HOUSTON — Cosmonauts Sergei Volkov and Alexander Samokutyaev will team outside the Russian segment of the International Space Station (ISS) on Aug. 3 for a scheduled 6-hr. spacewalk that will prepare the 10-year-old Pirs docking compartment for a future departure to free docking space for a new Multipurpose Laboratory Module.

The extravehicular activity (EVA), which is scheduled to get under way at 10:30 a.m. EDT, will include a range of activities with external Russian experiments as well as the deployment of Arissat-1, a 57-lb. educational satellite that commemorates the 50th anniversary of the first human spaceflight — Yuri Gagarin’s single orbit of the Earth on April 12, 1961.

The cosmonauts are expected to devote half the spacewalk to the transfer of Strela-1, a telescoping cargo boom, from Pirs to the two-year-old Poisk mini research module, docking compartment and airlock.

Cargo Transfer

Volkov and Samokutyaev will use the companion Strela-2 cargo boom, which also is anchored to Pirs, for the transfer. The extendable mechanical arms function like manual versions of the U.S. segment’s electrically powered Canadian robot arm to relocate bulky pieces of equipment during spacewalks.

Russia’s 21-ton Multipurpose Laboratory Module, outfitted with a European Space Agency robotic arm, is scheduled for launch aboard a Proton rocket in 2012. The new lab will be docked at the Earth-facing docking port of the Zvezda service module, which is currently occupied by the 3.5-ton, multiuse Pirs compartment.

U.S. and Russian spacewalk activity is expected to drop significantly with the retirement of NASA’s shuttle fleet following the 13-day, STS-135 supply mission to the space station in July.

The two station partners once sponsored an average of 12 EVAs annually. The total is expected to fall to one to three a year, as the focus of station activity shifts from assembly and outfitting to scientific research and technology demonstrations.

Arissat-1

Volkov, who conducted two spacewalks in 2008, and Samokutyaev, who will embark on his first outing, are scheduled to begin their EVA with the manual deployment of Arissat-1, a prototype for a series of educational satellites also known as Radioskaf-V.

The small spacecraft represent a collaboration between the Radio Amateur Satellite Corp., RSC-Energia, NASA’s office of education, the ISS National Lab project and the Amateur Radio on the ISS working group.

The prototype carries a single student experiment, a pressure sensor. The satellite will transmit images of the Earth from four cameras as well as greetings commemorating Gagarin’s historic flight in the native languages of students from around the world.

The cosmonauts also will install a laser transmitter for the high-speed transmission of Russian science data and Biorisk, an experiment that assesses the effects of the space environment on bacteria and fungi.