Being lowered from a helicopter onto a mountain peak to ski back country wilds sounds dangerous enough without going around deliberately triggering avalanches, but that's exactly the kind of thing ANSTO scientist Dr Warwick Payten gets up to in his spare time.

Warwick has spent the last five years applying his scientific know-how to a serious problem: predicting avalanches. He and the folks at Himachal Helicopter Skiing have developed a light-weight, easy-to-use probe for detecting unstable snow.

Called Sabre, it's basically a five metre long aluminium tube (which comes in sections that lock together) with sensors at one end and a small computer at the other. All the concerned skier has to do is push the pole into the snow pack. The sensors measure the snow's stiffness and temperature and the speed of the probe through the snow. Warwick's sophisticated data processing program then creates a graphical image showing a cross-section through the pack.

It doesn't matter if a strong person or a wimp pushes the probe, the computer takes it all into account. "You can even stop pushing, take your hands off, and start again," Warwick said.

To make the data easy to interpret, Sabre's sensors are calibrated to what skiers refer to as the "fist-hand-finger-pen-knife" scale. This comes from the traditional method of checking the snow pack -- digging a hole and punching the snow to see how hard it is.

The scale runs from snow soft enough to punch your fist into, through being able to force in a finger, to poking a pencil in, then only being able to stab the pack with a knife. This can easily take 40 minutes and is inherently subjective.

"Sabre provides skiers with the same info as a snow pit, but quickly," Warwick said. He reckons an entire slope can be checked in the time it would take to dig one pit.

There are other probes around, but, apart from being heavy and expensive, they don't measure temperature. Warwick explains this is important because there's a growing body of evidence to suggest that the so-called thermal gradient of the pack is an important indicator of avalanches.

"You can start with good snow, but it changes over time due to the different temperatures in the pack," he said. "Paradoxically, it's what's known as constructive metamorphosis that does the damage, because it tends to make the crystals grow so they slide over each other really easily." And slippery crystals mean weak snow.

To test his theories, Warwick digs pits to find a patch of bad snow, takes lots of measurements with Sabre, then deliberately triggers an avalanche and checks where in the pack the snow broke away.

It's a hairy business. Warwick tells of researchers digging a pit at the bottom of a slope, who saw that the snow pack looked a bit dodgy; while they were busy punching the snow, the slope above them released.

Needless to say, Warwick and his team don't make a habit of poking about at the bottom of mountains.

Ever the cautious scientist, Warwick is keen to collect more data to improve the accuracy of his computer program. But, as an enthusiastic extreme skier, he's very happy with the accuracy, reliability and usability of Sabre.