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Xuntian

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Xuntian
BERJAYA
Xuntian mockup, showing its 2-meter diameter telescope
NamesChinese space station survey telescope
Mission typeAstronomy
Operator
Mission duration10+ years (planned)
Spacecraft properties
Dry mass15,500 kg (34,200 lb)[1]
Start of mission
Launch date2027 (planned)[2]
RocketLong March 5B (5B-Y5)
Launch siteWenchang, LC-101
ContractorChina Aerospace Science and Technology Corporation
Orbital parameters
Reference systemLow Earth orbit
Altitude400 km (250 mi)[1]
Main telescope
Diameter2 m (6 ft 7 in)[1]
Focal length28 m (92 ft)[1]
Wavelengths
  • SC: 0.255–1 μm
  • HSTDM: 0.41–0.51 GHz[1]
Resolution0.15 arcsec

The Xuntian (Chinese: 巡天; pinyin: Xúntiān; lit. 'Tour of Heaven')[a] or Chinese space station survey telescope[5] (CSST) (Chinese: 巡天空间望远镜; pinyin: Xúntiān Kōngjiān Wàngyuǎnjìng) is a Chinese space telescope under development.[6][7]

The telescope will feature a 2-meter (6.6 foot) diameter primary mirror and is expected to have a field of view approximately 300 to 350 times larger than that of the Hubble Space Telescope.[8] Its 2.5-gigapixel camera is designed to survey up to 40 percent of the sky.

As of 2026, Xuntian is scheduled for launch in 2027 aboard a Long March 5B rocket. It is planned to operate in a co-orbital arrangement with the Tiangong space station, allowing periodic docking for servicing and maintenance.[9]

Overview

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The telescope uses an unobstructed off-axis optical design, avoiding diffraction effects caused by mirror support structures. This design is intended to improve image quality for observations including weak gravitational lensing measurements.

The primary mission consists of wide-field imaging and slitless spectroscopic surveys covering wavelengths from 255 to 1,000 nm. (Cosmological research is a major scientific objective,) particularly observations at medium and high Galactic and ecliptic latitudes. During its planned ten-year mission, the survey camera is expected to cover approximately 17,500 square degrees of sky in multiple bands, reaching point-source 5σ limiting magnitudes of about 26 (AB magnitude) in the g and r bands. The slitless spectrograph is designed to achieve an average spectral resolution of at least 200.

In addition to the main survey, the telescope will observe selected deep fields to greater depth than the wide-area survey.

The combination of high angular resolution, broad wavelength coverage, imaging and spectroscopic capabilities, and large survey area is intended to support studies of cosmology, galaxy evolution, and related fields.

Observations from Xuntian are expected to complement data collected by other optical space telescopes, including Hubble, Euclid, and Nancy Grace Roman.

Comparison with other optical space telescopes
Xuntian Hubble Euclid Roman
Launch 2027 (planned) 1990 2023 2026 (planned)
Mission duration 10 years (planned) 35+ years (ongoing) 6 years (ongoing) 5 years (planned)
Orbit LEO: 400 km (250 mi) LEO: 600 km (370 mi) Sun–Earth L2 Sun–Earth L2
Mirror diameter 2 m (6 ft 7 in) 2.4 m (7 ft 10 in) 1.2 m (3 ft 11 in) 2.4 m (7 ft 10 in)
Camera size (gigapixels) 2.5 0.016 0.6 0.3
Resolution (arcsec) 0.15 0.05 0.1 0.11
Field of view (deg2) 1.1[10] 0.002 0.91 0.28[10]
Survey area (deg2) 17,500 2 15,000 2,000[11]
Survey area (of sky) 40% 0.005% 33% 5%[11]

Instruments

[edit]
BERJAYA
Xuntian Space Telescope mockup, showing its docking port

Xuntian will have six scientific instrument bays, with plans to carry five instruments at launch:[1][12]

Survey camera

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The survey camera (SC), also known as the multi-colour photometry and slitless spectroscopy survey module, occupies the main focal plane. It comprises a seven-band photometry subsystem (NUV, u, g, r, i, z and y) and a three-band slitless spectroscopy subsystem (GU, GV and GI). The photometry subsystem uses 18 filters and covers about 60 percent of the focal-plane area, while the spectroscopy subsystem uses 12 gratings and covers the remaining 40 percent.

Integral field spectrograph

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The integral field spectrograph (IFS) provides spatial resolution of 0.2 arcseconds and covers wavelengths from 0.35 to 1.0 μm. It is primarily intended for observations of compact, bright targets, including galactic nuclei and star-forming regions.[13] The IFS can observe in parallel with the MCI.

Multichannel imager

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The multichannel imager (MCI) contains three channels covering wavelengths from the near-ultraviolet to the near-infrared. The channels operate simultaneously and use narrow-, medium-, and wide-band filters to conduct deep-field surveys across a field of view of 7.5′ × 7.5′. Combined observations are expected to reach depths of 29–30 AB magnitude. Planned scientific uses include studies of high-redshift galaxies, dark matter, dark energy, and calibration of photometric redshift measurements.[14] The MCI can observe in parallel with the IFS.[1]

Cool planet imaging coronagraph

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The cool planet imaging coronagraph (CPI-C) is designed for high-contrast direct imaging of exoplanets, with an inner working angle of 0.35 arcseconds at visible wavelengths. It is intended to follow up planets identified through radial velocity observations and to study planetary formation, evolution, and protoplanetary disks.[15] The instrument operates over wavelengths of 0.53–1.6 μm and includes seven broad-band filters.[1]

High sensitivity terahertz detection module

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The high sensitivity terahertz detection module (HSTDM) is designed for space-based observations of terahertz radiation, avoiding atmospheric absorption that limits ground-based observations. It is a high-resolution spectrometer and the first planned spaceborne heterodyne receiver to use a niobium nitride-based superconducting tunnel junction mixer.[16]

  • Estimated distribution of the observation pointing centers of the survey. The yellow circles in the bottom right figure are the selected deep fields.[17]
    Estimated distribution of the observation pointing centers of the survey. The yellow circles in the bottom right figure are the selected deep fields.[17]
  • Focal plane arrangement of the CSST survey camera
    Focal plane arrangement of the CSST survey camera
  • System throughput of CSST survey bands
    System throughput of CSST survey bands
  • Left: The transmission curves for the nine MCI medium-band filters from NUV to NIR bands. Right: The transmission curves for the seven survey camera filters.[14]
    Left: The transmission curves for the nine MCI medium-band filters from NUV to NIR bands. Right: The transmission curves for the seven survey camera filters.[14]

See also

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Notes

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  1. ^ The name "Xuntian" comes from the Chinese translation of Astronomical survey (巡天调查, Xúntiān Diàochá). Xuntian can also be literally translated as "surveying the sky"[3], "survey to heavens"[4] or "sky patrol".

References

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  1. ^ a b c d e f g h Hu Zhan (2019-11-05). "An Update on the Chinese Space Station Telescope Project" (PDF). National Astronomical Observatories.{{cite web}}: CS1 maint: url-status (link)
  2. ^ Jones, Andrew (January 19, 2026). "China previews how powerful its new Xuntian space telescope will be ahead of 2027 launch (video)". Space.com. Retrieved 2026-06-01.
  3. ^ ZHANG, Nannan (22 July 2022). "China Space Station Telescope 'Almost Complete'". China Academy of Sciences. Retrieved 14 March 2026.
  4. ^ "China's massive Xuntian Telescope set to beat NASA's Hubble Space Telescope". 2022-07-24.
  5. ^ "CSST科学工作委员会2026年度第一次会议在国家天文台召开". National Astronomical Observatories of China.
  6. ^ Gao, Ming; Zhao, Guangheng; Gu, Yidong (2015). "我国空间站的空间科学与应用任务" [Space Science and Application Mission in China's Space Station]. Bulletin of Chinese Academy of Sciences (in Chinese). 30 (6). CAS: 721–732. doi:10.16418/j.issn.1000-3045.2015.06.002. Archived from the original on 7 October 2021. Retrieved 2 May 2016.
  7. ^ "China Delays Launch of Its Xuntian Space Telescope". Scientific American. 21 Nov 2023. Retrieved 11 March 2024.
  8. ^ "Outgunning NASA's Hubble, China Claims Its Xuntian Telescope with 350-Fold Bigger View Can Unravel 'Cosmic Mysteries'". 8 May 2022.
  9. ^ Jones, Andrew (20 April 2021). "China wants to launch its own Hubble-class telescope as part of space station". Space.com. Retrieved 22 April 2021.
  10. ^ a b The Wall Street Journal (2022-09-23). The Tech Behind Next-Generation Space Telescopes. Retrieved 2025-01-05 – via YouTube.
  11. ^ a b Studio, NASA Scientific Visualization (2021-11-09). "Roman Space Telescope High Latitude Wide Area Survey". NASA Scientific Visualization Studio. Retrieved 2025-01-05.
  12. ^ Zhan, Hu (2021-04-01). "The wide-field multiband imaging and slitless spectroscopy survey to be carried out by the Survey Space Telescope of China Manned Space Program". Chinese Science Bulletin. 66 (11): 1290–1298. doi:10.1360/TB-2021-0016. ISSN 0023-074X. S2CID 234805827.
  13. ^ "Progress of the CSST-IFS". www.phy.cuhk.edu.hk. Retrieved 2023-12-02.
  14. ^ a b Cao, Ye; Gong, Yan; Zheng, Zhen-Ya; Xu, Chun (2022-02-01). "Calibrating Photometric Redshift Measurements with the Multi-channel Imager (MCI) of the China Space Station Telescope (CSST)". Research in Astronomy and Astrophysics. 22 (2): 025019. arXiv:2110.07088. Bibcode:2022RAA....22b5019C. doi:10.1088/1674-4527/ac424e. ISSN 1674-4527. S2CID 238857005.
  15. ^ Gao, Ming; Zhao, Guangheng; Gu, Yidong (2022). "Recent Progress in Space Science and Applications of China's Space Station in 2020–2022". 空间科学学报(Chin. J. Space Sci.). 42 (4): 503–510. Bibcode:2022ChJSS..42..503G. doi:10.11728/cjss2022.04.yg29. ISSN 0254-6124.
  16. ^ 张坤, 姚明; ZHANG Kun, YAO Ming (2023-03-07). "高灵敏度太赫兹探测模块氮化铌超导SIS混频器空间环境适应性研究". 红外与毫米波学报 (in Chinese). 42 (2): 188–192. doi:10.11972/j.issn.1001-9014.2023.02.006. ISSN 1001-9014.
  17. ^ Fu, Zhen-Sen; Qi, Zhao-Xiang; Liao, Shi-Long; Peng, Xi-Yan; Yu, Yong; Wu, Qi-Qi; Shao, Li; Xu, You-Hua (2023-06-02). "Simulation of CSST's astrometric capability". Frontiers in Astronomy and Space Sciences. 10. arXiv:2304.02196. Bibcode:2023FrASS..1046603F. doi:10.3389/fspas.2023.1146603. ISSN 2296-987X.
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