CASIC Helps Successful Launch of the "Tianzhou-2" Cargo Spacecraft


At 20:55 on May 29, the LongMarch-7 Y3 launcher carrying the Tianzhou-2 cargo spacecraft was launched from China Wenchang Spacecraft Launch Site, and about 604s later, the spacecraft successfully separated from the rocket and entered the pre-selected orbit precisely.  At 21:17, both spacecraft solar panels unfolded successfully,  marking a complete success of the launch.

Photo taken by Ju Zhenhua/Xinhua

After entering the orbit, Tianzhou-2 cargo spacecraft completed the entry state settings, and began a fast automated rendezvous and docking with the in-orbit space station core module rear hatch at 5:01 on May 30, which lasted about eight hours.

In this launch mission, CASIC, with its technical advantages in professional fields, undertook a series of development and security work and completed all tasks with high quality, helping the "Tianzhou-2" cargo spacecraft launch mission to be a complete success.

Rendezvous and docking

Space rendezvous and docking technology is one of the key technologies of manned spaceflight engineering. The microwave radar, accelerometer and many other key components undertaken by CASIC played an important role in the mission, which contributed to the successful completion of rendezvous and docking between "Tianzhou-2" and the Tianhe Core Module.

Microwave radar products developed by CASIC continues to play an important role in this mission as a key measurement sensor, outputting high-precision shoran, velocity and angle information during the long-range autonomous fast docking process, thus providing strong support for the rendezvous and docking tasks in the construction of the space station.

To complete spacecraft attitude correction during the  rendezvous and docking,  accelerometer is needed to accurately measure the relative position change of the Tianhe Core Module and "Tianzhou-2" cargo spacecraft. However, in the microgravity environment of space, the "slight movement" of attitude correction makes the measurable acceleration very small, posing a challenge for accelerometer development.  For example, observing the acceleration of an aerocraft during attitude correction in microgravity is as difficult as observing an ant pushing an elephant suspended in a vacuum.  To this end, CASIC has developed a precision inertial sensor to detect acceleration, which can "sense" the relevant states of the aerocraft with high accuracy and provide accurate acceleration measurement signals for the rendezvous and docking to ensure the success of the mission.

High-pressure self-locking valve, electromagnetic drag mechanism and many other key components played an important role in ensuring the smooth rendezvous and docking.  The high-pressure self-locking valve is mainly used in the attitude control system of Tianzhou-2 to ensure that the space laboratory can smoothly perform orbit maneuver and attitude correction in space as per the guidance command, so as to realize the precise control of the spacecraft.  The electromagnetic drag mechanism is mainly used in the final stage of rendezvous and docking, and its function is to drive the docking mechanism of the cargo spacecraft to achieve structural connection with the core module.

In addition, CASIC also tackled key difficulties like the instantaneous impact suffered by various small modulus gears in the space environment, the design of thin-walled components and asymmetric gears, and provided dozens of varieties and hundreds of gear transmission products such as precision gears for speed increase and reduction.

Build a comfortable space station

In this mission, CASIC specially developed "space massager device", environmental control and life support system were sent to the space by the Tianzhou-2 for the subsequent use of astronauts as living materials.

The mainframe, stimulation and communication cables of nerve muscle stimulator, which can be used for massage in space, were sent to the space by the Tianzhou-2 as one of the series products of the "space hospital".  It is mainly used for electrical pulse stimulation of astronauts to assist them in muscle fatigue recovery and muscle strength training to prevent muscle atrophy caused by long-term flight tests.  When astronauts need to exercise in the follow-up missions, they only need to take out the product from the "space express package", attach the stimulation electrodes to the designated positions, connect the product cable, turn on the power, then choose their own exercise mode for massage.

Among the materials sent to the space by Tianzhou cargo spacecraft, certain key medical instrumentation system and support materials have strong temperature sensitivity, and need to be stored in a special heat insulated "space refrigerator".  In order to meet the demands on light weight and outstanding insulation performance, CASIC, through a special process, made vacuum insulation panel, the "VIP" material called jokingly by the technical team.  These panels offer both excellent air barrier performance and puncture resistance, in addition, it can make the utmost of space.

"Heart to heart" with spacecraft

Using a variety of ground telemetry tracking and communication (TT&C) system, fixed pulse measurement radar, and crystal components, CASIC undertakes tasks like real-time monitoring of tracking, launch and control signals, exterior trajectory measurement system, communication support, and provision of reliable temporal frequency references.

CASIC has developed the measurement system PXI automatic TT&C portfolio, TT&C signal converter and other ground TT&C devices for the LongMarch-7 Y3, which successfully completed various tasks during the rocket testing, transfer and launch process.

During the ascending of the rocket, the two fixed pulse instrumentation radars developed by CASIC were used for exterior trajectory measurement, providing precise coordinate information such as rocket distance, orientation, pitch and radial velocity data in real time for the Wenchang Satellite Launch Center, so that once the rocket flight has deviated from the orbit, it can be detected immediately, thus ensuring flight safety.

During the period of launch, liftoff and in orbit, the surface acoustic wave products developed by CASIC like SAW filter and choke coil, provided communication support services for key parts like communication system transponders of the Tianzhou-2 cargo spacecraft.

After the rocket lifts off, the communication with the ground relies on the frequency signals generated by crystal components. CASIC has developed a series of supporting crystal components, which, like the "pulse" of the rocket, provide a reliable time and frequency reference for the success of the launch mission, working as an important reference indicator for the ground commanders to monitor the flight status.

Support systems of spacecraft

The spacecraft consists of several systems that are interlinked and closely related. In this mission, CASIC provides a series of high-end products to support the normal functioning of the spacecraft.

CASIC provided zinc-silver batteries and ground charging and discharging equipment for the LongMarch-7 Y3 to provide energy support for the rocket control system and measurement system instruments and equipment.

Most of the rocket engine fuel lines are rigid lines, however with frequent local thermal expansion and contraction, vibration, displacement and other adverse effects.  The metal hose developed by CASIC can eliminate these unfavorable factors and enable the fuel to "run free" in the piping system.

The electrical connector products provided by CASIC are mainly used in the spacecraft's star sensor, environmental control, receiver and transponder, computer, inertial navigation and other subsystems, carrier rocket distributor, cable system, telemetry and launch platform control systems, etc., which are the "blood vessel" and neural network for signal transmission and control of each subsystem; the supporting motor products include environmental control subsystem, docking mechanism subsystem, thermal control subsystem, etc., which can realize the circulation of air in the module, equipment heat dissipation and mechanism drive.

In addition, fuel filling system, high-end metal fasteners also played an extremely important role in this mission.

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