#1017 How do rats find landmines?

How do rats find landmines? They can sniff them out and the rats are light enough that they don’t set the landmines off.

It is estimated that there are 110 million landmines still buried around the world. These landmines are still active and they are buried in over 60 countries. Explosives do deteriorate with age, but a landmine can be active for decades. There are still bombs and explosives being found from the Second World War that are still active and very dangerous. Thinking that the mines will probably not work any more is not a solution and about 5,000 people a year are killed or injured by landmines. Many of them are children. Since 1975, landmines have killed or maimed over one million people.

Landmines are laid during a time of war and their goal is to keep enemy combatants away. They are extremely cheap to make and even factions in poor countries can afford thousands of them. The cheapest landmine costs about $3. Then, once the war is over, the combatants pick up and leave, but they don’t pick up and take their landmines with them because they are very cheap and easy to lay but very expensive and difficult to remove. These landmines are a hazard and they injure thousands of people a year, but they have more consequences than that. They hamper economic recovery because large areas of the country are no longer accessible or farmable. People cannot travel and cannot graze their animals or sometimes cannot get to water sources. This, coupled with the fear of never knowing where the landmines are, can prevent a country from recovering after a war.

How do landmines work? There are many different types of mines and there are mines aimed at stopping soldiers (anti-personnel) and mines aimed at stopping vehicles (anti-tank). There are hundreds of different types of mine within each category, but their detonation methods are relatively similar. There are blast mines and there are bouncing mines. Blast mines are buried shallowly in the ground, and they have a pressure plate that is placed just under the dirt. When a soldier stands on the pressure plate, it is depressed, and a spring pushes the firing pin down on the detonator, igniting the explosive. Bouncing mines are also buried in the ground and they can be activated with a pressure plate or a tripwire. When a soldier stands on the mine, the pressure plate pushes down the firing pin, but it doesn’t ignite the explosive straightaway. The firing pin ignites a timed charge on the explosive and some black powder at the same time. The black powder ignites a propelling charge that shoots the mine about 1.2 meters into the air, then the main explosive ignites.

How are mines removed? Generally, mine disposal experts go into a minefield wearing protective clothing and prod the ground with a skewer until they feel a mine. They then gingerly dig it up and defuse it. This is extremely risky as the mines can explode when being defused and the protective gear the specialists wear is not bombproof. Another way is to drive a heavy vehicle with chains or teeth on a large steel drum over the minefield. The weight of the vehicle detonates the mines, but it is sturdy enough to survive. The problem with this method is the mines can be driven deeper into the ground and the vehicles can miss a lot. Metal detectors are another method of finding them, but they can have trouble with different kinds of soil and don’t find all of the mines. Dogs are a very effective method. Dogs have a sense of smell that is millions of times better than ours and they can smell the chemicals in the explosives inside the mine, even under the ground. Dogs can find a lot more mines a day than any of the other methods, but even the weight of a dog can set a mine off. The dogs can also get confused if there are a lot of mines and they get bored easily.

Which brings us to mine disposal rats. Recently, Giant African Pouched rats have been used in mine detection and mine clearing. These rats weigh about 1.3 kg and they are about 30 cm long. Rats actually have an incredible sense of smell and it is, in some cases, better than dogs. On top of that, they are far lighter than dogs and there is no risk that they will set off landmines while hunting. They are also smart enough to be trained, but not smart enough to get bored. A trained landmine rat can clear a 200 square meter section of a minefield in about 20 minutes. That same area would take a human 4 days. When the rats find a mine, they stop and scratch the ground. The human handler then marks the place and they dig up the mine later.

It takes between six and nine months to train a landmine rat. They are trained to detect TNT, which is the most common explosive in landmines. The trainers start by teaching the rats to stop over a hole with TNT in it and they get rewarded with food. This is increased until they can wait for 5 seconds. Then they are presented with holes that have TNT and holes that don’t. They are rewarded if the stop over the holes with TNT and not rewarded if they stop over empty holes. The number of holes is increased and they are trained until they have a 100% success rate. Then they are trained to find metal eggs with TNT buried under the ground. This goes on until they have a 100% success rate. Then they are trained on fake landmines, and finally real landmines. They have an incredibly high success rate. It is estimated that rats have helped to clear over 100,000 mines so far. These rats have been called heroRATS. And that is what I learned today.

Image By From one to another – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5854666

Sources

https://apopo.org/what-we-do/detecting-landmines-and-explosives/about-landmines