Xuntian

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Xuntian (CSST)
Xuntian space telescope mockup
Mission typeAstronomy
OperatorCNSA
Mission duration10+ years (planned)
Spacecraft properties
Dry mass15,500 kilograms (34,200 lb)[1]
Start of mission
Launch date2026
Wenchang Satellite Launch Center
ContractorCASC
Orbital parameters
Reference systemLow Earth orbit
Main telescope
Diameter2 metres (6.6 ft)
Focal length28 m (92 ft)
Wavelengths255 ~ 1000 nm (Survey camera), 0.41~0.51 THz (590~730 μm) (Terahertz receiver)
Resolution0.15
arcsec
 

Xuntian (

gigapixel
camera.

As of 2024, Xuntian is scheduled for launch no earlier than late 2026

Long March 5B rocket to co-orbit with the Tiangong space station in slightly different orbital phases, which will allow for periodic docking with the station.[11]

An artist's rendering of the 2 m-aperture Survey Space Telescope (also known as the China Space Station Telescope, CSST)

This state-of-the-art telescope, characterized by its

terahertz receiver, a multichannel imager, an integral field spectrograph, and a cool planet imaging coronagraph.[12]

Estimated distribution of the observation pointing centers of the survey for 1, 3, 5, 7, 9 and 10 years, respectively. The yellow circles in the bottom right figure are the selected deep fields. All maps use an Aitoff projection in equatorial coordinates, with origin α = δ = 0 at the center and α increasing from right to left. Mean densities are shown for the observation pointing centers in cells of about 0.84 square degrees.
Estimated distribution of the observation pointing centers of the CSST survey for 1, 3, 5, 7, 9 and 10 years.[13]

The primary mission of the CSST revolves around high-resolution large-area multiband imaging and slitless spectroscopy surveys, spanning the wavelength range of 255–1,000 nm. Precise cosmology serves as the principal scientific driver behind this ambitious endeavor, with a focus on observing regions at median-to-high Galactic and ecliptic latitudes. Over a period of 10 years, the survey camera is slated to cover approximately 17,500 square degrees of the sky in various bands, reaching point-source 5σ limiting magnitudes of about 26 (AB mag) in g and r bands.

The CSST's spectral resolution (R=λ/Δλ) for the slitless spectrograph averages no less than 200, attaining wide-band-equivalent limiting magnitudes in GV (400–620 nm) and GI (620–1,000 nm) bands at about 23 mag. Beyond its wide-area survey, the CSST will target specific deep fields, aiming for observations that surpass the depth of the broader survey by at least one magnitude. The collective strengths of its angular resolution, depth, wavelength range, and capacity for both imaging and spectroscopy, coupled with extensive sky coverage, render the CSST survey highly competitive.

Notably, the CSST's observations are poised to complement and enhance other contemporaneous large-scale projects, including the Vera C. Rubin Observatory, the Euclid Space Telescope, and the Nancy Grace Roman Space Telescope. Together, these initiatives promise to yield unprecedented datasets that hold the potential for groundbreaking discoveries spanning the realms from our solar system to cosmology and beyond.

Xuntian Space Telescope mockup, showing its docking port

Instruments

Survey camera

The survey camera is also known as the multi-color photometry and slitless spectroscopy survey module. The module is located at the main focal plane and divided into the multi-color photometry submodule of 7 bands (NUV, u, g, r, i, z, y) and the slitless spectroscopy submodule of 3 bands (GU, GV, GI). The multi-color photometry submodule includes 18 filters, covering 60% of the area of this module. The slitless spectroscopy submodule includes 12 gratings, covering the other 40% of the area.

Focal plane arrangement of the CSST survey camera
System throughput of CSST survey bands

Terahertz receiver

The

heterodyne receiver using niobium nitride (NbN)-based superconducting tunnel junction (Superconductor-Insulator-Superconductor (SIS)) mixer (the NbN SIS mixer).[14]

Multichannel imager

Left: The transmission curves for the nine MCI medium-band filters from NUV to NIR bands, including the F275W, F336W, F375M, F450M, F500M, F630M, F763M, F845M and F960M. Right: The transmission curves for the seven survey camera filters, including the NUV, u, g, r, i, z, and y bands. The dotted curves show the detector quantum efficiency, and the dashed lines and the solid lines are the intrinsic transmission and the total transmission by considering detector quantum efficiency, respectively.
Transmission curves of MCI and the survey camera[15]

The Multichannel imager (MCI) has three channels covering the same wavelength range as the survey camera from the NUV to NIR bands, and these channels can work simultaneously. Three sets of filters, i.e., narrow-, medium-, and wide-band filters, will be installed on the MCI to perform extreme-deep field surveys with a field of view of 7.5′×7.5′. The magnitude limit can be stacked to a depth of 29–30 AB mag in three channels. It will study the formation and evolution of high-z galaxies, properties of dark matter and dark energy, and also can be used to calibrate the photo-z measurements with its nine medium-band filters for the main surveys.[15]

Integral field spectrograph

The CSST-IFS (

star-forming regions. [16]

Cool planet imaging coronagraph

The cool planet imaging coronagraph (CPI-C) aims to realize high-contrast (< 10-8) direct imaging of exoplanets with an inner working angle (IWA) of 0.35′′ in the visible (0.6328 μm). It plans to follow up exoplanets discovered by radial velocity observations, study planet formation and evolution, and probe protoplanetary disks.[17] CPI-C works at 0.53-1.6 μm and is equipped with 7 broad passbands.

See also

Notes

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

References

  1. ^ Hu Zhan (2019-11-05). "An Update on the Chinese Space Station Telescope Project" (PDF). National Astronomical Observatories. Archived from the original (PDF) on 2021-05-06. Retrieved 2021-10-23.
  2. ^ "China's giant Xuntian space telescope faces further delay until late 2026". South China Morning Post. Retrieved 25 May 2024.
  3. ^ "China Space Station Telescope "Almost Complete"". 2022-07-22.
  4. ^ "China's massive Xuntian Telescope set to beat NASA's Hubble Space Telescope". 2022-07-24.
  5. ^ "China Delays Launch of Its Xuntian Space Telescope". Scientific American. 21 Nov 2023. Retrieved 11 March 2024.
  6. doi:10.16418/j.issn.1000-3045.2015.06.002
    . Retrieved 2 May 2016.
  7. ^ "Outgunning NASA's Hubble, China Claims Its Xuntian Telescope with 350-Fold Bigger View Can Unravel 'Cosmic Mysteries'". 8 May 2022.
  8. ^ "China's giant Xuntian space telescope faces further delay until late 2026". South China Morning Post. Retrieved 25 May 2024.
  9. ^ "China Delays Launch of Its Xuntian Space Telescope". Scientific American. 21 November 2023. Retrieved 12 May 2024.
  10. doi:10.14005/j.cnki.issn1672-7673.20230911.001
    .
  11. ^ 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.
  12. S2CID 234805827
    .
  13. ISSN 2296-987X
    .
  14. ISSN 1001-9014
    .
  15. ^
    S2CID 238857005
    .
  16. ^ "Progress of the CSST-IFS". www.phy.cuhk.edu.hk. Retrieved 2023-12-02.
  17. ISSN 0254-6124
    .
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