HJ-1A/B/CPublishDate：2022-02-24

　　HJ-1A/B/C corresponding to environment and disaster monitoring and forecasting small satellite constellation A/B/C include two optical satellites - HJ-1A/B and one radar satellite HJ-1C, which can carry out large-scale, all-weather and 24h dynamic monitoring for ecological environment and disaster. These satellites are equipped with 4 remote sensors such as wide-coverage CCD scanner, infrared multispectral scanner, hyperspectral imager and synthetic aperture radar, comprising a more complete earth observation remote sensing series characterized by high and medium space resolution, high time resolution, high spectrum resolution and wide coverage.

　　HJ-1A/B satellites were launched at 11:25am on September 6, 2008. HJ-1A is equipped with CCD scanner and hyper spectral imager (HSI) and HJ-1B is equipped with CCD scanner and infrared scanner (IRS). Both scanners with the same design principle and sub-satellite point symmetrical arrangement divide field equally and observe in parallel to complete scanning and imaging for earth with swath width of 700 km, ground pixel resolution of 30m and 4 spectrum bands. In addition, one hyper spectral imager is mounted on HJ-1A to complete scanning and imaging for earth of swath width of 50km, ground pixel resolution of 100m and 110～128 spectrum bands and it also has 30°side-looking capacity and satellite-borne calibration function. One infrared scanner is mounted on HJ-1B to complete imaging for earth of swath width of 720km, ground pixel resolution of 150m/300m and near/short/medium/long spectrum bands. HJ-1A and HJ-1B have the same orbit with phase position difference of 180°. The revisit period of two CCD cameras is only 2 days after networking.

　　Launched on November 19, 2012, HJ-1C is equipped with S-wave band synthetic aperture radar (SAR) that has two working modes such as band and scanning with image swath widths of 40km and 100km respectively. HJ-1C SAR radar has 5m spatial resolution under single-look mode and 20m resolution under four directional-look mode.

　　Table 1 Parameters of HJ-1A/B satellite orbits　　

　　Table 2 Parameters of HJ-1C satellite orbit　　　　

　　Table 3 Parameters of main loads carried by HJ-1A/B/C　　

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