First Endeavour spacewalk under way

Endeavour's first of four planned spacewalks is under way outside the International Space Station.

Drew Feustel and Greg Chamitoff opened the Quest airlock hatch at 3:10 a.m. EDT, as the joined station and shuttle flew over the east coast of the Philippines.

You can follow all the action live by clicking on the NASA TV box at right.

Fuestel can be identified by the spacesuit with solid red stripes and the radio call sign "EV-1." His helmet camera shows No. 18 in the bottom right corner of the screen.

Chamitoff's suit has broken red stripes. He's called "EV-3" and also by his nickname of "Taz," and his helmet camera shows No. 20 .

"Welcome back to open space," mission specialist Mike Fincke radioed to Feustel as he embarked on his fourth spacewalk.

Fincke also congratulated Chamitoff on becoming the 201st human to walk in space.

"The dream comes true for me," said Chamitoff, who thanked his family for watching.

The pair's first task is to retrieve two experiments from a pallet on the left side of the station's main truss, or backbone.

The experiments known as Materials International Space Station Experiment (MISSE) 7A and 7B were installed in November 2009. Examples of MISSE containers, which investigate the long-term exposure of materials to the harsh environment of space, are shown at left.

A power cable and two pins must be removed to release each experiment, which will be brought home on the sidewalls of Endeavour's payload bay.

Feustel will then install MISSE 8 where 7A was located, while Chamitoff installs a light on a rail cart parked on the station's right side and a thermal cover on a rotating solar array joint.