CAPE CANAVERAL, Fla. A high-stakes mission to deliver a $164 million airlock to the International Space Station likely will get a green light from NASA Tuesday after a month-long analysis of fleeting problems with the outposts new $600 million robot arm.

Shuttle Atlantis, consequently, is expected to move this week to a beachside launch pad here at Kennedy Space Center, where the winged spaceship and the airlock will undergo final preparations for a mid-July launch.

"Thats great news," station flight engineer Jim Voss told colleagues at NASAs Mission Control Center in Houston during a space-to-ground radio chat Monday. "Looks like well be busy up here after all."

Atlantis and a crew of five astronauts are tentatively scheduled to blast off July 12 on a mission to mount the 6.5-ton airlock to the station, where it will serve as a staging area for spacewalking work outside the outpost.

The shuttles move out of a 52-story assembly building has been on hold now for two weeks to give engineers more time to sort out problems with the stations new Canadian-built robot arm, which is required to install the airlock.

At issue: A passing problem with the shoulder joint of the station arm, which failed to work properly when back-up control systems were used to operate it during tests in May.

NASA mission managers have feared the 57.7-foot (15.5-meter) arm might fail during the Atlantis flight, leaving the airlock stranded at the end of the crane-like device while astronauts were trying to mount it to the outpost.

A flight delay until September has been under consideration.

Both the arm and the shoulder joint, however, have been operating as advertised in recent weeks. Whats more, Voss and fellow flight engineer Susan Helms used back-up control systems to carry out a dry run of the airlock installation job last Thursday without encountering any problems with the joint.

NASA engineers, meanwhile, also have devised plans that would enable the airlock to be mounted to the station even if the shoulder joint problem cropped up again.

Couple all that together and many NASA engineers and managers now feel the agency is ready to press ahead with the Atlantis flight.

"It gives them a high degree of confidence that the arm is fully functional," said Kyle Herring, a spokesman for NASAs Johnson Space Center in Houston. "They feel comfortable that under just about any negative scenario they could get the airlock installed."

Station project managers gave the Atlantis flight a preliminary go-ahead Monday after meeting with engineers who have been investigating the shoulder joint problem. Astronaut Dan Burbank radioed the news up to the station crew late Monday afternoon.

Final approval to proceed with the flight is expected to come Tuesday when station managers meet with shuttle program counterparts.

Said Herring: "The plan just basically has to simmer overnight and be formalized."

Atlantis, meanwhile, now is tentatively scheduled to move to the launch pad Wednesday. A second dress rehearsal for the airlock installation job is to be carried out on the station Thursday.

A July 12 launch would come at 5:04 a.m. EDT (09:04 GMT), leading to a July 23 landing here at NASAs coastal Florida spaceport.

Shuttle Discovery then would follow Aug. 5 on a mission to ferry a new crew to the station and then return to Earth with Usachev, Helms and Voss.

Their replacements: U.S. astronaut Frank Culbertson and two veteran Russian cosmonauts, Mikhail Turin and Vladimir Dezhurov.