(AP) -- A pair of visiting shuttle astronauts ventured out on a spacewalk at the International Space Station on Monday, tackling a hodgepodge of maintenance jobs and an experiment to capture the invisible vacuum of space.
Stephen Bowen and then Alvin Drew floated out the hatch early, and went straight to work with an extension power cable.
Bowen, the lead spacewalker, is a last-minute addition to Discovery's last crew. He is filling in for an astronaut who hurt himself in a bicycle crash last month.
Drew, meanwhile, became the world's 200th spacewalker when he emerged from the 220-mile-high complex.
"Alvin will now be able to say that he works in a vacuum," Mission Control said.
Mission Control couldn't resist a little Academy Awards humor at the expense of injured astronaut Timothy Kopra, who monitored the action from a flight controller's seat. In a morning message to the Discovery crew, Mission Control sent up a cartoon showing a spacewalking astronaut - Bowen - holding an Oscar statue and giving an acceptance speech.
"... and I would like to thank all of the little people that made this EVA (extravehicular activity) happen," the cartoon spacewalker said. "And a special shout out to Timmy Kopra. Get well little buddy!"
There won't be another chance for Kopra, at least during a shuttle flight. This is Discovery's final voyage, and only two other shuttle trips remain. The fleet will be retired by summer's end.
This was the first of two spacewalks planned for Discovery's farewell flight. Among the chores: installing the extension cable, moving a broken ammonia pump to a better storage location and collecting a sample of the vacuum of space.
The quick cable hookup paved the way for Tuesday's planned installation of a small storage room at the space station. The chamber arrived aboard Discovery over the weekend.
As for the failed pump, it was replaced last summer in a series of urgent spacewalks. The space station residents ran out of time before they could secure the broken 780-pound device in its proper place. NASA hopes to return the pump on one of the two remaining shuttle flights.
In a lighthearted experiment saved for the end of the spacewalk, the astronauts planned to open a small hand-held bottle, ridding it of air and filling it with the vacuum of space.
NASA calls the Japanese education experiment "message in a bottle."
There's no message inside, but the bottle is signed by astronauts who have flown in space. It will be returned to Earth aboard Discovery next week and put on display in Japan. It's an effort by the Japanese Space Agency to increase public interest.
Bowen and Drew will go back out Wednesday for one last spacewalk.
Once back home, Discovery will be retired and sent to the Smithsonian Institution. It's NASA's longest flying shuttle, circling the planet for nearly a year during the course of 39 missions over 26 years.
Explore further: Spacewalking day for astronauts at space station