The United States Antarctic programme is using tractors to carry fuel to the South Pole to reduce the number of flights required to supply the world's southernmost research station.
Tractors were first used in Antarctica in 1958 by a team led by the late Sir Edmund Hillary - the first group to reach the South Pole using motor vehicles.
So far this summer tractors have travelled to the South Pole twice and have clocked up more than 5500km.
Operating in trains made up of three tractors, they have helped deliver more than 500,000 litres of fuel to the base, which would have required 65 flights to supply by air.
The US Antarctic Programme says the tractors have helped it to reduce its carbon footprint.