Station docking problem threatens shuttle launch

Space station Alpha

KENNEDY SPACE CENTER, Florida (CNN) -- A Russian-built cargo ship may have failed to dock properly with the international space station on Wednesday, putting Thursday's scheduled space shuttle launch in question.

The Progress cargo ship, carrying about a ton of provisions for the space station, attached to the docking mechanism, but ground controllers in Moscow received no indication it tightened up -- the sign of a successful "hard dock."

The failure threatened the upcoming shuttle launch, as space shuttle flight rules do not allow new spacecraft to dock at the space station when another craft is not firmly mated to its docking collar. Flight controllers in Russia worked Wednesday to understand the problem, acknowledging a broken sensor actually may have masked a successful cargo ship docking. NASA is set to talk to Russian mission control at 8 a.m. EST, and launch managers must decide whether to fuel up its shuttle, Endeavour, at about 10 a.m.

The launch of the shuttle and its seven-person crew is scheduled for 7:41 p.m. EST.

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The primary mission for Endeavour is to change out the space station's 3-man crew, with the current crew logging its 109th straight day in space on Wednesday. The shuttle's payload also includes more than two tons of food, hardware, experiments and thousands of small U.S. flags that will be given to relatives of terrorist attack victims.

The technical problems come amid heightened security concerns in the wake of the September 11 terrorist attacks and ensuing U.S. military action in Afghanistan.

Military fighter jets and helicopters have been flying over Kennedy Space Center in recent days, and the military presence on the ground and in the nearby waters has been beefed up as well.

On launch day a no-fly zone will extend 30 miles from the launch pad, closing several airports near the space center. Orlando's airport will remain open to commercial flights, but planes must fly in a tightened corridor away from the launch area.

The cargo ship's failure to dock with the space station may delay the Thursday launch of the shuttle Endeavour, above.

Three hours before liftoff, the restricted area for boaters will extend 60 miles from Kennedy Space Center -- a far cry from the usual three-mile limit. Onlookers also will not be able to gather on roads and causeways on NASA property.

While no specific threat was mentioned, Col. Samuel Dick, the Air Force officer responsible for launch security, noted that some of the September 11 hijackers identified by the FBI had lived and trained in Florida.

Weather may also delay the Endeavour's mission, as forecasters said there is a 40 percent chance conditions will not be acceptable for launch.