STS-132: Atlantis and the ISS set to bid farewell for likely the final time
There’s always a chance the unavoidable end of the shuttle program may be at least paced out via at least one additional flight, although the official schedule continues to dictate that Flight Day 10 of STS-132 will be the last time Atlantis will be docked with the International Space Station (ISS).
Her final hours with the orbital outpost have earned praise from engineers, managers and astronauts alike, most of whom have moved away from the politically correct “it” to the traditionally correct “her” when speaking directly of the famous spacecraft.
While the current NASA administrator is himself a veteran shuttle Commander, his comment that people will have forgotten how humans used to travel into space in 10 years time appears to have no basis in reality, if the tributes for the orbiter’s swansong mission – which continue to flood in from public and officials alike – are anything to go by.
Ironically, STS-132 (swapped with Discovery) – and STS-129 – weren’t originally manifested to Atlantis, with the previous plan to retire – or at least mothball – the orbiter after STS-125’s visit to service the Hubble Space Telescope.
Another stay of execution remains on the cards via STS-135, although that mission – if approved – may be handed to Discovery (article next week).
General Bolden, at least, remains less than enthusiastic about any plan that does not end the Shuttle Program as soon as possible, as he continues to champion the deeply unpopular proposal outlined in President Obama’s FY2011 budget.
For her part, Atlantis remains unfazed by her fate, and continues to behave impeccably on orbit, with only a small number of minor issues charged against the vehicle at the Mission Evaluation Room (MER), highlighted by the snagged cable on the Orbiter Boom Sensor System (OBSS) Pan/Tilt Unit (PTU).
“As far as the current mission goes, there was a little bit of bad luck,” noted SSP (Space Shuttle Program) manager John Shannon on the Shuttle Standup/Integration report (L2) – in reviewing the first part of the mission. “It was just very strange how that cable got routed right between the connector and the little stanchion piece that kept it from tilting up on our inspection.”
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While the unit is now able to translate through the required movements that will allow for the Laser Dynamic Range Imager (LDRI) to finally complete a full scan of Atlantis’ RCC panels, Mr Shannon praised the teams for utilizing a variety of assets to allow for the clearance of the vehicle’s Thermal Protection System (TPS) for entry.
“The team has done an amazing job of looking at options and alternative ways of getting inspection data. The RPM looked like it went really well. Overall, it looks like a really clean vehicle. There (were) really (no) reasons to suspect any damage to the vehicle. We will go do the risk trades to get as much inspection data as possible before undocking.”
Those discussions on whether to carry out a docked inspection during these late docked days on Station resulted in a decision to press ahead with a nominal Late Inspection plan – which will take place on Flight Day 11.
Although the discussions took several days to conclude, the process of clearing Atlantis from any TPS concerns was typically methodical, and carried out at a pace that ensured the Damage Assessment Team (DAT) presented their recommendations only when they were ready to do so.
All but one of the Atlantis’ array of thrusters will be available for undocking, following an issue with the L3D RCS (Reaction Control System) thruster’s heater shortly after entering orbit. However, concerns the thruster may start to leak – itself not a major impact – have been allayed by good temperature management whilst on orbit.
“All passive thermal temperatures are within acceptable range and all thermal systems are performing nominally except the L3D RCS thruster heater, which is failed off,” noted the MER (L2). “Current docked attitude is maintaining L3D temperatures within limits.
“No heater cycles have been observed on this thruster. The lowest injector temperatures observed during this shift were 71.7 deg F for fuel and 72.7 deg F for oxidizer.” A full overview of the L3D management plan for post docking will be published in the next article.
“25 of 38 primary thrusters have been fired. No new Primary thrusters were fired since previous report,” with all 38 thrusters set for a two pulse test on EOM-1 (End Of Mission minus one day) during pre-entry checkouts of Atlantis’ systems.
Atlantis’ three Auxiliary Power Units (APUs) and Fuel Cells all continue to show good health, bar a small issue with Fuel Cell 3 noted via its monitoring hardware – although the FC continues to operate nominally.
“All APU on-orbit parameters are nominal. All APU heaters are operating on the ‘A’ circuit. Subsystem performance is nominal. The PRSD (Power Reactant Storage and Distributation) O2/H2 manifold 2 isolation valves were cycled closed for crew sleep and reopened (prior to crew wake up).
“Fuel Cell 3, s/n 118, O2 flow meter indication continues to be erratic. It did indicate an increase in flow at the beginning of the fuel cell purge and a decrease at the end of the purge, verifying proper purge valve operation.”
According to the flight plan, the undocking late in the crew day will not allow for a water dump – as per usual – pending any change of plan by the Mission Management Team (MMT). However, Atlantis has enough spare capacity to allow the dump to occur on Flight Day 11 if required.
“Life Support Subsystem is operating nominal, working no issues. Total GN2 = 294.1 lbs. Total Supply water = 391.4 lbs (large transfer to ISS). Total waste water = 58.6 percent (100 lbs),” noted the MER’s most recent status report.
Nominal performance is mirrored throughout the system report, which has become the norm on most recent flights, though under appreciated given the complexity of the vehicle.
“A review of the GPS Data during this period confirmed that the GPS was operating nominally. The GPS team is not working on any issues or funnies,” added examples of the MER status overview. “The Flight Control System is operating nominally. All communications subsystems are performing well. The DPS (Data Processing System) HW (Hardware) team is not working any issues at this time.”
Atlantis is due to undock from the ISS at 10:22am Central Time, prior to a one lap flyaround of the Station, and the main separation burn at 12:05pm Central.