It's everyone's nightmare scenario: you're in Asda and they're all out of chocolate profiteroles.

Not to worry. Just stagger outside, hit the SOS button on your brand new Spot Satellite GPS Messenger unit and help will be on its way before you can say, "Wasting police time."

This new personal tracking and emergency unit can send text messages anywhere in the world via the Globalstar satellite constellation, alerting local emergency services in a flash.

Small wonder

The latest Messenger, announced today, weighs just 150g, making it 30 per cent smaller and lighter than the original Spot device. A new GPS chipset allows it to track your position under tree canopies or in genuine (rather than urban) canyons, and should also enable better and faster satellite acquisition.

The Spot isn't just for disasters. In its Tracking mode, the Spot sends regular position updates to allow friends and family to track your journey across suburban wastelands to Safeway, Lidl and Morrisons in your search for cream-filled pastries.

There's a new custom messaging mode that sends a pre-set email to personal contacts, plus an OK button for when you finally reach your destination.

Since its original launch in 2007, the Spot Messenger has helped in more than 250 rescues - which is either a good thing or demonstrates how easily people are tempted into attempting adventures beyond their abilities.

The new Spot Satellite GPS Messenger will be available in the autumn, price TBC.