According to the China Manned Space Engineering Office: At 6:59 Beijing time on January 6, 2022, after about 47 minutes of cross-system close coordination, the space station robotic arm transposition cargo spacecraft test was a complete success, which was the first time that China used the space station robotic arm to operate a large orbiting vehicle for transposition test.
In the early morning of January 6, the mechanical arm successfully captured the Tianzhou-2 cargo spacecraft, and the transposition test began at 6:12, after the Tianzhou-2 cargo spacecraft and the Tianhe core capsule were unlocked and separated, under the dragging of the mechanical arm, the core cabin node capsule sphere center was used as the center of the circle for plane transposition; and then reversed operation until the cargo spacecraft and the core capsule were re-docked and locked.
In this test, the feasibility and effectiveness of using the robotic arm to operate the transposition of the space station module were preliminarily tested, and the transposition technology of the space station module and the large-load control technology of the robotic arm were verified, which accumulated experience for the subsequent assembly and construction of the space station.
Why did Tianzhou-2 conduct an indexation test?
So, what is an indexation test and what is the purpose of the transposition test? Let's take a look.
China's space station is not a one-time launch molding, but needs to be assembled and built in space through multiple launches. At present, we have successively launched the Tianhe core module, the Tianzhou cargo spacecraft, the Shenzhou manned spacecraft, and two experimental modules will be launched in the follow-up.
Shi Jixin, overall deputy director of the space station of the Fifth Academy of Aerospace Science and Technology Group: In our normal construction process, our two experimental modules are docked to the forward pair, (experimental module I. docking) after the forward pairing interface, equivalent to it (experimental module I. ) stopped after this, when the experimental module II. comes, it (experimental module I. ) to give up this position.
Shi Jixin told us that in order to ensure that the two experimental modules launched later can successfully complete the task of substation, it is necessary to carry out the verification of key technologies for orbital transposition in advance, and the transposition test of Tianzhou-2 is for this purpose.
Shi Jixin, overall deputy chief designer of the space station of the Fifth Academy of Aerospace Science and Technology Group: If the transposition is not successful or there is no such function, our entire scale may be limited. This process is actually a technology that must be broken through in the construction of our entire space station. Only when we break through this technology can the entire space station be completed as scheduled.
How is the transposition test performed?
The robotic arm on the space station has previously assisted the astronauts to successfully complete four missions out of the capsule, but this time to move the cargo spacecraft, it is still a big test. So how is the transposition test carried out? What kind of plan did our space station designers design in order to successfully complete the task?
The transposition test of Tianzhou-2 was completed by the mechanical arm on the core module of Tianhe. First, the robotic arm needs to crawl ahead of time to the berth located near the node capsule in preparation for the transposition test. After that, grab the adapter of the Tianzhou-2 by way of capture.
Shi Jixin, overall deputy director of the space station of the Fifth Academy of Aerospace Science and Technology Group: Then at this time, I used the mechanical arm to push the cargo spacecraft to unlock first. After unlocking, let the robotic arm drive the cargo spacecraft to rotate, turn and then come back, come back again after returning, and then go to the cargo spacecraft again. It's a bit like the tower crane when we build a skyscraper, this tower crane is equivalent to our robotic arm, and each cabin is equivalent to our building materials, which is such a process.
Shi Jixin told us that in the process of transposition testing, the mechanical arm was connected to the core cabin at one end and the Tianzhou-2 at the other end, which was like a flat shoulder carrying two elephants. Such a structure is very fragile and can cause damage to the robotic arm, so the researchers have cleverly designed the transposition test.
Shi Jixin, overall deputy chief designer of the space station of the Fifth Academy of Aerospace Science and Technology Group: First of all, I stood up the space, and after standing up, I first turned it 90 degrees, and within the orbital plane is a flight of the smallest windward side, so that its aerodynamic disturbance is the smallest. After standing up, like a pendulum, the entire cabin is actually stable in gravity gradient, that is, no matter which direction it flips, it will eventually stay on the vertical axis.
Validated several key technologies for space station construction
In today's (6th) transposition test, the core capsule, the robotic arm, and the cargo spacecraft cooperate with each other, and the attitude is constantly changing, just like the Transformers in space. This dizzying series of operations has also validated many of the key technologies of China's space station construction.
According to experts, before the start of today's transposition test, they have carried out a large number of simulations on the ground to ensure the smoothness of the test, and this test is also a verification of the ground simulation system.
Shi Jixin, overall deputy chief designer of the space station of the Fifth Academy of Aerospace Science and Technology Group: Before I really do this experiment in the sky, I want to make a rehearsal on the ground, and then I want to rehearse the state of the heavens.
Experts also told reporters that the space station's robotic arm has assisted astronauts in completing four outgoing missions, but today's test is a test of the robotic arm's module transposition capability.
Shi Jixin, overall deputy chief designer of the space station of the Fifth Academy of Aerospace Science and Technology Group: The mechanical arm has never carried such a large load, like before we carried people out of the capsule, maybe an astronaut plus his spacesuit is about 300 kilograms of a load. Now we have to load nearly 9 tons, such a load is actually a test for the robot arm.
Shi Jixin introduced that the current State of China's space station system is very good, and today's test has also laid the foundation for the next two experimental modules to meet and dock and the construction of the space station.
Shi Jixin, overall deputy director designer of the space station of the Fifth Academy of Aerospace Science and Technology Group: It is a multi-system joint verification, first of all, the mechanical arm in the process of docking, in fact, its speed is not enough, so it is also necessary to GNC (guidance navigation and control) subsystem to give it a speed, so that the cargo spacecraft can successfully dock up. After docking, the docking mechanism also needs to dock again to capture, and then lock, and then the robot arm is evacuated again, so multiple systems must participate in the test verification inside.
The next step is to perform a manual remote operation experiment
After completing today's transposition test, the next step of the Tianzhou-2 cargo spacecraft will be to cooperate with the astronauts to complete the manual remote operation test. After the mission is completed, the opportunity will be chosen to re-enter the atmosphere.
On May 29, 2021, the Tianzhou-2 cargo spacecraft was successfully launched in Hainan, as the first ship of the cargo spacecraft in the construction stage of the space station, Tianzhou-2 not only carried a large number of astronaut living materials, extravehicular spacesuits, scientific instruments and other important materials, but also undertook the task of refueling the propellant of the space station.
On September 18, 2021, the Tianzhou-2 cargo spacecraft separated from the space station Tianhe core module rear port, and flew around to the forward port to complete the automatic rendezvous and docking, after the completion of today's transposition test, Tianzhou-2 next step will cooperate with astronauts to complete manual remote operation tests.
Yang Sheng, overall chief designer of the Tianzhou-2 cargo system of the Fifth Academy of Aerospace Science and Technology Group: The astronaut controls the cargo spacecraft in the core cabin, and then conducts manual remote control evacuation and docking tests. Now there are two modes of cargo ship rendezvous and docking, normal is automatic rendezvous docking, if there is an abnormal situation, we also have manual remote operation of the backup means, this is actually mainly for the backup of the means to do an on-orbit verification.
Yang Sheng introduced that after completing all the tasks, Tianzhou-2 will choose the opportunity to leave the core module of the space station, and will also pack the waste before leaving the orbit and burn it into the atmosphere, which is also one of the key technologies for the construction of the space station.
Yang Sheng, overall chief designer of the Tianzhou-2 freight system of the Fifth Academy of Aerospace Science and Technology Group: After these tasks are completed, according to its overall consumption and life span, it will choose the opportunity to leave the space station, and it will also bring the waste back to the atmosphere and burn it, so Tianzhou-2 should be a cargo spacecraft with the most tasks, the most arduous, and the docking time will be relatively long.
Source: CCTV news client