The Moon Rovers That Helped Clean Up Chernobyl

The disaster

Chernobyl is a city in the north of Ukraine. On 26 April 1986, the Chernobyl Nuclear Power Plant 14.5 kilometres away from the city, experienced a catastrophic explosion. The resulting fire sent a plume of radioactive smoke into the atmosphere, which spread over vast areas of the Western Soviet Union and Europe.

Official figures say 31 people died in the immediate aftermath, though the number of those whose lives were cut short as a result is estimated by some sources to be in the hundreds of thousands. People in the surrounding area had to be evacuated from their homes, never to return.

Here in the UK, the government banned the sale of sheep from thousands of farms, in case they had ingested plants containing radioactive material from the fallout. The last restriction relating to this was only lifted in 2012.

What is radiation, and why is it potentially harmful?

Radiation is energy travelling in the form of fast-moving sub-atomic particles or waves. Some radiation is harmless, like visible light from the Sun. However, ionising radiation can travel through substances and alter them. It can tear through human DNA, damaging the instructions for cell reproduction, leading to cancer and other diseases. Radioactive material can emit different kinds of radiation:

Alpha radiation consists of fast-moving helium nuclei. It can be stopped by skin or paper but can be very harmful if inhaled or ingested.

Beta radiation consists of high energy electrons. It can penetrate a few centimetres of water or human flesh. It can also be ingested or inhaled and remain in the body for years causing sickness.

Gamma rays are waves that can pass through the human body. It can be stopped by dense material, such as concrete. A high dose can be fatal in a short period of time.

Why were lunar rovers chosen to clean up Chernobyl?

Unlike Earth, the Moon has no atmosphere or magnetic field to protect it from radiation. The surface is continuously exposed to high energy particles from the Sun and deep space. The particles collide with the lunar surface at close to the speed of light, triggering nuclear reactions on impact that release yet more radiation. Any mission to the Moon has to be able to withstand these conditions.

The Soviet Lunokhod 1 was the first successful robot lunar rover. It landed on the Moon on 17 November 1970. Its electronic systems were hardened to resist radiation. Operators in the Soviet Union were able to drive the rover ten kilometres by remote control, before it eventually failed after 10 months.

In the aftermath of Chernobyl, Lunokhod designers were called back from retirement to quickly adapt the rovers for the nuclear disaster. They delivered two rovers, known as STR-1s, to the incident site. The rovers’ job was to clear the roof of radioactive graphite and nuclear fuel. They were more successful than many other robots the Soviets attempted to use. However, the STR-1s only managed to clear about ten percent of the roof before they succumbed to the radiation.

If radiation is so bad, how did the Apollo astronauts survive?

Radiation is often cited by conspiracy theorists as proof that the Moon landings were a hoax. However, while the risk to the health of astronauts who travel beyond low-Earth-orbit isn’t negligible, it isn’t an impossible obstacle. How harmful radiation is depends on the strength of the source, the distance you are from it, and how long you are exposed to it.

The radiation in the Chernobyl reactor building in the aftermath of the explosion would be fatal in just over a minute. When the STR-1s failed, humans had to take over, shoveling radioactive debris off the roof by hand. It took over 3,000 people to complete the task, as each individual only had 90 seconds to do what they could.

In comparison, it would take a whole year on the Moon to receive the maximum amount of radiation you can handle in a lifetime. All the Apollo missions were short, only a few days each, limiting the astronauts’ exposure. The missions were not without risk though. If there had been a particularly violent solar flare when the astronauts were conducting a spacewalk, they could have received life threatening doses of radiation.