Yaogan Radar Satellite

Synthetic aperture radar (SAR) imagery is a cost-effective technology. A radar satellite is capable of detecting objects on the ground even at night and through cloud cover. Yaogan 1, launched in April 2006, was China’s first SAR-equipped satellite. Since that time, a number of additional SAR satellites in the Yaogan series have been launched. The satellites’ radar reportedly operates in the L-band (1–2 GHz) and has resolution as low as 5 m. Yaogan 1 apparently broke up in February 2010, but Yaogan 3, 6, and 10 remained operational (“Yaogan Series,” 2010; “UCS Satellite Database”).

Some sources report Yaogan 6 as electro-optical, not radar, but this is probably in error. JB-7 has been used by some sources for the second generation radar satellite type.

Two generations of these spacecraft were all launched from Taiyuan into sun-synchronous orbits.

• Jianbing-5 - The first generation spacecraft [Yaogan-1, -3, -10] were launched into orbits with an inclination of about 97.8°, a period of about 97 minutes, and an altitude of about 610 by 620 kilometers. All three had nearly identical launch times of about 22:48 GMT. Although the RAAN (right ascension of ascending node) of Yaogan-1 is offset by almost exactly 120° from that of Yaogan-10, the later is probably a replacement for the former, suggesting that the nominal Jianbing-8 constellation is two spacecraft.
• Jianbing-8 - The second generation spacecraft [Yaogan-6, -13, -18] were launched into orbits with an inclination of about 97.5°, a period of about 94.5 minutes, and an altitude of about 480 by 510 kilometers. The orbit altitude and Descending Node time for Yaogan-18 are similar to the initial values for Yaogan 6 (2009-021A/34839) suggesting the new satellite may be supplementary to it, or a replacement for it. The roughly five year interval between the launch of Yaogan-6 and Yaogan-18 suggests that it is probably a replacement, and that the nominal Jianbing-8 constellation is two spacecraft.

Yaogan-18 was described by the Chinese as being "...used to conduct scientific experiments, carry out land surveys, monitor crop yields and aid in preventing and reducing natural disasters". The orbit altitude and Descending Node time are similar to the initial values for Yaogan 6 (2009-021A/34839) suggesting the new satellite may be a replacement for it, or supplementary to it.

Some Western sources claimed in the 1990s that China might be seeking European and Russian technology to facilitate construction of high-resolution radar satellites for all-weather targeting applications, particularly the location of naval forces in the Taiwan Straits. The source of this speculation remained unclear, and there were initially no concrete indicators of such Chinese programs. The high absentee ratio of space-based systems would provide a poor match with Chinese regional force projection capabilities.

China had also taken an interest in the potential civil applications of such a system in the aftermath of the flooding, landslides, and typhoon damage in 1994. While China has used optical and infrared imaging space-based civil remote-sensing systems, there is particular interest in active microwave imagery that can penetrate southern China's constant cloud cover.

The PLA and other parts of the state apparatus viewed radar satellite imagery as critical in China's ability to achieve information dominance. Unlike electro-optical systems, radar satellites, according to GSD Second Department advocates, can see through clouds, rain, and fog in order to detect targets on the ground or underground, and in or under the ocean. In addition, SAR satellites are extremely useful in tracking moving targets, and can be useful in satisfying military mapping requirements. Chinese engineers have been examining SAR satellites as a means to track enemy submarines in shallow waters. China has already fielded a real-time airborne synthetic aperture radar (SAR) system, and is working toward deployment of an indigenous space based SAR satellite.

Preliminary R&D on a space-based SAR satellite was reportedly initiated in the late 1980s, and model R&D began in 1991. In May 1995, SSTC and COSTIND approved the finalized design and work on associated high speed data transmission. While the first generation SAR satellite is in the prototype development phase, preliminary research has probably already begun on the second generation SAR satellite system. Key institutes involved in the indigenous development of synthetic aperture radar satellites include CAS' Institute of Electronics, CAST's 501st and 504th Research Institutes (Xian Institute of Space Radio Technology), Shanghai Institute of Satellite Engineering, and MEI's 14th Research Institute and the Southwest Institute of Electronic Equipment (SWIEE).

China's Yaogan-29 remote sensing satellite was launched on 27 November 2015 at 5:24 a.m. from Taiyuan launch site in Shanxi Province, north China. "The satellite will be used for experiments, land surveys, crop yield estimates and disaster relief." Yaogan-29 was carried by a Long March-4C rocket, the 219th mission for the Long March rocket family. Yaogan 29, boosted toward a 615 x 619 km x 97.8 deg sun synchronous low earth orbit, was thought to be a roughly two ton sythetic aperature radar imaging platform.

A Long March-2D rocket carryied a Ludikancha Weixing (LKW) series spacecraft, also known as ‘Land Surveying’ launched from the Jiuquan Satellite Launch Center in northwest China, March 17, 2018. China launched a land exploration satellite into a preset orbit at 3:10 pm. The satellite is the fourth of its kind used for remote sensing. Previous satellites on the series were the LKW-1 (43034 2017-077A) launched on December 2, 2017; the LKW-2 (43080 2017-084A) launched on December 23, 2017; and the LKW-3 (43146 2018-006A) launched on 13 January 2018.