Today’s spacewalk – the 2nd of 3 planned – began at 7:10 a.m. EST (1210 UTC) and will last 6.5 hours. This post has links to today’s live coverage, plus spectacular images from Saturday’s spacewalk.
NASA astronaut Barry Wilmore works outside the International Space Station on the first of three spacewalks preparing the station for future arrivals by U.S. commercial crew spacecraft, Saturday, February 21, 2015. Fellow spacewalker Terry Virts, seen reflected in the visor, shared this photograph on social media.
View larger. | Image credit: NASA
Today – February 25, 2015 – beginning at 7:10 a.m. EST (1210 UTC), International Space Station (ISS) astronauts are performing the second of three spacewalks to prepare the orbiting laboratory for future arrivals by U.S. commercial crew spacecraft. NASA TV coverage has begun and will go until 2 p.m. EST (1900 UTC) Wednesday. Watch here
NASA astronauts Barry Wilmore and Terry Virts completed the first spacewalk on February 21 and the third is scheduled for Sunday, March 1.
The spacewalks are designed to lay cables along the forward end of the U.S. segment to bring power and communication to two International Docking Adapters slated to arrive later this year. The new docking ports will welcome U.S. commercial spacecraft launching from Florida beginning in 2017, permitting the standard station crew size to grow from six to seven and potentially double the amount of crew time devoted to research.
Ground controllers have maneuvered the space station’s large robotic arm Canadarm2 in place for work planned for Wednesday’s spacewalk. Spacewalkers Barry Wilmore and Terry Virts will start their spacewalk at 7:10 a.m. EST to lay more cables and lubricate one of Canadarm2’s two latching end effectors, which serve as tip or base for the robotic arm. They will also prepare the Tranquility module for the relocation of the Permanent Multipurpose Module and the new Bigelow Expanded Activity Module later this year.
All three spacewalks are in support of the long-planned ISS reconfiguration from its current configuration, which was designed to support visiting Space Shuttles, to its new configuration optimived for future visiting commercial crew and cargo vehicles.
While cargo vehicles attach to the ISS using the process of berthing, whereby they are captured with the station’s robotic arm and positioned below a berthing port prior to being bolted into place, commercial crew vehicles will not use this method.
This is because the process of un-berthing takes a long time to complete, since cables and ducting between the visiting spacecraft and the ISS must first be manually disconnected, control boxes installed, hatches closed, and then the visiting spacecraft must be maneuvered away from the station with the robotic arm.
This means that berthing ports cannot support a rapid evacuation of crew from the ISS should it ever be necessary, which will be one of the primary roles of the commercial crew vehicles as they serve as “lifeboats” during their crew’s stay at the ISS.
Instead, crewed vehicles will attach to the ISS via a process of docking, whereby the visiting spacecraft flies itself all the way into its docking port and attaches via a capture ring striking a corresponding attachment mechanism.
Bottom line: NASA astronauts Barry Wilmore and Terry Virts aboard the International Space Station completed the first of three spacewalk on February 21, 2105. The second is scheduled for Wednesday, February 25 and the third for Sunday, March 1. The astronauts are securing cables to prepare the orbiting laboratory for future arrivals by U.S. commercial crew.
SOURCE::::: http://www.earthskynews.org
Natarajan
Take off with Natarajan 