Commander Jim Halsell and mission specialist Jeff Williams inside the Unity node. Photo: NASA

Commander James Halsell and pilot Scott Horowitz fired Atlantis' steering jets 27 times in 59 minutes Tuesday evening, raising the international space station's orbit by an average of 9.7 statute miles.

The rocket firings began at 8:02 p.m. EDT (0002 GMT today) and ended at 9:01 p.m. (0101 GMT). When the burns started, the station's orbit measured 208 miles by 203 miles. When the maneuver was complete, the orbit's apogee, or high point, was 219.5 statute miles and its perigee, or low point, was 212.3 miles. Two more reboost maneuvers will be staged Wednesday and Thursday to boost the station's orbit by a total of about 27 miles.

Putting to rest any lingering concerns about living conditions aboard the international space station, commander Halsell said today it's quieter aboard the station than the shuttle and that air quality, a concern since the last shuttle visit in 1999, "has been outstanding."

"We've had no operational impacts at all as a result of poor air quality," Halsell said. "The air has been just fine. It is true that when we first moved into the station the room here (in the Unity module) was slightly warm. But it cooled down just as soon as we were able to get all the hatches open and all the air ducts in place and the ventilation going.

"In general, the air quality has been outstanding," he said. "With regard to the noise, I was surprised. I had heard everybody's comments about how to expect loud noises. It is, in fact, quieter here than it is on board the shuttle and the shuttle is quiet enough to meet all the OSHA standards. So we have not experienced any problems with regard to living conditions on board the station."

Three of Halsell's crewmates - cosmonaut Yury Usachev, Susan Helms and James Voss - plan to spend three to four months aboard the station next year as the lab's second permanent crew. Halsell said all three now know what to expect and "they're enthusiastic about returning as a crew on board the station."

Pilot Scott Horowitz floats through the Zarya module. Photo: NASA

The last crew to visit the station reported pockets of stale air and symptoms from exposure to high carbon dioxide levels. The Atlantis astronauts implemented a few relatively simple fixes to alleviate the problem.

"There was a lot of concern about the air quality before we came up on this mission," said pilot Scott Horowitz. "As everybody knows, the last mission had a few problems with the air quality. All the folks who did the design and modification of our air ventilation system put their heads together and came up with some fairly simple mods.

"We just modified the position of a few valves, changed some of the duct work inside and added a few personal fans and that seems to have done the trick by re-routing the air," he said. "After we opened up the station, I noticed the air quality improved probably 100 percent after just a few hours."

As for the predicted high noise levels aboard the station, Horowitz said "it just sounds to me like a little bit of humming, motors in the background, actually. The noise level is a lot less than what I thought it would be. ... It's not very loud, I think all the insulation we've put on has helped a lot."

As of 1:30 a.m. EDT (0530 GMT) today, Voss, Helms and Usachev were busy installing a third replacement battery in the Russian Zarya module. The crew continues to make good progress and there are no technical problems of any significance.