Why are we building a telescope in Antarctica?

Please watch a "joyful" video first.

(Video source: Yang Chenwei, China Polar Research Center)

We walked through knee-deep snow to go to "work" because our job was to maintain the telescope built in Antarctica.

So why are we building a telescope at the South Pole?

Approaching the "extreme inaccessible to humans"

Antarctica is the southernmost continent on Earth. The ice sheet covers the continental rivers and seas of Antarctica like a hat, leaving only about 5% of the Antarctic surface exposed. The average ice thickness is 2 kilometers, and the lowest temperature detected is close to -100℃. Although the natural environment is harsh, the inland plateau of Antarctica is the best place for stargazing on Earth, especially Dome A, the highest point in the inland area, which is known as the "inaccessible pole for humans" (Ma et al. 2020 Nature).

Schematic diagram of Antarctica and China's Antarctic research station

(Image source: Li Zhengyang, Nanjing Institute of Astronomical Optics and Technology, Chinese Academy of Sciences)

Dome A, at an altitude of 4,100 meters, has thin air, an average annual temperature of -56°C, a polar night lasting up to 3 months, and about 90% clear nights. It is precisely such a cold, dark, dry, and stable airflow natural condition that makes Dome A have the clearest view of astronomical observation on the ground. The "quasi-space" astronomical observation conditions are a rare resource supporting the development of Antarctic astronomy. (Here is the clearest starry sky on Earth)

my country established the first inland Antarctic research station, Kunlun Station, at Dome A in 2009. Relying on Kunlun Station, the research units of the Chinese Academy of Sciences and the China Polar Research Center have developed a number of astronomical observation equipment, including the Antarctic Survey Telescope (AST3-2), which detected one of the optical counterparts of gravitational waves for the first time in human history.

Astronomical equipment at Kunlun Station in Dome A, Antarctica

(Image source: Li Zhengyang, Nanjing Institute of Astronomical Optics and Technology, Chinese Academy of Sciences)

Zhongshan Station astronomical station connects my country's Antarctic astronomical observation chain

Antarctica is an advantageous place for "space and astronomical observation". Developing Antarctic astronomy and building first-class astronomical observation equipment independently developed are of great significance to my country's astronomical exploration and deep space exploration.

The Chinese Polar Research Center, the National Astronomical Observatory of the Chinese Academy of Sciences and the Nanjing Institute of Astronomical Optics and Technology of the Chinese Academy of Sciences have formed a scientific research team (hereinafter referred to as the Polar Innovation Team). They plan to build an astronomical observation link of Zhongshan Station-Taishan Station-Kunlun Station based on my country's Antarctic research stations, and promote the systematic development of Antarctic astronomical observations.

Zhongshan Station is located on the edge of the Antarctic continent and is the gateway to the deep interior of Antarctica. As a scientific research station manned all year round, Zhongshan Station provides a solid base for the operation and maintenance of astronomical equipment at Kunlun Station, and also provides precious first-hand real-time observation and test data for the independent research and development of Antarctic astronomical equipment. During China's 32nd Antarctic scientific expedition, Zhongshan Station installed the first astronomical optical telescope, the "Bright Star Survey Telescope (BSST)" and carried out winter observation experiments.

The Antarctic Bright Star Survey Telescope takes star maps at Zhongshan Station

(Photo credit: Jiang Peng, China Polar Research Center)

During China's 38th Antarctic scientific expedition, the Polar Innovation Team established the first astronomical observation platform at Zhongshan Station in Antarctica, installing a small telescope array consisting of five tubes, which can simultaneously carry out astronomical observations in four optical bands and near-infrared bands. The small telescope array was independently developed by the Polar Innovation Team. The single tube has a diameter of 150 mm and has the ability to conduct large-field surveys. All five tubes are mounted on a direct-drive equatorial mount, which can carry out time-domain astronomical observations of extrasolar planets and space environment monitoring.

Zhongshan Station Small Telescope Array

(Image source: Li Zhengyang, Nanjing Institute of Astronomical Optics and Technology, Chinese Academy of Sciences)

The Antarctic telescope can also "move to shoot" in extremely low temperatures

To match the excellent Antarctic observatory site, Antarctic astronomical optical equipment needs to achieve high-precision tracking and measurement of moving astronomical targets, and obtain accurate data such as continuous luminosity and color changes of stars.

The small telescope array on the astronomical observation platform of Zhongshan Station includes 4 optical band telescopes (single-telescope diameter 150mm, field of view diameter 6°) and 1 near-infrared 0.9-1.7 micron observation telescope (diameter 200mm, field of view 7′×5.6′). The five telescopes are integrated and mounted on a direct-drive equatorial mount, with arc-second pointing and sub-arc-second tracking accuracy, which can lock celestial targets into the telescope's observation field of view and carry out high-precision photometric and color measurements.

The Antarctic Telescope is like an athlete's mobile target shooting in the Winter Olympics. It needs to stably hit a one-yuan coin 5 kilometers away in extremely low temperatures (-45 degrees Celsius at Zhongshan Station) and in the test of wind, frost and snow, which is extremely difficult.

Yang Chenwei carries out routine observation tasks during winter

(Photo credit: Ji Tuo, China Polar Research Center)

Scientists staying at Zhongshan Station in Antarctica are conducting orderly observations and photographing through indoor remote-controlled telescopes during the winter. Currently, the telescope is operating well, and a large amount of professional data will be transmitted back to China in the future for systematic analysis by researchers in the rear.

Photos of the astronomical observation platform and telescope array at Zhongshan Station

(Photo credit: Ji Tuo, China Polar Research Center)

In Antarctica, finding answers to the universe's ultimate questions

Thousands of years ago, Qu Yuan asked the sky: How can we know the shape of the upper and lower parts? Where do the sun and the moon belong? How are the stars arranged?

Thousands of years later, we are searching for those answers in Antarctica.

(Video source: @李航_Antarctic)

my country has built a series of optical astronomical observation equipment in Antarctica, including the China Star Small Telescope Array (CSTAR), the Antarctic Sky Survey Telescope (AST3), and the Antarctic Bright Star Survey Telescope (BSST), and has achieved outstanding scientific results such as photometric observations for the search for gravitational wave optical counterparts (Hu et al, Science Bulletin, 2017, Purple Mountain Observatory, Chinese Academy of Sciences) and the search for exoplanet candidates (Zhang et al, APJs, 2019, Nanjing University).

Small telescope array takes star maps at Zhongshan Station

(Photo credit: Yang Chenwei, China Polar Research Center)

At present, the first batch of astronomical optical equipment deployed by the Polar Innovation Team in Antarctica is mainly composed of large-field, small and medium-sized aperture survey telescopes. It plans to search for exoplanets in the sky area near the South Celestial Pole and carry out multi-band photometry and near-infrared band observation experiments. Through the search and photometry observation of exoplanets, scientific questions such as whether there are Earth-like planets in the universe and whether humans are alone can be answered (Liu et al, AJ 2018).

References:

[1] Ma, B., Shang, Z., Hu, Y. et al. Night-time measurements of astronomical seeing at Dome A in Antarctica. Nature 583, 771–774 (2020).

[2] Hu L. et al. Optical observations of LIGO source GW 170817 by the AST3-2 at Dome A Antarctica. Science Bulletin 62, 1433-1438 (2017).

[3] Zhang H. et al. Exoplanets in the Antarctic Sky. I. The First Data Release of AST3-II (CHESPA) and New Found Variables within the Southern CVZ of TESS. The Astrophysical Journal Supplement Series 240:16 (32pp) (2019)

[4] Liu HG. Et al. Searching for the Transit of the Earth mass Exoplanet Proxima Centauri b in Antarctica. The Astronomical Journal 155:11(10pp) (2018)

Author unit: Nanjing Institute of Astronomical Optics and Technology, Chinese Academy of Sciences

Source and author: Science Institute, Li Zhengyang

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