The second part of the Chinese space docking trilogy has premiered with the successful launch of the unmanned Shenzhou-8 at 21:58 UTC on Monday. The launch took place from 921 / SLS-1 Launch Pad at the Southern Launch Site of the Jiuquan Satellite Launch Center using the Long March-2F (Y8) launch vehicle.
The mission of Shenzhou-8 is scheduled for a mission of three weeks, during which time it is expected to dock twice with unmanned space module TianGong-1 that was launched on September 29.
This module is part of China’s space station and is an experimental space laboratory that will be mainly used to carry out the rendezvous and docking test, as well as the mastering of the technologies related to rendezvous and docking and accumulate the experience for the construction, management and operation of a space station.
Providing everything continues to go according to plan, and after all the systems are verified on both vehicles, the first docking is expected to take place on November 3.
TianGong-1 and Shenzhou-8 will stay docked for 12 days, after that undocking will occur and a second docking manoeuvre will take place. After another period of docking, the unmanned spacecraft will be commanded via autonomous flight to return to Earth.
Preparing for launch:
Large-scale testing of the Shenzhou-8 has begun at the end of March 2011 after functional and mechanical tests. Launch was originally schedule to take place at the end of October, but the SJ-11 ShiJian 11-04 loss – due to a CZ-2C Chang Zheng-2C second stage failure on August 18 – led to a delay to the docking mission launch.
Eventually, the capsule arrived at the Jiuquan Satellite Launch Center on August 26 and the CZ-2F Chang Zheng-2F launch vehicle for the Shenzhou-8 launch arrived at Jiuquan on September 24, just five days before the TG-1 TianGong-1 launch.
At the end of September the state news media said that “the unmanned Shenzhou-8, part of China’s first spacecraft rendezvous and docking mission, would be launched in early November.”
Citing Niu Hongguang, deputy commander-in-chief of the program, Xinhua then said that “the launch was not been affected by the postponed lift-off of the Tiangong-1 space module.” With the successful launch of TianGong-1 on September 29, rumours started to surface about a possible November 1 launch date for Shenzhou-8.
After the launch of TianGong-1, the Beijing Special Engineering Design and Research Institute, the main designer of the launch system used at the Jiuquan Satellite Launch Center, renovated and upgraded the equipment at the launch site.
The new equipment and technologies dramatically increased the reliability of satellite launches and greatly shortened the launch time preparation. The system for voice transmitting between the spacecraft and the ground in this mission is newly designed and is more advanced than that used in Shenzhou-7 – via the replacement of a wireless signal transmission system using optical fibber for improved the quality of voice and image transmission.
On October, 26 the Chang Zheng-2F launch vehicle with the Shenzhou-8 capsule was transported to the launch platform and on October 29 specialists and technicians conducted a simulated launch of Shenzhou-8 with all the equipments and systems working normally. The exercise was under the coordination of the Beijing Aerospace Flight Control Center, the command center for Chinese space program.
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During the exercise, the compatibility and connectivity of different systems involved in the mission were tested, and results indicated that the systems were all ready for the launch.
Experiments on Shenzhou-8:
There are several experiments on board Shenzhou-8 in a total of 17 research programs, including the Project SIMBOX, a cooperation project between China and Germany.
Among the research programs, 10 will be conducted by China, six by Germany and one is a joint research program. The cooperation agreement was signed in May, 2008 – and this is the first time China manned space program will carry out an international cooperation in the field of space life sciences.
The leadership and organization of the German side is up to the DLR (German Aerospace Center) and the technical requirements are implemented by Astrium.
SIMBOX is the first non-Chinese experiment equipment aboard Shenzhou, the showpiece of China’s manned space flight. On board Shenzhou-8 are 17 German and Chinese experiments in the field of biomedicine participate, including plants, animals and human cells of the immune and nervous system that will be exposed to the environment of space for a period of three weeks. The effects of spaceflight on the samples will then be examined after the end of the mission.
DLR’s Space Agency has funded the program and is the project leader of the National Space Program SIMBOX. The science plant consists of a centrifuge and oven, including over 100 experimental chambers and the six experiments of German research institutions. Industrial prime contractor for the development and construction of the experimental apparatus is Astrium.
The overall responsibility for the mission is on the Chinese side at CMSEO. The Chinese Organization of Space Science (Gessa) is responsible for the coordination and technical support within the scientific payload of the Chinese manned space program.
In 2008, the first draft of the experiment was reviewed for technical feasibility (available volume, materials, etc.) and on January 2009 the first prototype was handed over to the Working Group for its first tests. The materials used on the experiment were tested for biocompatibility. In February the first prototype test was carried out successfully and the experiment went on to further development with more biocompatibility tests starting in March.
In 2010, the hardware was developed at Astrium and in December 2010, the final flight hardware was delivered to the SIMBOX team.
In April 2011, a complete test sequence under starting conditions was carried out successfully in Beijing. In October the German team travelled to the Jiuquan Satellite Launch Center to prepare the experiment for launch. In the meantime in Beijing, all the partners as the German Aerospace Center and the Chinese organization for manned space flight simulated the complete sequence of the science mission. The result: “Green light” for a launch on 30 October 2011.
Other items on Shenzhou-8 include the “dreams” of more than 40,000 people that are stored as text and video on a micro chip. The 42,891 “dreams” were selected from a pool of 12 million in line with the criteria of “positive and passionate”, said Feng Chunping, president of China Space News, the activity sponsor.
Proposed by Chinese citizens, university students and children from orphanages, most dreams expressed longing for space, hopes for a stronger nation, and a greener and better society.
Some are bold hopes, like the one one person wrote saying that China’s future space station should develop a function to collect space debris. Others are practical. Zhou Maocuo and Jia Linlin from an orphanage in Beijing said their dream is to have a stable home.
Prior to the launch of Shenzhou-8 spacecraft the TianGong-1 orbit was adjusted to a 343 km altitude near circular orbit. This phase adjustment was needed to achieve the right height and the right place for docking. At 1134UTC on October 30, the unmanned module completed a 180 degree turn to align for the upcoming Shenzhou-8.
The first phase of the docking manoeuvre will take place at a distance of 52 km from TianGong-1 with the monitoring center system analysing the parameters of Shenzhou-8. At this distance both spacecrafts will be able to read the relative position and velocity of each other.
The docking manoeuvres will start when the two vehicles are 20 km apart. In the second stage of the process there will be three parking points at 5 km, 400 m, 140 m. In the parking points, their relative positions have to remain according to plan, so the ground staff can determine their status and decide whether to continue or revoke the docking. Shenzhou-8 will act as the “active vehicle”, while the TianGong-1 will act “passive vehicle”.
Sensors on both will start given information about the velocity and distance. With the distance getting closer the data sent to the ground control data will be more accurate, so that ground-based monitoring and control personnel can carefully monitor the operations.
The relative velocity of the two vehicles will slowdown to 0.2 meters per second relative speed and the lateral deviation of no more than 18 cm. Final command for docking will take place at 1,000 meters distance.
After soft docking, it will take 15 minutes to tighten the locks and then the control center will adjust the cabin environment, such as temperature, pressure, in accordance with manned conditions for future manned flight.
The two spacecrafts will remain docked for 12 days and after that they will separate to try a new docking at an yet undetermined date. After another (shorter) period of docking operations, Shenzhou-8 will return to earth within a day.
For the docking Shenzhou-8 and TianGong-1 are equipped with a docking mechanism similar to the Russian APAS-89/95. The mechanism consists of a docking port, radio beacons and transponders, communication antenna, UHF radar, laser rangefinder, and a electro-optical tracking system. The diameter of the hatch is 0.8 meters.
The TianGong-1 spacecraft is expected to stay in orbit for two years and rendezvous and dock with three different spaceships. Beyond the Shenzhou-8, Shenzhou-9 and Shenzhou-10 will make similar missions and at least one of the two is to be manned.
The taikonauts will stay a maximum of two weeks on board. Before taikonauts climb on board TianGong-1, the conditions inside its experimental module will be adjusted to ensure they can live in an environment that contains enough oxygen, moisture and heat to be safe.
TianGong-1 will be placed on a near circular 350 km orbit after two orbiting manoeuvres and prior to the Shenzhou-8 launch this orbit will be reduced to 343 km. Two days after launch, the docking between the two vehicles will take place.
In the future the TianGong will be upgraded to a cargo vehicle to service the Mir-class station with its core module due to launch in 2020, but before that China plans to launch the TG-2 TianGong-2 in 2014 (to develop the necessary technologies for water and oxygen regeneration necessary for short-term stay in orbit and to carry out some scientific experiments) and TG-3 TianGong-3 in 2015/2016.
TG-3 will probably be equipped with two docking ports, this way allowing a permanent residency of the module. TG-3 mission is going to be the development of the technologies necessary for medium- to long-term orbit stay and to carry out more sophisticated scientific researches and experiments.
The Shenzhou-8 spacecraft:
Considerable modifications have been made to the previous versions of the Shenzhou vehicle to prepare Shenzhou-8 for the docking mission. According to Chinese media, more than 600 modifications have been made, while nearly devices account for about 15 percent of the total. These modifications had the objective to arm the vehicle with automatic and manual rendezvous and docking capabilities, as well as to enhance the performance, safety and reliability.
The Shenzhou spacecraft was designed and developed by many of organisations participating on the Chinese human space program. The primary contractor was the China Academy of Space Technology (CAST) and was responsible for the overall concept of the vehicle.
Qi Faren was appointed the chief designer of the Shenzhou design team in 1992, being later succeeded in 2004 by Zhang Bai-Nan. Qi Faren was also the chief designer of DongFanf Hong, China first satellite.
CAST was responsible for the design of the Orbital and Re-entry Module, and the Shanghai Academy of Spaceflight Technology (SAST) was responsible the design of Service Module, as well as the electrical power system, propulsion system, and telemetry, tracking and communications systems. The development of onboard application payloads was made by the China Academy of Science.
The development of the environment control and life support system was tasked to the Institute of Space Medicine Engineering and the Academy of Aerospace Solid Propulsion Technology was responsible for the launch escape system.
Shenzhou was based on the Russian Soyuz-TM spacecraft and can carry up to three astronauts inside its Re-Entry Module. This module provides a fully pressurised and habitable living space in all phases of the mission, but the taikonautas can also use the Orbital Module that provides additional habitable space for conducting scientific experiments.
This module is equipped with navigation, communications, flight control, thermal control, batteries, oxygen tanks, and propulsions systems.
The Orbital Module has a length of 2.80 meters, a mass of 1,500 kg and a diameter of 2.25 meters. Is equipped with two solar panels for power generation (0.5 W) and each panel is 2.0 meters by 3.4 meters. This module is equipped with a propulsion system comprised of 16 small thrusters distributed by four groups.
The Re-entry Module has a length of 2.50 meters, a mass of 3,240 kg and a diameter of 2.52 meters. This module is equipped with a heat shield with a mass of 450 kg.
The Service Module has a length of 3.05 meters, a mass of 3,000 kg and a maximum diameter of 2.80 meters. Is equipped with two solar panels for power generation (1.5 W) and each panel is 2.0 meters by 7.0 meters.
This module is equipped with the Shenzhou main propulsion system that consists of four high-thrust main engines and 24 smaller-thrust control engines, as well as four 230-litre propellant tanks containing a total of 1,000kg N2O4/MMH liquid propellant.
The four main engines (2.5kN) are located at the base of the spacecraft’s Service Module. The spacecraft also has eight (in four pairs) 150N pitch and yaw thrust vectors, eight (in four pairs) 5N pitch and yaw thrust vectors and eight (in four pairs) 5N roll / translation thrust vectors.
Like on Soyuz manned space craft, on re-entry, the orbital and service modules are separated and discarded, and then the re-entry module makes a ballistic descent through the atmosphere. Primary landing target is located in Inner Mongolia.
The launch vehicle:
Shenzhou-8 was launched by the CZ-2F Chang Zheng-2F, possibly the CZ-2F/G variant of the launch vehicle usually used for the previous manned Shenzhou program.
This launch vehicle, developed by the China Academy of Launch Vehicle Technology under the China Aerospace Science and Technology Corporation, is different from the original “Shenjian” (Devine Arrow) version that was developed from the CZ-2E Chang Zheng-2E launch vehicle, which in turn was based on the proven flight technology of the CZ-2C Chang Zheng-2C launch vehicle.
Conceptual design of the CZ-2E launch vehicle began in 1986, and the vehicle was launched on the world launch services market following a successful test flight in July 1990.
To meet the requirements of the rendezvous and docking mission, the Chang Zheng-2F suffered nearly 170 technical modifications and used five newly developed technologies. After it was transported to the Jiuquan launch center on September it was submitted to different technical tests in preparation for launch.
This vehicle is going to be used for the launch of the TianGong-1 module and the future cargo vehicles until a more powerful launch vehicle is available.
A substantial difference on this rocket with the previous that was used for the FG-1 launch is the use of the launch escape tower and usual fairing, similar to the Russian model used on the manned program.
Other characteristic of this version is the fact that is capable of more precise orbit insertion accuracy. This is possible with the introduction of improved navigation systems and complex guidance system features real-time input to the rocket to orbit parameters, and use GPS data outside the measurement error correction parameters so as to achieve double redundancy. Also, more propellant is loaded on the boosters, thus increasing the firing time.
Like the CZ-2F, the CZ-2F/G Chang Zheng-2F/G is a two stage launch vehicle that uses four strap-on boosters during the first stage phase. Overall length of the CZ-2F/G is 58.0 meters (including the launch escape system) with a 3.35 meter core stage and a maximum diameter of 8.45 meters. At launch it has a 497,000 kg mass, being capable of launching 8,600 kg cargos into a low Earth orbit.
For the CZ-2F launch vehicle, the LB-40 strap-on boosters have a length of 15.326 meters, diameter of 2.25 meters, a gross mass of 40,750 kg and an empty mass of 3,000 kg. Each booster is equipped with a fixed nozzle YF-20B engine that consumes UDMH/N2O4 developing 740.4 kN of sea lever thrust. Burn time is 127.26 seconds.
The L-180 first stage has a length of 28.465 meters, diameter of 3.35 meters, a gross mass of 198,830 kg and an empty mass of 12,550 kg. It is equipped with a YF-21B engine pack that consists of four YF-20B engines that consumes UDMH/N2O4 developing 2,961.6 kN of sea lever thrust. Its burning time is 160.00 seconds.
The L-90 second stage has a length of 14.223 meters, diameter of 3.35 meters, a gross mass of 91,414 kg and an empty mass of 4,955 kg. It is equipped with a YF-24B engine pack that consists of one fixed nozzle YF-22B main motor with a swivelling vernier four YF-23B engines.
The engines consume UDMH/N2O4 developing 738.4 kN (main engine) and 47.07 kN (vernier) of vacuum thrust. Total burn time is 414.68 seconds (301.18 seconds burn time for the main engine).
This launch was the 149th Chinese orbital launch, the 149th launch of the Chang Zheng launch vehicle family, the 50th successful orbital launch from the Jiuquan Satellite launch Center, and the 12th successful orbital launch from China this year.
The launch site:
The Jiuquan Satellite Launch Center, also known as the Shuang Cheng Tze launch center, was the first Chinese satellite launch center.
The site includes a Technical Centre, two Launch Complexes, Mission Command and Control Centre, Launch Control Centre, propellant fuelling systems, tracking and communication systems, gas supply systems, weather forecast systems, and logistic support systems. Jiuquan was originally used to launch scientific and recoverable satellites into medium or low earth orbits at high inclinations.
The manned program uses the South Launch Site Pad 921. This was built in the late 1990s and later added with the 603 Launch Platform for unmanned satellite launches. Apart of the launch pads, the launch complex has a technical centre where take place the preparations of the launch vehicle and spacecraft. The technical center is composed of the launch vehicle processing and vertical assembly building, spacecraft processing buildings, solid rocket motor processing building, buildings for liquid-propellant storage and processing and the launch control center.
For the TianGong-1 launch the launch site was equipped with an updated computer center, command monitoring systems and increased ability to adapt to changes in mission conditions, as well as the resources to handle both the launch and command duties.
An integrated simulation training system for space launching has also been developed for the docking mission. Engineers also conducted a two-month comprehensive technical check on equipment at the launch site from March to May.
The safety and reliability of all the instruments have been significantly improved. Orbital launches from Jiuquan are supervised from the Mission Command and Control Centre that is located in the Dongfeng Space City, 60 km southwest of the satellite launch center.
The umbilical tower is 75 meter-high steel structure that is designed to service the launch vehicle and spacecraft with electricity, gases and fluids, also providing facilities for pre-launch checkouts and crew entrance / emergency exit. The tower is equipped with a loading crane, a cargo elevator, and an explosion-proof elevator for the mission crew.
In time of emergency, a canvas slide escaping system is available for taikonauts to exit the launch pad. Power supply and other support equipment are located inside an underground room underneath the umbilical tower.
The umbilical tower comprises a fixed structure and a pair of six-floor rotating platforms. Once the launch vehicle arrives at the launch pad, the rotating platforms are swung around the vehicle to allow the fuelling and final checkout procedures.
The umbilical tower also contains an environmentally controlled and protected area for taikonauts to enter the spacecraft. Rotating platforms are swung open one hour prior to launch. Four swing arms provide connections for electricity, gases and fluids to the launch vehicle, and are retracted few minutes before launch.
The launch vehicle is carried on a mobile launch platform from the vehicle assembly building to the launch pad. The mobile launch platform moves on a 20 meter wide rail track and carries the launch vehicle vertical stack on a maximum velocity of 25 meters/min.
The platform has a length of 24.4 meters, width of 21.7 meters, and 8.34 meters height, weighing 750,000 kg. It takes 60 minutes to complete the 1,500 meter journey to the launch pad.
The first orbital launch took place on April 24, 1970 when the CZ-1 Chang Zheng-1 (CZ1-1) rocket launched the first Chinese satellite, the Dong Fang Hong-1 (04382 1970-034A).
(Images via: ChinaNews.cn, CCTV, Xinhua, various Chinese media – all linked on the live thread. 3D rendering by Junior Miranda).