ISS Prepares for Busy Upcoming Year of Logistics Operations

by Pete Harding

The ISS Program is gearing up for what will be a very busy upcoming year of logistics operations, with a total of eleven Visiting Vehicles (VVs) scheduled to visit the orbital outpost in 2011. Manifested arrivals consist of five Russian Progresses, three SpaceX Dragons, one Orbital Cygnus, one Japanese HTV, and one European ATV. At least one, and possibly two Space Shuttles are also scheduled to visit the station next year.

Destination ISS:

The large amount of VVs arriving at the ISS in 2011 will make stowage aboard the station extremely challenging, due to the volume of cargo that needs to be accommodated.

However, a major benefit to ISS logistics in 2011 will be the Permanent Multipurpose Module (PMM), set to arrive on STS-133/ULF-5 in November. The PMM will accommodate eight racks in total – four Zero-G Stowage Racks (ZSRs) and four Resupply Stowage Racks (RSRs).

Each set of four racks will be arranged in a circumferential fashion around the module. Eight rack bays will be left unoccupied, able to be filled by “soft stowage” such as Cargo Transfer Bags (CTBs). This extra stowage space will greatly increase the amount of stowage that can be accommodated on ISS in the post-Shuttle era, without occupying any space in the laboratory modules.

ISS logistics in 2012 – which is set to be a tough year for ISS supplies due to the absence of the Space Shuttle – will be greatly benefitted by flying the currently unfunded STS-135 mission, planned for June 2011. STS-135 would carry the Multi Purpose Logistics Module (MPLM) Flight Module-2 (FM-2) called Raffaello.

The MPLM would carry its full complement of 16 resupply racks for launch and entry, meaning that large amounts of supplies could be stored in the Station’s PMM. Many unwanted items could be returned to Earth in order to free up space aboard the ISS for stowage.

A large number of VVs are currently in various stages of processing around the globe, including locations such as Baikonur in Kazakhstan, Tanegashima in Japan, Kourou in French Guiana, and Kennedy Space Center in Florida, USA.

The first VV to arrive in 2011 will be Japan’s H-II Transfer Vehicle (HTV), following on from its debut flight in September 2009, when it lifted off atop a H-IIB rocket from the Tanegashima Space Center (TNSC) in Japan.

Following a seven-day free flight, it successfully rendezvoused with the ISS, whereupon it was grappled by the Space Station Remote Manipulator System (SSRMS), prior to being berthed to the Nadir port of Node 2.

The HTV is comprised of four main components – the Pressurised Logistics Carrier (PLC), Unpressurised Logistics Carrier (ULC), Avionics Module, and Propulsion Module. The vehicle is capable of launching 6,000kg of cargo to the ISS, and disposing of an equal amount when the vehicle burns up in Earth’s atmosphere upon completion of its mission.

The PLC can carry eight racks in total. Bay one can carry four International Standard Payloads Racks (ISPRs), than can be removed from the HTV and transferred to the ISS. Bay two can hold four HTV Resupply Racks (HRRs), which are fixed to the HTV and cannot be removed.

The ULC carries one Exposed Pallet (EP), which is removed from the ULC by the SSRMS once the HTV arrives at the station. The EP can be configured to carry Japanese Exposed Facility (EF) payloads, or US Orbital Replacement Units (ORUs).

Once the newly delivered payloads have been removed from the EP, unwanted payloads can be attached to the EP, and the EP re-inserted into the ULC for disposal upon re-entry. The ULC is a major benefit to the HTV, as it provides a capability that does not feature on any other currently operational VV.

The HTV-2 mission, which will be the second flight of the HTV, is currently scheduled to launch from TNSC on January 20th, 2011, and rendezvous with the ISS for a subsequent berthing to the Node 2 Nadir port on January 27th. After a stay lasting less than a month, HTV-2 will be un-berthed from the ISS on February 24th.

During the HTV-1 mission in 2009, the HTV was berthed to the ISS using the SSRMS, which was controlled by the crew from a Robotics Workstation (RWS) in the US Lab. However, for the HTV-2 mission, the crew will use the RWS in the Cupola, which will provide them with increased situational awareness by enabling a 360 degree view of the exterior of the station.

The Cupola was designed specifically for this purpose, and the HTV-2 mission will be the first proper test of its capabilities.

HTV-2 will launch two brand new science racks in its PLC that will be installed in the Japanese Pressurised Module (JPM). The installation and commissioning of these racks will initiate the 2nd phase of Japanese Experiment Module (JEM) utilisation, the first phase having begun in August 2008 with the initiation of JEM’s first experiment.

The first of the two new racks is called Kobairo, officially known as the Gradient Heating Furnace (GHF). The GHF is a high-temperature electrical furnace that will be used to generate large scale, high-quality crystals from melting materials. It features a vacuum chamber and three independent heaters, each capable of producing temperatures ranging from 500 to 1,600 degrees C, and it will be able to accommodate up to 15 different samples at any one time.

The GHF experiments will be controlled from the ground, with the results being sent directly to the ground – meaning that less crew time will be required to perform & record results of the experiments. Kobairo will be installed in the JPM, in rack bay Forward 3 (JPM1F3).

The second of the new racks is the Multipurpose Small Payload Rack (MSPR). MSPR is a multipurpose rack that will be used for many different functions. The rack consists of three main components – the Work Volume (WV), Work Bench (WB), and Small Experiment Area (SEA).

The WV is a 350 litre volume that will accommodate many different types of small experiments and equipment. It includes standardised power and data connections, and standardised interfaces for mounting experiments in the volume. Its aim is to expedite the process of producing small experiments by allowing them to be manufactured quickly and cheaply, as the supporting systems for the experiments will already be present in the WV.

One notable experiment that is already planned for the WV, to be launched on a later flight, is the Aquatic Habitat (AQH), which will be used to breed small fish in order to study their responses to microgravity and cosmic radiation.

The WB is a 0.5m squared deployable table that will be used for a variety of purposes, such as performing experiments, or as a platform for a laptop computer used to monitor experiment data. The SEA is a 70 litre space that will accommodate small experiments that do not need many power and data resources, while MPSR will be installed in JPM rack bay Aft 4 (JPM1A4).

Upon completion of cargo transfers from the PLC to the ISS, the crew will transfer unwanted trash from the ISS to the PLC.

Trash items will include packing foam, Resupply Stowage Platform (RSP) and Integrated Stowage Platform (ISP) racks from the PMM, which are not needed on orbit and will be disposed of in order to free up space in the PMM, and the empty Structural Launch Enclosure to Effectively Protect Robonaut (SLEEPR), which by then will have done its duty of protecting Robonaut 2 during its launch in the PMM on STS-133/ULF-5.

HTV-2’s ULC will carry an EP with two US ORUs attached – a Flex Hose Rotary Coupler (FHRC), and Cargo Transportation Container number 4 (CTC-4).

The FHRC is a component of the station’s External Thermal Control System (ETCS), and facilitates the transfer of ammonia across the rotating Thermal Radiator Rotary Joint (TRRJ). The CTC is a multipurpose container that is used to launch & store smaller external ORUs for the station, such as Remote Power Control Modules (RPCMs).

Once HTV-2 is berthed to the ISS, the EP will be extracted by the SSRMS and handed off to the JEM RMS. The SSRMS will then change base to the Mobile Base System (MBS), where it will pick up the Special Purpose Dextrous Manipulator (SPDM) “Dextre”.

The SPDM will then grapple the FHRC, and the SSRMS will manoeuvre the SPDM to the Starboard side of the station, whereupon the SPDM will install the FHRC onto an unoccupied Flight Releasable Attachment Mechanism (FRAM) on the inboard-facing side of ExPrESS Logistics Carrier-4 – which is set to arrive at the station on STS-133/ULF-5 in November.

The same process will then be repeated for CTC-4. Once the EP has been emptied of both its ORUs, the SSRMS will insert it back into HTV-2’s ULC.

This operation will be the first ever operational use of the SPDM, following the cancellation of a planned task to R&R an RPCM due to this summer’s Pump Module (PM) failure. However, according to recent Station Operations Readiness Review (SORR) notes – available in full on L2 – a SPDM demonstration will be performed during the week of December 5th, in order to verify that the SPDM is ready to move the FHRC & CTC-4 when HTV-2 arrives.

HTV-2’s preflight processing is currently moving along at a steady pace, according to a HTV status presentation (L2), with all activities on schedule to support a January 20th launch date. According to the presentation, PLC cargo loading started on September 3rd, and on September 9th, the EP arrived at TNSC.

The Kobairo/GHF rack was also accepted at TNSC on September 9th. The FHRC was accepted at TNSC on September 14th, the MSPR on September 15th, and CTC-4 on September 17th. Both the FHRC and CTC-4 were transferred to TNSC from KSC in Florida.

The presentation also notes that following a cargo integration review, NASA cancelled ~50kg of cargo from HTV-2’s manifest, and therefore JAXA have added 50kg of dummy cargoes. Another item of interest in HTV-2’s processing flow relates to one of two Proximity Operations (PROX) transponders, which exhibited a larger than expected time delay. As such, it was replaced with a PROX transponder originally designated for HTV-3.

(Part two of this ISS 2011 preview will cover Europe’s ATV-2, SpaceX’s Dragon, and Orbital’s Cygnus spacecraft.)

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