AT the foot of snow-capped Tanggula Mountain, astronomers are listening to the universe and probing its depths by analyzing cosmic rays streaming into the mountain basin 4,300 meters above sea level.

The observatory and surrounding apparatus is part of China's quest to explore the universe from the world's highest cosmic ray laboratory. It uses 789 matrix detectors and 5,000 square meters of carpet detectors to study the incoming rays.

The Yangbajing Cosmic Ray Observatory in the Yangbajing basin of the Qinghai-Tibet Plateau is 90km from Lhasa, capital of the Tibet Autonomous Region.

"Tibetan people believe that the sky is sprinkled with souls and Buddhas. It is hard for them to imagine cosmic rays," says 45-year-old researcher Tenzin Norbu, deputy director of the School of Science of Tibet University in Lhasa.

Tenzin Norbu, a physics graduate of Tibet University, says his research on cosmic rays is focused on the origin of the universe.

"The initial conclusion is that most of the high-energy micro-particles in the universe originated in fixed stars and have lived in the solar system for one million years or longer," says Tenzin Norbu, who started his research in 1991 and has spent one or two months in the observatory every year since then.

"The job of communicating with the universe may sound kind of cool, but for me, it is actually staying in the observatory, processing statistics," he says.

"To dig into the origins of the universe is extremely hard work and will take a long time. However, I believe the answer will be revealed someday," he says.

China launched a large cosmic ray research project in the 1980s. A batch of 49 matrix detectors at Yangbajing, the highest-altitude observatory in the world, was built by Chinese and Japanese researchers at that time.

The observatory became the world's largest high-altitude cosmic ray research base in the 1990s after its number of matrix detectors was gradually increased to 189. "The air is clean at 4,300 meters. We have anywhere between 290 and 310 sunny days annually, which makes the observatory the best place to 'listen' to the universe," says Chen Wenyi, head of the observatory.

Lonely work

"My job sounds very romantic, but it is actually very lonely," says Chen, standing near the observatory's matrix detectors. He has worked there for 20 years since graduating from the Institute of High Energy Physics at the Chinese Academy of Sciences.

The matrix detectors are about one meter tall, and their white covers have turned yellow from exposure to the elements.

Surrounded by rough wire fences, the detectors stand silently among snow-capped mountains.

Across the road, there are carpet detectors housed under colorful steel structures, giving them the appearance of a pile of building blocks under the firmament.

"I was the only one here for most of the past 20 years," says Sichuan Province native Chen, who lives alone in a tiny white bungalow.

"I can only go home once a year," he says, staring at photos of his wife and daughter on a wall near his bed. He calls himself a "lonely listener to the universe."

His living area is connected to the observatory's equipment monitoring room by a narrow corridor. Computers buzz in the equipment room, refreshing data from the detectors.

"This is where our data is first processed. After processing, it is provided to researchers all over the world for free, allowing others to listen to the universe with our ears," Chen says. Chen's work is quite repetitive, and has rarely changed since he first went to work.

"Twenty years ago, I was extremely romantic. I even believed that I could receive signals from aliens. But 20 years passed, and I saw no evidence," he says.

However, he is not as lonely as he used to be.

As the observatory's research continues, Chinese, Italian and Japanese experts now visit the observatory more frequently. The resident population sometimes increases to five or six people.

One frequent guest is Zhang Yong, a researcher from the Institute of High Energy Physics at the Chinese Academy of Sciences.

"The carpet detectors are very important in researching the origin of the universe, detecting dark matter and discovering new galaxies," Zhang says. "When we 'listen' to the depths of the universe, we can get a glimpse of how it came to be," he says.

"Although there is a long way to go in revealing the origins of the universe, it might be known by mankind one day," he says.

Tibetan astronomy

The Qinghai-Tibet Plateau has long been a popular location for astronomers, both amateur and professional. The 13th king of Tibet's Yuyuhun Kingdom, who reigned from 481 to 490 AD, built an observatory among the mountains and deserts of Qinghai Province's Haixi Mongolian and Tibetan Autonomous Prefecture.

The observatory remained standing long after the king's reign ended.

The 2,000-year-old practice of Tibetan astronomy is still very much alive as well, as practitioners in Tibet, Qinghai and other provinces and regions are keeping the tradition going.

"We are writing our 2012 almanac right now. It has taken us months, but it will be finished soon," says Tsetop, deputy director of the Tibetan Astronomy Institute under the Hospital of Traditional Tibetan Medicine in Lhasa.

"Tibetan astronomy is a complex subject. Only well-educated people are capable of learning it," says 52-year-old Tsetop.

"We can foretell planting times, weather conditions and eclipses by calculating the movement of the planets using a sand table, which is a tradition that is still valid today," he says.

Sales of the almanac exceed 100,000 copies annually. It is sold in Tibetan populated regions in China, as well as in India and Nepal, Tsetop says.

In August the observatory's "eye" will be enlarge. A sub-millimeter telescope will be built by the National Astronomy Observatory of the Chinese Academy of Sciences, Tibet University and the University of Cologne in Germany. It will make the Yangbajing observatory the largest sub-millimeter observatory in the northern hemisphere, he says. China will be one of only a few countries to have such a telescope.

"It might be quiet here," says Tenzin Norbu, "but the universe is not silent. It is always changing and trying to tell us its secrets."