A spacewalking astronaut put aside the impending birth of his daughter and blazed through his first-ever venture outside the International Space Station on Saturday.

Expectant father Randolph Bresnik and Michael Foreman were so far ahead despite their late start and interrupted sleep the night before - false fire and decompression alarms jolted them awake - that their commander handed them extra work.

The spacewalkers installed new antennas, relocated a monitor for electrical hazards, set up an attachment for a spectrometer due to arrive next year, and hooked up a wireless video system for spacewalkers' helmet cameras. Then they released another payload platform.

Baby Bresnik had yet to make an appearance by the time the six-hour spacewalk ended Saturday afternoon. Bresnik's wife, Rebecca, had been expected to give birth to their second child Friday, back home in Houston. They have a 3-year-old son, adopted from Ukraine.

The astronauts and Mission Control agreed before Saturday's spacewalk to hold off on any news if the birth occurred while the men were outside. Everyone wanted Bresnik, a 42-year-old Marine, focused on the spacewalk because of the extra risk posed by working outside.

That didn't stop Bresnik from appreciating the view of Earth. He was mightily impressed as he started on his work outside.

As they soared over Houston, the spacewalkers took time for a little sightseeing. They joked that they could see their homes and hear their commander urging, "Get back to work."

The spacewalk was delayed more than an hour by false decompression alarms that rang through the orbiting complex late Friday, for the second night in a row. The high-pitched beeps - emanating from a new Russian research chamber - triggered a series of smoke alarms. The racket woke up the astronauts and disrupted spacewalk preparations.

Right before the spacewalk, the combined crews attached a giant platform full of spare parts to the exterior of the space station, using robot arms. It was the second such shelf to be installed this week. Atlantis hauled up nearly 15 tons of equipment to keep the outpost running long after the shuttles' retirement next year.

One more spacewalk is planned on Monday. The shuttle will remain at the station until the day before Thanksgiving. Landing would be the day after.