China sent the core module of its space station into a planned orbit on April 29. The space station has a designed lifespan of ten years, but designers believe it could last more than 15 years with appropriate maintenance and repairs.
The space station will face various threats and challenges in the cosmos, such as atomic oxygen, ultraviolet radiation, vacuums, temperature changes, space debris, and microgravity.
These may cause the material performance to decline or induce failures, thus shortening the service life of products and equipment such as extravehicular cables, surface coatings, and optical lenses.
According to Zhou Jianping, chief designer of China's manned space program, maintainability is one of the space station's advantages compared with its predecessors. Maintenance and repairs can ensure the technological upgrade and long-term and reliable operation of the space station.
"To ensure the service life of the space station in orbit reaches 15 years, we have taken long life, reliability, maintainability, and safety into consideration in the design stage," said Hou Yongqing. Hou is a deputy chief designer of the space station system at the China Academy of Space Technology (CAST), under the China Aerospace Science and Technology Corporation.
Based on the long life and reliability of the system and products in the space station, the designers prepared in-orbit fault diagnosis, response plans, and maintainability design, Hou added.
"We will store the backup of the important equipment in orbit, and if this equipment fails, astronauts will directly replace the faulty one with the backup," said Bai Linhou, another deputy chief designer at the CAST.
Bai added that if something is wrong with the software program, the engineers can prepare the modified program on the ground, upload it to the space station by fast-speed space-ground link, and overwrite the faulty program.
The space station has a health sub-system to ensure long service life, including monitoring the payloads and station's structural state in real time, locating space debris, and sending alerts to ground and astronauts for quick response.
The sub-system can also monitor the pressure inside the cabin and send alerts at different levels according to various pressure indicators.
Hao Chun, director of the China Manned Space Agency (CMSA), said the in-orbit maintenance and change of payloads would become astronauts' regular work to extend the service life of the space station.
"We have developed a series of ground training facilities and equipment for astronauts' missions, such as extravehicular activities, extravehicular repairs and maintenance, and equipment replacement," he said.