Following the decision to move Discovery’s STS-133 launch date target to No Earlier Than (NET) February 3, NASA managers have begun realigning the International Space Station (ISS) manifest. An April 1 placeholder has been selected for Endeavour’s STS-134 mission, while Japan’s HTV resupply vehicle is also involved in supporting the manifest changes.
With the root cause into what caused two stringers to crack on Discovery’s External Tank (ET-137) during tanking continuing, managers decided to take the “next step” via demonstrations, such as building a test rig with a stringer set-up – likely to be located at the Marshall Space Flight Center (MSFC) – along with an instrumented Tanking Test out at the Pad.
A preliminary schedule for the instrumented Tanking Test has already been created, with a plan to conduct the test on December 15, replacing an original plan to press forward with a non-instrumented tanking next week – as much as that was only a preliminary option.
“An option to perform an un-instrumented tanking test is (was) being considered. CTS (Call To Stations) NET Monday, 12/6, and tanking NET Wednesday, 12/8. The plan is to go down to T-31 seconds and secure,” noted the NASA Test Director on Friday morning (L2).
“While the team prepares for a tanking test, the PRCB (Program Requirements Control Board) yesterday did not provide direction as to when the tanking test would occur.”
Space Shuttle Program (SSP) manager John Shannon addressed the media on Friday, noting that on consideration a non-instrumented Tanking Test would be “too gross”.
Discussions over the coming days will decide on the forward plan for setting up ET-137’s flange regions with instrumentation – which will include the removal and replacement of BX-265 Thermal Protection System foam from the tank – along with a pad flow schedule to refine the date the of the test.
This effort will be the major focus of Discovery’s flow for the interim, with ordnance disconnects – originally scheduled for the weekend – cancelled, while Backscatter imaging of the ET LH2 flange is continuing.
STS-133 Specific – Includes all ET issue content – Articles: http://www.nasaspaceflight.com/tag/sts-133/
Several in-depth articles will follow in the coming days on the continuing root cause evaluations.
The STS-133 delay will have major impacts on Japan’s H-II Transfer Vehicle-2 (HTV-2) “Kounotori”, that is scheduled to launch to the ISS on 20th January 2011.
Inside HTV-2’s Unpressurised Logistics Carrier (ULC) will be an Exposed Pallet (EP), which will be carrying two Orbital Replacement Units (ORUs) for the US segment of the station. The first ORU is the Flex Hose Rotary Coupler (FHRC), and the second is the Cargo Transportation Container-4 (CTC-4).
The FHRC and CTC-4 will be installed onto the ISS’s ExPrESS Logistics Carrier-4 (ELC-4), which currently resides in the Payload Bay of Space Shuttle Discovery on LC-39A at KSC. Under original plans, ELC-4 was set to arrive at the ISS months ahead of HTV-2, when Discovery was planned to visit in late 2010. However, now that STS-133 has been pushed into February 2011, HTV-2 will arrive at the ISS before ELC-4.
As such, ISS Program Managers have devised a plan that enables the FHRC and CTC-4 to be installed directly onto ELC-4, without having to adjust the launch date of HTV-2.
Following HTV-2’s launch on 20th January and a seven day free flight, HTV-2 will be captured by the Space Station Remote Manipulator System (SSRMS) and berthed to the Nadir port of Node 2 on 27th January. Node 2 Nadir is currently the primary port for all Common Berthing Mechanism (CBM) compatible Visiting Vehicles (VVs).
In the days following the HTV-2 berthing, the ORU-laden EP will be extracted from HTV-2’s ULC with the SSRMS, and attached to the Japanese Exposed Facility (JEF) on the Port side of the station. Following the completion of this procedure, the SSRMS will un-berth HTV-2 from the Node 2 Nadir port, and transfer it to the Node 2 Zenith port directly above the Nadir port.
The Node 2 Zenith port is currently reserved as a back-up port in case the primary VV port is unusable.
The reason for re-locating HTV-2 to the Node 2 Zenith port is to provide clearance for Space Shuttle Discovery when it docks to the ISS on 5th February. If HTV-2 were berthed to the Node 2 Nadir port during the STS-133 mission, it would preclude payloads from being removed from Discovery’s Payload Bay by the SSRMS.
Following Discovery’s visit and the installation of ELC-4 onto the Nadir side of the Starboard 3 (S3) Truss, the two ORUs will be removed from the EP, still attached to the JEF, with the Japanese Experiment Module (JEM) RMS.
They will then be handed off to the Special Purpose Dextrous Manipulator (SPDM) “Dextre” on the end of the SSRMS, and installed onto ELC-4. HTV-2 will then be relocated back to Node 2 Nadir, and the EP removed from the JEF and reinserted into the ULC.
The Permanent Multipurpose Module (PMM) being launched on STS-133 contains many racks used to retain cargo during launch, but that are useless on-orbit. The Expedition 26 crew will be working hard to unload these racks quickly, so that they can be transferred to HTV-2 for disposal before it is un-berthed from the ISS in mid-March.
We may also see Robonaut 2 (R2), being launched in the PMM on STS-133, being unpacked soon after launch, as its Structural Launch Enclosure to Effectively Protect Robonaut (SLEEPR) is planned to be disposed of on HTV-2.
In order to accomplish all these extra objectives, the HTV-2 mission will be extended to 60 days. This busy period of work aboard the ISS will be further complicated by the arrival of Europe’s Automated Transfer Vehicle-2 (ATV-2) on 27th February, two Russian Progress undockings, one Progress docking, and two Russian Orlan spacewalks.
ISS Specific Articles: http://www.nasaspaceflight.com/tag/iss/
On 20th December, a test of the SPDM will be conducted in order to verify that it is ready to perform ORU ops. during HTV-2. For this test, the SPDM will pick up a CTC, and manoeuvre it around in order to test its dexterity.
Endeavour’s STS-134 mission has also been slipped from its February launch date, moving to a placeholder of April 1 – a date which will continue to be refined based on the status of her older sister’s successful completion of her mission.
(Further updates and articles will follow. Refer to live coverage threads linked above. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used, Lead: NASA.gov. Within the article: via L2 acquired presentations and NASA.gov).