, but he will be OK. However, there could be an impact to his duties for shuttle Discovery’s STS-133 mission to the International Space Station. That possibility still is being evaluated,” noted NASA.gov.
“Further details of his injury are not being released at this time due to concerns for his medical privacy.”
If rumors of a broken hip are true, the retired US Army Colonel may risk yet another slip to the STS-133 mission, given the Shuttle Program no longer has backup crewmembers in training. The other alternative would be to replace Kopra with an experienced spacewalker who could take up his tasks on Discovery’s final mission – if such a crewmember swap is possible.
All scenarios remain hypothetical until the extent of Kopra’s injury is known, at which point NASA managers will make a decision on the most viable forward path for the mission and the crew.
(Further updates and articles will follow. Refer to live coverage threads linked above. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used, NASA.gov and via L2 acquired PRCB presentations).