A 1982 portrait photo of Huang and his wish, in writing, to contribute to the country's development. [Photo/Xinhua]

"It was stressful to always rush him to the airport," Liu says.

But Liu says he came to recognize the importance of Huang's work. "I didn't immediately realize he was a scientist because he seemed as ordinary as anybody."

One day, Huang seemed to sense Liu's reluctance to take him to the airport at midnight.

"He said: 'I'm serving the country. And you're serving me. So you're contributing to the country'. I thought he was bragging. Now, I realize what he meant," Liu recalls.

Huang often asked his office building's gatekeeper to stay late.

"He frequently worked until midnight or even daybreak," says the Party secretary of Jilin University's geo-exploration faculty, Huang Zhongming.

"The building should close by midnight."

Eventually, the guard stopped asking him to leave.

Colleagues called him a workaholic. But Huang Danian preferred a different label.

"China needs lunatics to become stronger. I would be satisfied if I could be one of them," he said earlier.