These unexploded land mines are often covered by vegetation or buried in the ground, which makes them difficult to detect safely, inhibiting efforts to demine these areas.
Currently available solutions aren’t always ideal. Ground-penetrating radar scanning is effective at finding mines, but is slow and tends to be expensive. People will often walk fields with metal detectors or sniffer animals, which while not costly in terms of money, has the added factor of being extremely dangerous.
But there’s nothing engineers like more than a challenge to improve the world with technology. While we’ve already seen experimental solutions such as rolling, wind-powered devices used to intentionally detonate mines for clearing a field, the search for a better detection solution is ongoing.
Enter civil engineering doctoral student Paul Manley.
Where Civil Engineering Meets Plant Biology
Manley’s masters thesis focused on plant biology, which at first glance may not stand out as an expected start to a PhD in civil engineering—much less leading to a way of detecting landmines.
But Manley’s research during his masters degree at Virginia Commonwealth University examined plant responses to the presence of explosive compounds, such as TNT.
So how can this be leveraged to detect land mines?
Manley’s current doctoral research at Missouri University of Science and Technology is part of a larger research project into how climate affects plant health, part of a five-year NSF grant being shared across nine institutions including Missouri S&T, which aims to better understand climate variability and its potential agricultural, ecological and social impacts.
Manley was looking at hyperspectral imaging of agricultural areas, with a camera that collects images across hundreds of bands that can detect subtle changes in how plants gain or lose water and nutrients, or how they biochemically respond to stress.
With such detailed imagery, Manley realized that this tech could do more than monitor agricultural crops—it could be used to save lives.
“Currently, you have people walking around minefields, leading animals on leashes, tilling up the surface to just detonate the mines and get it over with, or they are using ground-penetrating radar to detect these in the subsurface,” Manley said. “These detection methods are really slow, they are expensive and they all involve people out in the minefields doing this work, so it’s dangerous.”
Drones above the Field
Drones and other unmanned aerial vehicles (UAVs) are already a promising choice for landmine detection, so bringing the hyperspectral camera setup into the mix made sense.
“The technology was available for manned flights, but it’s much more expensive,” Manley said. “You either hire the service or buy all the sensors—not to mention the requirement of a plane. Scaling down to the UAV level is really just the next progression.”
So, what effects on plant life is the imaging camera able to detect?
“If a land mine or other unexploded ordnance leaks or was partially detonated, the explosives will leach out into the soil and are mobile,” Manley explained. “Explosive ingredients such as RDX, also known as T4, get into groundwater, while TNT tends to stay in the roots. And RDX is readily taken into the leaves.”
“These explosives are absorbed by the plants, where they cause various physiological and morphological changes, depending on the explosive and the amount. You will see things like chlorosis and necrosis in leaves, leaf drop and stunted growth. Hyperspectral sensors have been designed to detect these changes based on how light is reflected off the leaves,” he continued. “These sensors don’t necessarily detect the change, but when you compare it to a known healthy sample, you can see the effects.”
As he progresses in his research, Manley hopes to use the technical capabilities of UAVs with the imaging of plant health to help disarm minefields around the globe.
“Right now, we’re still in the greenhouse stage,” Manley said. “This spring and summer, I plan to set up mesocosms and actually image them with our UAV. I’d like to do field work in areas with contamination, if possible. Surprisingly, people in charge of land contaminated with explosives aren’t so open to having you fly a UAV and take pictures.”
“Eventually, my goal is to apply this potentially life-saving research where it’s needed,” he added.“Tens of thousands of people are hurt or killed by landmines each year. I hope this work will help to prevent the needless injuries and deaths caused by landmines around the world.”
For more on drones and landmine detection, check out “Dutch Drone Detects and Detonates Landmines.”