CAPE CANAVERAL, Fla. -- Over the past three months, Kennedy Space Center workers have tripped, dropped things, banged into sensitive equipment, and started fires in a string of accidents that have left one person dead.
The space agency has launched investigations into three accidents -- the death of a worker who fell off a roof, the bumping of space shuttle Discovery's robotic arm by a platform, and damage last week to an instrument that supplies power to the orbiters.
But since the beginning of the year, there have been 20 other occasions in which a worker was injured or equipment was damaged in excess of $25,000.
There were 14 incidents during the same time period last year.
''There's enough going on that we're very, very concerned," said Bill Parsons, deputy director of Kennedy Space Center.
One explanation for the accidents may be that workers have been out of the rhythm of preparing for shuttle launches, since there has been one liftoff since the Columbia disaster in early 2003, Parsons said.
''I think anytime you have big gaps in between doing something that's like launching shuttles . . . or things like that, you are always concerned that you've lost a little bit of your edge," Parsons said.
Workers had been under pressure to meet a May launch date for Discovery, but the flight was pushed back to July last month so that technicians could replace troublesome sensors in the fuel tank.
Senior managers and contractors have been urged to get out in the field to talk to workers about any problems, and to emphasize safety and discipline.
A July launch also could be threatened by a new problem -- ''whiskering" on a shuttle engine circuit board.
Whiskering is the formation of thin metallic protrusions that could lead to a short circuit.
''It's a problem that has been around for years," said Kyle Herring, a spokesman for the National Aeronautics and Space Administration. ''It's probably of greater interest now because we're getting ready to fly."
In one incident in January, workers started a fire while repairing the roof of the Vehicle Assembly Building.
In March, broken glass from a lamp fell into Discovery's payload bay.
Workers cleaning it up the next day dented Discovery's robotic arm.
Three days later, an X-ray film container was dropped on shuttle Endeavour.
James Kennedy, space center director, called a two-hour work stand-down in mid-March to re-emphasize safety after another fire was started by roofers at the assembly building. But the accidents didn't stop.
The next day, roofer Steven Owens, 46, tripped on a wire and fell off a warehouse -- the first worker death at the space center since 1989.
Last week, electronic equipment was damaged at a spare parts depot, and workers dropped a lamp on the nose of an external fuel tank while they were repairing it.
Lynn Beattie, a Machinists union leader at the space center, said he believes accidents simply are being reported more than in the past.