Hadfield prepared for spacewalking
A view like no other
Chris Hadfield arrived at the International Space Station (ISS) prepared to lead an assortment of spacewalks—activities outside the orbiting science laboratory intended to keep it safe for its six astronauts and productive for a growing number of science experiments. The two-time spaceflight veteran is also trained to lead a response to a serious external breakdown that could jeopardize the future of the entire outpost.
Recalling the challenge and lure of his previous extravehicular activities (EVA), or spacewalks, Hadfield says, "The risk is high. It's like the most complicated surgery a surgeon can do. It's also a tremendous personal experience. It's moving as a human to witness the Earth, the Station and the universe in a single glance."
The list of possible two-person spacewalks on the Station's US Operating Segment that await Hadfield and his crewmates include the replacement of a failed electronics box called a Main Bus Switching Unit (MBSU), the deployment of power and data cables to prepare for the arrival of a new Russian science module and the installation of grapple bars on two cooling system radiator panels.
"We are trained to do all of those things. We have deep skill sets," said Hadfield, who could be paired with either NASA astronauts Kevin Ford, Chris Cassidy or Tom Marshburn. "But it's not a make or break thing. We will do whatever the program asks."
The scheduling depends on the long-term reliability of the MBSU, which sustained a partial failure in late 2011; the timing of the Russian lab launch; and the flight rate of the first US commercial supply missions, which included some of the spacewalk hardware.
To be eligible for spacewalks, Station crews train in basic EVA skills that could be crucial to any task, including saving the lab from serious failures involving the vital solar power, thermal control and life support systems, computer networks or the communication and navigation hardware. The National Aeronautics and Space Administration (NASA) managers maintain a list of a dozen or so external components—called the Big 12—whose failure would require the astronauts to break with their science routine and join with Mission Control in orchestrating a repair within one to two weeks. The failure of any of these components could mean losing the Station, so the stakes are high.
There are two training sites. Both feature large swimming pools where the buoyancy of the water simulates weightlessness. NASA's Neutral Buoyancy Laboratory (NBL) is located near the Johnson Space Center in Houston. The NBL stretches 62 metres long and holds over 23 million litres of water, large enough to submerge mockups of the equipment spacewalkers will work with in orbit. Cosmonauts train in the smaller Hydrolab, located at the Yuri Gagarin Cosmonaut Training Center in Star City, near Moscow.
The US spacesuit is called the Extravehicular Mobility Unit (EMU), Russia's the Orlan. Both of the bulky garments provide protection from the lethal vacuum of space, solar and cosmic radiation, tiny meteoroid impacts and extreme temperature swings, as the ISS moves from sunlight to darkness.
The Space Station is equipped with US as well as Russian airlocks.
Once they emerge, spacewalkers tether themselves to the outside of the Station to prevent themselves from drifting away. NASA's suit is also equipped with SAFER, a jet back that a displaced spacewalker could use to steer himself back to the outpost.
Should Hadfield perform a spacewalk during Expedition 34/35 it will be his third, having conducted two previously in 2001 when he installed Canadarm2 to the ISS.
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