On 10 April 2018, China sent three Yaogan-31 spacecrafts and a microsatellite on a Long March 4C booster rocket. The uninformed surprise launch was performed at 00:25 a.m. EDT from the LC43 launch complex at the Jiuquan Satellite Launch Centre (JSLC) located in China’s Gansu Province. Details of the mission as well as the pre-launch preparations were discretely kept under the wraps by the country. Beijing didn’t even release any Notice to Airmen (NOTAM) informing that the launch was imminent. It is assumed that the flight lasted for approximately 15-20 minutes ending it spacecraft separation deploying the satellites into a low-Earth Orbit (LEO).

As per the tracking data published by the U.S. military, the three-stage, liquid-fueled rocket placed the four satellites in orbit around 1,100 km above the Earth with an inclination of 63.4 degrees to the equator.

The three Yaogan satellites namely, Yaogan-31 01A, 01B and 01C, each fitted with two deployable solar arrays were the primary payloads of the rocket and will be employed for electromagnetic surveys and other associated technology tests. However, the technical details of these spacecraft are unknown. 

Contrary to the official statements released by Beijing, Western analysts suspect that the trio satellites of the Yaogan Weixing-31-01 mission are of military nature and assumedly employ either optical or synthetic aperture radar (SAR) sensors.  It is suspected that this mission is similar to the Yaogan-9, 16, 17, 20 and 31 missions in which the satellites are in a formation similar to that of NOSS system, considered as the Jianbing-8 military series. The satellites are designed to locate and track foreign warships and to collect optical and radio electronic signatures of the maritime vessels which will be used with other information valuable to the Chinese maritime forces.

The National Institute of Advanced Studies located in Bangalore, India, in its report, suggest that the Yaogan satellites might be part of an anti-ship ballistic missile (ASBM) system that China is developing.

China had launched the first Yaogan satellite back in April 2006, followed by another three of the series launched on 25 January 2018 and the recent ones on 10 April.

Along with the three Yaogan spacecraft, a micro nanotechnology experiment satellite whose identity remains undisclosed was also launched.

It was the 271st orbital flight of the Long March rocket series overall and a record-breaking 11th mission for China this year till now. Beijing’s next launch is scheduled to take place on 21 April when it will deliver the Apstar 6C communications satellites aboard Long March 3B booster into space.