SDGSAT-1 (Sustainable Development Science Satellite 1)

Overview

The Sustainable Development Science Satellite 1 (SDGSAT-1) is the first Earth science satellite designed and developed by the International Research Center of Big Data for Sustainable Development Goals (CBAS). The mission was supported by the Big Earth Data Science Engineering Programme (CASEarth), a project of Chinese Academy of Sciences (CAS) to utilise Earth observation (EO) data to support global progress toward the 17 Sustainable Development Goals (SDGs) of the United Nations (UN) 2030 Agenda for Sustainable Development (2030 Agenda). Although Landsat and MODIS products are widely applied across various SDGs, and other EO systems such as the Advanced Land Observing Satellite (ALOS), Sentinel, Gaofen (GF), and Fengyun (FY) satellites address some of the SDGs, with Sentinel datasets providing particular relevance to SDGs 2, 4, 7, and 14, SDGSAT-1 is the first satellite specifically dedicated the measurement of the SDGs. SDGSAT-1 is the first satellite of the Sustainable Development Satellite Constellation, a series of polar orbiting satellites dedicated to measuring traces of global anthropogenic activities. 1) 2) 3)

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SDGSAT-1 aims to depict traces of anthropic activity by exploring the interaction between human activities and environmental change to address the socioeconomic and environmental dimensions of the SDGs related to the 2030 Agenda. This includes human settlement patterns and water quality variation (SDG 2 and SDG 6), urbanisation patterns (SDG 11), energy consumption and climate change (SDG 13), as well as coastal ecology and terrestrial and marine environments (SDG 14 and SDG 15). Its secondary objective is to test new methods for low-light surface environment detection under night light or moonlight conditions. 1) 4) 5)

The satellite synergistically uses three sensor payloads, the Thermal Infrared Spectrometer (TIS), Glimmer Imager (GLI), and Multispectral Imager (MSI). The sensors work in day and night observing modes: "Thermal Infrared + Multispectral" during the daytime and "Thermal Infrared + Glimmer" at night.

Various onboard calibration modes are applied to support the monitoring, evaluation, and study of SDGs, including side slither, black-body and cold-sky, vicarious, and cross calibration. In side slither calibration, the satellite rotates by 90° in its yaw axis to scan horizontally. Black-body and cold-sky calibration is used mainly by TIS, whereby the sensor is rotated to view a black-body and deep space, respectively, to evaluate the payload’s absolute radiometric uncertainty and stability. Vicarious calibration is conducted regularly on all the sensors to assess their status, with consideration of surface and atmospheric characteristics. The cross-calibration mode compares the SDGSAT-1 payloads with counterparts’ onboard satellites such as Landsat-8, Sentinel-2, and satellites carrying the Visible/Infrared Imager and Radiometer Suite (VIIRS) instrument when their orbits intersect. 6) 1) 7) 31)

SDGSAT-1 provides a “data-knowledge-service” model, with the data processing and management subsystem of the ground segment transforming raw data into value-added analysis ready data (ARD). Level 4 (L4) products are freely accessible globally on the SDGSAT website, launched in September 2022 to promote multidisciplinary research on SDGs and fill in existing data gaps that limit progression of the 2030 Agenda. 1) 8)

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SDGSAT-1 imagery can be used for applications in urban development, disaster response, environmental change tracking, agricultural productivity improvement, and marine conservation. The high-quality imagery of urban lighting patterns, industrial activity, and environmental changes, supports evidence-based decision-making that directly contributes to the implementation of the UN 2030 Agenda. 1)

SDGSAT-1 GLI captures nighttime light, similar to the DMSP-OLS (Defense Meteorological Satellite Programme - Operational Linescan System) and NPP-VIIRS (National Polar-orbiting Partnership - Visible/Infrared Imager and Radiometer Suite) remote sensing systems, but with higher spatial resolution. This imagery allows for high-resolution mapping of nighttime light distribution and atmospheric pollution levels, for applications including calculating county-level poverty indices (SDG 1), assessing environmental health risks (SDG 3), examining energy efficiency and policy (SDG 7), and monitoring urban development (SDG 11). GLI promotes marine conservation (SDG 14) by enabling ship detection, with the support of MSI and TIS imagery allowing improved ship wake feature extraction and vessel identification. 1) 9)

The combination of SDGSAT-1 TIS imagery with Landsat OLI imagery has enhanced the accuracy and granularity of industrial heat source identification for the monitoring of industrialisation (SDG 9). TIS imagery allows for resource prospecting (SDG 12), through the classification of minerals from their unique spectral signatures, and monitoring of offshore hydrocarbon infrastructure. This provides improved Arctic Sea ice detection over MODIS imagery, aiding the tracking of climate change impacts (SDG 13). 1) 10) 11)

MSI imagery is used specifically for monitoring vegetation and water resources (SDG 6), enabling assessments of water quality monitoring, suspended sediment concentration, and total suspended matter, as well as improving classification of turbid and eutrophic waters. Its high spatial resolution also enhances detection of harmful algal blooms (HABs) and supports oceanic vortex analysis using deep learning methods. While TIS monitors desertification and soil salinity patterns, and MSI land cover change detection. 1) 8)

When combined with VIIRS imagery, SDGSAT-1 GLI imagery was used after the Turkey-Syria earthquakes on February 6, 2023, to map and assess the impacted areas. The simultaneous operation of the three SDGSAT-1 sensors allows for detailed monitoring of wildfire spatial distribution and post-fire impacts. 1) 12)

As shown in Figure 3, GLI enables applications in air pollution monitoring (SDG 3), light source classification (SDG 7), disaster damage assessment (SDG 11) and TIS measures industrial heat emissivity (SDG 9), ice dynamics (SDG 13), and wildfire extent (SDG 15). While MSI supports vegetation growth monitoring (SDG 2), lake water quality evaluation (SDG 6), and ocean eddy detection (SDG 14).

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Spacecraft

The satellite system has a mass of 753 kg, of which 386kg is attributed to the three sensor payloads. A large solar panel array is deployed on the spacecraft's port side, and on the starboard side, an Earth shield blocks Earth's infrared emissions to keep a low-temperature environment for the TIS sensor. 1)

The attitude and orbit control subsystem (AOCS) provides zero-momentum-three-axis stabilisation control, ensuring the spacecraft's stability particularly for performing data collection and calibration maneuvers. The telemetry, tracking, and command (TT&C) subsystem antennas operate in the S-Band. An onboard solid-state data recorder allows for the storage of 1 TB of sensor data. The integrated electronics subsystem controls various tasks, including power distribution, temperature control, orbit and attitude control, imaging and data acquisition, and data downlinking to ground stations. 1)

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Launch

SDGSAT-1 was launched by CAS on November 5, 2021, aboard a Long March-6 (CZ-6) carrier rocket from the Taiyuan Satellite Launch Center (TY LC) in Shanxi province, China. 7) 4)

Orbit

The satellite operates in a near-polar, sun-synchronous orbit with an altitude of 505 km and inclination of 97.5°. SDGSAT-1 orbits Earth every 90 minutes with a descending node equatorial crossing time (ECT) of approximately 10:00 AM mean local solar time (LST), resulting in a repeat cycle of 11 days. 4) 1) 6)

Mission Status

• October 31, 2025: A study into illumination sources using SDGSat nighttime light imagery found that SDGSAT-1 was highly effective in distinguishing various types of light sources, with an overall accuracy of 92% for artificial light at night (ALAN) and 95% for streetlights. 13) 14)

• October 24, 2025: The ‘Big Earth Data in Support of the Sustainable Development Goals (2025) — Special Report for a Decade of the SDGs’ report was released by CBAS with the following insights from SDGSAT-1:
  • SDGSAT-1’s three sensors provided data of marked spatial differences in the water-friendly index of urban areas in 11 Sustainable Development Agenda Innovation Demonstration Zones in China, for the development of targeted policies for urban water friendliness and livability (SDG 6.3/6.6). 15)
  • The SDGSAT-1 40 m color nighttime light imagery revealed that 68.7% of nighttime urban road lighting in China in 2023 is accounted for by high-efficiency lighting sources and the complete phase-out of low-efficiency sources could save approximately 4.4 billion kWh annually (SDG 7.3). 15)
  • SDGSAT-1 showed Southeast Asia to be severely affected by heat stress, with the average heat-related mortality in major cities of the Global South having risen to 0.36%, continuing the upward trend from 2015 to 2024 (SDG 11.b). 15)

• September 27, 2024: The SDGSAT-1 satellite has imaged over 9500 scenes of Africa, which after orthorectification processing comprises 12 images based on SDGSAT-1 sensors, with 11.42 GB of data. 29)

• September 7, 2024: CBAS released an atlas of remote-sensing thermal infrared images at the 4th International Forum on Big Data for Sustainable Development Goals in Beijing based on data from SDGSAT-1. 28)
• September 7, 2023: CBAS released an atlas of urban nighttime light remote-sensing data based on 10-meter resolution nighttime light data captured by SDGSAT-1. 27)
• May 15, 2023: Over 90,000 images and approximately 168 TB of L4 data had been produced from SDGSAT-1. 8)
• October 31, 2022: CBAS and Complutense University of Madrid jointly released the first light pollution data of the Iberian Peninsula, Spain, based on three-band color low-light data from GLI sensor on board SDGSAT-1. The data is accessible here: https://pmisson.users.earthengine.app/view/sdgsat-1-p-iberica (shown in Figure 11). 16)

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• October 2022: The Level 4 data products acquired and processed by the sensors aboard SDGSAT-1 reached approximately 40,000 scenes, each covering 300 square kilometres, and totaling approximately 215 TB. 17)
• September 19, 2022: CBAS announced the launch of the SDGSAT-1 Open Science Programme to provide free access worldwide to data from SDGSAT-1 to promote multi-disciplinary research on SDGs. 17) 18) 19) 20)

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• September 7, 2022: Prof. Guo Huadong, Director General of CBAS, announced CBAS’ new mission to collaborate with the international scientific communities and stakeholders to develop the "Sustainable Development Satellite Constellation Plan" at the 2022 International Forum on Big Data for Sustainable Development Goals (FBAS 2022). 22)
• July, 2022: SDGSAT-1 completed six months of on-orbit testing and entered its operational phase. 17)
• September 6, 2022: The Alliance of Sustainable Development Goals Satellites, composed of seven member institutions operating approximately 60 satellites, was established in Beijing, China at FBAS 2022 to support the implementation of the UN 2030 Agenda for Sustainable Development. 21)
• April 25, 2022: CBAS released a dataset of ortho-corrected data products from SDGSAT-1 of imagery of the BRICS Countries (Brazil, Russia, India, China, and South Africa). 30)

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• December 20, 2021: SDGSAT-1 downlinked its first remote sensing images of multiple cities and regions, including Beijing, Shanghai, the Yangtze River Delta, Lake Namtso in Tibet, Aksu Prefecture in Xinjiang, and Paris in France. 23) 24)

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• November 5, 2021: SDGSAT-1 was launched by CAS aboard a Long March-6 (CZ-6) carrier rocket from TY LC in Shanxi province, China. 7) 4)

Sensor Complement

SDGSAT-1 carries three sensor payloads: Thermal Infrared Spectrometer (TIS), Glimmer Imager (GLI), and Multispectral Imager (MSI) which it uses synergistically in day and night observing modes to support the monitoring, evaluation, and study of SDGs. 6) 1) 7)

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Thermal Infrared Spectrometer (TIS)

TIS, provided by CAS, is a thermal infrared imaging radiometer with a one-dimensional scanning mechanism, black body calibration with full field of view (FOV), cryogenic radiation surface, a long-wave infrared detector refrigerator component, and an integrated electronics box, among other subsystems. 1) 26)

The full-optical-path low-temperature design allows it to detect surface temperature changes as low as 0.2 K, allowing accurate surface energy distribution mapping. This capability allows TIS to monitor land and sea surface temperature, providing insights into natural and urban heat energy distributions. Additional applications include crop cultivation and pest and disease control. 23) 17)

 
The TIS optical system adopts a whisk-broom mechanism, utilising four refractive lenses and a temperature control system to detect thermal variations in Earth's surface. These detections have an accuracy of noise equivalent differential temperature (NEDT) under 0.07 K at 300 K, with a spatial resolution of 30 m and a cross-track swath width of 300 km across three spectral bands: 8.0–10.5 μm, 10.3–11.3 μm, and 11.5–12.5 μm. 26) 1) 6)

The noise generated by the instrument's thermal radiation signal is reduced by the all-optical cryogenic optical system, and a Time-Delay-Integration (TDI) signal processing mode is used to improve the Signal to Noise Ratio (SNR). 1)

The TIS can be used simultaneously with MSI during daytime acquisition, and GLI at night, or in a single sensor observing mode. The three types of data this provides supports the study of the SDG targets related to human-nature interactions. To ensure the collection of high quality data for numerous applications, SDGSAT-1 employs various onboard calibration modes, including lunar calibration and blackbody calibration. 7) 1) 6)

Glimmer Imager (GLI) and Multispectral Imager (MSI)

The low-light level Glimmer Imager (GLI) detects the intensity and distribution of night lights to infer the level of social and economic development and patterns of human settlements. The Multispectral Imager (MSI) can be used to analyse changes in glaciers, melting snow and vegetation coverage, as well as monitor the color index and transparency of bodies of water, using its two deep blue bands and one red-edge band. 23) 17)

GLI and MSI, both provided by CAS, share an integrated imaging system made up of two identical imagers operating in a push-broom configuration, together producing a total swath width of 300 km. GLI operates with a spatial resolution of 40 m in the RGB bands and 10 m in the panchromatic band, while MSI achieves a 10 m spatial resolution. 1)

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The imaging system uses an array of Complementary Metal Oxide Semiconductor (CMOS) detectors which have been coated by different spectrum filters to allow multiple imaging functions within a single integrated device. This allows GLI to capture in panchromatic, red (R), green (G), and blue (B) bands, and MSI to image across seven multispectral bands. The system uses an electronic imaging driver to switch between the imagers, allowing the GLI to operate during the night, in the TIR+Glimmer data collection mode, and the MSI at daytime in the TIR+Multispectral mode. This is achieved using the face-array CMOS window function, which allows the CMOS sensor to output only the detector lines in the coating region of the panchromatic and RGB bands in the GLI working model for efficient light capture in night imagery. The same function is used to output the seven multispectral bands in the MSI working model for detailed multispectral imaging during daytime operation.1) 8)

To meet the distinct technical demands of GLI’s low-light operation and MSI’s variable illumination, the system utilises a common optical path for both instruments, a small F-number off-axis three-mirror-anastigmatic (TMA) optical design, and digital TDI. 1)

Ground Segment

The SDGSAT-1 ground segment is made up of the ground support subsystem, the data receiving subsystem, and the data processing and management subsystem. The ground support subsystem monitors the satellite and its payloads, detects and responds to on-orbit anomalies, performs telemetry communication and data analysis, and plans and executes data acquisition schedules based on user demand. 1)

An onboard two-dimensional point beam antenna working in the X-Band is used to downlink the sensor data at a rate of 2 × 800 Mbps, in either real-time or played back from the onboard solid-state data recorder. Data is downlinked to the China Remote Sensing Satellite Ground Station (RSGS), which has receiving stations across China, in Miyun in Beijing, Kashgar in Xinjiang Autonomous Region, and Sanya in Hainan Province. The data is then conveyed through a dedicated terrestrial optical fiber network to the RSGS headquarters in Beijing for subsequent processing and analysis. 1)

The data processing subsystem carries out the decompression, archiving, cataloging, radiometric and geometric corrections, and geocoding of the received data to generate standard products of the three types of imagery data from Level 0 (L0) to Level 4 (L4).

The decompressed L0 raw data undergoes radiometric correction for the Level 1 (L1) product. The Level 2 (L2) product is derived from the L1 data through systematic geometric correction. Using ground control points (GCPs), precise geometric corrections are then applied to produce the Level 3 (L3) product. The L4 data products are based on L3 products that have been ortho-rectified using a Digital Elevation Model (DEM) so that each pixel accurately corresponds to its real location on Earth, and outputted in a standardised format. The data processing subsystem can automatically generate L4 products within 24 hours of data reception. These products are uploaded onto the SDGSAT-1 Open Science Program platform to be freely accessible to the global scientific community for a wide range of SDG-related research and applications. 1) 2)

References  

1) Guo et al., “The SDGSAT-1 mission and its role in monitoring SDG indicators,” 1 October 2025, URL: https://doi.org/10.1016/j.rse.2025.114885 

2) OSCAR, “Satellite Programme: Sustainable Development Science Satellite,” URL: https://space.oscar.wmo.int/satelliteprogrammes/view/sdgsat

3) CBAS, “SDGSAT-1 Satellite Data,” URL: https://sdg.casearth.cn/en/mobile/datas/SDGSAT

4) OSCAR, “Satellite: SDGSAT-1,” URL: https://space.oscar.wmo.int/satellites/view/sdgsat_1

5) CBAS, “SDGSAT-1 MISSION Mission Objectives,” URL: https://www.sdgsat.ac.cn/satellite/task

6) CBAS, “SDGSAT-1 MISSION Satellite Description,” URL: https://www.sdgsat.ac.cn/satellite/describe 

7) CBAS, “SDGSAT-1 MISSION Overview,” URL: https://www.sdgsat.ac.cn/satellite/intro 

8) CBAS, “SDGSAT-1: The Satellite and Open Science Program,” 15 June 2023, URL: https://earthobservations.org/storage/documents/Events/Open-Data-Open-Knowledge-workshop/Session-1/Presentation%204%20-%20Yubao%20Qiu%20-%20China.pdf

9) Yu et al., “Temporal expansion of the nighttime light images of SDGSAT-1 satellite in illuminating ground object extraction by joint observation of NPP-VIIRS and sentinel-2A images,” 1 September 2023, URL: https://doi.org/10.1016/j.rse.2023.113691

10) Huang et al., “Thermal Discharge Temperature Retrieval and Monitoring of NPPs Based on SDGSAT-1 Images,” 27 April 2023, URL: https://doi.org/10.3390/rs15092298

11) Huang et al., “DynIceData: a gridded ice–water classification dataset at short-time intervals based on observations from multiple satellites over the marginal ice zone,” 3 July 2023, URL: https://doi.org/10.1080/20964471.2023.2230714

12) Yu et al., “Assessing changes in nighttime lighting in the aftermath of the Turkey-Syria earthquake using SDGSAT-1 satellite data,” 15 May 2023, URL: 10.1016/j.xinn.2023.100419

13) CBAS, “Satellite Technology Sheds Light on Urban Nightscapes: SDGSAT-1's Role in Tackling LED Light Pollution,” 9 January 2024, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=3902ddba-da4d-4dcd-8902-d7e7703cdecd

14) Yin et al., “Identification of illumination source types using nighttime light images from SDGSAT-1,” 21 December 2023, URL: https://doi.org/10.1080/17538947.2023.2297013

15) CAS, “Big Earth Data in Support of the Sustainable Development Goals 一 Special Report for a Decade of the SDGs,” September 2025, URL: https://sdgs.un.org/sites/default/files/2025-09/Big%20Earth%20Data%20in%20Support%20of%20the%20Sustainable%20Development%20Goals%20%282025%29%20%E2%80%94%20Special%20Report%20for%20a%20Decade%20of%20the%20SDGs.pdf

16) CBAS, “Light pollution data from the Iberian,” 27 December 2023, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=682c3c68-125a-4ff2-b146-215df7efbf0c

17) CBAS, “We cordially invite you to participate!” 10 November 2022, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=9c971a90-5523-4d4e-97a1-e4673c2e30db

18) DBAR, “SDGSAT-1 Open Science Program,” URL: https://www.dbeltroad.org/index.php?m=content&c=index&a=lists&catid=133

19) CBAS, “Announcement on the Launch of SDGSAT-1 Open Science Program,” 19 September 2022, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=c51de2aa-7372-43bb-9f5b-43dc00462eb8

20 ) International Journal of Digital Earth, “Innovative approaches and applications on SDGs using SDGSAT-1,” 29 January 2024, URL: https://www.tandfonline.com/journals/tjde20/collections/SDGSAT1

21) CBAS, “China sets satellite observation alliance,” 9 September 2022, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=d45d7734-44aa-4002-bb63-850fff064c3c

22) CBAS, “2022 International Forum on Big Data,” 7 September 2022, https://www.sdgsat.ac.cn/dynamic/detail?id=73e4a67e-c97b-4f20-94d4-30b7c713a57d

23) CBAS, “China's Earth science satellite transmits,” 21 December 2021, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=7227f0bf-2947-412a-9816-b407197d4a44

24) CBAS, “China unveils first images taken by,” 21 December 2021, URL: https://www.sdgsat.ac.cn/dynamic/detail?id=b883681e-7828-44af-b74a-2e483583a0d9

25) Li et al., “On-orbit monitoring flying aircraft day and night based on SDGSAT-1 thermal infrared dataset,” 1 December 2023, URL: https://doi.org/10.1016/j.rse.2023.113840

26) OSCAR, “Instrument: TIR,” URL: https://space.oscar.wmo.int/instruments/view/tir

27) CBAS, “First Atlas of Urban Nighttime Light Remote-sensing Data Unveiled,” 7 September 2023, URL: https://www.sdgsat.ac.cn/publicationsDetail?id=1730724809218

28) CBAS, “China Releases World's First Atlas of Remote-sensing Thermal Infrared Images,” 7 September 2024, URL: https://www.sdgsat.ac.cn/publicationsDetail?id=1730480238897

29) CBAS, “SDGSAT-1 data product for Africa,” 27 September 2024, URL: https://www.sdgsat.ac.cn/publicationsDetail?id=1730440435719

30) CBAS, “Data Product of Sustainable Development Science Satellite 1 (SDGSAT-1) for BRICS Countries,” 4 September 2025, URL: https://www.sdgsat.ac.cn/publicationsDetail?id=1730452110341

31) CBAS, “SDGSAT-1 Data Users Handbook (Draft),” September 2022, URL: http://60.245.209.56/preview/20221125/c84c0b5d89984cd384ffa05dbb163d14.pdf