In December 2018, when he heard that the Jiayuguan section of the Great Wall may see snow, he traveled 22 hours from Beijing by train to get there.

The temperature was－28 C, and the cold winter only left him one chance to launch his drone before sunset to capture the Great Wall covered in snow. However it was so cold that the device which controls the drone suddenly stopped working. Yang Dong opened his winter jacket to tuck the device inside to try and warm it up again.

The sudden exposure to the cold numbed his whole upper body and the hand that held the tablet. He fumbled with frozen fingers to get the tablet up and running and finally got the shot he wanted－the whole place covered in snow－but at a small cost, as the next day when he got up, his finger was badly swollen with mild frostbite.

He hatched a plan last year to take a series photos of the 13 passes of the Great Wall under snow. With five done, he hopes to finish the project in three years. Like all the journeys he's embarked upon, he's on course to finish it.

Contact the writer at liyingxue@chinadaily.com.cn