Metal detectors can’t distinguish a landmine (top left) from junk, but the new radar-based Rascan device creates images (bottom row) that could at least double detection rates

Never let it be said that rubbish collectors aren’t some of the bravest people on Earth. I don’t mean the nice people who empty your bin, but the experts who scour the forgotten fields of past conflicts, first with sniffer dogs, then metal detectors, and finally with long-bladed knives, stretched out on their stomachs while nervously probing the ground ahead.

Their usual name is minesweepers, but their profession would be more accurately categorised as waste removal. The UN estimates that there are more than 100m landmines in the world, which kill some 5,000 people every year. Yet minesweepers spend 90 per cent of their time digging up pieces of harmless junk on the off-chance it could cause an explosion. “You get a signal