SHENZHOU

The most substantial challenge of project 921 was the manned spacecraft itself. Appointed chief designer was a person then unknown outside China (and probably little inside China either). Qi Faren, born in Fuxian, Liaoning, in 1933, represented the main design team from CAST, assisted by the Shanghai Academy of Space

The Shenzhou design: unlike Soyuz, there are double sets of panels. Courtesy: Mark Wade.

Technology (SAST). He had graduated from the Beijing Institute of Aeronautics and Astronautics in the historic year of 1957 and, 13 years later, was involved in the building of China’s first satellite, Dong Fang Hong. He then went on to lead the Dong Fang Hong 2 and 3 programs and the Feng Yun 2. He was appointed general designer and leader of project 921 in 1992, with 1,000 scientists and engineers under his command.

At first sight, Shenzhou looks like the Russian Soyuz, a design going back to 1960. Like Soyuz, Shenzhou comprises a service or propulsion module, descent cabin, and orbital module. The service module contains four re-entry rockets with variable thrust (2,500 N, 150 N, 25 N), 28 maneuvering engines with variable thrust (150 N, 5 N), two solar panels, and radiators to discharge heat. The headlamp­shaped, sometimes called beehive-shaped, descent module has room for three, possibly four, crewmembers. It has a 65-cm hatch at the top, two portholes, a sighting window, and two parachutes (main and reserve). The orbital module, at the front, has two solar panels, maneuvering engines, two portholes, and room for a scientific package on the front. The cabin is designed to provide the astronauts with air, a temperature of 17-25°C, and humidity of 30-70%. For all its similarities with Soyuz, there were differences:

• Shenzhou is larger: 9.15 m long compared to 6.98 m;

• Shenzhou is wider, at 2.8 m in diameter, compared to 2.6 m;

• Shenzhou is heavier, at 7.79 tonnes compared to 7.2 tonnes;

• Shenzhou has solar panels reckoned to deliver up to three times more power than Soyuz: 1.53 m wide, span 17 m at the back, and placed not only the on the service module (24 m2), but also on the orbital module, span 10.4 m (although the latter were not deployed on Shenzhou 1 and 7);

• the orbital module is heavier (2 tonnes), can be left in orbit for independent flight, and has four groups of four maneuvering engines; it is longer than Soyuz: 2.8 m compared to 2.2 m;

• the descent module is slightly larger: 2.517 m in diameter (Soyuz was 2.17 m) and longer (2.5 m compared to 1.9 m), but has the same aerodynamic shape, with a volume of 6 m3;

• the propulsion or service module is 2.94 m in length and 2.8 m in diameter, compared to Soyuz’s length of 2.3 m and diameter of 2.2 m; it has four engines, compared to a single one on Soyuz;

• the escape tower is similar: 7.16 m long, diameter from 33 cm to 70 cm [3].

In other words, Shenzhou follows the general configuration of Soyuz but is far from a copy. The Chinese themselves made comparisons between Shenzhou and Soyuz. Overall internal volume is 13% larger, making Shenzhou, they say, larger, roomier, and better. It has a different docking system: an androgynous petal-style docking system, rather than the probe-and-drogue of Soyuz. Table 8.5 compares the two. As may be seen, Shenzhou is clearly influenced by the Soyuz design, but to describe it as a “copy” would be both inaccurate and unfair. The Chinese became sensitive to allegations of copying and at press conferences stressed that Shenzhou was “Made in China” (“Made in China” stated emphatically in English).

The Shenzhou fairing is 15.1 m long, 3.8 m in diameter, and it weighs 11.26 tonnes. Its tower can be ignited at any time from 15 min before launch to 130 sec after lift-off, when it is then fired free, while the shroud remains in place to 200 sec: its top motors can be used to pull Shenzhou free should an emergency develop during these later stages of launch. The escape system can be activated by the yuhangyuan, mission control, or by the automatic guidance system should it detect that the rocket is heading badly off course. Different combinations of its four engines can be used for escape below 39 km (the first three sets), 39-110 km (the second and third sets), and to whisk the tower away if still unused (the small top set). Escape at low altitude would be a memorable experience, pulling 20 G. A similar launch escape system was once used when a Soviet rocket exploded on the pad in September 1983. Cosmonauts Vladimir Titov and Gennadiy Strekhalov were grateful when it did indeed work as advertised. They had a bumpy landing but were very much alive. Development of the escape system proved to be one of the most difficult parts of the design and it took two years to make a successful test.

The escape tower might be called upon to work but, at the other end of the mission, the parachute of the descent module must always work. Here, the Chinese made the largest ever parachute for a returning manned spacecraft. The landing sequence would trigger as the descent module reached subsonic speed 15 km above

	Shenzhou	Soyuz*
Complete spacecraft
Weight	7.8 tonnes	7.21 tonnes
Length	9.15 m	6.98 m
Diameter	2.8 m	2.6 m
Propulsion module
Weight	3 tonnes	2.95 tonnes
Propellant	1.1 tonnes	900 kg
Length	2.94 m	2.3 m
Diameter	2.8 m	2.2 m
Base	2.8 m	2.72 m
Solar panels	Two of 24 m2	Two
Descent module
Weight	3.2 tonnes	3 tonnes
Length	2.5 m	1.9 m
Diameter	2.5 m	2.17 m
Orbital module
Weight	2 tonnes	1.3 tonnes
Length	2.8 m	2.2 m
Diameter	2.8 m	2.25 m
Solar panels	Two of 12 m2	None

* This is the TM version, which operated from 1986 to 2002. The current TMA-OM is larger.

the ground. First, the hatch cover is jettisoned and the pilot chute comes out for 16 sec to slow the module from 180 m/sec to 80 m/sec. Next, the deceleration chute comes out, slowing the cabin to 40 m/sec, bringing out the main parachute. This is a huge canopy, at 80 m tall, 30 m across, weighing 90 kg, with an area of 1,200 m2 – 20% broader than the Soyuz parachute, held by 100 25-mm-diameter cords, each able to bear a weight of 300 kg. Once it billows out, it slows Shenzhou to its descent speed of between 15 m/sec and 8 m/sec. The parachute is made of 1,900 pieces of thin strong fabric able to withstand high loads and temperatures of up to 400°C. Should something go horribly wrong, like the parachute twist or Roman candle, then a reserve parachute can be ejected. This is much smaller – 63% of the size of the main chute, at 760 m2. The heat shield is then dropped at 5 km. But, assuming all is well, the final action takes place as the cabin comes in to land. Just 1 m above the ground, a gamma detector senses the touchdown and fires solid-fuel retrorockets to cushion the final descent to 1 m/sec, simultaneously severing the parachute so that it will not drag the cabin in a high wind. Once landed, the cabin includes survival suits, sleeping bags, radio beacon, smoke generator, signal rockets, dye, mirror and compass, life raft, pistol, knife, first aid, and even shark repellant. The main beacon begins sending signals from the end of blackout at 243 MHz while the spacecraft is still 40 km up, while the astronauts themselves can erect two high-frequency transmitters once they land. They also have a beacon to transmit on the international emergency frequency of 406 MHz.

The orbital module is sufficiently large for basic comforts to be provided for the orbiting yuhangyuan. They can sleep in sleeping bags mounted on the wall. A sealed plastic tent is provided so that they may shower – a facility never provided on Soyuz. Developing the spacecraft took much longer and was much more difficult than expected. By 1997, it had got little further than the shell of the prototype in the workshop, to the extent that opponents of the project made a fresh attempt to have it canceled. A counter-proposal for an unmanned lunar program to replace Shenzhou reached the state council, but Prime Minister Zhu Rongji would not approve such a late, radical change of course. The engineers decided, meantime, to buy time by putting into orbit a minimalist prototype, with an all-up version to follow later.