STS-133: ISS Gears Up for Discovery’s Arrival – Soyuz Flyaround Update
With the countdown clocks now ticking down for the launch of STS-133 at the Kennedy Space Center (KSC), the crew of the International Space Station (ISS) have been hard at work this past week, reconfiguring the station for the arrival of Discovery this Saturday. The reconfiguration period is set to continue this week, as the ISS and Expedition 26 crew gear up for STS-133 docked operations.
Visiting Vehicle Docking Port Shuffle:
The major task accomplished by the crew last week was the relocation of Japan’s H-II Transfer Vehicle-2 (HTV-2) “Kounotori” from the Nadir port of Node 2 to the Zenith port of Node 2. The purpose of the relocation was to clear the way for payload extractions from Shuttle Discovery’s Payload Bay (PLB) when Discovery docks to Pressurised Mating Adapter-2 (PMA-2), located on Node 2 Forward.
Following on from hatch closure between HTV-2 and Node 2 Nadir last Thursday (17th February) evening, Friday (18th February) morning saw Flight Engineer-5 (FE-5) Paolo Nespoli and FE-6 Cady Coleman unberth and remove HTV-2 from Node 2 Nadir and began the six hour robotics sequence to manoeuvre HTV in between the Japanese Pressurised Module (JPM) and the Port 1 (P1) Truss.
The never-before-performed manoeuvre, executed flawlessly by the Space Station Remote Manipulator System (SSRMS) and controlled from the station’s Cupola, was completed successfully when HTV arrived at the Node 2 Zenith port later in the afternoon.
Once the berthing sequence had been completed, Node 2’s Zenith hatch was opened on Friday evening. A new, specially-constructed contingency power jumper was installed in order to provide backup power to HTV, should it be needed.
Such backup power was not an issue when HTV was on Node 2 Nadir, as that port was designed for Visiting Vehicles (VVs) and so all the necessary connections to support those vehicles were present at the module’s launch. However, Node 2 Zenith was never intended to be a VV port under original ISS plans, and so a contingency power supply is not available.
Since its launch in 2007, Node 2 Zenith has been designated as a backup VV port, and ISS managers identified the lack of a contingency power supply as an issue and subsequently manifested contingency jumpers on the STS-133 mission. The contingency jumpers provide back-up power to VVs on Node 2 Zenith by connecting them to power supplies on Node 2’s Forward-Overhead bulkhead.
STS-133 was originally scheduled to arrive at the ISS ahead of HTV-2, but due to repeated delays to the STS-133 mission, HTV-2 has arrived at the ISS ahead STS-133 and the contingency jumpers. Discovery’s docking has facilitated the need for HTV-2’s relocation to Node 2 Zenith, and so a situation arose where the required jumpers were on the ground inside the Permanent Multipurpose Module in Discovery’s PLB.
Retrieving the jumpers from the PMM, in order to deliver them to the ISS ahead of the HTV-2 relocation via a Russian Progress vehicle, was not an option as no access to the PMM is available while it is secured in Discovery’s PLB. Therefore, ISS engineers developed a plan to construct a jumper from scavenged parts already present on ISS.
Although the Node 2 Zenith hatch was opened last Friday evening, HTV-2’s hatch will not be opened until today (Monday 21st February). HTV-2 will be relocated back to Node 2 Nadir on 7th March, following the departure of Shuttle Discovery.
Following on from the successful HTV-2 relocation, Russia’s Progress M-07M/39P vehicle, which had been docked to the Service Module (SM) Aft port since 12th September last year, undocked from the ISS yesterday (Sunday 20th February) at 1:12 PM GMT.
During the undocking, Russian thrusters were in control of the station’s attitude control. US Control Moment Gyroscopes (CMGs) resumed control of the ISS later on Sunday. Following the undocking, 39P was commanded to conduct it’s de-orbit burn for a destructive re-entry over the Pacific Ocean at 4:12 PM GMT on Sunday.
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The 39P undocking has cleared the SM Aft port for the arrival of Europe’s Automated Transfer Vehicle-2 (ATV-2) “Johannes Kepler”, which is currently chasing down the ISS following its launch from Kourou in French Guiana last Wednesday (16th February).
Due to the one day slip of ATV’s launch (from Tuesday to Wednesday), ATV’s automatic docking to the SM Aft port also slipped by one day, to this Thursday (24th February) – the same day as the scheduled launch of Discovery on STS-133. This creates some schedule issues, due to the fact that ATV-2’s successful docking is a Launch Commit Criteria (LCC) for STS-133.
In the unlikely event that ATV-2 should fail to dock with the ISS, Shuttle and ISS managers would be faced with a decision for which there would be very little time for discussion. As such, pre-defined options have already been put in place to aid the decision making process.
Should ISS managers determine that ATV’s docking failure is a simple issue that can be easily resolved, STS-133 and Discovery will stand down for 48 hours in order to give ATV time to make a second docking attempt at the station.
However, should ISS managers determine that ATV’s docking failure is a more complex issue, requiring further study and analysis before a second docking attempt can be made, the ATV will be sent into a parking orbit and Discovery will launch as planned.
The time-critical decision is driven by the fact that ATV-2’s docking to the ISS will occur roughly two hours after External Tank (ET) fuelling is scheduled to begin for Discovery’s launch. As such, if a docking failure occurs, a decision will need to be made extremely quickly as to whether to park ATV and proceed with fuelling and launch, or re-attempt a docking in the following days and stand Discovery down.
STS-133 Specific – Including ET Stringer Issue – Articles: https://www.nasaspaceflight.com/tag/sts-133/
If the decision to stand down was taken, then ET-137 would need to be drained of propellants, thus using up another of the ET-137’s limited number of cryogenic cycles (although 11 cryo cycles still remain before ET-137 reaches its limit).
If ATV docks successfully on Thursday as planned, the ISS crew will ingress ATV that same day, in order to have it “open for business” by the time Shuttle Discovery arrives two days later. ATV-2 was scheduled to perform a test reboost of the ISS on Friday (25th February), one day prior to the scheduled STS-133 docking. However, due to the one day delay of ATV-2’s docking, it is not currently known whether this reboost will be performed or not.
In preparation for the docking, FE-5 Paolo Nespoli and Russian cosmonaut FE-1 Alexander Kaleri have been conducting Onboard Training (OBT) aboard the ISS last week. The OBT consisted of a computer-based program that simulates ATV’s approach to the station, including failures and anomalies in the approach.
Although ATV’s approach and docking to the ISS is fully automated, Both Nespoli and Kaleri will be on hand during the docking to assume manual control in the event of a problem occurring in the approach.
ISS Reconfiguration for STS-133:
Following the successful relocation of the HTV last Friday, the Mobile Servicing System (MSS) was reconfigured to support the STS-133 mission.
These reconfigurations consisted of the SSRMS “walking off” from the Mobile Base System (MBS), where it had been located for the HTV relocation, to Node 2’s Power & Data Grapple Fixture (PDGF). Following the SSRMS walk-off, the Mobile Transporter (MT), with MBS attached, translated from Worksite-5 (WS-5) to WS-3. The Special Purpose Dextrous Manipulator (SPDM), based on the Lab PDGF and holding onto HTV-2’s external payloads, then completed a body roll manoeuvre.
The Expedition 26 crew will be hard at work this week reconfiguring the interior of the ISS to support STS-133, according to an Increment 26 Status document obtained by L2.
Tasks to be completed this week include swapping over two Minus Eighty-degree Laboratory Freezer for ISS (MELFI) racks. MELFI-2, currently located in the Lab Starboard 1 location, will be swapped with MELFI-3, which is currently located in the JPM Aft 1 location.
The Centerline Berthing Camera System (CBCS), which aids ISS robotics operators by providing them with live video views of modules approaching their berthing ports, will be installed and checked out at the Node 1 Nadir port this week in order to support PMM berthing during STS-133. PMA-2, to which Space Shuttle Discovery will dock, will be pressurised and leak checked this week. A great deal of stowage relocation and “pre-pack” for STS-133 will also be conducted this week.
The Expedition 26 crew will also spend time this week bringing themselves up to speed on the STS-133 mission by reviewing procedures and timelines uplinked to them from the ground, and holding conferences with ground controllers to discuss STS-133 mission activities. A conference with the STS-133 crew was held last week.
Crews will also conduct Rendezvous Pitch Manoeuvre (RPM) training, which involves reviewing heat shield photography targets and practising photographing an imaginary Shuttle through the ISS SM windows.
ISS ECLSS Status:
An ISS Systems Status document, obtained by L2, gave an overview of the current status of the ISS Environmental Control & Life Support System (ECLSS), which will be needed to support the STS-133 crew during their stay on the station.
The Oxygen Generator Assembly (OGA), located in the Oxygen Generation System (OGS) rack at Node 3 Aft 5, will be down during the STS-133 mission, as it is currently under investigation by ground specialists due to concerns regarding the pH levels in the system.
The document notes that the OGA was activated at 50% mode for four days from 31st January to 4th February. Recirculation loop samples were taken and initial analysis showed that the pH levels of the samples were “in family with expected results”.
Another item mentioned in the document related to the station’s Water Processor Assembly (WPA), which is located within the Water Recovery System-1 (WRS-1) and WRS-2 racks, installed at Node 3 Deck 5 and Deck 4 respectively. The WPA converts urine and condensate into drinkable water for the station crew.
On 8th February, the WPA’s Mostly Liquid Separator (MLS) failed during a process cycle, which meant that the WPA was unable to process condensate or urine. As such, the ISS crew was required to redirect condensate collection from the WPA to the condensate tank in the Lab.
The WPA’s waste water tank was used to collect Urine Processor Assembly (UPA) distillate. The crew also used an Iodinated Contingency Water Container (CWC-I) to fill the WPA’s water storage tank, for delivery to the Portable Water Dispensed (PWD) to be used for crew consumption.
This configuration would create issues for STS-133 – not because of lack of water – but because of the difficulties associated with keeping track of water in the Lab condensate tank, which collects condensate, the WPA’s waste water tank, which collects UPA distillate, and the WPA’s water storage tank, which provides drinking water for the crew.
The issue of keeping track of all these water locations would be even more challenging during the STS-133 mission, as Discovery’s crew would be using the Waste & Hygiene Compartment (WHC), thus producing more urine and increasing UPA processing, and because the extra crewmembers would be producing more condensate in the ISS’s atmosphere, requiring collection by the condensate tank in the Lab.
Also, some of the STS-133 crewmembers may wish to use the ISS’s PWD for drinking water, but without the WPA to convert UPA distillate and condensate into drinking water, the PWD tanks would be emptied at a faster rate than normal, requiring more manual filling by the ISS crew.
Following a quick study by the Flight Investigation Team (FIT), all evidence pointed to the Pump/Separator Orbital Replacement Unit (ORU) as the failed component. The Pump/Separator ORU had been Removed & Replaced (R&Rd) on a previous occasion, and a new ORU was recently delivered to the ISS inside Japan’s HTV-2.
The FIT instructed the ISS crew to command the WPA to standby mode, which would activate the Pump/Separator so that it could be checked out. The pump turned on at the expected speed, and so the WPA was commanded to process mode, which was again nominal. The WPA was thus considered to be back to normal operational mode.
The WPA continued to operate nominally for two to three process cycles, however, on 17th February, the WPA Pump/Separator again failed in a similar manner to the first failure. The WPA was power-cycled and the pump turned back on as expected. On the morning of 18th February, the WPA processed nominally.
The failure occurred on the same day that HTV-2’s hatch was due to be closed for its upcoming relocation to Node 2 Zenith, and so ground control teams had FE-5 Paolo Nespoli retrieve the spare Pump/Separator ORU from HTV before the hatch was closed, so that it would be available should the FIT deicide to R&R the pump.
Teams met to discuss the WPA failures and possible plans of action to rectify the problem, should they be needed. Teams also worked to develop a plan for STS-133 that does not involve using water converted from UPA distillate – thus protecting against a UPA failure during STS-133.
However, at the STS-133 Flight Readiness Review (FRR) last Friday, it was decided that the ISS ECLSS would not impact STS-133’s target launch date.
Soyuz Flyaround Latest:
The Soyuz TMA-01M/24S flyaround, also being referred to as a flyabout by NASA, is still not certain to happen, as managers at the FRR on Friday decided to make a GO/NO-GO decision for the flyaround during the STS-133 mission.
The decision would be made by Flight Day-6 (FD-6), and would be dependent upon completion of all EVA tasks and no requirement for a Focused Inspection (FI) of Discovery’s heat shield. The Russian space agency, Roscosmos, would have the final say in the decision.
The desire to perform the flyaround manoeuvre seems to be strong, as noted by Associate Administrator for Space Operations Bill Gerstenmaier during last Friday’s post-FRR press conference. According to Gerstenmaier, the images taken during the flyaround would serve engineering purposes, as well as provide for some stunning views.
Gerstenmaier said that never-before-seen views of the ISS’ Truss, Multi Layer Insulation (MLI), and potential Micro Meteoroid Orbital Debris (MMOD) strikes would be gained during the flyaround.
Gerstenmaier also said that Soyuz flyarounds would become more common in the future, when the Shuttle will no longer be available to perform flyarounds of the ISS and gather much-needed images of potential damage to the station’s exterior.
As such, performing a Soyuz flyaround during STS-133 would be good practice for future operations.
The latest proposal for the flyaround would likely involve a one day to extension to the STS-133 mission, with the flyaround occurring on FD-10/Saturday 5th March – one day prior to Discovery’s undocking from the ISS.
NASA sent their proposal for the flyaround to Roscosmos last Saturday (12th February). The proposal that Roscosmos sent back to NASA differed wildly from the proposal that NASA sent to Roscosmos. The new Roscosmos proposal was seen in a stunning Soyuz Flyaround CGI Video, available to download on L2.
At the start of the flyaround manoeuvre, the ISS would be in its standard attitude for Shuttle docked operations, the negative X axis in Velocity Vector (-XVV) Torque Equilibrium Attitude (TEA). For the flyaround, the ISS would first manoeuvre to the Soyuz undocking attitude, which would place the Zenith, or -Z side of the ISS in the Velocity Vector (-ZVV).
The Soyuz TMA-01M/24S spacecraft would then undock from Mini Research Module-2 (MRM-2) and back away from the ISS. This would provide for some views of the Zenith side of the ISS with the curvature of the Earth as a backdrop.
The ISS would then conduct a roll manoeuvre on the negative Y axis, in order to put the station the correct attitude for the Soyuz redocking. During this manoeuvre, the 24S crew would gain some spectacular side-on views of the ISS, its VVs and Shuttle Discovery, with the curvature of the Earth as a backdrop.
24S would then flyaround to line back up with MRM-2’s docking port, and initiate the approach to re-dock. Views of the Zenith side of the ISS with the surface of the Earth below would be available during this manoeuvre.
Once 24S re-docked to MRM-2, the hatches would be opened and the spectacular historical images would be downlinked to the ground for release to the public.
(Numerous articles will follow. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers – which will ramp up into full Flight Day coverage during the mission. Images used, via NASA.gov/NASA TV, and L2).