How do you spot a tool bag in space?
 |  Track the tool bag  |
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Losing a tool bag can be inconvenient, but when you're 212 miles above the Earth it's a whole different matter.
Last week American astronaut Heidemarie Stefanyshyn-Piper was forced to watch her tools - reportedly worth £70,000 - float off when the backpack-sized bag slipped out of her grip.
The accident happened as she was cleaning grease off her gloves while fixing a gummed-up joint on the International Space Station's solar panel. The bag went into orbit and has become a "must see" among some competitive stargazers in recent days.
You can calculate precisely where something will be in space at any given time thanks to Newton's first law of physics. It states that any object moving in a straight line tends to remain in such a state unless acted upon by an external force.
This also applies in space, the only difference being things move in an orbit. And because space is so vast and empty, a tool bag is unlikely to be knocked off its course by anything else.
| THE ANSWER  Precise location can be plotted using Newton's first law of physics Size of space means it's unlikely to be hit by anything else or be anything else  |
As scientists know information like the size of the tool bag and where it was lost, it is possible to do the orbital calculations to determine where it will be and when.
A computer model has been developed for the tool bag (see link below answer box). But finding its exact location in the sky depends on your location on Earth. For example, it will appear lower in the sky from the north of England and Scotland than the south.
Equipped with your latitude and longitude coordinates, the model will calculate the time to see the tool bag, the altitude it will be at and the magnitude, which specifies its brightness compared with stars. Usually the bag has a negative magnitude, say astronomers, meaning it is one of the brightest objects in the night sky apart from the moon and planes.
But before that you will also need the right equipment - binoculars or a telescope and "even then it will be difficult to see," says Dr Robert Massey of the Royal Astronomical Society.
But the typically large distances between things in space also means it's unlikely anything else will be in the same position at the same time, says Robin Scagell, of the Society for Popular Astronomy. So what you track will almost certainly be the tool kit.
Burn up
"Most people have been playing too many computer games and think space is full of chunks of rock and debris, but it isn't," he says.
"There are things out there, but they are likely to be meteors the size of a grain of coffee and many miles apart. Even if they did hit the tool bag they would have little impact."
| WHO, WHAT, WHY?  A regular feature in the BBC News Magazine - aiming to answer some of the questions behind the headlines |
What you will see is another matter. The bag will have no structure or shape but will look like a faint star whizzing through the sky. But it will be easily distinguishable from a plane because it won't have red and green navigation lights.
"It will be a speck of light which will not be visible to the naked eye," says Dr Massey. "I wouldn't waste too much time looking out for it. Looking at the actual space station where the bag was lost is far more interesting."
Disclaimer: It could equally as easily have been a gentleman.
