STS-129: Atlantis in clean launch ahead of opening TPS inspections

by Chris Bergin

Only three minor foam liberation events have been noted in initial ascent imagery evaluations, with External Tank ET-133 appearing to perform extremely well during launch. Further checks will take place via Flight Day 2’s opening Thermal Protection System (TPS) inspections which utilize the orbiter’s robotic arms for the first time during STS-129.

Countdown review:

Atlantis officially beat her sister Discovery on the record low amount of Interim Problem Reports (IPRs), with a total of just 54 listed for her flow since returning from the STS-125 Hubble Space Telescope servicing mission – four of which were added during the final day of S0007 (Launch Countdown) operations.

“IPR 50: Waist tank quantity fell below 5 percent during tank drain. No CDR was on station to closes the valve when needed. The primary concern is bottoming out the bellows (nesting,” listed the first issue by the NASA Test Director on Monday morning, before being cleared.

The next IPR related to Ground Support Equipment (GSE), which regularly has minor leaks during the pad flow. This issue – associated with the LH2 Tail Service Mast (TSM) – was already in the process of being cleared by the time it made IPR 51.

“IPR 51 taken by MPS (Main Propulsion System): To document a helium leak in the LH2 TSM,” added the processing report. “Launch Accessories changed out a union and nose seal, performed a nominal leak check, and continued closing out the TSM.”

Listed as a constraint to coming out of the T-9 minute hold, IPR 52 related to a control system associated with 78 pad and MLP (Mobile Launch Platform) cameras.

A2Although this IPR was no fault of Atlantis, the requirement to document every angle of her launch is vital/ Thankfully, control was re-established, allowing this constraint to be filed to paperwork for post launch assessments.

“IPR 52: During surveillance, the Photo Optical Control Systems (POCS) A and B locked up and lost ability to control film cameras located at Pad-A and the MLP. POCS controls 78 cameras throughout the LC39 area.

“Trouble shooting consisted of performing a power cycle to the control system. Control was re-established and is currently being monitored. This has been a very stable system and this failure is not known to have occurred before. Constraint: S0007.200 Step 16-1157.

The two remaining constraints were also cleared in plenty of time to avoid any need for discussion at final Mission Management Team (MMT) meeting during the 45 minute built in hold – the first relating to an middeck payload connection, while the second was associated with the Merritt Island Launch Annex (MILA) communication systems.

“IPR 54 to PTC (Payloads): During the IVT for middeck payload, CB5 on Panel M063P was closed in lieu of CB4. CDR verified that there was nothing mated to J5 on the Panel. Payloads turned off power to the experiment prior to repositioning closing the correct CB,” added the NTD report.

“IPR-53: During Comm Activation, the C+T lab was unable to lock on to engine data. MILA was able to lock to the vehicle FM downlink and RPS was able to successfully frame sync the data from all three Main Engine sub-carriers satisfying the OMRS (Operational Maintenance Requirements and Specifications) requirement.

STS-129 Specific Articles:

“This indicates there is no problem with the vehicle FM system and no further vehicle troubleshooting is required. The C&T station is a non-critical system used as an independent monitor to support launch activities. There is no OMRS requirement for the C&T Lab to provide FM deviation data during S0007.200. This item will be transferred to a PR (Problem Report).”

A4The only real issue that required engineering discussions during the latter part of the count was the noise on Fuel Cell 2’s H2 pump, with an indication that may have been indicative of dropping a phase for some unknown reason.

With a similar condition was noticed on Atlantis during her previous mission – STS-125 – the issue was put down to the instrumentation that is very sensitive to AC phase adjustments associated with items such as the brightness of the orbiter’s cabin lights.

As expected, all three Fuel Cells performed nominally during Atlantis’ ascent.

Flight Day 2 – TPS Surveys:

With the handheld photography and ET Umbilical Well imagery in the process of being downloaded to the ground for the Damage Assessment Team (DAT) to begin their evaluations into any foam liberation events, FD2 will take a first look at the health of Atlantis’ heatshield.

A3Shortly after reaching orbit on Monday evening, Atlantis’ Payload Bay Doors were opened, followed by the deployment of her Ku-band antenna. Atlantis’ Remote Manipulator System (RMS) was also activated ahead of Flight Day 2’s inspections, along with initial post-launch checkouts.

With the NC2 and NC3 Rendezvous burns planned into the flight day, the main role for the crew will be the unberthing of the Orbiter Boom Sensor System (OBSS) via the RMS, in order to carry out surveys of Atlantis’ wing and nose cap, before heading to the OMS Pods to check for any tile damage or protruding blankets.

“TPS Surveys: All RCC (Reinforced Carbon Carbon) is inspected during the OBSS Starboard Wing, Nose Cap, and Port Wing surveys. The two wing surveys also cover most of the areas of the crew cabin. The OMS Pod is inspected using a handheld camera to take pictures from the aft flight deck windows,” noted Flight Readiness Review (FRR) mission outline documentation (L2).

“The OBSS survey procedures incorporate the use of supplemental IDC (Digital Camera) images during LDRI (Laser Dynamic Range Imager) scans, thus reducing the likelihood of needing Focused Inspection. The OBSS unberth procedure incorporates the LDRI 3D calibration and the starboard survey the flat field calibration.

Three crewmembers are required continuously during the surveys, two for the SRMS/OBSS ops and one to operate the situational awareness cameras and sensors. Only two crewmembers are required during unberthing and berthing operations (non-laser ops).

A5Scans of the entire starboard wing are not easily performed, or are impossible to perform while docked, which results in those areas being scheduled first. The surveys are scheduled to continue through the night passes, but the crew may elect to pause if the night time visuals are not sufficient.

“The LDRI survey attitude requires no sun within a +/-20 degree field of view (FOV) of the laser bore-sight. Additionally, no sun can be within a 10 degree half-cone directly behind the instrument; however it is highly desired to keep the sun at a 90 degree half cone behind the instrument as long as it’s not directly behind.”

Although Flight Day 3’s RPM (Rbar Pitch Maneuver) – carried out “underneath” the ISS ahead of docking – will provide a near-complete overview of Discovery’s heatshield, the OBSS inspections will give the opening insights into the extent of any damage sustained during the ride uphill.

The key focus will be on the External Tank (ET-133), especially the Ice Frost Ramps (IFRs) – with the LO2 ramps also being filmed from a minicam on the flight deck during Atlantis’ ascent. Foam losses from the tank can usually be a baseline for tracking where and when they may of impacted on the orbiter.

Based on the initial data, no “major” foam loss events have been observed – with only three events, all occurring after the time period where they can be a damage threat to an orbiter. However, a lot of work is required to study each element of camera, radar and onboard camera footage, usually taking several days to collate.

L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

Related Articles