Long March 3B lofts LaoSat-1

by Rui C. Barbosa

The Chinese have launched the LaoSat-1 communications satellite for Laos at 16:07 UTC on Friday. The launch was conducted by the Long March-3B/G2 (Y38) launch rocket – launching from the LC2 Launch Complex of the Xichang Satellite Launch Center.

LaoSat-1 Launch:

On February 25, 2010, China Great Wall Industry Corporation (CGWIC), China Asia-Pacific Mobile Communications Satellite Company Limited (APMT) and Laos National Authority for Science and Technology (NAST) under Prime Minister’s Office PDR, jointly signed the Contract for Lao Satellite Broadcasting and Telecommunication System Construction (LaoSat-1).

This was the fifth satellite contract signed by CGWIC on an in-orbit-delivery basis with international customer.

According to the contract, satellite would be manufactured on the basis of the DFH Dongfanghong series of platforms designed and developed by China Academy of Space Technology (CAST) and would be launched by an LM-3B launch vehicle provided by China Academy of Launch Vehicle Technology (CALT) from the Xichang Satellite Launch Centre (XSLC).

China Satellite Launch & Tracking Control General (CLTC) would undertake the launch and TT&C operation.

On August 10, 2013, China Asia-Pacific Mobile Telecommunications Satellite Co., Ltd. (China APMT), a subsidiary of China Aerospace Science and Technology Corporation (CASC), completed a preliminary design review for the LaoSat-1 satellite. A delegation from Laos and experts from China Academy of Launch Vehicle Technology, China Academy of Space Technology, China Great Wall Industry Corporation, and other related units attended the review panel.

At the end of the meeting the parts present came to an agreement on the satellite system. Successful completion of the preliminary design review allowed then China APMT to proceed to the critical design review.

On 18 August 2014, APT Satellite entered into a satellite program consultancy contract with China APMT, to form a project advisory team to provide advisory and consultation services on the technology, progress of construction and quality guarantee in respect of LaoSat-1 satellite.

The services covered the periods including the stages of assembly, integration and testing of the satellite, the launch site operation, until the in-obit acceptance of LaoSat-1 satellite.

2015-11-20-132013The LaoSat-1 satellite is the first to use the DFH-3B bus. The DFH-3B bus is an updated version of DFH-3 bus, a communications satellite bus whose capability is between high and medium ones. It adopts a hexahedral structure, consisting of propulsion, service and communication modules, communication antennas and solar arrays and adopts 3-axis stabilized attitude control.

The bus is applicable to communications and navigation satellites and deep space probes through adaptive modification.

Its dimensions 2.20×2.00×3.10 meters and its general launch mass is 3.800 kg. Payload capacity is between 400 kg to 450 kg. Solar array output is 5500W and payload power consumption is between 3000W to 4000W. Its lifetime is between 12 and 15 years.

The communications payload on LaoSat-1 is composed by 14 Extended C-band and 8 Extended Ku-band transponders. The satellite will be stationed at 128.5° and it will have a service life of 15 years.

Launch vehicle and launch site:

To meet the demand of international satellite launch market, especially for high power and heavy communications satellites, the development of Long March-3B (Chang Zheng-3B) launch vehicle was started in 1986 on the basis of the fight proven technology of Long March launch vehicles.

2015-09-12-163133Developed from the Chang Zheng-3A, the Chang Zheng-3B is at the moment the most powerful launch vehicle on the Chinese space launch fleet.

The CZ-3B features enlarged launch propellant tanks, improved computer systems, a larger 4.2 meter diameter payload fairing and the addition of four strap-on boosters in the core stage that provide additional help during the first phase of the launch.

The rocket is capable of launching a 11,200 kg satellite to a low Earth orbit or a 5,100 kg cargo to a geosynchronous transfer orbit.

The CZ-3B/G2 (Enhanced Version) launch vehicle was developed from the CZ-3B with a lengthened first core stage and strap-on boosters, increasing the GTO capacity up to 5,500kg.

On May 14, 2007, the first flight of CZ-3B/G2 was performed successfully, accurately sending the NigcomSat-1 into pre-determined orbit. With the GTO launch capability of 5,500kg, CZ-3B/G2 is dedicated for launching heavy GEO communications satellite.

The rocket structure also combines all sub-systems together and is composed of four strap-on boosters, a first stage, a second stage, a third stage and payload fairing.

2015-09-12-163210The first two stages as well as the four strap-on boosters use hypergolic (N2O4/UDMH) fuel while the third stage uses cryogenic (LOX/LH2) fuel. The total length of the CZ-3B is 54.838 meters, with a diameter of 3.35 meters on the core stage and 3.00 meters on the third stage.

On the first stage, the CZ-3B uses a YF-21C engine with a 2,961.6 kN thrust and a specific impulse of 2,556.5 Ns/kg. The first stage diameter is 3.35 m and the stage length is 23.272 m.

Each strap-on booster is equipped with a YF-25 engine with a 740.4 kN thrust and a specific impulse of 2,556.2 Ns/kg. The strap-on booster diameter is 2.25 m and the strap-on booster length is 15.326 m.

2015-09-12-164401The second stage is equipped with a YF-24E (main engine – 742 kN / 2,922.57 Ns/kg; four vernier engines – 47.1 kN / 2,910.5 Ns/kg each). The second stage diameter is 3.35 m and the stage length is 12.920 m.

The third stage is equipped with a YF-75 engine developing 167.17 kN and with a specific impulse of 4,295 Ns/kg. The fairing diameter of the CZ-3B is 4.00 meters and has a length of 9.56 meters.

The CZ-3B can also use the new Yuanzheng-1 (“Expedition-1″) upper stage that uses a small thrust 6.5 kN engine burning UDMH/N2O4 with a specific impulse at 3,092 m/s. The upper stage is able to conduct two burns, having a 6.5 hour lifetime and is capable of achieving a variety of orbits. This upper stage was not used on this launch.

2015-11-03-014940Typical flight sequence for the CZ-3B/G2 sees the launch pitching over 10 seconds after liftoff from the Xichang Satellite Launch Centre. Boosters shutdown 2 minutes and 7 seconds after liftoff, separation from the first stage one second latter. First stage shutdown takes place at 1 minutes 25 seconds into the flight.

Separation between the first and second stage takes place at 1 minute 26 seconds, following fairing separation at T+3 minutes 35 seconds. Stage 2 main engine shutdown occurs 326 seconds into the flight, following by the shutdown of the vernier engines 15 seconds later.

Separation between the second and the third stage and the ignition of the third stage takes place one second after the shutdown of the vernier engines of the second stage. The first burn of the third stage will last for 4 minutes and 44 seconds.

After the end of the first burn of the third stage follows a coast phase that ends at T+20 minutes and 58 seconds with the third stage initiating its second burn. This will have a 179 seconds duration. After the end of the second burn of the third stage, the launcher initiates a 20 second velocity adjustment maneuver. Spacecraft separation usually takes place at T+25 minutes 38 seconds after launch.

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

XSLC is mainly used to launch broadcast satellites, communication satellites and meteorological satellites. The launch center headquarters being located in Xichang City, 65 km from the launch site. Xichang has a subtropical climate and the annual average temperature is 14.2ºC. The ground wind in the area is usually very gentle in all the four seasons.

2015-07-25-130117XSLC provides full domestic and international telephone, fax and internet services for the user via a cable and satellite communication network. XSLC includes the Headquarters (located in Xichang City), Launch Center (technical center and two launch complexes), Communication Center, Mission Command and Control Center (MCCC), tracking stations and other logistic support systems.

XSLC includes the LV Processing Building (BL), SC Processing Buildings (BS2 and BS3), Launch Complex No.2 (LC2) and Launch Complex No.3 (LC3). The ground support systems are comprised of the Mission Command and Control Center (MCCC), Tracking Stations and Communication Center.

The Technical Center consists of the LV Processing Building (BL), SC Processing Buildings (BS2 and BS3), Solid Propellant Motor (SPM) Testing and Processing Buildings (BM), X-ray Building (BMX), Propellant Storage Rooms (BM1 and BM2), Power Station, Truck-Barn, etc. The LV and SC will be processed, tested, checked, assembled and stored in the technical center.

The first launch from Xichang took place at 12:25UTC on January 29, 1984 when the Chang Zheng-3 (Y-1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit.

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