STS-134: Endeavour heading towards S0007 preparations – mission extended
With a large amount of contingency in her pad flow, Endeavour’s processing pace has slowed down this week. The flow is expected to ramp up on Friday as preparations begin for S0007 (Launch Countdown) operations. While the feared government shutdown was averted, memos pre-empting the possibility revealed some insight into the latest launch window planning and mission duration.
Friday was looking like the last day of processing for an unknown amount of time, given the lack of agreement between lawmakers in Washington, DC. A shutdown would not have caused an immediate delay to STS-134, even if the shutdown had lasted just over a week, given the 8-9 days of contingency time that has been built into the pad flow.
“LH2 tank replenish was completed Friday. AMS (Alpha Magnetic Spectrometer -2) off-line testing was completed Friday evening. Pending data review, the next AMS power-up is expected post-launch,” noted the NASA Test Director (NTD) report (L2) this week on what would have been the final tasks in the flow ahead of the shutdown, which included the closure of the latest Interim Problem Report (IPR), relating to a bus error.
“MSBLS (Microwave Scan Beam Landing System) 90-day time and cycle testing was completed on Friday. IPR-0037 IDP1/MFD2 troubleshooting was completed Friday with nominal results. The bus error was unable to be recreated. Timing indicates that this anomaly occurred very close to crew egress during TCDT (Terminal Countdown Demonstration Test). The IPR will likely become a UA (Unexplained Anomaly).”
Good news was also reported on the Engineering Review Board (ERB) evaluations into a second severe weather event over the launch pad 39A in recent weeks, confirming no repair work is required.
“The ERB reviewed data from last week’s severe weather outbreak at Friday’s Noon Board. No issues are expected. GUCP (Ground Umbilical Carrier Plate) guide pin checks are complete with acceptable results. Hail damage on the tank has been reviewed with no rework required. All other walkdowns are now complete with no findings. Loads analysis evaluations are ongoing and will be presented this week.”
STS-134 Specific Articles: https://www.nasaspaceflight.com/tag/sts-134/
In preparation for the shutdown, Endeavour’s hatch was closed and access removed. This task was reversed on Monday as the workforce returned to an uninterrupted schedule.
“OV-105/SRB BI-145/RSRM 113/ET-122 (Pad-A): Access to the crew module was restored yesterday following actions taken to support the potential government shutdown over the weekend. The airlock hatch was opened in preparation for Thursday’s EMU (Spacesuit) functional checkout. LO2 tanker replenishment (two waves) is scheduled for Thursday,” added the NTD.
Due to the delay of the launch date to April 29 – due to a conflict with the Russian Progress schedule – the flow will remain relaxed for most of this week, ahead of Friday, which will mark the beginning of preparation for the S0007 Launch Countdown.
A full set of center memos informing their respective workforces on what the forward plan would involve were sent out on Friday, with information specific to the three orbiters at the Kennedy Space Center (KSC) noting only a minimum support posture would be involved.
“STS-134 and STS-135: All scheduled operations will conclude Friday; after which the minimum support posture will be maintained,” noted one of the memos (full set on L2).
“OV-103 (Discovery): Processing to support hazardous hypergolic de-service operations will continue until all OMS (Orbital Maneuvering System)/RCS (Reaction Control System) and APU (Auxiliary Power Unit) safing operations are complete.
“This will continue until the vehicle is in a safe configuration (currently scheduled to complete late Sunday evening, April 10). At the conclusion of hazardous operations, the minimum support posture will be maintained.”
However, with lawmakers averting the shutdown at the 11th hour, memos were immediately sent out to reverse the plan and inform the workforce to return to their nominal work schedule.
“Government Shutdown Update: A short term Continuing Resolution (CR) was signed on Saturday and a government shutdown was averted. The latest CR provides funding to government agencies through Thursday while the official spending bill agreed to Congress is formally written.
“It is anticipated the spending bill will be passed by Congress and signed by the President prior to Friday. KSC is continuing with normal operations, therefore all civil servants and contractors are expected to report to work on their next scheduled work day at their normal arrival time.”
Notably, teams were informed on the stance of STS-134’s mission as it stood going into what they thought would be a shutdown, meaning the information remains applicable at this time.
“Current launch options remain April 29th to May 2 or 3 depending on what (an upcoming Atlas (launch) does, then picking back up May 7th or 8th,” noted one MOD memo (L2), which outlined to launch opportunities for Endeavour’s final mission. “We can support a full 16 day flight for the first few days of the launch window before having conflicts with Soyuz 25S undock if it remains on May 16th.”
Based on Wednesday’s decision by the Space Shuttle Program (SSP) to officially baseline an additional day to the STS-134 mission – Endeavour’s flight is currently set for a 15 day mission, with the caveat of potentially adding another day when on orbit.
However, such an additional day won’t be required to create space for a Soyuz flyabout of the ISS/Endeavour stack, after the event was called off.
“Fly-about has been officially been turned OFF for STS-134/ULF6 – now it’s STS-135/ULF7s turn,” added the MOD memo. “Thanks to those who have been involved in trying to make this work out for this flight and make sure to make the data available to our STS-135/ULF7 friends to take advantage of.”
As was described in the NASASpaceflight.com article revealing the decision to cancel the flyabout for STS-134, the changes to the upcoming Soyuz schedule was one of the main reasons to switch the flyabout’s focus to STS-135.
“The Russians have indicated that they will likely be delaying 27S launch from 5/30 to 6/7. 27S is the vehicle replacing 25S and the Russian preference for ULF6 flyabout is 25S. To support the flyabout the Russians were considering accelerating the 25S departure,” noted another MOD memo.
“All this plus the 25S departure activities that would occur during ULF6 would result in a negative crew time impact for ULF6 as well as the stage afterward. For those reasons it has been decided to not pursue the flyabout for 134/ULF6. We anticipate that 25S landing will now slip by a similar amount to the 27S slip, but that has not yet been confirmed.”
A lot of work from a mission standpoint will be required to approve the flyabout on STS-135, due to challenges relating Atlantis’ docked mission timeline. However, managers are looking at plans to mitigate such concerns (which will be the basis of an upcoming article on STS-135).
“Also, in discussions with the Russian management on this change it was agreed to pursue a flyabout on STS-135/ULF7 utilizing the 26S Soyuz from MRM2. I would envision that to be the same scenario as we have previously worked for the flyabout on 133/ULF5 and for 26S on 134/ULF6,” added the MOD.
“As we get more details for the 135 case we’ll get the team together to work through the details. I understand the timeline challenges that this presents. We’ll need to include those impacts as we work through the details and look for ways to mitigate them.”
(Images via L2, L2 Documentation, MaxQ Entertainment/NASASpaceflight.com and NASA.gov)