Xinhua News Agency, Beijing, April 1 Question: Aerospace experts interpret the "return" of the Tianzhou-2 cargo spacecraft
Xinhua News Agency reporters Huang Yichen, Liu Yi, Sun Luming
On March 31, the Tianzhou-2 cargo spacecraft successfully completed its scheduled mission and re-entered the atmosphere in a controlled manner. A small amount of debris fell into the predetermined safe waters of the South Pacific Ocean.
Since its launch on May 29, 2021, Tianzhou-2 has been in orbit for more than 300 days.
Why did Tianzhou-2 choose to "go home" at this time?
What "firsts" and "bests" did it set?
What are the similarities and differences between Tianzhou-3 and Tianzhou-4?
Xinhua News Agency reporters interviewed Li Zhihui, deputy commander of the Tianzhou-2 cargo spacecraft of the Fifth Academy of China Aerospace Science and Technology Corporation, and Jiang Ping, deputy commander of the Tianzhou-2 mission of the Beijing Flight Control Center.
Keyword 1: Release two major signals
The return of Tianzhou-2 released two major signals: the return of Shenzhou 13 is imminent, and Tianzhou-4 is ready to go.
Jiang Ping introduced that during the operation of the space station, the normal residence period of the astronaut crew is 6 months, which means that crew rotation and cargo replenishment are carried out every six months——
When taking off, the cargo spacecraft must arrive at the space station before the manned spacecraft, carrying on-orbit resident materials, space station backup equipment, space science payloads, additional propellants and other upward materials to the space station.
When evacuating, the cargo spacecraft usually precedes the manned spacecraft and takes away most of the space life waste.
After bidding farewell to the Tianzhou-2 cargo spacecraft, the in-orbit Shenzhou 13 astronaut crew is making preparations for the spacecraft's return, and plans to return to the ground in mid-April.
"The design life of Tianzhou-2 is 2 years, and the return at this time is also to 'let Xian' Tianzhou-4 and rationally use the docking port of the cargo spacecraft." Li Zhihui said.
The Tianhe core module is equipped with 5 docking ports, of which the rear docking port and the forward docking port are used to dock the cargo spacecraft.
After Tianzhou-2 returned, a docking port was vacated, and together with Tianzhou-3, which had been in orbit for nearly 200 days, waited for Tianzhou-4.
Key word 2: fast rendezvous
After Tianzhou-2 was separated from the core module of the space station, it made full use of the propellant margin of the spacecraft and successfully carried out a 2-hour rapid rendezvous test between the cargo spacecraft and the space station.
"In this rapid rendezvous test, we controlled the cargo spacecraft to complete the process from entering orbit to rendezvous with the space station within 2 hours. If this technology is applied to subsequent missions, it will not only greatly improve mission efficiency, but also further shorten the time for astronauts. The time spent in a confined space." Jiang Ping said.
The Tianzhou series of spacecraft have witnessed the rapid development of my country's rendezvous and docking technology.
Tianzhou-1 has made three rendezvous and docking with Tiangong-2 space laboratory, and the first rendezvous and docking lasted about two days; Tianzhou-2 has made four rendezvous and docking with Tianhe core module, and the first rendezvous and docking lasted about 8 hours.
Keyword 3: Controlled Deorbit
Li Zhihui introduced that the deorbiting and active destruction of Tianzhou-2, which has completed its mission, is another vivid practice of peaceful and scientific utilization of space resources, and demonstrates my country's responsibility as a responsible space power.
"There are two ways to return to the earth after the spacecraft is controlled to deorbit. One is a manned spacecraft with a recovery and landing system to ensure that the astronauts return home safely; The orbiting spacecraft re-enters the atmosphere for destruction," Li Zhihui said.
At present, most of the Tianzhou-2 has been ablated, and a small amount of debris has sunk into the uninhabited area of the South Pacific. This area is also an international low-orbit spacecraft re-entry area.
Keyword 4: All-rounder
Jiang Ping introduced that during the orbital flight of Tianzhou-2, a number of extended application tests such as spacecraft orbiting flight, robotic arm transfer cabin verification, and manual remote operation rendezvous and docking were completed as planned. Management has accumulated experience.
"During the execution of various tasks in orbit of Tianzhou-2, the Beijing Flight Control Center accurately completed ground command and control and operation management, and carried out emergency response to faults or abnormalities in a timely manner," Jiang Ping said.
"The main function of Tianzhou-2 is to supply materials, and secondly, it is the 'power compartment' of the entire space station assembly." Li Zhihui introduced that the space station assembly is given priority to supply energy through the cargo spaceship, and the cargo spaceship is used as the assembly's attitude and orbit adjustment. Actuator, thereby relatively prolonging the service life of the core compartment engine.
This year marks the 30th anniversary of the establishment and implementation of China's manned space project, and it is also the year of the decisive battle for the construction of the space station.
According to the overall plan of the manned spaceflight project, this year will also organize the implementation of six flight missions, including the Wentian capsule, the Mengtian capsule, the cargo spacecraft, and the manned spacecraft.
"Tianzhou-3 and Tianzhou-4 have similar functions, mainly for material supply. At present, Tianzhou-2, as the first cargo spacecraft in the stage of China's space station, is still the cargo spacecraft that undertakes the most test tasks." Li Zhihui said.