Chinese astronomers want to build an observatory on the Tibetan Plateau
More than 2.5 miles in altitude, Lenghu is “known to have clear skies,” said Licai Deng, a scientist at the Chinese Academy of Science and a coauthor of the new study. “At the same time, the Lenghu area has an amazing scenery similar to Mars.” Deng said the local government, eager to attract tourists interested in astronomy and geography, hired his team to survey the area and see if it was a good place to build an observatory.
Four main factors affect how suitable any location is for astronomical research. The first is if it has clear skies-that means there is no thick cloud formation, and very little light pollution. The second is the stability of local wind and weather conditions-and what effect the wind has on optical and infrared observations at night (even the most airborne particles can be disruptive). The third is if the site is connected to infrastructure (such as electricity) and can be accessed without much hassle. And finally, you want a place where the night sky can be protected from human activity.
High-altitude spots like Lenghu are of great interest to astronomers, as there is little atmosphere to observe while looking at objects in space. The researchers surveyed the Lenghu area for three years, measuring sky darkness, weather, atmospheric conditions, and more. They found that the area scored even slightly on all four factors like other potential sites surveyed in the Tibetan Plateau. In many ways, the researchers think, this could be much better than there are sites in Hawaii and Chile. There is less variability in air temperature and more stable atmospheric conditions, and the sky is relatively clear. The amount of water vapor in the air is also small, which is especially useful for infrared observations caused by cosmology. About three decades of weather records reveal an average of 0.71 inches of rain a year. “In this context, Lenghu has the potential to host many facilities,” Deng said.
In the long run, Lenghu may be better protected from the effects of human activity than Hawaii or Chile. The town passed laws in 2017 to preserve dark skies, so light pollution should remain minimal.
“The results shown for the Lenghu site are almost as good as those found for Mauna Kea, which is widely considered to be one of the best sites in the world,” he said. Paul Hickson, an astronomer at the University of British Columbia in Vancouver, who had previously conducted site tests on Dome A in Antarctica. “One thing that’s even more appealing about this location is the attention given to preventing light pollution.”
In some ways, this new research is a testament to China’s current astronomical plans for the area around Lenghu. Plans include a 2.5-meter imaging survey telescope that begins construction this year, a 1-meter infrared telescope that will be part of an international row of eight telescopes, and two others. still 1.8 meters and 0.8 meters, for planetary science.
As Deng said, Tsinghua University and the University of Arizona are collaborating on the construction a 6.5-meter telescope to run the Saishiteng Mountain summit. And there are initial plans for a 12-meter telescope to be located there as well. “It will flood the top of the mountain,” Deng said.
These instruments go a long way to get China on the map where infrared and optical astronomy matter – they are similar to some “big” telescopes operated in places like Chile. But they are still pale compared to the “more numerous” observatories built around the world, such as the 24.5-meter Giant Magellan Telescope in Chile, the Thirty Meter Telescope in Hawaii, and the 39.3-meter Largest Telescope in Chile. The kind of science that can be extracted from instruments is expected to open up a new era in astronomy. If China is serious about building a more ambitious astronomy program, it should be quick to catch up.
Good thing, then, that it has the Tibetan Plateau. “High, dry, isolated mountains are often the best places for astronomy,” Hickson said. “There may be other potential sites, perhaps even better, in the Tibetan Plateau that have not yet been explored.”