The Dark Sky Sanctuary near the border between India and China houses the Himalayan Chandra Telescope. The photograph, captured in 2018, shows Mars approaching Earth, an event that occurs once every two years. Photo credit: Dorje Anchuk
Under the clear night skies along the India-China border, a sense of hope for the future stretches across the heavens. Written by Rag Kurnad and Anmol Tiku, September 19, 2020
Ladakh, often referred to as “the Roof of the World,” is one of the highest regions on Earth. Despite the dangers of altitude sickness, severe cold outside the summer months, and narrow roads prone to landslides, its breathtaking beauty is well worth the visit. The slopes, adorned with mineral hues reminiscent of tie-dye patterns, encircle gleaming lakes fed by glaciers. By day, the landscape is pristine, and by night, it reveals some of the clearest skies in the world, studded with stars. For centuries, this area has been a crossroads for trade caravans and travelers from across Asia.
In Merak, the pilot telescope represents India’s effort to build one of the world’s largest solar telescopes. This equipment was manufactured in Nanjing with the collaboration of Chinese scientists. Photo credit: Anmol Tiku
Yet, along the southern shore of Pangong Lake, a cluster of pale buildings focuses not on the ground but on the sky. At its center, a modest aluminum shed houses a solar telescope. Despite recent skirmishes and India’s COVID-19 lockdowns, the telescope has diligently tracked solar flares. Located near Merak village, this observatory is one of two in Ladakh, both situated on the Changtang Plateau just miles from the L.A.C. The other observatory, near the village of Hanle, was once the highest in the Eastern Hemisphere until a higher one was built beyond the border by China.
During summer, Merak is covered in barley fields. On clear mornings, Stanzen Thundu, a 31-year-old with a sun-weathered face, drives from the village to the telescope, opening the shutter to direct the telescope’s lens toward the sun. The telescope filters light, isolating wavelengths known as Hα, a narrow band that reveals vast movements of gas and energy beneath the sun’s surface. During a recent visit, Thundu demonstrated the computer files, pointing out red spots on the solar chromosphere. “Here’s an active region, so if we focus on it, we might see solar flares or jets,” he explained.
Until a generation ago, Thundu’s family, like many in the Changtang Plateau, engaged in pastoralism. “Everyone kept livestock and was essentially nomadic,” he said. “We didn’t have yaks, but we kept sheep and goats, taking them to the high-altitude pastures with our grandfather, especially during holidays.” The livestock stayed in these pastures during summer, moving to warmer grazing areas as directed by his grandfather. Thundu spent his winters skating on the frozen surface of Pangong Lake.
In 2006, when Thundu was just 17, a team from the Indian Institute of Astrophysics (I.I.A.) arrived in Merak with an ambitious and extraordinary goal. They sought to construct the world’s largest solar telescope in a village that could only be reached through some of the highest mountain passes on Earth, with no power or telephone connectivity. Initially, they set up a small test telescope with Thundu’s assistance. This device, manufactured and tested in Nanjing with the help of I.I.A.’s Chinese collaborators, had arrived at its location near the western edge of Tibet.
Today, while researchers in southern India analyze the data from this telescope, it is monitored by local youths from Merak. “This is our philosophy,” said G. C. Anupama, the head of I.I.A. based in Bangalore. “It has a dual benefit: the locals take pride in being involved in scientific activities, preventing their isolation. And in situations like today, they continue to operate the observatory. Data remains accessible, and science is unaffected.”
In May, the Indian Department of Science and Technology reaffirmed plans to build a larger 2-meter National Large Solar Telescope. At the Merak site, Thundu keeps a blueprint of the six-story structure as his screensaver. He hopes the “2-meter telescope” will bring transformation without disrupting the community. “In the coming years, I believe this village will become more curious and interested in scientific matters,” he remarked. His aspiration is for Ladakh to foster a new vision defined by cooperation, scientific discovery, and inclusive development. “With the arrival of the 2-meter telescope, many new jobs will be created. I think Merak will become as famous as Hanle,” he added.
Some of the Champa people, the indigenous inhabitants of the Changtang Plateau, continue their pastoral lifestyle, raising yaks, sheep, and the prized Pashmina goats that produce the finest wool. Photo credit: Dorje Anchuk
In 1994, when the I.I.A. team surveyed Ladakh for the clearest skies in India, they discovered an untouched site in Hanle. A dry expanse at the edge of the Changtang Plateau suddenly transformed into a thriving wetland, with a high ridge at its center. Locals referred to this ridge as Digpa Ratsa Ri. From its summit, the surrounding mountains lay low on the horizon, and a perfect expanse of blue sky stretched above.
Thanks to its altitude and the surrounding plains, Hanle’s skies excel in two qualities that astronomers call “seeing.” Transparency refers to the condition where there are minimal obstructions to light. In Hanle, the ring of mountains blocks clouds and rain, and with no towns, industries, or highways to pollute the air or brighten the sky, the atmosphere remains pristine. “Everything there seems closer than it actually is,” said Dorje Anchuk, the chief engineer at the Indian Observatory in Ladakh. He described the sensation of driving towards an object, feeling as if the distance never decreases.
The second quality, “seeing,” is optimal when atmospheric turbulence causes minimal light distortion. Typically, bands of gas or aerosols cause starlight to travel in a zigzag pattern, resulting in twinkling stars and blurry images for astronomers. To achieve the best transparency and seeing, one must be entirely outside the atmosphere. Thus, in 2001, Frontlinemagazine dubbed Hanle as “the closest place India has to owning a space telescope at present.”
The telescope in Hanle was named “Himalayan Chandra” in honor of the astrophysicist Subrahmanyan Chandrasekhar, who received the Nobel Prize in 1983. Its value lies not only in its access to pristine skies but also in its strategic location on the opposite side of major Western observatories in Hawaii and Chile. As Earth rotates, celestial objects setting in the western sky become visible again in Asia. According to Anupama of I.I.A., “Take supernovae as an example—they explode and fade away over time. This represents a temporal evolution.” These phenomena, termed “transients,” require global tracking by telescopes. Anupama noted that the Chandra telescope has “filled the gap between telescopes in Australia and the Canary Islands.”
Since the inauguration of Himalayan Chandra in 2000, other telescopes have gathered around Digpa Ratsa Ri. They were constructed incrementally during the brief snow-melting period amidst Ladakh’s harsh winters, where temperatures plummet to -20 degrees Celsius. The Major Atmospheric Cherenkov Experiment (MACE) telescope, built by India’s leading nuclear research center, is set to become the world’s second-largest gamma-ray telescope. Additionally, the Indian Space Research Organisation (ISRO) plans to add a telescope to monitor space debris and protect India’s ambitious satellite programs. As the Hanle complex expands, it will aim to study nearly every aspect of the sky, from supernovae in distant galaxies to blazars just above Earth’s orbit.
For centuries, the Hanle Monastery has dominated the local landscape. Established in the 17th century along the Ladakh-Tibet trade route, this route was closed following the 1962 war between India and China. Photo credit: Dorje Anchuk
Since 2012, Hanle Observatory has gained a counterpart across the border. That year, the Chinese Academy of Sciences established its own observatory in the Ali region. Situated just 70 miles from Digpa Ratsa Ri, Ali is at an elevation nearly 2,000 feet higher. This development briefly stirred Indian media, as reports suggested that Ali was in Aksai Chin, an area claimed by India. In reality, Ali is located in Tibet, and the issue faded from memory but lingered in the minds of Hanle astronomers.
The most advanced project at the Ali Observatory, the C.M.B. Polarization Telescope, is scheduled to commence this year. This telescope, costing tens of millions of dollars, aims to probe primordial gravitational waves to understand the very early universe after the Big Bang. This initiative reflects China’s ambition to transform the Tibetan Plateau into “Asia’s Atacama” and place itself at the forefront of global astronomical research. Competing with this vision will be challenging for India. “With the current infrastructure, we cannot project Hanle in such a manner,” said Anupama. “However, in the coming years, we hope Hanle will gain competitiveness and be recognized as a superior observatory.”
Despite their strategic rivalry, the relationship between the two countries in terms of astronomy is not as frosty as one might expect. Over the past decade, China and India have utilized “astro-diplomacy” to build international relations and enhance scientific standing. In 2014, the two nations designated astronomy as a field for collaboration and pledged mutual support for projects like the solar telescope in Merak. Many I.I.A. alumni have taken up postdoctoral positions at the Chinese Academy of Sciences, and senior faculty members from both institutions co-author papers. India and China are also part of a five-country collaborative project to build the Thirty Meter Telescope (T.M.T.), which will be three times larger than existing telescopes in Hawaii. Astronomers from Bangalore and Beijing meet via video conference with colleagues from the U.S., Japan, and Canada every few weeks to tackle T.M.T. challenges. Once completed, this telescope will offer unprecedented observational power over the northern hemisphere sky.
Young monks gaze at the Indian observatory on Digpa Ratsa Ri. Locals generally support these telescopes for the employment and eco-tourism they generate. Photo credit: Anmol Tiku
In January 2019, Prime Minister Narendra Modi’s administration announced plans to construct the world’s largest solar power plant on the Hanle Plain, surprising Indian astronomers. Such a large-scale power plant would entail lighting, construction, and changes to the local climate, potentially obstructing the view of Hanle’s telescopes. Professional telescopes require isolation to function effectively. They need either to be situated far from society or for nearby residents to maintain quiet.
In Hanle, the local population is limited to a few small settlements and the 17th-century Tibetan Buddhist monastery known as Hanle Gonpa. In its early days, the head monk of Hanle granted permission to relocate a stupa from the summit of Digpa Ratsa Ri, and later, the Dalai Lama performed the dedication ceremony for the Himalayan Chandra telescope. Since then, a harmonious balance has been achieved between the local inhabitants and astronomers. The telescope has brought roads, good jobs, and modest tourism to the area. Much like Stanzin Tundup in Merak, the people of Hanle also hope for the flourishing of astronomy. This field promises high-value employment that supports the old ways of life rather than replacing them.
Following the government’s announcement, local residents, astronomers, and wildlife advocates in Hanle have been actively lobbying for the relocation of the solar power plant. “We are still addressing the issue,” said Anchuk. “Even a small amount of light from such a plant can deteriorate the conditions because we are observing very distant objects.” The solar power plant poses a threat not only to India’s clearest skies but also to the pastoral communities and wildlife below. In response to the emerging threat of development, I.I.A. and the district council have proposed something unprecedented in India: the establishment of a dark sky sanctuary.
The idea that a clear night sky represents a natural heritage worth preserving is relatively new, applicable not only to Ladakh but also to other regions. In recent decades, international movements have gained momentum, advocating for areas free from light pollution. In 2007, the La Palma Declaration, supported by UNESCO, asserted humanity’s “right to view the starry sky,” and that year, Quebec, Canada, saw the designation of the world’s first international dark sky reserve. Most dark sky reserves are designed to protect telescopes, such as the Ngari Dark Sky Reserve surrounding the Ali Observatory in China. Spanning approximately 1,000 square miles, this reserve is one of the largest of its kind, with all artificial lighting carefully regulated within its boundaries. The proposed Hanle reserve would cover an area roughly 30 miles in radius—three times the size of China’s reserve. “If the Ngari and Hanle reserves were to join forces, it would significantly boost our astronomy efforts,” Anchuk remarked. He believes that the two reserves would also contribute to the protection of terrestrial ecosystems and cultural heritage.
There is something profoundly moving about this symmetry: two star reserves established on either side of an adversarial border. In both India and China, efforts to preserve dark skies face the logic of industrial development. Astronomers on both sides of the L.A.C. (Line of Actual Control) could potentially leverage each other’s strengths to make this endeavor a reality. This could foster a more peaceful competition driven by existing scientific endeavors in Ladakh, local partnerships, and the drive to expand our cosmic horizons. “The universe is too vast,” Anchuk said. “We can move forward together.”
The Reference Article 天体望遠鏡と暗空保護区: ラダックから宇宙の神秘を守る科学と協力の未来
