HOUSTON — Russia’s Progress 52 cargo capsule docked with the International Space Station late July 27, delivering 2.8 tons of supplies including a NASA tool kit intended to accelerate the troubleshooting of the water leak in European Space Agency astronaut Luca Parmitano’s spacesuit which forced the early termination of a July 16 spacewalk.

Troubleshooting supervised by NASA’s Mission Control is now focused of the Primary Life Support System (PLSS), or the backpack incorporated into the U.S. shuttle-era spacesuits. The PLSS holds breathing oxygen, CO2 removal hardware, a battery power source and a water storage tank for the suit’s water-circulating cooling system.

U.S. astronauts Chris Cassidy, Parmitano’s partner on the July 16 excursion, Karen Nyberg and Parmitano are expected to carry out additional troubleshooting of the PLSS organized by NASA’s Mission Control this week, using tools and parts from the tool kit, NASA spokeswoman Brandi Dean said July 29.

The PLSS subcomponents of greatest interest are the internal sublimator, gas trap, condensate water relief valve and water separator. Inspections by the ISS crew of the CO2 removal system, water relief valve, separator and cross loop plumbing prior to the Russian freighter’s arrival did not reveal obvious signs of a problem, leaving the gas trap assembly as the next area of interest, Dean said.

The spacewalk, scheduled for 6.5 hr., was terminated at 93 min. after an estimated 1 to 1 1/2 liters of water leaked into Parmitano’s suit, including into his helmet. Working by memory, the 36-year-old Italian Air Force test pilot made his way back to the safety of the U. S. airlock as blobs of water formed around his eyes, ears and nose. Had he choked, Parmitano could have drowned, NASA’s Mission Control said after the stricken spacewalker was safely out of the suit.

Scheduled U.S. spacewalks are on hold until the cause of the leak is determined and repairs can be made. Last week, NASA appointed a five-member Mishap Investigation Board to establish a cause, identify contributing factors and formulate changes in spacesuit maintenance and operating procedures as warranted.

The Progress 52 carried out an automated linkup with the ISS Russian segment Pirs module on July 27 at 10:26 p.m. EDT, following an “express” four-orbit, six-hour trip from launch to rendezvous.  The Progress capsule lifted off atop a Soyuz booster from the Baikonur Cosmodrome in Kazakhstan at 4:45 p.m. EDT July 27, or 2:45 a.m. local time July 28.

Last year, Russia initiated a series of Soyuz crew transport as well as Progress cargo “express” missions as an alternative to the typical two-day launch-to-docking flight profile.

Other Cargo

The freighter’s cargo includes spare parts, research gear and other equipment; propellant for ISS maneuvers; water; and compressed air and oxygen.

Meanwhile, the ISS crew is preparing for the arrival of the Japan Aerospace Exploration Agency’s (JAXA) fourth H-II Transfer Vehicle (HTV-4), or Kounotori, supply craft. The HTV-4, loaded with 3.9 metric tons (4.3 tons) of pressurized and 1.5 metric tons of unpressurized cargo, is scheduled to lift off from the Tanegashima Space Center on Aug. 3 at 3:48 p.m. EDT.

The HTV-4 would rendezvous with the station on Aug. 9. Nyberg, Cassidy and Parmitano will be standing by at the controls of the ISS Canadian robot arm to grapple the JAXA freighter and berth it to the U.S. segment Harmony module. Grapple is scheduled for 7:29 a.m. EDT.

Over the weekend, flight control teams also wrestled with a series of computer processor interruptions aboard the European Space Agency’s Albert Einstein Automated Transfer Vehicle-4 supply ship. The ESA freighter carried out an automated docking with the ISS Russian segment on June 15, initiating a six-month stay. The four processors resumed normal function on July 29, but the reason for the difficulties had not yet been resolved.