NASA is delaying plans for a late August resumption of U. S. maintenance spacewalks outside the International Space Station, activities that were suspended more than a year ago when cooling system water flowed into the spacesuit helmet of European Space Agency astronaut Luca Parmitano.
U.S.-orchestrated spacewalks, previously set for Aug. 21 and 29, will be rescheduled for later this year, following the delivery of new spacesuit batteries launched aboard the next SpaceX Dragon cargo delivery mission tentatively planned for September.
Preparations for the late August excursions were shelved following an Aug. 5 decision by ISS mission managers to replace the batteries in the NASA space suits currently on the station because of concerns with the performance internal fuses during ground testing. The Dragon mission offers the next delivery opportunity.
European Space Agency astronaut Luca Parmitano before cooling system water intruded into his NASA space suit helmet. NASA photo
Scheduled U.S. spacewalks to address all but emergency external ISS maintenance needs were suspended when cooling system water flowed into the helmet of the NASA suit worn by Parmitano during a July 16, 2013 spacewalk. With water massing around his eyes, ears and mouth, the Italian astronaut made his way back to the safety of the station's U.S. airlock.
A NASA investigation traced the problem to a buildup of silica particles in the fan pump separator, a mechanism located in the portable life support system backpack of the spacesuits. The silica's source was further traced to filters in the cooling system that circulates water throughout the shuttle-era garments.
During the Aug. 21 spacewalk, Swanson and fellow NASA astronaut Reid Wiseman were to replace a failed sequential shunt unit that has interrupted some of the distribution of solar power to the station. Wiseman and European Space Agency astronaut Alexander Gerst were to follow on Aug. 29 with a spacewalk to move an inactive ammonia pump module from a temporary location on the station's solar power truss to a stowage platform near the U.S. air lock.
Since Parmitano's close call, NASA has carried out three "contingency" spacewalks -- the most recent on April 23 to replace a faulty computer controller and earlier ones on Dec. 21-24 to remove and replace the ammonia pump with a faulty flow control valve that hobbled the station's thermal control system.
As a consequence of the U.S. delays, the next ISS spacewalk is set for Aug. 18. Russian cosmonauts Alexander Skvortsov and Oleg Artemyev are prepared to deploy a small satellite and prepare a platform on the Russian segment for external science experiments.