In remote control Nancova village in southern Angola, from halo The Trust, a British demining charity, watched intently as a drone circled a nearby hillside. It is scanning the terrain below, using thermal sensors to pick up temperature differences, which could reveal the whereabouts of landmines laid decades ago during the country’s devastating civil war.
“If you have an object buried in the ground, it will heat and cool at a different rate than the soil,” Michael Nevard said. halohead of R&D. “So if you take the image at the right time of day, you’ll see a kind of thermal shadow.”
Demining is a very slow process that still relies on men and women in body armor and metal detectors methodically searching the ground for signs of mines, one square meter at a time. This is a job that cannot be rushed. Angola has been at peace for more than two decades, but more than 1,000 uncleared minefields remain across the country claiming lives and stifling development. It will likely take another 20 years to clear them.
But advances in aerial imaging are now picking up speed. Drones equipped with thermal sensors or light detection and ranging devices, or lidar for short, can help pinpoint minefields and landmines from the air. This makes removing them on the ground much safer and faster.
Different types of sensors are suitable for different environments. The large diurnal temperature range in southern Angola is suitable for the thermal system, but tree cover will make the thermal system ineffective. LiDAR sensors can see through the canopy to see important clues to the ground below. “Thirty years later, things like craters and trench lines are almost invisible,” Mr Newald said. “If you fly over it with a standard camera, you can’t see it at all. But lidar will map it in 3Man. This can give us a very clear idea of where the minefields are. “
Drones aren’t the only recent development in demining. A new generation of ultra-sensitive metal detectors developed by gold miners can find landmines buried much deeper in the ground, as well as those with low metal content that might otherwise go unnoticed. A system combining metal detection and ground-penetrating radar, designed for the U.S. military, also began to aid in demining.
Other advancements are less high-tech. A simple potato harvester is often ideal for clearing ground anti-personnel mines. “There is no silver bullet that works everywhere,” Mr Newwald said. “The key is matching the tool to the threat and the terrain. But under the right conditions, you can double, triple, sometimes quadruple your productivity.”
No matter how sophisticated the equipment, someone with basic tools can usually accomplish the task of finding and detonating a mine. Use wooden sticks to mark suspected mines; simple metal tools to dig them out.
For Angolans who have grown up with the constant threat of landmines, anything that speeds up their clearance is welcome. “We will be free only when the landmines are gone,” said Donisa Kasanga, a farmer in her 70s who lost her leg when she stepped on a landmine on her way home from her fields. “It’s like we’re living in a cage.” ■