With a 4-inch gap in the space shuttle's heat-protecting blanket not appearing to be an urgent problem, the crew of Atlantis yesterday readied itself for what NASA called a delicate ballet with the international space station.

Then the shuttle today will begin a weeklong docking with the orbital outpost.

Atlantis's seven astronauts spent much of yesterday on a mandatory inspection of the shuttle's delicate heat tiles, outer edges, and blankets for problems similar to the kind that caused the fatal Columbia accident in 2003. No glaring problems were reported.

But late Friday and early yesterday, the crew spent extra time using a robot arm to look at a gap in a thermal blanket on the left side of the shuttle. The gap, about 4 inches, is the result of an unusual fold in the blanket, not a debris hit -- which caused Columbia's fatal problem, NASA spokeswoman Lynette Madison said.

The area does not get hotter than 700 degrees Fahrenheit during the shuttle's return to earth and is not a place where NASA is usually concerned about potentially fatal problems, she said. Still, engineers were using photos to create a three-dimensional model of the gap just in case.

"They don't think it's much of a concern," Madison said.

As part of the normal day-after-launch tile inspections, astronaut Patrick Forrester used the shuttle's robot arm and a boom extension to examine its wings and outer edges.

©REUTERS/NASA TV
A torn insulation blanket (upper right) on the port side of the Shuttle Atlantis was shown in this video grab Friday.

Atlantis's seven-man crew was closing the gap between it and the space station by about 800 miles every 90-minute orbit. Atlantis is scheduled to dock with the space station at 3:38 p.m. today.

Before the docking comes some delicate maneuvering, which is risky but has appeared effortless in 20 previous tries.

"Two vehicles weighing 230,000 pounds going 17,500 mph, it's tough stuff," Mission Management Team leader John Shannon said.

Atlantis commander Rick Sturckow will move the shuttle until it is 600 feet below the station and then make the shuttle turn a 360-degree backflip in just nine minutes. The last few feet of the docking occur so slowly that Atlantis will get only an inch closer to the station every second.

Once the shuttle and station connect, they will stay locked until June 17.

During the 11-day flight, the astronauts will deliver a new segment and a pair of solar panels to the orbiting outpost. They plan three spacewalks -- on Monday, Wednesday, and Friday -- to install the new equipment and retract an old solar panel.

Today, astronaut Clayton Anderson will replace astronaut Sunita Williams as the US representative aboard the space station.

Williams, a former Massachusetts resident who has spent the past six months in orbit, will return to earth aboard Atlantis.

About an hour after launch, NASA managers said initial checks found nothing to worry about. One piece of foam that appeared to come off the shuttle's fuel tank -- which bore ugly white patches from repaired hail damage that had delayed the flight by three months -- about 135 seconds after launch did not seem to hit the shuttle, shuttle program manager Wayne Hale said.

"The tank performed in a magnificent way, despite having several thousand repairs to it," Hale said at a news conference. The debris "should not be a hazard that late in the flight."

The first shuttle launch of the year helped put NASA back on track after a run of bad luck and scandal on the ground during the first half of the year.

In the past few months, NASA has seen the arrest of astronaut Lisa Nowak in an alleged plot to kidnap her rival for a shuttle pilot's affections; a murder-suicide at the Johnson Space Center in Houston; and the derailment of a train carrying rocket-booster segments for future shuttle launches.