CAPE CANAVERAL, Fla. -- The second space shuttle launch of 2006 is on track for Aug. 27 if NASA resolves a pair of technical issues as expected.
Shuttle managers wrapped up a two-day flight readiness review yesterday with a decision to proceed with Atlantis' 11-day construction flight to the International Space Station.
However, engineers continue to examine two issues.
One involves bolts that secure an antenna to Atlantis. The other is a malfunctioning heater on another orbiter's hydraulics unit.
A recent engineering study showed that two of the four bolts holding a communications antenna to the forward wall of Atlantis' cargo bay are too short and might be engaged by only a few threads. Specifications call for at least six threads.
The concern is that the antenna might be jarred free during launch and fall the length of the shuttle's 60-foot cargo bay. The resulting collision could cause serious damage.
Atlantis has flown 26 missions as is, and engineers are analyzing whether the two properly installed bolts are enough to safely secure the antenna.
If mission managers determine the risk presented by the suspect bolts outweighs the hazards posed by a difficult repair at the launch pad, the work will be done next week.
A decision is expected this weekend. The repair would take a couple of days.
"I think it is likely we will change these bolts out," said Wayne Hale, NASA's shuttle program manager, "but the analysis is still ongoing."
Engineers also are trying to run down the cause of a minor problem that cropped up during shuttle Discovery's flight last month: a malfunctioning thermostat on one of the ship's three hydraulics units.
Similar systems on Atlantis have checked out OK and the anomaly isn't expected to hold up next week's launch, even if it can't be definitively explained.
In a turnabout from Discovery's launch review, NASA safety head Bryan O'Connor and chief engineer Chris Scolese cast "go" votes yesterday during a unanimous final poll on whether Atlantis was ready to fly.
Their dissent in July was related to a continuing concern about the foam insulation that covers the outside of the shuttle's external fuel tank.
The tank has 37 small foam ramps that, according to a hotly debated NASA risk assessment, pose a significant threat if chunks of foam break free and strike the shuttle during the early stages of launch.
NASA plans to redesign the ramps, but a new version is not expected to be ready until next year. No significant foam loss from the so-called ice-frost ramps was detected during Discovery's liftoff in July.
Last month, O'Connor and Scolese recommended making the modification before launching Discovery largely because of the risk assessment's findings. This time, however, although the ice-frost ramps are unchanged from the last mission, both voted "go."
O'Connor's rationale for signing the official flight readiness certificate, which he also did last month despite his no vote, was that the space station offered the astronauts a haven if their ship was damaged during launch.
If the launch proceeds Aug. 27, liftoff would be targeted for a five-minute window opening at 4:29 p.m.
Atlantis' crew of six plans to deliver a 17-ton structural truss to the station that includes a pair of power-producing solar panels. Astronauts will install the truss during three challenging spacewalks outside the outpost.
Michael Cabbage writes for the Orlando Sentinel.