What is the Tianzhou 1 and why does it matter in China’s ambitious space mission?
Spacecraft will act as supply vessel as part of ambitious plans to build a space station orbiting the Earth
Tianzhou-1, China’s first space cargo ship, is due to be launched on Thursday evening from a space centre in southern Hainan province.
The craft will be put into orbit by a Long March-7 Y2 carrier rocket blasting off from Wenchang Space Launch Centre.
The Tianzhou-1 forms part of China’s ambitious plans to build an orbiting space station. Construction of the project is due to begin next year and be completed by about 2020.
On its maiden flight, the cargo craft will dock with the small, orbiting Tiangong-2 space laboratory.
The Tianzhou will ultimately be used to carry supplies to up to six astronauts living on board the space station.
Some will spend up to a year living and working in orbit and they will need constants supplies of basics such as food and water.
The space station will also need to be refuelled regularly to resist the Earth’s gravitational pull, or to change course to avoid collisions with orbiting space junk and debris.
Tianzhou-1 is an unmanned supply ship. It will dock with the space station automatically in futures missions, unload its cargo and fuel, then leave with waste before plunging into the atmosphere to burn-up.
Dr Yang Yuguang, secretary general of the International Space Transport Association and a senior researcher in the Chinese space industry, said China’s space station will not be able to function over the long term without the support of a large, advanced space freighter.
“This is the ultimate reason why China is building up a cargo fleet,” he was quoted as saying by the People’s Daily.
Tianzhou-1 is just over 10 metres high, about the height of a three-story building and is the single largest spacecraft China has built.
Its solar wings, when fully extended, match the width of a basketball field. It is larger than the Tiangong space laboratory it will dock with during this month’s mission.
The cargo craft can carry a payload of up 6.5 tonnes, twice that of vessels built by Russia and the United States, according to Chinese scientists.
Japan has developed a craft of a similar size, but it needs a robotic arm to dock with the International Space Station. The European spacy agency developed a freighter that could carry a larger load, but it is no longer in service.
Morris Jones, a space expert based in Australia, said the cargo ship was a great achievement for China.
“Only Europe, Russia and China have developed freighters that can refuel a space station. America has not done this,” he said.
Two cargo ships under development or in service in the US, the Cygnus by Orbital Sciences Corporation and Dragon by SpaceX, have a single-compartment design with no room for fuel.
“Tianzhou is a large spacecraft with more volume than freighters from the USA and Russia. It can thus carry more cargo than some other freighters,” said Jones.
“Different versions are designed to carry different combinations of pressurised cargo, which goes straight to the interior of the space station, and unpressurised cargo, which is unloaded in open space and attached to the exterior of the space station,” he added.
The Chinese space authorities also say Tianzhou-1 is the lightest space cargo ship ever made.
Bai Mingsheng, chief designer of the craft, told China’s state television: “The carrying capacity of Tianzhou is designed to match the scale of the space station, to meet the principle of the highest carrying capacity with the lowest structural weight.”
A significant part of the weight reduction comes from the widespread use of new alloys and carbon fibres, according to state media reports.
Zhou Jianping, chief designer of China’s manned space programme, said the first flight of the Tianzhou-1 was a milestone in China’s ambitious space missions.
“The success of Tianzhou means the official completion of the space laboratory phrase. We can start building the space station from now on,” he told mainland media.