credit JAXA / caption: Will JAXA's first H-IIB Transfer Vehicle make its September flight?
Perhaps its because the Japan Aerospace Exploration Agency is planning a double first with the maiden launch of its new Mitsubishi Heavy Industries H-IIB rocket and flight of its H-IIB Transfer Vehicle (HTV) resupply spacecraft payload but NASA is already re-organising Space Shuttle payloads to ensure the new International Space Station crew of six that is stood up come May can be maintained
"A good deal of the current [Space Shuttle Endeavour STS-127] upmass manifest [is to] be replaced with food and other consumables", says NASA. This is to avoid problems that could occur for a six-person ISS crew due to of delays to JAXA's 1 September H-IIB Transfer Vehicle maiden flight and Space Shuttle Discovery's 6 August STS-128
Space Shuttle Endeavour is to roll out to Kennedy Space Center launch complex pad 39B on Friday 17 April to act as the "launch on need" aka rescue Shuttle if anything goes wrong with the Shuttle Atlantis STS-125 mission slated for 12 May. STS-127 is likely to launch in late June
NASA's ISS programme decided in the first quarter that to sustain the six person crew in the event of HTV and STS-128 being delayed photographic and television related items for ISS were removed from STS-127 as was "the new faster laptop, the T61P". This could now be flown to ISS on a future Russian Progress cargo vehicle flight
NASA says "the older A31P [laptop] is minimally acceptable on orbit [track and capture] training tool for the upcoming HTV mission in September, and that it was highly desirable to have a T61P to run the higher fidelity training tool. With the older tool, there is an increased risk of missed capture or bumped grapple fixture."
NASA's HTV preparation also includes possibly flying equipment on future Progress vehicles. The Progress 34, set to fly 24 July, could carry a backup robotics workstation, which consists of its primary computer, called the "central electronics unit" (CEU), used to control the ISS remote manipulator system, aka robot arm, and the CEU's display and control panel. This will only occur if there is an RWS failure before the July flight
However NASA says: "Two RWS's are required to provide a "hot backup" capability for HTV capture. Hot backup is considered to be a mission success capability from an [operations] perspective."
This "hot backup" capability is to ensure that if there are any station robotic arm failures during HTV capture and berth the crew could use the alternate RWS assuming the original failure is with the primary RWS
NASA is concerned about RWS failures where the captured HTV "wind mills," rotates about its snare point, that could need an HTV command for it to separate from the robotic arm's grapple fixture