By Irene Klotz
CAPE CANAVERAL, Fla. (Reuters) - Two veteran Russian cosmonauts floated outside the International Space Station on Wednesday to replace experimental equipment that is testing how materials and biological samples fare in the harsh environment of space.
Station flight engineers Yuri Malenchenko and Sergey Volkov left the station's airlock at 7:55 a.m. EST for what was expected to be a 5-1/2-hour spacewalk, a live broadcast on NASA Television showed.
Among the cosmonauts’ first tasks was to cast off a flash drive into space, giving a ceremonial send-off to recorded messages and video from last year’s 70th anniversary of Victory Day, said NASA mission commentator Rob Navias.
Victory Day commemorates the former Soviet Union's victory over Nazi Germany.
The flash drive eventually will re-enter Earth’s atmosphere and burn up.
Malenchenko, who was making his sixth spacewalk, and Volkov, on his fourth, then collected samples from outside the airlock’s hatch door and from a window. The swabs will be analyzed to determine how much residue from the station’s steering thrusters has built up on the surfaces.
Working 250 miles (402 km) above Earth, Malenchenko and Volkov made their way to the site of a seven-year-old science experiment holding plant seeds, bacterial spores fungi and other samples. The equipment was to be removed and replaced.
The research is designed to test how well biological samples and various materials, such as coatings used on spacecraft, withstand the extreme temperature swings and high radiation of space.
The station is a $100 billion research complex owned and operated by 15 nations. Rotating crews of astronauts and cosmonauts have staffed the orbital outpost since November 2000.
(Reporting by Irene Klotz; Editing by Paul Simao)