Like the Soyuz, it consisted of a forward orbital module, a re-entry capsule, and an aft service module. Unlike the Soyuz, the orbital module was equipped with its own propulsion, solar power, and control systems, allowing autonomous flight. Shenzhou would be used to develop manned spaceflight techniques (extravehicular activity, rendezvous and docking) and later serve as a ferry to Chinese space stations. Like Soyuz, derivatives could be used as a lunar orbital and landing spacecraft.
The Shenzhou project received limited funding, resulting in a protracted development program. Work began in 1992, with annual unmanned flights finally beginning in the winter of 1999/2000. The development of Shenzhou's thirteen sub-systems took the effort of thousands of engineers and technicians in 300 organizations in China. The first manned flight came in the autumn of 2003.
The Development of the Shenzhou
The Chinese perfected ballistic re-entry vehicle techniques very early in their space program. The abortive Shuguang-1 project to launch a Chinese man into space was cancelled for political reasons in 1972. The FSW unmanned reconnaissance satellite began a series of successful recoveries in 1976.
Nevertheless low-key development work on manned spaceflight continued. In 1978 photos were released showing Chinese astronauts in impressive space suits being trained in altitude chambers and at the controls of an elaborate space shuttle-like cockpit. A fleet of ships for recovery of capsules at sea was built. In May 1980, a ballistic missile re-entry vehicle was recovered from the South Pacific after a sub-orbital launch. But in December 1980 Wang Zhuanshan, the Secretary General of the New China Space Research Society and Chief Engineer of the Space Centre of the Chinese Academy of Sciences, announced that Chinese manned flight was being postponed because of its cost.
After a ten-year hiatus, China began preliminary work on manned spaceflight again in July 1985. The decision came against a background of vigorous international space activity. The United States had its Strategic Defense Initiative and Space Station Freedom. The Soviet Union had its Buran shuttle system, Mir and Mir-2 space stations, and its own star wars program. Europe was developing the Hermes manned spaceplane, and Japan the Hope winged spacecraft. Even India and China were taking on ambitious space projects. It seemed China would have to take action to remain a world power.
Ren Xin Min, the leading Chinese rocket expert of the time, believed that China should make a space station its national goal. This would develop all aspects of space technology, including modern launch vehicle capabilities. In early spring 1986, members of a standing committee of the Chinese Academy of Sciences (Wang Da Hang, Wang Ganchang, Yang Jiachi, Chen Fangyun) proposed a family of seven Project 863 plans to accelerate Chinese technical development. These numbered plans covered biology, astronautics, information technology, military technology, automation, energy, and materials science. Astronautics plan 863-2 included a section 863-204 space transportation system, which would service a section 863-205 space station. It was estimated that two years would be needed for concept studies.
An expert group was established for the 863-204 shuttle, and issued a tender call to Chinese industry within two months of starting work. Sixty days later 11 alternate proposals were delivered, of which six were selected for feasibility studies. These were delivered in June 1988. The proposals ran the gamut from highly advanced two-stage-to-orbit reusable space shuttles to modest ballistic capsule designs. The latter proposal was from Department 508 of the Fifth Academy (now the Chinese Academy of Space Technology, CAST). They proposed a manned space capsule, recovered by parachute, similar to the Soviet Soyuz spacecraft. Department 508 argued that the Chinese industrial and technical base was not realistically up to developing winged reusable spacecraft, and that this would take a very long time and would not be flying until well into the 21st Century. A capsule should be developed in any case as a lifeboat for the space station, and would provide a Chinese manned space capability by the year 2000 - and until a winged spacecraft was available.
17 experts met in Harbin during 20-31 July, 1988, to make final assessments and recommend a course of action. It finally concluded that development of a winged reusable space shuttle system was acceptable as a national long-term goal to guide technology development. But China did not have the aerodynamic or rocket technology to develop a hypersonic aircraft with reusable rocket engines. The two designs that were considered technically achievable ranked very close in the expert's rating system - the Tian Jao 1 manned spaceplane with a score of 83.69, and the Department 508 manned space capsule with a score of 84.00.
The space capsule advocates pointed out that the development cost would be relatively modest, since China already had the boosters to launch it, and had proven ballistic capsule re-entry and recovery technology. They repeated that such a capsule would in any case be needed as a lifeboat for a Chinese station, and that the capsule would be safer and more reliable than a spaceplane design. The Chinese aeronautical industry in fact did not have the existing technical base to build a true supersonic cruise aircraft, let alone a hypersonic aircraft.
The spaceplane advocates pointed out that the space capsule approach did little to advance the Project 863 objectives of leapfrogging Chinese technology to a world-class 21st Century level. Indeed China might even invite international contempt by flying a 1960's-type design.
The final 863-204 Expert Commission report in July 1989 advocated building the manned capsule, with a first flight date of 2000. This would satisfy the leadership's desire for an early Chinese manned space capability, and establish the essential earthly infrastructure and spacecraft subsystems technology for more advanced systems. However in parallel development of technology for a two-stage-two-orbit horizontal takeoff and landing reusable space shuttle would be pursued, with a first flight date of 2015.
The report failed to impress the government. Chinese leader Deng Xiaoping rejected both plans, saying that neither could be flying in his lifetime. The Chinese space establishment went back to the drawing board.
Deng stepped down as Chairman of the Central Military Commission in 1989. In his absence the Chinese military decided it could safely lend its critical support to a manned space program. In January 1991 the Air Ministry established a manned space program office with Liu Jiyuan as its head. After that things moved quickly. On 15 March 1991 Project 863 leader Ren Xin Min was called to a meeting with Premier Li Peng. Ren Xin Min presented a more modest manned space development plan, using the existing Long March CZ-2E booster to launch a manned ballistic capsule into orbit. There was no longer any mention of development of hypersonic reusable winged space shuttles. Li Peng was especially gratified to see the funds previously spent on the Long March rocket being put to good use, and work on the project began in earnest.
During the course of 1991 three proposals were made for a spacecraft designed within the 8-metric ton payload capability of the CZ-2E:
Ren Xin Min brought 10% scale models of the proposed designs to a final evaluation board on 8 January 1992. Perhaps unsurprisingly, the decision was taken to proceed with Ren Xin Min's three-module/autonomous orbital module concept. On 1 August 1992 Li Peng attended the final meeting of the board and where the following program plan was presented:
The final plan was approved on 21 September 1992, and Project 921 to create a Chinese manned space capability began in earnest. Wang Yongzhi was made responsible for overall project management. At CAST, Qi Faren was responsible for the spacecraft itself. The design of the service module was assigned to SAST under Qi Faren's direction. CALT was to design the CZ-2F man-rated modification of the CZ-2F.
Wang Yongzhi was responsible for much more than just the development of a new spacecraft and modified booster. Implementing the program required modernization of the Chinese technology base and infrastructure, and this was in fact its main purpose. A complete new technology vertical assembly building, mobile launch vehicle transporter, and launch pads had to be built in Jiuquan (Xu Kejun chief designer). An integrated approach to recovery of the manned spacecraft, including land, sea, and air vehicles, was developed by Zhao Jun for use in the primary landing zones at Siziwangqi and Alashanyouqi in Inner Mongolia. A new unified S-band spacecraft tracking and control network was developed under the leadership of Yu Zhijian. This included new tracking sites outside of Chinese territory, a new tracking ship, the upgrade of existing tracking stations and ships, and a new flight control centre in the north-east suburbs of Beijing. Astronaut training and crew technology was non-existent in China, and this capacity was developed by Shu Shuangning at the Aerospace Medical Engineering Research Institute. Of the total $2.3 billion program cost through the first manned flight, $ 1.0 billion went to infrastructure.
A rearguard action was fought to try to include new booster development. In October 1993 the Shanghai Astronautics Bureau proposed development of six large carrier rockets and eight new spacecraft, including a manned one, for inclusion in the Eight and Ninth Five Year Economic Plans. But this was not approved. Shanghai's program for development of a new generation of liquid oxygen / kerosene rockets was shelved, and those resources were instead put into the development of large solid motors for military use.
Russian assistance to the program began as early as May 1991, when Russian lecturers briefed the Chinese engineers on the capabilities and potential of their Soyuz spacecraft. This was followed by two-year fellowships for 20 young Chinese engineers in Russia during 1992-1994. In September 1994 Chinese President Jiang Zemin visited the Russian Flight Control Centre in Kaliningrad and noted that there were broad prospects for co-operation between the two countries in space. In March 1995 a deal was signed to transfer manned spacecraft technology to China. Included in the agreement were training of cosmonauts, provision of Soyuz spacecraft capsules and life support systems, androgynous docking systems, and space suits. In 1996 two Chinese astronauts, Wu Jie and Li Qinglong, began training at the Yuri Gagarin Cosmonaut Training Centre in Russia. After graduation these men returned to China and began selection of a cadre of 12 Chinese astronauts.
Design was completed in August 1995 and construction began of four ground-test prototypes of the spacecraft - two structural test versions, one thermal test model, and an electrical test vehicle. Many difficulties were encountered. The Chinese had been quoted what they considered exorbitant prices to acquire key Russian technology, and in those cases they had to develop their own solutions. Even the decision to use an enlarged aerodynamic copy of the Soyuz capsule did not mean extensive development testing was not required. Characterizing the heat shield performance of the capsule, particularly around the critical porthole areas, required testing at TsNIIMASH facilities in Russia in the summers of 1995, 1998, and 1999. Welding and sealing of the re-entry vehicles frame encountered numerous difficulties, as did SAST's qualification testing of the propulsion systems and service module. Tests of the launch escape system in April and August 1995 were failures, and first succeeded only in April 1997. But the successful design was 900 kg overweight, and a weight reduction program was necessary. In May 1998 a mock-up of the CZ-2F launch vehicle and Shenzhou spacecraft were rolled out for facilities tests. The first completely successful test of a production-weight launch escape system was finally accomplished on 18 October 1998.
In June 1999, coincident with public announcements that the first unmanned test of the spacecraft would be made in October, photographs of the CZ-2F launcher with a Soyuz-style shroud appeared mysteriously on the Internet. They were said to have been scanned from a brochure of an Inner-Mongolian construction company that had worked on the launch facilities. The shroud was consistent in shape and size with that portrayed in the 1992 drawing of the cancelled Shanghai lox/kerosene launch vehicle. It had many similarities with Russian Soyuz shrouds, but comparison with photos of Soyuz shrouds to the same scale showed it to be much larger.
In July, completion of the fourth Yuan Wang tracking ship was announced, ready for deployment with its three sister ships in October. Then in early August rumors spread in the Far Eastern press of a propellant explosion in Jiuquan that involved manned spaceflight hardware. This was denied by Chinese officials a few days later, but suddenly the predicted date for the first unmanned launch of the Shenzhou changed from October to 'sometime in 1999'. In fact the program was encountering serious delays, and the only way to make the deadline of the first unmanned launch by the end of 1999 was to take the ground electrical test model of the spacecraft and fly that in space. So the first Shenzhou would have functioning service module and re-entry vehicle, but the orbital module would be a nearly inert mock-up.
Meanwhile Russo-Chinese co-operation continued. In August 1999 at Star City, in a large room on the second floor of the Hydrolab, 15-20 Chinese staff continued work. Their activities seemed to be associated with flying experiments on the Russian zero-G aircraft and not EVA training. The Russian Air Force personnel that run the Hydrolab were also responsible for the aircraft
The experiments being flown originated from Mr. Qin Yi of the Oriental Scientific Instruments I&E; Group. The project was administered at Star City by Mr. Yuri L. Bogoroditsky, Chief of Foreign Economic Development, Gagarin Cosmonaut Training Centre.
The possibility of an imminent launch was signaled by the departure of the four Yuan Wang tracking ships from their home port. Three of the ships were stationed in the southern hemisphere near latitude 35 S: one off the coast of Namibia, one off the south-west coast of Australia, and one in the mid-Pacific on the International Dateline. The fourth ship was off the southern coast of Japan (for tracking the end of the launch phase and recovery of the capsule in the case of an abort). Land-based tracking sites were located at the Jiuquan launch site, West China, South Africa, and Pakistan.
The unmanned first test flight of a prototype of the Chinese Project 921-1 spacecraft took place 49 days after the planned date of October 1, 1999. Chinese President Jiang Zemin personally named the spacecraft 'Shenzhou' (variously translated as 'Vessel of the Gods', 'Divine Craft', 'Divine Mechanism'; but also a play on a name for China). Film released of the flight verified the existence of the new man-rated CZ-2F launch vehicle, its vertical assembly building, and showed the true configuration of the spacecraft for the first time.
Despite rumors at several points during the following year, the next unmanned test did not occur until January 2001. The second flight carried a monkey, a dog and a rabbit in a test of the spaceship's life support systems. Shenzhou 2 demonstrated multiple restarts of its propulsion system and made three orbit-raising maneuvers during its flight. After seven days in orbit, the descent module and service modules separated from the forward orbital module. After retrofire by the service module, the descent module separated and landed in Inner Mongolia. Lack of post-recovery photographs led to speculation that the recovery may have been unsuccessful. Again the orbital module continued in controlled orbital flight, conducting zero-gravity experiments.
The second Shenzhou saved 100 kg in mass using a new wire harness mounting technique. Training of the Chinese astronauts was reported to be proceeding with commissioning of a unique form of zero gravity trainer. The consisted of a chamber, 15 m in diameter and 21 m high, installed in a vertical wind tunnel. Wind speeds of up to 150 km/hour levitated the astronaut trainees.
Shenzhou 3 was launched in March 2002 and the program pace began to pick up. This was the first launch with a live launch escape system. Shenzhou 4, launched in December 2002, was the final dress rehearsal for a manned launch. Even the crew for the first manned flight were placed in the capsule, and went through all procedures up to a certain point in the countdown. They then left the capsule, and the mission proceeded unmanned. All systems checked out perfectly, and China was poised for its first attempt at a manned flight in October 2003. And what was the cost of all this? In 2003 the president of the company that builds the Shenzhou capsules, Zhang Qingwei, told a Chinese newspaper that Beijing had spent about $2.3 billion on its manned space program in recent years.
Description of Shenzhou
The spacecraft strongly resembled the Russian Soyuz spacecraft, and like the Soyuz, consisted of a forward orbital module, a re-entry capsule, and an aft service module. The configuration was very much like the original Soyuz A design of 1962 (itself, in turn, alleged to be very similar to the US General Electric Apollo proposal of the same period). Horizon sensors were located at the middle bottom of the service module, as on the Soyuz spacecraft. Two pairs of solar panels on the service and orbital modules had a total area of 36.72 square meters, with a maximum power output of 3.5 kW, and an average electrical power of over 1.45 kW (nearly three times that of Soyuz and about that of the original Mir base module). Unlike the Soyuz, the orbital module was equipped with its own propulsion, solar power, and control systems, allowing autonomous flight. The orbital modules could be left behind as autonomous space laboratories. A stretched version would provide an 8-metric ton space laboratory for use in Project 921 Phase 2. In Phase 3 of Project 921 the modules could be left attached to the 20-metric ton space station as additional station modules. The basic spacecraft was capable of manned missions of up to 20 days, with autonomous missions of the orbital module of up to a year. Within the cabin of the spacecraft, maximum noise level was 125 dB during launch and re-entry, and 75 dB during in-orbit operation. Maximum G forces were 4 G's during normal lifting re-entry, 11G's during an uncontrolled ballistic re-entry, and 17 G's in an emergency abort.
Detailed descriptions of each of Shenzhou's three modules are provided below.
The dimensions of the Shenzhou's modules have been officially announced. An estimate of the mass breakdown of the Shenzhou, in comparison with the Soyuz, would be as follows:
Soyuz Shenzhou Complete Spacecraft: Total Mass-kg 7,250 7,840 Length-m 7.48 9.25 Diameter-m 2.72 2.80 Span-m 10.06 17.00 Service Module Total Mass- kg 2,950 3,000 -of which, propellant,kg 900 1,000 Length-m 2.60 2.94 Diameter-m 2.17 2.50 Diameter base-m 2.72 2.80 Re-entry Vehicle Total Mass-kg 3,000 3,240 Length-m 1.90 2.06 Diameter-m 2.17 2.52 Orbital Module Total Mass-kg 1,300 1,500 Length-m 2.98 2.80 Diameter-m 2.26 2.25
Launch Escape System
The escape tower would fire to pull the Shenzhou capsule and orbital module away from the booster in the event of a major booster malfunction from 15 minutes before launch to the point of payload fairing jettison at T+160 seconds. The system consisted of the escape tower, the upper portion of the payload fairing, and the orbital and descent modules. This complete assembly had a total mass of 11,260 kg, and was 15.1 m long and 3.8 m in diameter. The system was designed for a reliability of 0.995. The tower itself was 8.35 m long and equipped with six solid propellant motors. These consisted of four axial vernier motors, a low altitude separation motor with eight nozzles, and a medium altitude escape motor with four nozzles. In the upper shroud were four motors used for escape at high altitude, and two motors used for shroud separation. Four grid-like aerodynamic flaps on the upper shroud stabilized the assembly during an abort.
When the fault monitoring management system on CZ-2F booster sensed an emergency situation, it automatically activated the launch escape system. Ground controllers could also activate the system by command if deemed necessary. On manned flights the astronauts could manually activate the system from within the capsule. There were three escape modes:
From launch to 39 km attitude, at T+120 seconds: The upper shroud, together with the orbital module and re-entry vehicle of the spacecraft, would be pulled away from the lower shroud, service module, and failing booster by the escape tower. The low- or medium-altitude escape motors of the escape tower would be used as appropriate to the flight regime.
From T+120 seconds to T+160 seconds, after separation of the escape tower, the high altitude escape mode would be used. This used solid propellant motors in the upper shroud to pull the orbital module and re-entry vehicle away from the booster.
After T+160 seconds, and jettison of the spacecraft shroud, an abort would consist simply of booster shutdown, separation of the re-entry vehicle, and an emergency re-entry leading to a recovery either on Chinese territory or off the southern coast of Japan.
Many, many thanks to Chen Lan for providing original Chinese-language source material for this project, and to WXJ for the translation.
Crew Size: 3. Habitable Volume: 14.00 m3. RCS Coarse No x Thrust: 16 x 150 N. RCS Fine No x Thrust: 32 x 5 N. Spacecraft delta v: 380 m/s (1,240 ft/sec). Electric System: 3.50 kWh. Electric System: 1.45 average kW.
Shenzhou consists of the following modules:
It was the same form as that of Soyuz, but longer, fatter, and the flared base was less pronounced. As on Soyuz, the bottom portion of the module was used as an external radiator surface for the spacecraft's thermal regulation system. Two solar panels, with a total span of over 17 m, deployed from the sides of the service module. Unlike those of Soyuz, these could be rotated to obtain maximum solar insolation regardless of spacecraft attitude. Roll and translation attitude control engines were arranged at the forward end of the service module. Within the flared base of the module a unique arrangement of thrusters (firing from the outer rim of the flared base toward the central axis of the spacecraft) controlled pitch and y
Within the service module there were several ellipsoid-shaped compartments that housed avionics, electrical, and environmental control system equipment. Also located in the service module were the nitrogen and oxygen gases for the environmental control system. These were stored in steel alloy spheres at a pressure of 21 Mpa. To reject the 1 kW of heat generated by Shenzhou's crew and internal systems, a cooling system used heat pipes to conduct heat from internal systems to the external radiator.
Primary electrical was provided by the two solar panels, which had a total area of 24.48 square meters. Each panel was in four sections, which were folded during launch. The two panels on the orbital module were of two sections each, and provided an additional 12.24 square meters of panel area. The back surface filled silicon solar cells of the arrays had an efficiency of 14.8%. Sun sensors between the panels measured the sunlight incidence angle which allowed the panels to be automatically commanded to an optimum angle. Silver-zinc batteries in the service module could provide six hours of emergency power in case of failure of the solar arrays. The spacecraft's power bus operated at 28 V and a peak power of 3.5 kW.
The unified propulsion system of the service module fed both attitude control and main engines from four 230-litre propellant tanks loaded with 1,000 kg of N2O4/MMH propellants. The engines were pressure fed using six 20-litre titanium cold gas tanks pressurized to 23 Mpa. This gas was used to force propellant at 2 Mpa using diaphragms within the propellant tanks. The engines consisted of:
RCS Coarse No x Thrust: 8 x 150 N. RCS Fine No x Thrust: 16 x 5 N. Electric System: 2.40 kWh. Electric System: 1.00 average kW.
Gross mass: 3,000 kg (6,600 lb).
Unfuelled mass: 2,000 kg (4,400 lb).
Height: 2.94 m (9.65 ft).
Diameter: 2.50 m (8.20 ft).
Span: 17.00 m (55.00 ft).
Thrust: 10.00 kN (2,248 lbf).
Specific impulse: 290 s.
The Cox Report asserted that the Russians provided the Chinese with a complete Soyuz spacecraft. After the launch press reports quoted "high-ranking Russian space officials" as saying that China purchased a Soyuz re-entry capsule from RKK Energia in the mid-1990's in a private deal. However the capsule supplied contained a minimum of actual hardware. Unlike the Soyuz, the umbilical to the service module differed in detail and appeared to enter the capsule higher up on the main body. The capsule provided Soyuz-style molded seats for three crew. The astronauts were presented with modern flat-panel display instrumentation. A Russian-type Vzor optical device provided a means of manually orienting the spacecraft for retrofire. Unlike Soyuz, it did not function as a periscope, and provided no forward view during docking operations. Manual control of the spacecraft was via Soyuz-type hand controllers.
The structure of the re-entry vehicle used a titanium frame, with aluminum alloy sidewalls, base, and pressure vessel. The module had the Soyuz classic 'headlight shape', with a diameter of 2.517 m and a length of 2.500 m from the forward hatch lip to the base of the heat shield. The crew entered and exited through a hatch around 70 cm in diameter at the top of the capsule. Two small portholes, around only 30 cm in diameter, provided a limited view outside. The optical device used for orienting the spacecraft manually for re-entry was similar to the Russian Vzor, but with a larger aperture. It featured eight side ports for ensuring the spacecraft was correctly aligned for retrofire. Since it did not function as a periscope and provided a view forward, future docking activities would require use of television or control of the spacecraft from a separate station in the orbital module.
The interior space of the capsule was limited to six cubic meters by the housings for the main and back-up parachutes. There were three crew sheets, facing a high-technology control panel consisting of an array of flat panel screens, caution warning panels, annunciator panels. The integrated digital display system consisted of two multi-functional color LCD displays, fed from redundant controllers. The LCD panels were high resolution, capable of displaying complex graphics. Maps of any point of the world, either the current location of the spacecraft or that of possible landing zones, could be called up at will. A voice synthesizer was integrated into the caution and warning panel to alert the crew audibly when there was any deviation to normal operations. The cabin interior was lit by individually-adjustable fluorescent lamps.
Arranged on the exterior of the capsule were six antenna mounts, the exhaust nozzles of the attitude control system used during re-entry, and a Soyuz-like patch panel for connection of gas, liquid, electrical, and electronic services from the service module. Most cabin internal equipment was installed beneath the three crew seats.
From left to right these seats would be occupied by a payload specialist, a commander/pilot, and a copilot/flight engineer. Each crew member was provided with a space suit derived from the Sokol suit used aboard Soyuz; a survival suit for post-landing situations; underwear; coveralls for working in the cabin during the mission; a headset; medical monitoring sensors; a personal survival kit, an individually-contoured seat liner; and a sleeping bag.
Each crew member's survival kit contained his selection of space food for the mission, optimized for the Chinese palate. Reserves of food were kept in case of unplanned mission extensions. There was even food in tubes that could be consumed while sealed up in the spacesuit in the event of extended cabin depressurization. The survival kit also contained a personal emergency radio beacon, smoke generator, signal rocket, flash light, dye marker, mirror, compass, life raft, pistol, knife, shark repellent, lighter, first aid kit, and emergency water.
The medical monitoring system recorded each crew member's pulse, respiration rate, body temperature and blood pressure. A medical kit provided medicines and simple instruments for in-flight emergencies and illnesses.
The environment control system regulated supply of nitrogen and oxygen to control the cabin pressure, circulated and purified the cabin air, controlled the cabin temperature and humidity control, and included smoke and fire monitoring and removal provisions. The system kept the cabin atmosphere at 81 to 101 kPa, oxygen partial pressure at 20 to 24 kPa, humidity at 30% to 70%, and temperature at 17 to 25 deg C. During re-entry, cabin temperature could go up to 40 deg C. There was a spacesuit loop for keeping the crew alive using umbilicals connected to their spacesuits in case of cabin depressurization. Provisions for disposing of body wastes and unused food have not been explicitly described. The system was fed by steel alloy nitrogen and oxygen gas bottles, at pressure of 21 Mpa, located in the service module. A separate supply of gas bottles were mounted in the re-entry vehicle cabin for emergencies and during re-entry.
The guidance system determined spacecraft attitude and position using digital and analogue sun sensors, infrared horizon sensors, a strapdown inertial measurement unit, and a global positioning system receiver, all feeding triple-redundant majority-voting computers. Normally the spacecraft would be oriented and maneuvered automatically. However in the event of a system failure, the crew could manually orient the spacecraft using the Vzor device and hand controllers, and manually command and time retrofire. The computers were loaded with Chinese-developed software using novel techniques for control of the booster during ascent, in-orbit update and alignment of the inertial platform, and automated diagnosis and self-repair in case faults were detected. During re-entry the software commanded real-time flight of the capsule using lift to minimize heating and G-forces while ensuring a landing within an ellipse 30 km in range and 15 km laterally
Shenzhou radio systems used a number of new technologies including unified S-band, digital video and voice processing, remote control and voice encryption, GPS based orbit determination, ablative and microstrip antennae, and high capacity solid-state storage technology. The system had 17 antennae and operated in the C, S, L, UHF, VHF, and HF bands. The in-orbit tracking and control subsystem had a GPS receiver, S-band transponders, a C-band single-pulse radar transponder, telemetry equipment and antennae. Data transmission was via a Unified S-Band System. This was compliant to international standards and combined telemetry, command, voice and video signals into one data stream. As a back-up voice and biomedical data were redundantly combined into a second data stream and transmitted through a VHF transceiver. Three rescue beacons aided in recovery. A 243 MHz VHF beacon started transmitting after the capsule left re-entry blackout, at 40 km altitude. An HF transceiver transmitted the capsule's precise location based on its GPS receiver, and also provided two-way analogue voice communications. A 406 MHz international Emergency Position Indicating Radio Beacon provided a method of locating the capsule in case it came down away from recovery forces. The crew also had handheld emergency 406 MHz transceivers.
Shenzhou's 21 avionics black boxes communicated to one anther as a distributed computer network using a dual-redundant MIL-STD-1553B data bus. The Central Terminal Unit in the re-entry module controlled all three modules during flight. After retrofire and separation of the other modules it controlled the RV during re-entry. The Central Terminal Unit was a triple-redundant fault tolerant computer using majority voting to meet a Fail Operational -Fail Safe requirement. A second Central Terminal Unit in the orbital module was a dual-redundant computer. It would automatically come on line if the primary system in the re-entry vehicle failed. It also controlled the orbital module during autonomous missions of up to six months after the re-entry vehicle had returned to earth.
Other avionics boxes on the bus included six single-board-computer based remote terminal units, two in each module, to collect data and transfer signals; a dual-redundant data transmission and control unit in the propulsion module; 11 interface units of other subsystems; and an emergency data recorder in the re-entry module. The latter had 10 MB of solid-state memory and was built to withstand 10,000 G's and a temperature of 1200 deg C for 30 minutes.
To control orientation after separation of the orbital and service modules and during re-entry, the re-entry vehicle had eight 150 N thrust monopropellant hydrazine engines, pressure-fed from two rubber bladder tanks containing 28 kg of propellant. These were pressurized from two 4.5-litre titanium 23 Mpa gas tanks.
Following re-entry, the landing system went into operation. At an altitude of 10 km the parachute hatch was jettisoned, and two pilot parachutes deployed. These pulled out the drogue parachute, followed by the ring-sail main parachute, which had an area of 1200 sq m and a mass of 90 kg. In the event of a parachute failure, a back-up parachute with an area of 760 square meters was used. Deployment of the parachutes was guaranteed by an air-bag in the compartment (failure of the parachutes to be ejected from the compartment resulted in the death of Vladimir Komarov in Soyuz 1 in 1967).
Below 6 km altitude the heat shield was jettisoned, exposing a gamma ray altimeter and the four nozzles of the soft-landing retrorockets. As the capsule approached the ground, the capsule converted from single-point to two-point suspension under the main parachute, and its vertical velocity declined to 8 m/s. The altimeter ignited four solid propellant retrorockets at one meter over the ground, reducing final impact velocity to 3.5 m/s. In case of failure, the crew seats were fitted with shock absorbers to guarantee an uncomfortable but survivable landing. After landing, a visual flashing beacon went into operation to assist recovery forces in locating the capsule at night. If the capsule splashed down in water, fluorescent dye was released into the water to assist sighting from the air.
Crew Size: 3. Habitable Volume: 6.00 m3. Heat shield: 450 kg (990 lb). RCS Coarse No x Thrust: 8 x 150 N. RCS Propellants: 28 kg (61 lb).
Gross mass: 3,240 kg (7,140 lb).
Height: 2.50 m (8.20 ft).
Diameter: 2.52 m (8.26 ft).
The orbital module was jettisoned before retrofire. Early models were equipped with their own solar panels and propulsion for autonomous flight after separation. When Shenzhou was later used to shuttle astronauts to the Tiangong space laboratory or later larger, multi-module space station, the orbital module was fitted with a Russian-style androgynous docking system at the forward end of the orbital module, and the solar panels were eliminated.
The module was a semi-monocoque aluminum structure, cylindrical, 2.250-m in diameter and 2.800 m long. This length did not include an equipment pallet mounted on the forward end, which varied from flight to flight. A large 80-cm-diameter EVA hatch was located in the lower portion of the module, with a 48-cm diameter porthole above that, very unlike Soyuz. A rectangular equipment package could be mounted on the opposite side of the orbital module. Also on that side was a second smaller window. The lateral sides of the module were used for mounting of the rotating solar panels when fitted. At the base of the orbital module was a 70-cm-diameter hatch providing access to the re-entry vehicle. Presumable a similar hatch would be located at the nose for docking missions.
The equipment pallet varied from mission to mission. Shenzhou 1 and 2 flew with dummy or partial electronic intelligence packages, a complex arrangement of equipment mounted at the top of the orbital module. This included a semi-circular ring which provided mounting for rectangular instruments around its exterior. Three perpendicular 0.4 m extendible booms were deployed as well, part of an experimental magnetic attitude sensing and control system. Shenzhou 3 and 4 flew with the complete electronic intelligence payload mounted on the nose. As analyzed by veteran space-radio expert Sven Grahn, this consisted of two major components. UHF emission direction-finding was accomplished by three earth-pointing television-aerial type antennae deployed on long telescoping booms. These would function in the UHF band between 300 and 1,000 MHz, covering a variety of civilian and military emission sources. They were supplemented by seven horn antennae arranged in an arc. These would detect and localize radar transmissions. This combination would allow coverage of the entire earth below as the orbital module passed over the earth's surface.
Given that China had not previously flown a major ELINT satellite, this was an enormous leap in Chinese military surveillance from space. Each orbital module remained in space as long as eight months after the other modules return to earth. That means the orbital modules of the Shenzhou spacecraft have been scanning the earth 90% of the time, day in and day out, since Shenzhou 3 was launched in March 2002. Data was dumped in ten-minute bursts when the spacecraft pass over Miyun, near Beijing. These missions would have given China's equivalent to the American National Security Agency an excellent introduction into capabilities and problems in flying an operational ELINT satellite over a variety of targets and seasons of the year. The main objective, as was the case for low-altitude Soviet systems, would be to keep track of the US Navy, particularly carrier groups. Observations by Shenzhou 4 during the Iraq War would have been an intelligence windfall for the Chinese.
Shenzhou 5's equipment included an imaging reconnaissance package. This consisted of two cameras with an aperture of 500 - 600 mm. The close-look camera was mounted in the equipment pallet at the nose of the spacecraft in a rectangular housing, 0.900 m x 1.268 m x 0.86 m. Zhang Houying of the Chinese Academy of Sciences gave the ground resolution of this close-look CCD camera as 1.6 m. The other camera was mounted in the porthole above the orbital module's main hatch. The use of two differing cameras indicated a hyper-spectral, multi-resolution, combination mapping/close-look system.
Shenzhou 6, with a longer-duration crew of two, dispensed with the forward equipment pallet with the close-look camera, but retained the other camera and rectangular external payload package. Another instrument package was mounted aft of the nose.
Shenzhou 7, the first EVA mission, differed from earlier missions in having its solar panels, 16 thrusters, and all other sub-systems used for independent flight removed. Additions for the EVA role included five gas bottles (mounted on the forward end of the orbital module), two external cameras, handrails, and a space exposure experiment that was retrieved by the astronauts. In addition, a subsatellite, weighing 40 kg, and with diameter of 40 cm, was mounted at the top of the orbital module. Released after the EVA, it relayed back images of Shenzhou 7 from close range, then backed to a distance of several kilometers, testing network technology with the Shenzhou and the orbital module after the deorbit of Shenzhou 7.
Shenzhou 8 and subsequent missions have an EPAS-type universal docking mechanism fitted to the forward end of the capsule. All other external payloads seem to be eliminated, available mass being needed for the additional external hatch forward, the docking collar, docking mechanism, and avionics, antennae, lasers, and other components of the rendezvous and docking systems.
A Central Terminal Unit in the orbital module was a dual-redundant computer that controlled the spacecraft during autonomous flight. It would also automatically come on line if the primary system in the re-entry vehicle failed during manned operations. The orbital module's autonomous on-orbit tracking and control subsystem consisted of S-band transponders, telemetry equipment and antennae. Thermal control of the module was via external louvers. Orbital module power was provided by two solar panels, each in two section, with a total area of 12.24 square meters. These charged nickel-cadmium batteries within the module for power when in the earth's shadow.
Four groups of four 5-N thrusters may be mounted at the base of the orbital module. These provided an autonomous attitude control and maneuvering capability to the orbital module when in free flight. They also presumably could serve as a backup to the main orientation system in an emergency. The system used hydrazine monopropellant, pressure-fed at 23 Mpa from a 7-litre titanium cold gas tank. The thrusters were plumbed into redundant groups.
Habitable Volume: 8.00 m3. RCS Coarse No x Thrust: 16 x 5 N. Electric System: 1.20 kWh. Electric System: 0.50 average kW.
Gross mass: 1,500 kg (3,300 lb).
Height: 2.80 m (9.10 ft).
Diameter: 2.25 m (7.38 ft).
Span: 10.40 m (34.10 ft).
AKA: Project 921-1.
Gross mass: 7,840 kg (17,280 lb).
Unfuelled mass: 6,840 kg (15,070 lb).
Height: 9.25 m (30.34 ft).
Diameter: 2.52 m (8.26 ft).
Span: 17.00 m (55.00 ft).
Thrust: 10.00 kN (2,248 lbf).
Specific impulse: 290 s.
First Launch: 1999.11.19.
Last Launch: 2011.10.31.
Number: 8 .
The Yuanwang-3 tracking ship off the coast of Namibia picked up the spacecraft's signal at 18:49 UT, and commanded retro-fire. This time the spacecraft accepted the command, which probably saved the entire program. The spacecraft passed out of range of the tracking ship nine minutes later. Its trajectory arced over Africa, skimmed the coast of the Arabian peninsula, and then over Pakistan, before re-entering over Tibet.
Following re-entry, the drogue chute deployed at an altitude of 30 km with the capsules soft-landing rockets firing 1.5 m above the ground. The capsule landed at 41 deg N, 105 deg E, (415 km East of its launch pad and 110 km north-west of Wuhai, Inner Mongolia), at November 20 19:41 UT. The spacecraft had completed 14 orbits of the earth in 21 hours and 11 minutes.
After the flight it was reported that not a single primary spacecraft system had failed, so none of the back-up systems were tested. The touchdown point was only 12 km from the predicted position. The soft landing braking rocket worked well - no damage was found to the capsule structure, heat shield or the seals. The jettisoned heat shield, parachute hatch, and drogue chute were found within 5 km of the landing point. The orbital module, which separated prior to retro-fire, continued in controlled flight until 27 November, when it decayed and reentered the atmosphere. A primary payload returned by Shenzhou were 100 kg of seeds, considered valuable to the Chinese after one day of exposure to the space environment. The Chinese space tracking fleet returned from the Shenzhou mission between 12 December 1999 and 4 January 2000. During their 259-day voyage, the four ships traveled 185,000 km and experienced some heavy seas while tracking and communicating with the Shenzhou for a total of 150 minutes. Additional Details: here....
The launch was originally scheduled for January 5, but the second stage of the launch vehicle was dented by an access platform while being prepared for roll-out in the vehicle assembly building. This caused several days of delay until it was cleared for flight. Shenzhou 2 made three orbit-raising manoeuvres during its flight, reaching a 330 x 345 km orbit by the end of the initial phase of the mission. Ninety minutes before landing the orbital module depressurised, and the spacecraft went briefly out of control. However this was regained after venting of the atmosphere from the module ended. The descent module and service modules separated from the forward orbital module and external pallet normally. After retrofire by the service module, it separated and the descent module landed at 11:22 GMT on January 16 in Inner Mongolia. Lack of post-recovery photographs led to speculation that the recovery may not have been completely successful. The Shenzhou orbital module had its own solar panels and remained operational in orbit, conducting scientific experiments. It was actively controlled for six months, maneuvering in orbit several times (reaching a final orbit of 394 x 405 km). It then was allowed to decay and reentered the atmosphere at 09:05 GMT on August 24, 2001. The reentry point was near 33.1 deg S in latitude and 260.4 deg E in longitude, over the western Pacific Ocean between Easter Island and Chile.
The highly conservative mission plan was for Yang to remain in the Shenzhou re-entry capsule for the entire 21-hour mission, and not to enter the orbital module. He had two rest periods of three hours each, and was scheduled to eat once or twice meals of what was said to be a superior form of Chinese space food. Frequent communications sessions, including colour television links to the spacecraft, were made possible by China's four tracking ships deployed in the oceans of the world.
As the spacecraft was in its 21st orbit, the orbital module separated. It would stay in the 343 km orbit for a planned six-month military imaging reconnaissance mission. Retrofire was commanded via a tracking ship in the Atlantic off the coast of Africa. Shenzhou-5 landed only 4.8 km from the aim-point in Inner Mongolia with the parachute being sighted by the ground recovery forces prior to landing. Yang landed after 21 hours 23 minutes aloft.