Launch Date Expected Today for Shuttle Atlantis
A banner cheers the space shuttle on as it reached Launch Pad 39B at NASA's Kennedy Space Center on Aug. 2, 2006.
Credit: NASA/T. Gray.

NASA shuttle managers are expected to decide later today whether the Atlantis orbiter and its six-astronaut crew will launch toward the International Space Station (ISS) on Aug. 27.

A flock of up to 300 shuttle engineers, managers and contractors are concluding a two-day Flight Readiness Review for Atlantis' STS-115 mission at NASA's Kennedy Space Center (KSC) in Cape Canaveral, Florida to decide, among other things, whether four bolts connecting the orbiter's Ku-band antenna to a forward right payload bay wall will have to be replaced on the launch pad.

"They'll come together with a plan and get a decision on what we should do," NASA KSC spokesperson Bruce Buckingham told SPACE.com Tuesday, adding that a potential fix is not expected to significantly impact the planned space shot.

Atlantis is currently set to launch no earlier than 4:30 p.m. EDT (2030 GMT) from Pad 39B on an 11-day trip to the ISS. The STS-115 crew, commanded by veteran shuttle flyer Brent Jett, will deliver a new solar array and truss segment to the station in NASA's first major construction flight since late 2002.

Shuttle fuel tank also under scrutiny

A standard meeting before any shuttle flight, this week's Flight Readiness Review also includes discussions on whether Atlantis' external tank is fit for the nearly nine-minute trip into orbit. The foam insulation-covered, 15-story fuel tank carries the same modifications as one which fed the Discovery shuttle's July 4 launch.

Those modifications - aimed at reducing the amount of foam insulation debris shed at launch - include the removal of a large, foam-clad wind screen that once covered wiring and pressurization lines. Like Discovery's fuel tank, Atlantis' does not carry any changes to a series of 37 so-called ice-frost ramps, which are NASA's next target for modifications.

"I particularly, based on what I understand, expect to see no basic change from a debris hazard standpoint," NASA shuttle program manager Wayne Hale told reporters in a Friday briefing.

Fuel tank foam shedding has been a prime concern since the 2003 Columbia accident, when a chunk of insulation fell during launch and breached the orbiter's heat shield along its left wing leading edge. The damage led to the loss of the shuttle and its crew during reentry.

A large piece of foam also fell from an external tank's protuberance air load (PAL) ramp during NASA's first post-Columbia shuttle flight in July 2005, prompting the ramp's removal for Discovery's STS-121 mission last month - a fix that performed well - and Atlantis' upcoming launch.

With the PAL ramp gone, ice frost ramps are now NASA's next target for elimination, but their continued presence on shuttle fuel tanks prompted two top NASA safety officials to vote against launching Discovery's STS-121 mission.

"We have a full court press going on to redesign those," Hale said of the ice frost ramps. "We're going to be taking them into the wind tunnel in September."

Hale added that of the top two candidate modifications for fuel tank ice frost ramps, one calls for a hardy titanium shell to replace ramp insulation, but tests remain to make sure the potential fix will not form ice when a shuttle tank is filled with its super-cold liquid oxygen and liquid hydrogen fuel.

The first shuttle flight to carry an ice frost ramp fix on its external tank is expected to be NASA's fourth post-Columbia mission, slated to launch between February and March of 2007, Hale said.

Meanwhile, NASA will discuss the results of today's STS-115 Flight Readiness Review meeting during a live NASA TV broadcast to begin no earlier than 2:00 p.m. EDT (1800 GMT).

You are invited to follow the briefing via SPACE.com's NASA TV feed, which is available by clicking here.