Recent progress of Earth observation satellites in China

Currently, there are 32 Earth observation satellites in orbit. Since 2022, China has launched 9 Earth observation satellites which are shown in Table 1. This article introduces the recent progress of Earth observation satellites in China, especially the satellite operation, data archiving, data distribution and data coverage.

Table List of new Earth observation satellites in China

In this work, researchers provide a introduction of total 9 Earth observation satellites in section 1.

LT-1A and LT-1B are shown in section 1.1. The Land Exploration Satellite 1 project is an important component of the national medium and long term civilian space infrastructure development plan (2015-2025), and it is also the first scientific research satellite project approved by the plan. Featuring all-weather, all-time, multi-mode, and multi-polarization capabilities, they can be applied in geology, land use, Earthquake, disaster reduction, surveying and mapping, forestry, effectively enhancing China’s capacity for independent satellite detection and prevention of geological disasters. LT-1A and LT-1B operate on a sun-synchronous orbit at an altitude of 607 kilometers, equipped with advanced L-band multi-polarization multi-channel SAR payloads. The article lists the imaging mode of LT-1A and LT-1B in a table format.

GF-3C satellite is shown in section 1.2. GF-3C is one of the two operational satellites outlined in the national medium and long term civilian space infrastructure development plan (2015–2025). Its primary payload is a C-band synthetic aperture radar. This satellite fully inherits the technical solutions of the GF-3 satellite. It is designed to operate for eight years in orbit and features a suite of 12 conventional imaging modes. The imaging mode of GF-3C is shown in a table.

Section 1.3 is an introduction to the DQ-1 satellite. DQ-1 operates in a Sun-synchronous orbit and boasts a comprehensive array of payloads. It is not just a research satellite in the nation’s medium and long term development plan for civil space infrastructure; but also a world pioneer, being the first satellite capable of detecting carbon dioxide laser. Equipped with five advanced remote sensing instruments, it promises to significantly enhance global capabilities in carbon monitoring and atmospheric pollution detection. The payloads of DQ-1 are listed in a table.

The introduction of Carbon Monitoring Satellite for Terrestrial Ecosystems (CM-1 Satellite) is in section 1.4. As the world’s first satellite to combine active and passive observation for forest carbon sink monitoring, its successful launch signifies China's entry into the era of remote sensing-based carbon sink monitoring. t is equipped with four satellite payloads: a multi-beam lidar, a multi-angle multispectral camera, a hyperspectral detector, and a multi-angle polarization imager. The payloads of CM-1 are listed in a table.

The introduction of HJ-2E and HJ-2F are in section 1.5. As outlined in the national medium and long term civilian space infrastructure development plan (2015–2025), the HJ-2E and HJ-2F satellites operate in a sun-synchronous orbit at an altitude of 499 kilometers. Their primary payload is an S-band synthetic aperture radar. These twin satellites will form a network, marking the initial establishment of a constellation of satellites for emergency management and ecological environment monitoring. The article lists the imaging mode of HJ-2E and HJ-2F in a table format.

Section 1.6 is an introduction to the GF-5 01A satellite. GF-5 01A is a successor to the Gaofen-5 satellite. It boasts three payloads: the Advanced Hyperspectral Imager for the Visible and Shortwave Infrared (AHSI), the Wideband Thermal Infrared Imager (WTI), and the Environmental Monitoring Instrument for Atmospheric Trace Gases (EMI).

Section 1.7 is an introduction to the JZ-1 satellite. It is a remote sensing research satellite outlined in the national medium and long term civilian space infrastructure development plan (2015–2025). It is operated in a near 36000-kilometer inclined geosynchronous orbit. JZ-1 satellite is the world's first geosynchronous orbit SAR (Synthetic Aperture Radar) satellite, equipped with an L-band SAR as its primary payload. The satellite is currently undergoing in-orbit testing.

Next, the researchers described the operation of these 9 satellites.

Section 2 is the statistics of satellite imaging operation. In daily situations, the imaging is arranged comprehensively based on user demands and satellite constraints. The researchers analyzed the imaging data of GF-3C/LT-1A/LT-1B/HJ-2E/GF-5 01A(infrared)/GF-5 01A (hyperspectral) since their launch, such as number of imaging turns, imaging time, track adjustment.

Section 3 is the statistics of satellite data archiving since launch. The data acquired by the satellites will be processed into Levels 0 and 1 for storage. The researchers analyzed the data archiving of LT-1A/LT-1B/GF-3C/HJ-2E/HJ-2F/GF-5 01A, such as the number and capacity of Level 0 and Level 1.

Section 4 is the data distribution of LT-1A/LT-1B/GF-3C/DQ-1 (WSI)/CM-1 (DMC)/HJ-2E/GF-5 01A/HJ-2F since launch. The data of China Earth observation satellites are distributed to the research institutions, governments, commercial companies and individuals. The researchers analyzed the number of data distribution of these satellites.

Section 5 is the data coverage of typical sensors on LT-1A/LT-1B/GF-3C/CM-1/HJ-2E/HJ-2F/GF-5 01A. The researchers analyzed the standard products distribution of typical sensors and calculated the coverage area of these data.

This article introduces the recent progress of Earth observation satellites in China since 2022, especially the satellite introduction, satellite operation, data archiving, data distribution and data coverage. After more than 20 years of development, Earth observation satellites possess the capability to observe across multiple spectral bands, under all weather conditions, and at all times. The increasing number of civilian Earth observation satellites and diverse payload types have promoted the development of remote sensing technology applications. At the same time, the improvement of remote sensing technology application level has put forward higher requirements for satellite payload indicators and image quality, promoting the development of civilian Earth observation satellites and ground processing systems.

By 2030, the number of Earth observation satellites in China will reach 40, and the payload and orbit types will become more diverse, further improving the high spatial, high temporal, high spectral, and high radiation resolution. Earth observation satellites will provide rich, stable, and sustainable scientific data for various fields of national economy and people’s livelihood, promote the further improvement of remote sensing technology application level, and create greater social and economic benefits.

See the article：

Recent Progress of Earth Observation Satellites in China

https://doi.org/10.11728/cjss2024.04.2024-yg23

https://www.cjss.ac.cn/cn/article/doi/10.11728/cjss2024.04.2024-yg23