Spacewalkers to soak up powerful space radiation

International space station

(CNN) -- Is radiation a danger factor in space? That is one of many things two astronauts onboard the international space station crew will test Wednesday during a spacewalk expected to last more than six hours.

NASA flight engineers Carl Walz and Dan Bursch are scheduled to begin their foray into space from the Quest Airlock starting shortly after 7:00 a.m. EST.

The spacewalk will be the first use of Quest since July 2001 and will set the stage for four more upcoming spacewalks from the U.S.-built airlock.

Those walks will be to attach the first of several large truss segments to the station during a shuttle mission currently scheduled for early April.

On this trip outside, Walz and Bursch will be wearing devices that monitor space radiation dosages encountered by the eyes, internal organs and skin. The experiment will help scientists better understand the effects of intense space radiation and design better spacesuits for future spacewalkers.

Walz and Bursch, both of whom performed spacewalks last month, will take their orders from Russian commander Yuri Onufrienko, who will choreograph the walk from his perch inside the space station.

The Americans will perform a bevy of maintenance tasks on the outside work detail. Walz will remove four thermal blankets from the Z-1 truss, the base structure for the U.S. solar array on the space station.

Walz, from left, Onufrienko and Bursch in recent interview with CNN

Bursch will pick up tools to take back inside the station so the next spacewalking team will be able to use them on a future mission.

The veteran spacewalking team will also test some electrical circuitry, tighten loose latches, and take some high frontier insurance pictures of dings and dents on station radiators.

The Expedition Four crew is in its third month of a planned five-month stay on the station.

The next shuttle flight is scheduled for February 28. That mission, on space shuttle Columbia, will be a Hubble Space Telescope repair mission and will not visit the international space station.