Sunday, August 01, 2010

Long March launches fifth GPS satellite for China

August 1st, 2010 by Rui C. Barbosa

China launched its fifth satellite as part of its GPS satellite navigation system, with BeiDou-2 IGSO-1 placed into orbit via the CZ-3A Chang Zheng-3A (CZ3A-17/Y16) launch vehicle. Launch from the Xi Chang Satellite Launch Center, in Sichuan Province occured at 5:30am local time on Sunday.

Chinese Launch:

The satellite that was launched is the first BeiDou-2 IGSO (Inclined GSO) satellite of the system. This constellation of satellites will eventually consist of 35 vehicles, including 27 MEO satellites, 5 GSO satellites and 3 IGSO.

The satellites will transmit signals on the following carrier frequencies: 1195.14-1219.14MHz, 1256.52-1280.52MHz, 1559.05-1563.15MHz and 1587.69-1591.79MHz, notably overlaying the Galileo PRS band and the GPS M-code.

According to International Telecommunications Union (ITU) regulations, the frequencies have to be used within a certain time period. The priority for using the frequencies is given in order of reception of the requests at ITU, made seven years in advance.

The BeiDou-2 was developed in the basis of the DFH-3 satellite platform and has a lifespan of 8 years.

The Compass Navigation Satellite System (CNSS) is China’s second-generation satellite navigation system capable of providing continuous, real-time passive 3D geo-spatial positioning and speed measurement.

The system will initially used to provide high-accuracy positioning services for users in China and its neighboring regions, covering an area of about 120 degrees longitude in the Northern Hemisphere. The long-term goal is to develop a global navigation satellite network similar to the GPS and GLONASS.

Like their American and Russian counterparts, CNSS will have two types of services; a civilian service that will provide an accuracy of 10 meters in the user position, 0.2 m/s on the user velocity and 50 nanoseconds in time accuracy; and the military and authorized users service, providing greater accuracy.

The first phase of the project will provide for the coverage of the Chinese territory, ahead of the future use of the Compass constellation for the entire globe.

Previous BeiDou satellites were launched on October 30, 2000 ‘BeiDou-1A’ (Catalogue Number: 26599 International Designation: 2000-069A); December 20, 2000 ‘BeiDou-1B’ (26643 2000-082A); May 24, 2003 ‘BeiDou-1C’ (27813 2003-021A); February 2, 2007 ‘BeiDou-1D’ (30323 2007-003A); April 13, 2007 ‘BeiDou-2 Compass-M1′ (31115 2007-011A); April 14, 2009 ‘BeiDou-2 Compass-G2′ (34779 2009-018A), January 16 ‘BeiDou-2 Compass-G1′ (36287 2010-001A) and June 2, 1010 ‘BeiDou-2 Compass-G3′ (36590 2010-024A).

China used their CZ-3A Chang Zheng-3A launch vehicle to loft BeiDou-2 IGSO-1 uphill. The CZ-3A is a large-scale three-stage liquid launch vehicle, which has inherited the matured technology of the CZ-3 Chang Zheng-3.

An upgraded liquid hydrogen and liquid oxygen cryogenic third stage has been developed to enable CZ-3A performing greater geostationary transfer orbit (GTO) capability. The CZ-3A is equipped with a more flexible and sophisticated control system which supports substantial attitude adjustments to orient the payloads before spacecraft separation and provides adjustable satellite spin-up rotation rate.

It has paved the way for the development of CZ-3B Chang Zheng-3B and CZ-3C Chang Zheng-3C, and become the workhorse of GTO launches for China.

The CZ-3A can also be used for LEO, SSO and polar orbit missions, as well as dual-launch and multiple-launch missions. The launch capacity of the CZ-3A to GTO is 2.650 kg, the lift-off mass is 241.000 kg, the overall length is 52.5 meters, the diameter of first stage and second stage is 3.35 meters, the diameter of third stage is 3.0 meters, and the maximum fairing diameter is 3.35 meters.

The first stage and second stage of CZ-3A employ storable propellants, i.e. unsymmetrical dimethy1 hydrazine (UDMH) and nitrogen tetroxide (N2O4), and the third stage uses cryogenic propellants, i.e. liquid hydrogen (LH2) and liquid oxygen (LOX).

On the first stage, the CZ-3A uses a DaFY6-2 engine with a 2961.6 kN thrust, while the second stage is equipped with a DaFY20-1 main engine (742 kN) and four DaFY21-1 vernier engines (11.8 kN each). The third stage is equipped with two YF-75 engines (78.5 kN each).

The fairing diameter of the CZ-3A is 3,35 meters and has a length of 8.89 meters.

CZ-3A consists of rocket structure, propulsion system, control system, telemetry system, tracking and safely system, coast phase propellant management and attitude control system, cryogenic propellant utilization system, separation system and auxiliary system, etc.

The CZ-3A has a 100 percent launch success rate since its maiden flight on February 8, 1994 when it successfully launched two experimental satellites. And it was awarded the ‘Gold Launch Vehicle’ title by China Aerospace Science and Technology Corporation in June 2007.

China used a CZ-3A to successfully launch the Chang’e-1 lunar satellite on October 24, 2007, which indicated that has taken a substantial step for lunar exploration.

This was the 125th successful Chinese orbital launch, the 124th launch of a Chang Zheng launch vehicle, the 54th successful orbital launch from the Xi Chang Satellite Launch Center, the third successful orbital launch from the Xi Chang in 2010 and the fifth successful orbital launch from China in 2010.

The Xi Chang Satellite Launch Centre is situated in the Sichuan Province, south-western China and is the country’s launch site for geosynchronous orbital launches.

Equipped with two launch pads (LC2 and LC3), the centre has a dedicated railway and highway lead directly to the launch site. The Command and Control Centre is located seven kilometers south-west of the launch pad, providing flight and safety control during launch rehearsal and launch.

Other facilities on the Xi Chang Satellite Launch Centre are the Launch Control Centre, propellant fuelling systems, communications systems for launch command, telephone and data communications for users, and support equipment for meteorological monitoring and forecasting.

The first launch from Xi Chang took place at 12:25UTC on January 29, 1984, when the CZ-3 Chang Zheng-3 (CZ3-1) launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit. The launch of the new BeiDou-2 satellite was the 52nd successful orbital launch from Xi Chang.

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