International Space Station Expedition 20 Commander Gennady Padalka, Flight Engineer Michael Barratt and spaceflight participant Guy Laliberte have landed safely in their Soyuz TMA-14 on the steppes of Kazakhstan Sunday morning. The trio left the ISS just a few hours prior to landing, leaving a Station that is now busily working through its Expedition 21 cycle.
Soyuz TMA-14 Return:
Soyuz commander Padalka piloted the Russian spacecraft to a parachute-assisted landing at 12:32 a.m. EDT at a site northeast of the town of Arkalyk. The landing marks the end of a six month mission for commander Padalka and NASA’s Barratt. Laliberte spent 11 days on Station, following his arrival on Soyuz TMA-16.
Russian recovery teams were soon on the scene via their fleet of helicopters, with the hatch opening just moments after landing. The crew members will return to the Gagarin Cosmonaut Training Center in Star City, outside of Moscow, for reunions with their families.
A few issues had to be resolved ahead of undocking, relating to a sensor and a changeout of a LiOH cartridge.
“Early in the morning, Padalka and Barratt worked in the Soyuz TMA-14/18S for the scheduled testing of the spacecraft’s SUDN MCS (Motion Control System) procedures at 4:49am -5:15am EDT, but they ran into an anomaly when posigrade (forward-pushing) KDU thrusters did not fire when commanded,” added a status report.
“Normally these thrusters are not used for the retrograde burns required for the undocking, but Moscow has scheduled a second MCS test (ahead of undocking). The anomaly is not seen as a major problem and is not expected to affect the Soyuz undocking on 10/10 since it does not interfere with the spacecraft’s ability to undock and reenter the atmosphere.
“Padalka supported a re-test of the 18S SUDN MCS (Motion Control System) with a thruster firing. Again telemetry was not received from one thruster. However, all indications are that the posigrade thruster is completely functional and fired nominally. Preliminary investigation points to a sensor problem – that sensor will be masked. No impact to nominal Soyuz 18S undocking, reentry, or landing operations.
“Soyuz TMA-14/18S ppCO2 Analyzer: Moscow also reported the failure of the ppCO2 (Carbon Dioxide Partial Pressure) analyzer in 18S, requiring Padalka to install an unused LiOH absorber cartridge in the Descent Module and staying an additional hour in the spacecraft to verify its correct operation.”
The successful landing adds confidence to the veteran Russian vehicle’s robustness, following the off-nominal ballistic re-entries of Soyuz TMA-10 and 11. The nominal re-entry and landing follows the issue-free returns both for Soyuz TMA-12 and TMA-13.
The ballistic re-entry – a degraded mode for landing, which initiates a steep trajectory, resulting in a much shorter than planned re-entry, exposing the crew to up to 10G – for TMA-10 and TMA-11 resulted in an investigation to find the root cause of problem with the separation between the Descent Module and the rest of the vehicle.
The Soyuz Vehicle consists of three modules: the Orbital Module, the Descent Module (DM), and the Instrumentation/Propulsion Module (IPM). All three modules nominally separate simultaneously, shortly after the deorbit burn is completed – at around 140 km altitude.
The two “off nominal” re-entries in 2007 and 2008 were the fault of separation failures on the modules, thus initiating the ballistic return for their three person crews.
“In October 2007, Soyuz 14S (TMA 10) undocked from ISS and landed in Kazakhstan. The Instrument and Propulsion Module and the Descent Module failed to separate when commanded,” a large investigation document, available on L2, outlined. “Vehicle trims in a hatch-forward configuration when modules fail to separate. The modules eventually separated at approximately 80 km.
“Subsequently the “Ballistic Mode” was entered (steeper trajectory, higher G-loads) and the vehicle successfully landed at the ballistic landing site. A special commission was formed to investigate these events.
“In April 2008, Soyuz 15S (TMA 11) undocked from ISS and landed in Kazakhstan. The Instrument and Propulsion module and the Descent Module again failed to separate when commanded. Vehicle trims in a hatch-forward configuration when modules fail to separate. The modules eventually separated at approximately 60 – 66 km.
“The “Ballistic Mode” was entered and the vehicle successfully landed at the ballistic landing site. Two commissions were formed to investigate these events: External Commission headed by Koroteev from the Keldish Institute. RSC-E internal Commission headed by Lapota.”
On both occasions, the failure of one or more pyro bolts – which initiate separation – was deemed to be the root cause of the modules remaining together, prior to the eventual release of the DM due to aerodynamic drag and mainly heating loads.
The investigation’s findings pointed to the long-term exposure to electromagnetic emissions on-orbit, and their potential to cause issues with the pyro bolts.
Mitigation came via corrective action on the grounding issues at the Plane 1 pyro lock location, physical separation of the pyro firing cables, and lockwiring the pyro connectors. Engineers also replaced the pyro bolts with a more robust design that is less susceptible to the electromagnetic environment.
Engineers also instituted a software change that uses the IPM thrusters to force the vehicle to re-enter ‘sideways,’ increasing heat loading on the truss, helping lead to truss failure and earlier separation. This mitigation process appears to be working, as per another successful re-entry and landing.
Click here for the full article based on the investigation presentation acquired by L2:
With the Soyuz TMA-14 departing, the ISS turns its attention towards not only the upcoming arrivals of the next Progress resupply ship – which launches next week – and the November STS-129 mission with Shuttle Atlantis, but also to the final “docked” days of the Japanese HTV (HII Transfer Vehicle).
The ISS crew have been working on manual and robotic transfers between the vehicle and Station, ahead of its ungrappling later this month.
“H2 Transfer Vehicle (HTV) Exposed Pallet (EP) Transfer and Insertion – Flight Engineer (FE)-2 Nicole Stott and FE-5 Frank DeWinne successfully maneuvered the JEM Remote Manipulator System (JEMRMS) to grapple the EP from the JEM Exposed Facility (JEF),” noted the latest MOD 8th Floor News memo, available on L2.
“Then the JEMRMS handed off the EP to Space Station Remote Manipulator System (SSRMS). FE-2 Stott and FE-4 Thirsk operated the SSRMS to install the EP into the HTV Unpressurized Logistics Carrier (ULC).
“For the install, the SSRMS Force & Moment Accommodation (FMA) function was enabled to limit forces and moments during the EP install along the guide rails. This was the first-ever operational use of FMA and the system worked well.
“After releasing the EP, SSRMS was then maneuvered back to an HTV pre-grapple position. System performance was nominal throughout. After the EP insertion, the Ready To Latch (RTL) bolts were all latched nominally.”
Also being worked on the ISS are the preparations for the full use of the Special Purpose Dexterous Manipulator (SPDM) – or Dextre. The Canadian robot will be used for – among other tasks – the transfer of ORUs (Orbital Replacement Units) on the outside of Station.
“The robotics team continued their work on checking out the SPDM. The SPDM Backup Drive Unit (BDU) was exercised to control both the ORU and Tool Changeout Mechanisms (OTCM),” added the 8th Floor. “Various SPDM functions were also checked out since the uplink of the recent MSS 6.1 software load. The checkouts included: functionality for OTCM mechanisms; body joint maneuvering; maneuvering arms 1 & 2.
“The Robotic Micro-Conical Tools (RMCT) were grappled nominally and then the RMCT launch locks were released and the tool were released and maneuvered clear of the Tool Holster Assembly (THA) to a stow position.
“Everything is looking good for any future R&R activity. Due to the high activity leading up to ULF3, the Program has decided not to currently pursue the previous objective to perform a swap of two Truss RPCMs.
“The current thinking is to change out one of the truss RPCMs with one in the CTC box (Cargo Transfer Carrier) that is installed on an External Logistics Carrier (ELC) flying on ULF3. The MOD robotics team will be working with the Program regarding what the sequence of events should be for this new goal.”
Meanwhile, the ISS continues to wait on a decision over its lifetime, with the Augustine Review into the Human Space Flight program continuing to favor options that would allow for the ISS to be extended to 2020. Deorbing the Station around 2015-2016 is now highly unlikely to become a reality.
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.