Space Programme

Reach for the stars

China plays catch-up with Lenghu observatory


Guizhou’s vast radio telescope

Chinese astronomy has a long history with the earliest known solar observatory – in Taosi, Shanxi province – dating back around 4,100 years.

Despite those early beginnings, China lags behind in its star-gazing today. It has smaller telescopes than the United States and no “top-level”, dark-sky observation centre.

Now all that is about to change with the construction of several new observatories in Lenghu – a remote town in the arid western province of Qinghai. Spread across mountain slopes, this new centre will be the first in the Eastern hemisphere to match powerful observatories such as Mauna Kea in Hawaii, Roque de los Muchachos in Spain and Cerro Tololo in Chile.

The centre’s location means that scientists will have new ability to monitor astronomical events from the Eastern hemisphere.

“Now, there are just gaps in time. There are parts of the Earth that aren’t covered. By putting an observatory in this longitude range in the middle of continental Asia, that gives us that extra time coverage that we don’t have now,” Patrick McCarthy, the director of America’s National Optical-Infrared Astronomy Research Laboratory, told the Smithsonian Magazine.

McCarthy added that round-the-clock coverage is especially important during the monitoring of rare events such as the mergers of black holes or neutron stars because “every data point counts”.

Confirmation that the Chinese are building the new base on the Tibetan plateau came with the publication of an article in Nature magazine in August by the head of China’s National Optical and Infrared Telescope team, Deng Licai.

Building these bases is tricky because locations need the rare combination of high elevation, frequent clear skies, an arid climate and low levels of light pollution.

Lenghu, which experienced a short-lived oil boom in the 1960s, wasn’t in the early running for the new site as other places in Xinjiang, Tibet and Sichuan had already been earmarked as potential locations for the observatory.

But the local government lobbied Deng, the telescope boss, to visit. Despite its ghost-town appearance – only a hundred residents – Lenghu ticked all the boxes. There were even a few yardangs ­– strange protuberances of bedrock, similar to those found on Mars – for good measure.

Moreover, the local government has guaranteed that commercial development triggered by the arrival of the scientists won’t lead to light pollution. “Night-sky protection in the whole area of Lenghu will be guaranteed by law,” the report in Nature said.

The complex is already under construction and will be largely operational next year, Deng told China News Weekly. Initially Lenghu will house telescopes of under eight metres in diameter. Over time, there are plans to install larger instruments so that the Chinese can close the star-gazing gap with other countries, which are already constructing telescopes of greater aperture.

Currently the largest optical telescope in China has an aperture of just five metres. The largest one in the US is double that size.

“The ability of Chinese astronomers to collect faint starlight from the distant universe has fallen behind the world’s advanced level by more than 10 times, and is in danger of falling further by more than a hundred times,” one commentator complained.

Perhaps it feels uncharacteristic for China to be so far behind its peers in optical telescopes, given that it is home to the world’s largest radio telescope – the 500 metre diameter FAST dish in Guizhou.

The lag, say experts, is largely a result of delays in deciding on the best location for an observatory. And while other countries have gone overseas to find the right sites for their observatories – Chile, with its excellent climatic conditions, hosts European and US research centres, for example – China was always determined to find a site on home soil.

Deng says the new centre won’t be parochial in its ambitions, however, claiming that it will help scientists across the globe.

“There are only a handful of high-quality astronomical sites that meet the requirements for very large next-generation facilities on earth… a good site on the Tibetan Plateau will serve as a bridge between existing observatories,” he declared.

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