December 18, 2013
U.S. astronauts aboard the International Space Station area readying their NASA spacesuits, including the protective garment that leaked water into a helmet during a July 16 excursion, for a series of spacewalks intended to repair a crippled external cooling system.
Veteran NASA astronaut Rick Mastracchio and Mike Hopkins, a first-time flyer, will tackle the repairs intended to address a faulty flow control valve in a refrigerator-sized pump control module over three spacewalks. The tasks for each spacewalk are as follows:
Dec. 21: Deactivate and loosen fasteners on the Loop A cooling system pump; de-mate ammonia coolant lines and electrical connectors on the pump.
Dec. 23: Remove and replace the 780-lb. pump module. A spare is stowed near the work site along the onboard section of the station’s right-side solar power truss. Temporarily stow the failed pump module at the work site.
Dec. 25: If not accomplished previously, re-stow the failed pump module; clean up the work site; and put away tools. Engineers believe the old pump module could be equipped with a new flow control valve in the future and perhaps installed again.
Each of the 6- to 7-hr. excursions is scheduled to start at 7:10 a.m. EST. The schedule may change, but NASA would like to complete the repairs by Dec. 30, when Sun angles on the station’s orbital plane exceed thermal limits for external activities through Jan. 9.
Hopkins will don the spacesuit worn by Italian astronaut Luca Parmitano on July 16, when 1 to 1 1⁄2 liters of water flowed into his helmet during an excursion with NASA astronaut Chris Cassidy. Though the root cause is still under investigation, engineers believe the fan pump separator in his personal life support system (PLSS) backpack became blocked.
The fan pump separator in Hopkins’ suit was replaced, as well as internal water lines. Both suits have also been equipped with makeshift internal snorkels fabricated from plastic tubing and wrapped in Velcro to secure them in place. If water began to leak again, an astronaut can place his mouth over one end of the tube. The far end extends to an air pocket in the midsection of the suit.
In addition, the spacewalkers will place pads atop their heads fashioned from off-the-shelf water absorbency pads, wrapped in T-shirt cotton and topped with additional absorbency material. The pads can absorb 600-800 milliliters of water, according to ground tests.