China conducts debut launch of Long March 6

by Rui C. Barbosa

China initiated a new era in its space exploration with the debut of a new family of launch vehicle. The first Long March-6 (Chang Zheng-6) rocket was successfully launched from the Taiyuan Satellite Launch Center, with a multi-payload cargo of 20 small satellites. Launch took place at 23:01:14.331 UTC on Saturday.

Long March 6:

The CZ-6 Chang Zheng-6 is a liquid-propellant, small-load space launch vehicle developed by Shanghai Academy of Spaceflight Technology (SAST).

The launch vehicle is based on the 3.35m-diameter boosters, which have been developed as a strap-on booster for the CZ-5 family of SLV.

2015-09-19-234604The core stage consists of a single 120t-thrust YF-100 engine that burns oxygen and kerosene (LOX/Kerosene) propellant, which causes less pollution compared to the UDMH/N2O4 (nitrogen tetroxide) propellant currently in use.

The Long March-6 is designed for small-load launch missions, with a sun-synchronous orbit (700km SSO) capability of 1,080 kg.

In September 2009, the Chang Zheng-6 launch vehicle development program was officially approved by the Chinese Government and the first flight was expected to take place in 2013. SAST was tasked with the development of the new launch vehicle in July 2008.

2015-09-18-204409Overall length is 29.237 m with a total mass at liftoff of 103,217 kg. Dry mass of the three stages combined is 9,020 kg. Fairing diameter is 2.25 m / 2.6 m, and the vehicle is capable of launching a payload of 1,080 kg to a 700 km SSO orbit (500 kg if only Chinese tracking stations are used).

The first stage has a 3.35 meter diameter and is equipped with a single YF-100 engine, consuming 76,000 kg of kerosene RP-1/LOX. The YF-100 engine is capable of a ground thrust of 1,177 kN and a ground specific impulse of 2.9 km/s. Burn time is 155 seconds. The first stage uses four 1000 N thrusters for roll control.

The second stage has 2.25 meter diameter and consumes 15,150 kg of kerosene RP-1/LOX. It is equipped with a YF-115 developing 147.1 kN (sea level) or 176.5 kN (vacuum), with a vacuum specific impulse of 3.35 km/s. The second stage uses four 25 N thrusters for roll control.

2015-09-19-234713The third stage is equipped with four engines with 4 kN (each), along with eight 100 N thrusters for attitude control. The engines are powered by a mixture of kerosene and hydrogen peroxide.
The Long March-6 first cargo:

Twenty small Chinese satellites are the cargo of the Long March-6 first mission.

The ZDPS-2 Zheda Pixing-2 satellites is a dual satellite platform mission designed by Zhejiang University to provide a technology demonstration of guidance, navigation and control (GNC) strategies for spacecraft formation flying.

2015-09-18-221447ZDPS-2 is the latest Nano-satellite mission of Microsat Research Center, Zhejiang University. It constitutes an in-orbit test platform for formation flying technology with two identical nano-satellites, ZDPS-2A and ZDPS-2B.

The main objectives of ZDPS-2 mission are to demonstrate advanced guidance, navigation and control algorithms for formation flying; in-orbit performance test of self-designed ammonia micro-propulsion system; validate the precision of the S-Band Inter-Satellite Pseudo-Noise (PN) code ranging system; to validate the dual-frequency GPS receiver and the relative orbit determination algorithm; and to validate the MEMS accelerometer in-orbit calibration algorithm.

The main subsystems and components of the ZDPS-2 gained space heritage on the ZDPS-1A mission launched on September 22, 2010. Both ZDPS-2A and ZDPS-2B are 25 × 25 × 25 cm cube-shaped and weigh around 12 kg.

The satellites are equipped with tri-junction Ga-As solar cells as the primary power, tiled on all six planes of the satellite body, which have a 26.8% theoretical efficiency, and a Li-ion battery pack of ten cells from Sanyo serves as the secondary power. The transceiver works under the Universal S-Band (USB) TTC system, enjoys uplink data rates of 2kbps and adjustable downlink data rates of 1kbps-64kbps.

The on-board computer (OBC) is composed of multi-CPU with FPGA, providing a universal computing, storage, management platform for command execution, TT&C, attitude & orbit control, payloads, etc.

Sub-degree level attitude measurement will be achieved through a 3-axis magnetometer, a 3-axis MEMS gyroscope, four-quadrant analog sun sensors mounted on six surfaces and a digital sun sensor.

Attitude control utilizes a momentum wheel, installed on the pitch axis, to provide both momentum bias and reaction actuation for pitch attitude maneuver, and three orthogonally mounted magnetic coils provide active control torque for detumbling and three-axis stabilization, with pointing accuracy of better than 2° and steady precision 0.1°/s.

2015-09-19-234713In order to obtain an accurate absolute position and velocity measurement, ZDPS-2 carries two GPS receivers. A UNICORE dual-frequency GPS receiver provides single point positioning accuracy of 2m (RMS), with observational data updating rate up to 10Hz. A Zhejiang University developed GPS receiver provides absolute position accuracy of 2m and velocity of 0.2m/s. A dual-frequency GPS antenna is mounted on the face opposite to the ground (-Z plane).

ZDPS-2A&B are each equipped with an S-Band inter-satellite communication transceiver to exchange position and velocity data, capable of providing data transmission rate of 8kbps and a maximum communication range of 5km. In addition, an S-Band PN code ranging system is designed to provide PN code rate of no more than 2Mcps and ranging accuracy of 4cm for 1Mcps code rate. It could support for multiple composite codes such as JPL1999, T2, T4 and so on.

The satellites are both equipped with a propulsion system, either of them can be treated as chief or deputy. The system uses liquid ammonia as a propellant with ISP greater than 900Ns/kg. With the fuel mass of 0.318kg and the satellite mass of below 12 kg, the system can provide a total ΔV of 24m/s.

2015-09-18-221550Nine CAS-3 satellites were onboard. Originally named Chinese Amateur radio Satellite 3, six of these satellites have been renamed XW-2 Xiwang-2 (Hope-2), XW-2A through XW-2F. All XW-2 satellites were developed by DFH Satellite Co. Ltd and CAMSAT.

Xiwang-2A (CAS-3A) features a 398 × 398 × 398 mm cubic body with body mounted solar cells and a mass of approximately 25 kg mass. It features a three-axis stabilization system. The micro-satellite will be used for atmospheric physics experiments and amateur radio missions.

The amateur communications payload consists of U/V 20 kHz wide transponders with 145 MHz CW beacon and 19k2 GMSK AX25 telemetry downlinks. Two small satellites, XW-2E and XW-2F, will fly piggyback on top of XW-2A.

Xiwang-2B (CAS-3B), Xiwang-2C (CAS-3C) and Xiwang-2D (CAS-3D) are a constellation of three identical Chinese micro-satellites that will be used for atmospheric physics experiments and amateur radio missions.

The satellites are cubic bodies with dimensions of 246 × 246 × 246 mm with body mounted solar cells and a mass of approximately 10 kg mass. They feature a three-axis stabilization system. The amateur communications payload consists of U/V 20 kHz wide transponders with 145 MHz CW beacon and 19k2 GMSK AX25 telemetry downlinks.

2015-09-18-220952The XY-2 Xinjishu Yanzheng-2 will test two kinds of electric propulsion engines (electric propulsion Hall LHT-100 engine and a magnetic and electric propulsion Hall engine) developed by the China Aerospace Science and Technology Corporation. The satellite was developed by Shenzhen DFH and has a mass of 130 kg.

Xiwang-2E (CAS-3E) and Xiwang-2F (CAS-3F) are two identical picosatellites that will fly piggyback on top of the XW 2A satellite. The small satellites will be used for amateur radio mission only. They have a cubic shape similar to a CubeSat-1U with dimensions 116 × 116 × 116 mm. The have a mass of approximately 1.5 kg mass each. The amateur communications payload consists of U/V 20 kHz wide transponders with 145 MHz CW beacon and 19k2 GMSK AX25 telemetry downlinks.

Developed by Shenzhen Aerospace Dongfanghong HIT Satellite Ltd. and CAMSAT, the DCBB (CAS-3G) is a CubeSat-U for the University educational purposes.

2015-09-18-221832LilacSat-2 (CAS-3H) was developed by the Harbin Institute of Technology. This is a low-cost, nano-satellite for education, amateur radio communication and technology demonstration, providing hands-on experience for students who would not otherwise have the opportunity to build flight hardware for a space mission.

The 11 kg satellite is a cube-shaped 20 × 20 × 20 cm object carrying four payloads: a thermal infrared camera; an SDR based multi-band receiver, for reception and decoding of signals from AIS, ADS-B, etc.; a V/U amateur radio SDR platform; and a FPGA software testing platform . It can be configured as an FM repeater or an APRS digipeater. It will also provide a VHF CW beacon and UHF 9k6 BPSK telemetry downlink; and an FPGA software testing platform.

LilacSat-2 will operate on a 520 × 520 km altitude orbit with an inclination of 97° on a mission from 3 to 6 months long.

NUDT-Phone-Sat (CAS-3I) was developed by the National University of Defense Technology and CAMSAT and is an experimental pico satellite based on smartphone technology. Its dimensions are 98 × 98 × 7 mm and has a weight of 100 g.

Situated in the Kelan County in the northwest part of the Shanxi Province, the Taiyuan Satellite Launch Center (TSLC) is also known by the Wuzhai designation. It is used mainly for polar launches (meteorological, Earth resources and scientific satellites).

The launch center has two single-pad launch complexes, a launch area for the new Long March-6 rocket, a technical area for rocket and spacecraft preparations, a communications centre, a mission command and control centre, and a space tracking centre.

The stages of the rocket were transported to the launch centre by railway and offloaded at a transit station south of the launch complex. They were then transported by road to the technical area for checkout procedures.

The launch vehicles were assembled on the launch pad by using a crane at the top of the umbilical tower to hoist each stage of the vehicle in place. Satellites were airlifted to the Taiyuan Wusu Airport about 300km away and then transported to the centre by road.

The TT&C Centre, also known as Lüliang Command Post, is headquartered in the city of Taiyuan, It has four subordinate radar tracking stations in Yangqu (Shanxi), Lishi (Shanxi), Yulin (Shaanxi), and Hancheng (Shaanxi).

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