In an embarrassing turn of events for Heidemarie Stefanyshyn-Piper, 45, an astronaut granted the honour of becoming the first woman to lead a spacewalk, a valuable toolkit went into orbit after she lost her grip on it and watched it float away during a repair mission outside the International Space Station.
In a separate development, one of two spiders sent to the space laboratory aboard the shuttle Endeavour last week was also added to the missing list after the crew checked its living quarters and discovered that it had vanished.
Keen to quash fears that the absent arachnid may be marauding around the space station, Nasa managers insisted that the spider was not exactly lost. It just couldn't be found.
"We don't believe that it's escaped the overall payload enclosure," assured Kirk Shireman, Nasa's deputy space station programme manager, adding hopefully: "I'm sure we'll find him spinning a web sometime here in the next few days."
Ms Stefanyshyn-Piper's tools, contained in a briefcase-sized bag that worked loose from its anchoring point on her spacesuit as she embarked on a six-hour 40-minute spacewalk to help fix a stiff joint on the station's solar arrays, joins 217,000 other items of orbital debris now circling the earth.
"Oh great," she sighed, after spotting it slip away. "All it takes is one small mistake for a tether not to be hooked up quite correctly or to slip off, and that's what happened here," said lead spacewalk officer John Ray.
Nasa has an entire department at the Johnson Space Centre in Houston, Texas, dedicated to tracking so-called space junk – most of it derelict spacecraft and launch vehicles, or pieces from broken satellites – anxious to ensure that none of it could collide with the station or shuttle. Even the tiniest fleck of paint from a defunct rocket has been enough to crack the windscreen of the space shuttle in the past.
High-powered telescopes on the ground were trained on the runaway bag – which contains two special grease guns, a putty knife and cloth mitts – to track its path, and hasty calculations made to plot its risk potential.
Ms Stefanyshyn-Piper will have to share her colleague Stephen Bowen's grease guns when they both venture outside today to continue their work on the jammed solar panels, which are used to soak up energy from the sun to power the station's life support systems. Meanwhile, astronauts were hoping to solve the mystery of the missing spider, which was reported AWOL after Endeavour's crew cracked open the cargo container in which its specially-designed tank was transported as part of a science experiment.
Astronauts suspect that the female orb-weaver spider, which is non-venomous and was meant to be the back-up should the chief spider be incapacitated, may have simply gone for an impromptu spacewalk into her neighbour's tank, craving the luxury of a little extra room.
But the lead spider is so confused by the zero-gravity conditions that it has filled its tank with a tangle of silk to try to stop itself floating around and cure its space sickness, obscuring the search for the runaway.
Spatula and a spring among orbiting junk
THE toolkit is not the first item to be lost during a spacewalk, but it is the largest.
Previous lost property includes a 14in spatula dropped in 2006 by the British-born astronaut Piers Sellers, who returned to work in Houston to find colleagues had hung new tools above his desk poking fun at his slip-up.
In September 2006, astronaut Joe Tanner, working outside the space station with his colleague Heidemarie Stefanyshyn-Piper, accidentally released a bolt, spring and washer.
During a spacewalk in March 2001 to mount important equipment to the space station, a foot attachment used to anchor spacewalkers to the end of the space shuttle Discovery's robotic arm managed to float free from astronaut Jim Voss and was lost in space.
Later in the mission, Discovery's thrusters had to be fired to move the spacecraft to a higher orbit to dodge the menacing piece of space junk, which could have caused catastrophic damage if it had hit the shuttle.
Nasa and its international partners will today mark ten years since construction of the International Space Station began.
The most complex scientific and technological venture ever undertaken, it was built by a coalition of Nasa and the Russian, Canadian, Japanese and European space agencies.