China’s small Kuaizhou 1A rocket has launched the latest satellite in the Jilin-1 Earth-imaging constellation Wednesday, in a low-key mission out of the Jiuquan Satellite Launch Center. Kuaizhou lifted off at 06:19 UTC (14:19 Beijing time), deploying its payload into a sun-synchronous orbit.
Wednesday’s launch carried the Jilin-1 Gaofen-02F satellite, continuing deployment of the commercial remote sensing satellite network under development by the Chang Guang Satellite Technology Corporation. Gaofen, meaning “high resolution,” signifies the satellite’s role within the wider Jilin-1 system and is not to be confused with the series of larger imaging satellites of the same name that are operated by the Chinese government.
The Jilin-1 constellation, which is expected to consist of up to 138 satellites by the end of the decade, contains different types of satellites to perform different roles. In addition to the Gaofen satellites’ high-resolution imaging mission, other satellites in the constellation provide video capture, wider-area, and multi-spectral imaging.
Kuaizhou-1A ascends from Jiuquan. (Credit: CCTV)
Deployment of Jilin-1 began with a Chang Zheng 2D launch in October 2015 which carried the first four satellites. These included the Jilin-1 Lingqiao Yanzheng technology demonstrator, also known as the Smart Verification Satellite or Jilin-1LQ, an optical imaging satellite, Jilin-1 Guangxe-A, and a pair of Jilin-1 Shipin video-recording satellites. In the six years since, over thirty satellites have been deployed.
The Gaofen part of the constellation consists of two series of spacecraft: Gaofen-02 and Gaofen-03. The Gaofen-02 satellites, including the one deployed by Tuesday’s launch, are larger than their Gaofen-03 counterparts, with masses a little under 250 kilograms. Equipped with a push broom imager, Jilin-1 Gaofen-02F will be able to image the Earth at resolutions better than 0.75 meters in panchromatic mode, capturing light at wavelengths between 450 and 700 nanometres. It can also operate in multi-spectral mode across four optical and near-infrared channels, with a resolution of about three meters.
Wednesday’s launch marks the sixth flight of a Jilin-1 Gaofen-02 satellite, following the successful deployment of Jilin-1 Gaofen-02D last month. Both the 02C and 02E satellites were lost in launch failures last year – 02C aboard a Kuaizhou 1A rocket and 02E on the maiden flight of the larger Kuaizhou 11. Thirteen of the smaller Jilin-1 Gaofen-03 spacecraft are also in orbit.
Like most of its predecessors, Jilin-1 Gaofen-02F rode to orbit aboard a Kuaizhou 1A rocket. The launch was coordinated by the ExPace Technology Corporation, a subsidiary of the state-owned China Aerospace Science and Industry Corporation (CASIC), and took place from the Jiuquan Satellite Launch Center (JSLC).
A Jilin-1 Gaofen satellite in pre-launch processing
Jiuquan, one of China’s four main launch sites, is located in the Gobi Desert about 200 kilometers northeast of the city of Jiuquan. The JSLC was the site of China’s first orbital launch in 1970 when a Chang Zheng 1 rocket orbited Dong Fang Hong I from what is now the facility’s north site. Today only the launch pads of the South Launch Site continue to be used for orbital missions, with two launch pads at Site 43 used by the large liquid-fuelled Chang Zheng rockets.
Close to the Chang Zheng pads, Complex 43/95 houses launch facilities shared between several of China’s smaller solid-fuelled rockets including the Kuaizhou 1A. It was from one of these pads that Wednesday’s launch took place.
The Kuaizhou 1A, or KZ-1A, is the smallest member of the family of Kuaizhou rockets that ExPace offers for commercial launches. Capable of placing an approximately 400-kilogram payload into low Earth orbit, this four-stage vehicle uses three solid-fueled stages with a small liquid-fueled upper stage to complete orbital insertion. It has been speculated that the rocket may be a derivative of the Dongfeng 21 missile which entered service with the People’s Liberation Army in 1991.
Kuaizhou 1’s first launch likely took place in March 2012, when China conducted a mysterious sub-orbital launch out of Jiuquan. When the Kuaizhou made its first publicly announced – and orbital – launch in September 2013, the launch hazard areas lined up with that previous launch, indicating that it was likely a test flight of the new rocket. The first Kuaizhou 1A launched in January 2017, with the two rockets differing in that the Kuaizhou 1 is designed to launch payloads that are integrated into its upper stage, while the 1A deploys free-flying satellites.
The Kuaizhou-1A launch vehicle prior to flight
The name Kuaizhou, meaning “Quick Vessel”, reflects its designers’ ambitions of it being a quick-reaction launch vehicle, able to put satellites into orbit at short notice if required. To highlight one aspect of its quick-turnaround capability, two launches were staged on the same day, six hours apart, out of the Taiyuan Satellite Launch Center in December 2019.
Tuesday’s launch marked the fifteenth flight of the KZ-1 rocket overall, its fourteenth orbital launch, and the thirteenth flight of the KZ-1A variant. All but one of Kuaizhou’s previous launches have been successful – the exception being the Jilin-1 Gaofen-02C launch last year when the rocket is believed to have suffered an upper stage issue and failed to reach orbit. Tuesday’s launch is the second since the failure, with the previous KZ-1A mission at the end of September marking the rocket’s return to flight.
Once assembled in a horizontal integration building, Kuaizhou requires minimal launch infrastructure at the pad itself, with a mobile launcher transporting, erecting, and firing the rocket. Kuaizhou’s solid-fueled first, second, and third stages burned in sequence to propel Jilin-1 Gaofen-02F towards orbit, with the satellite enclosed within the rocket’s payload fairing during the early stages of flight. This fairing separated shortly after reaching space, at which point the vehicle had cleared the atmosphere and its protection was no longer required.
Following third stage burnout, Kuaizhou’s fourth stage took over. Burning liquid propellants, this stage was used to inject the payload precisely into its planned 535-kilometer sun-synchronous orbit. With orbital insertion completed, Jilin-1 Gaofen-02F separated to begin its own mission.
(Lead photo: Kuaizhou-1A lifts off with Jilin-1 Gaofen-02F. Credit: CCTV)