Caretakers are turning to computers to save the frescoes of China's Dunhuang caves on the ancient Silk Road from half a million tourists a year, the Bloomberg reported.

Officials will scan 45,000 square meters (54,000 square yards) of frescoes, or about the area of 10 football fields, and 3,390 Buddhist statues. The images will form a virtual-reality tour for visitors to see before they enter the grottoes. The project, a collaboration with the Mellon Institute in Pittsburgh, may take five years to record the first 20 of 492 caves, said Fan Jinshi, director of the Dunhuang Research Institute.

"Because tourists must use flashlights when they enter the grottoes, they get vague impressions of what they see,'' Fan said. "The digital displays give them a better-informed tour and save them the trek to caves they're not interested in.''

Reducing the time visitors spend inside the caves helps cut the levels of carbon dioxide and moisture, emissions that break down the delicate dye-on-plaster of the murals and statues.

Dunhuang was a trade hub on the Silk Road during the Sui Dynasty (AD 581-618) and Tang Dynasty (AD 618-907), when caravans bearing Chinese tea and silk for Persia and Europe stopped at its oases. The area was also a religious center, where the aesthetics of Buddhism, Islam, Tibetan sects, Sogdian and Tangut cultures were displayed in clay sculptures and cave murals.

Construction of the caves began in the fourth century by a monk called Yuezun and continued until the 14th century. The earliest of Dunhuang's grottoes at Mogao date to the Northern Liang period (366-439). One of the largest caves features a 26- meter (85-feet) sitting Buddha made during the Tang Dynasty.

Seeping Rain

Tourists are not the only threat to the relics. Caretakers have been working since 1989 with Los Angeles-based Getty Research Institute to preserve 16 large sutras in cave 85, a chamber commissioned in 867 depicting the life stories of King Divi before he reached enlightenment to become the Buddha.

The murals, painted in mineral and plant dye over plaster, have been peeling away from their bedrock because of increasing moisture and mineral salts that crystallize from seeping rain water, Fan said in the April 30 interview.

There are a total of 812 caves along a 1.7 kilometer (1 mile) of cliff face, hewn into the sandstone of the Mingsha Mountains in the Gobi desert. The Mogao caves were designated in 1991 as a World Cultural Heritage Site by the United Nations Education, Scientific and Cultural Organization. Tourists to Mogao reached 550,000 last year, from about 200,000 in 1998.

"I'm sure we'll easily top the 2006 numbers this year,'' said Fan, 68. "The number of visitors jumped especially after 1998, with improved highways, faster trains and a larger airport in Dunhuang.''

Relic Hunter

Some efforts already are under way to regulate visitor numbers to Dunhuang. Caretakers open as many as 80 caves to tourists during the peak season from July to September, leaving 30 caves opened during the rest of the year. Tour operators must reserve in advance and follow designated routes, she said.

The Dunhuang digital archive will include images from the caves as well as frescoes and scriptures from the area that now reside in the world's museums, including the British Library.

The new technology "will allow a clearer view of every detail of the frescoes before you pick your route through the grottoes," Fan said. "It lets us preserve while allowing access."

(Agencies via CRI.cn May 31, 2007)