"It was quite a challenge. I miss sunshine so much," he said. Chief designer Liu said keeping the students busy with gardening could be good therapy to cope with isolation.

The volunteers had access to the Internet. They could also play chess, do yoga and ride exercise bikes. They also studied English and listened to the radio. Volunteers had to take pyschological and health checks every week, said Liu Dianlei, another volunteer.

"Isolation kept us focused on our papers and experiments. We also sought fun. I performed little bit of magic to entertain the group," he said.