China launches second pair of Yaogan 32 satellites on Chang Zheng 2C

by William Graham

China launched a pair of military satellites aboard its CZ-2C (Chang Zheng 2C) rocket Wednesday, November 3. Lifting off from the Jiuquan Satellite Launch Center at 07:43 UTC (3:43 EDT), the CZ-2C deployed the two Yaogan 32-02 spacecraft into sun-synchronous orbit following a short ascent.

Wednesday’s launch had originally been slated for mid-September. While the reason for its lengthy delays has not been announced, reports around the time of the original launch date suggested that an issue had arisen with valves on the rocket, necessitating repairs before the launch could proceed.

Yaogan 32 Group 02, or 32-02, consists of two satellites. While officially remote sensing platforms are operated by China’s Ministry of Agriculture, this is a cover for the military nature of their mission.

Yaogan Weixing, usually shortened to Yaogan, is Chinese for “remote sensing satellite.” China uses this name for military payloads when it does not want to acknowledge the identity or mission of the spacecraft. This convention is similar to the “USA” designations assigned to military spacecraft of the United States and the “Kosmos” designations used by Russia.

China began using the Yaogan name in 2006 and initially assigned numbers sequentially in the order the satellites launched. Since 2007 the system has become more complicated, with designations from Yaogan 30 onwards being re-used for subsequent–likely related–missions. 

Therefore, Yaogan 32-02 is the second pair of satellites to bear the Yaogan 32 designation–with Group 01 having launched in October 2018.

Liftoff of Chang Zheng 2C with Yaogan-32 Group 02. Credit: CCTV News

Very few details of the payload itself have been made public. Following the launch of the previous Yaogan 32 satellite pair, Chinese media reported their mission as “electromagnetic environment surveys”–which was previously used as cover for signals intelligence satellites. 

The United States NRO (National Reconnaissance Office) operates similar pairs of formation-flying satellites for signals intelligence, such as the NOSS, or Intruder spacecraft. Their purpose is believed to be locating and tracking ships from their radio transmissions.

There are two problems with identifying the Yaogan 32 spacecraft as a Chinese equivalent of NOSS, however. The first is the orbit in which the first pair of spacecraft operate. The Yaogan 32 spacecraft are in a sun-synchronous orbit at an altitude of about 700 kilometers. This differs from the approximately 1,100-kilometer, 63-degree orbits used by the US satellites.

The second is the existence of the Yaogan 31 satellites, the latest in a series of three-satellite clusters which appear to mirror the Intruder satellites more closely. The first two generations of the American constellation also used groups of three satellites, and the Yaogan 31 spacecraft are in similar orbits to their likely American counterparts.

And while a sun-synchronous orbit does not rule out a signals intelligence mission, it remains to be seen what the actual nature of these satellites are and why they operate in pairs. It is also currently unclear how many pairs of the Yaogan 32-type satellites China intends to launch.

The rocket

Wednesday’s mission was carried out by a CZ-2C (Chang Zheng 2C) rocket with a YZ-1S (Yuanzheng 1S) upper stage. Also known as the Long March 2C, the two-stage CZ-2C is the smallest of China’s legacy Chang Zheng rockets, derived from the Dongfeng 5 missile.

The CZ-2, -3, and -4 are interconnected developments from this missile that have formed the backbone of China’s space program since its early days. They are essentially China’s second generation of rockets, following the short-lived Chang Zheng 1–which itself was derived from the earlier Dongfeng 3 missile.

A past CZ-2C rocket lifts off from the launch pad. Credit: China Central Television

China launched its first satellite, Dong Fang Hong 1, via a Chang Zheng 1 in April 1970. A follow-up launch a year later orbited Shi Jian 1, but after this, the CZ-1 gave way to a pair of more capable rockets derived from the Dongfeng 5. Due to politics within China, the near-identical FB-1 (Feng Bao 1) and CZ-2 (Chang Zheng 2) were developed in parallel by competing design bureaus.

While the FB-1 flew first, it was retired after the political faction that backed it fell out of favor. The initial Chang Zheng 2A would quickly evolve into the Chang Zheng 2C. Because this design has continued to undergo improvements over the years, it still remains in service.

The Chang Zheng 2C is at the centerpiece of its generation of Chinese rockets–with several modified variants used as the core of other Chang Zheng vehicles.

The Chang Zheng 3 added a cryogenic upper stage for geostationary launches; this was followed by the upgraded CZ-3A. The CZ-3B and -3C added side-mounted liquid-fueled boosters to the Chang Zheng 3A design to further increase its payload capacity. 

The Chang Zheng 4 series–originally designed as a backup to the CZ-3 in the event the cryogenic stage could not be developed–uses a storable-propellant upper stage for mostly sun-synchronous launches.

The enhancements made to the Chang Zheng 2 design for the CZ-4 series were fed back into the CZ-2 line with the Chang Zheng 2D, which operates alongside the CZ-2C. This also formed the basis for the short-lived Chang Zheng 2E–an interim version incorporating four booster rockets to increase performance for commercial missions.

The boosters were then used in conjunction with a solid-fuel kick motor carried as part of the payload to launch several communications satellites before the Chang Zheng 3B entered into service. 

The Chang Zheng 2F–which also features these four boosters–is used by China’s human spaceflight program.

The crewed Shenzhou 10 mission lifts off from Jiuquan on a Chang Zheng 2F rocket on 11 June 2013. Credit: CNSA

In the last few years, China has begun to fly its next-generation Chang Zheng 5, 6, 7, and 8 vehicles. These are a series of clean-sheet designs which have been built from the ground up for space launches, as opposed to being offshoots from a missile program. They are expected to eventually replace their predecessors, but for now, the majority of China’s military launches continue to use the older rockets.

For the Chang Zheng 2C, the addition of the YZ-1S upper stage made the rocket into a three-stage vehicle. The YZ-1S allows the rocket to carry heavier payloads, leaving the second stage on a suborbital trajectory and entrusting orbit insertion to the upper stage–which can perform a circularization burn at the apogee, or the highest point, of its trajectory. 

In this configuration, the CZ-2C/YZ-1S can place up to 2,000 kilograms of payload into low Earth orbit.

Yuanzheng 1S, whose name means “Expedition,” is a derivative of the YZ-1 upper stage that has been used in conjunction with the larger Chang Zheng 3B and 3C rockets to help deploy Beidou navigation satellites into precise orbits. The YZ-1S is a simplified version designed for shorter-duration missions in low Earth orbit as opposed to the medium Earth orbit and geosynchronous orbit insertions required for the Beidou missions.

Render of a BeiDou-3 satellite in orbit, as rendered by J Huart.

The stage can restart multiple times, potentially allowing deployment of multiple payloads into different orbits–though Wednesday’s flight likely involved a single insertion burn followed by a deorbit burn after spacecraft separation.

The Chang Zheng 2C can fly from the Jiuquan, Taiyuan, and Xichang Satellite Launch Centers, with Wednesday’s flight lifting off from pad 43/94 at Jiuquan. This is one of two Chang Zheng launch pads on what is known as the “South Launch Site,” with the other–Site 43/91–used for crewed Shenzhou launches.

These pads are served by a shared assembly building, allowing rockets to be integrated vertically atop a mobile launch platform which then rolls along rails to the launch pad.

Located about 38 kilometers south of the older launch pads previously used by the Chang Zheng 1 and early Chang Zheng 2 missions, the southern part of Jiuquan also includes facilities for smaller rockets. These include the Kuaizhou, Chang Zheng 11, and the new generation of small commercial rockets being developed by Chinese firms.

Wednesday’s launch was China’s 41st of the year, keeping up a relentless pace that has characterized Chinese space efforts over the last few years. It comes a week after the previous mission from Jiuquan, which saw a smaller Kuaizhou 1A rocket deploy the Jilin-01 Gaofen-02F satellite–a mission that had also been heavily delayed.

(Lead image: Chang Zheng 2C moments after launch. Credit: CCTV News.)

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