Mission "Chang'e-4" - scientific equipment on the landing module and the satellite transponder

Against the background of the travel data of the “Yuytu-2” rover on the lunar surface, interest in events and experiments taking place on the stationary landing module “Chang'e-4” is much less pronounced, and the scientific equipment for studying the space environment has been installed there. complex experiments are also performed.


The next decade will be the time of extended exploration of the lunar surface, interesting discoveries are waiting for us, and man will again walk on the moon.

So far, scientists and engineers have been doing this - like this:





But now, on Earth, in the production departments and laboratories of the Chinese Academy of Space Technologies, work is underway on making, testing and preparing for the launch of new lunar modules, each of which approximates the reality of a live crew landing on the moon, and not just guided robotic stations and rovers.







Traces on the back of the moon rover "Yuytu-2" - the path of the first lunar day



At what stage is the Chinese program for exploring the moon now and what will happen next? Here you can find out from these wonderful slides about the “Chang'e-4” mission:



In fact, if you go uphill on the steps that you yourself are doing, then you can reach its summit, albeit slowly, but now you can bring new people to the summit, who will spend much less time on the first steps.

So did the Chinese scientists and engineers, breaking the lunar research program into several steps. Moreover, they further translated all the experience gained in the implementation of the decisions of each stage to develop a new stage. And now this is the fourth iteration of the exploration of the moon. Soon the fifth - an autonomous expedition with the return to Earth.

And when there is a carrier rocket (a series of “Changzheng” (Long March)), its cosmodromes , highly qualified engineering personnel, who work around the clock and take pride in their work, every year the man-made cosmic lunar cosmic development becomes more and more intense. -speed, picking up the course and opening up new horizons and opportunities for its creators.



But it was on the fourth mission that I had to use all the functionality of the previous decisions and get the opportunity to realize for the first time on the far side of the moon:

• organize the data transmission channel “the reverse side of the moon-earth” using a repeater satellite;
• full control of surface-launched vehicles (TT & C - tracking, telemetry and command subsystem), using the subsystem of tracking, telemetry and transmission of control commands.

One of the main problems in the study of the far side of the moon is the problem associated with the organization of communication, because the devices on the far side of the moon are not available for communication directly from Earth, therefore a separate communication satellite is needed for relaying signals.

The Tseutqiao repeater satellite (triage bridge), launched on May 21, 2018, operates in a halo-orbit around a special gravitationally stable Lagrange point Earth-Moon L2, from which it can maintain direct visibility with the Earth and the lunar back side at any time for data exchange between the PMU and modules of the Chang'e-4 project.



Also on the Tseutsyao satellite relay, a low-frequency spectrometer (relay LFS) with three five-meter antennas is installed, with the help of which the low-frequency radio emission of the early Universe is recorded, which allows studying its structure.



The scheme of the organization of communication Earth-back side of the Moon



Flight diagram of the mission "Chang'e-4" to the moon:



The reverse side of the moon is more often subject to falling meteorites, so the relief there is very complicated, which creates a high risk for an abnormal landing, which can lead to a tilting or complete loss of the landing module in the process of landing.

For the “Chang'e-4” mission, a relatively safe calculation site was chosen for landing in the Karman crater, within which there are extensive flat patches on the surface.



At the design stage, artificial intelligence technologies were introduced into the onboard computer systems of the landing machine “Chang'e-4”, which allowed different project modules to become much smarter and more autonomous than the previously launched ones.

An array of special sensors and cameras measuring various parameters of speeds and distances, which can also process real-time 3D images, were installed on the elements of the Chang'e-4 descent module so that the onboard systems could analyze and correct themselves during the landing procedure parameters and information on the situation, including information about the current position, angles and inclination to the surface, quickly identify unstable (dangerous) elements on the surface (stones, small craters) and be able to evade from such obstacles to the extreme point of no return in the process of landing in automatic mode without operator intervention on Earth.




January 4, 2019, after all the stages of the successful landing procedure and the installation of independent communication channels with Chang'e-4 devices (the landing module and the rover), began the era of exploration of the far side of the moon.




The missions of the Chang'e-4 began to send photographs of the lunar surface:



The landing module "Chang'e-4" and the rover "Yuytu-2" are equipped with special cameras, spectrometers, radars, detectors and dosimeters, both from China and from international production:



International scientific equipment:



Scientific data collected with the help of the Chang'e-4 mission are transmitted to a special space research center and the national astronomical observatory, where arrays of the obtained data are identified, cataloged by experiments, stored, analyzed and transmitted to research laboratories and academies of sciences.





What awaits us in the very near future?

The mission "Chang'e-5" with the return module to Earth, which will deliver several kilograms of lunar soil for new research and discoveries.



And then ... The Poles of the Moon will be a new direction of research - these are already the missions of Chang'e-6 (7-8), some of which are planned to be completed until 2030.



And the apogee of all these developments, projects and years of work and flights should be a full-fledged space lunar station (including orbital modules and ground facilities and infrastructure):



But before the events planned for the next decade, it is necessary to find answers to many complex space issues, and some of them can be solved with the help of scientific instruments that are installed on the landing module “Chang'e-4”, the rover “Yuuta-2” and the satellite-transponder “ Tseyutsyao.



Low Frequency Spectrometer (LFS) - installed on the Chang'e-4 landing module and the Tseuqiao satellite transponder.

The Earth has the ionosphere, which makes it difficult to receive low-frequency radio signals from space. To receive and analyze the weak signals emitted by numerous distant celestial bodies, such radio astronomy experiments should be carried out in outer space, helping us to study the origin and evolution of stars, galaxies and the Universe.



The data and results of similar experiments in near-earth orbits are also sensitive to electromagnetic interference from the Earth's surface, but there is no such interference from the Earth on the far side of the Moon.

In the mission "Chang'e-4" simultaneously involved:

• Chinese low-frequency spectrometer LFS, mounted on the landing module "Chang'e-4";
• Dutch-Chinese low-frequency spectrometer LFS, installed on the satellite relay Tseyutsyao (Netherlands-China Low-Frequency Explorer (NCLE)).

The LFS (Low Frequency Spectrometer) low-frequency spectrometer, designed to study solar flares and solar activity, is now used in the Chang'e-4 mission for conducting low-frequency radio astronomical observations of the Universe, the Sun, and other celestial bodies.

However, these observations are complicated by the fact that the Chang'e-4 modules also emit many low-frequency electromagnetic signals. According to the data that the engineers have already received from the Chang'e-4 landing module, there is still a lot of work to be done to remove interference and emit low-frequency radio signals from the Universe, especially from the Sun.

Therefore, the analysis and comparison of the spectrometer data from the lunar surface with the data of the spectrometer on a satellite-transponder, allow us to obtain a more understandable scientific picture of this problem.

The outer part of the LFS low-frequency spectrometer is three five-meter antennas.









Main characteristics and scheme of low-frequency spectrometer LFS:



The main characteristics and scheme of the low-frequency spectrometer on the Tseutsyao satellite transponder:



The German neutron dosimeter (LND), created by scientists at the University of Kiel, is installed on the Chang'e-4 landing module.



After all, the moon does not have an atmosphere, and cosmic radiation directly bombards the lunar surface. As a result of reactions between particles of cosmic rays and the material of the lunar surface, gamma radiation and neutrons are formed, whose radiation coefficient is higher than that of protons, electrons and photons, and their radiation is very harmful for living organisms on the surface (crews of future lunar stations).



Using the LND dosimeter of the Chang'e-4 project, it is planned to investigate the lunar radiation environment and collect data that can be used for future radiation protection of the inhabited lunar bases.

The main characteristics of the dosimeter LND:



On the rover "Yuytu-2" installed Swedish scientific device ASAN (Advanced Small Analyzer for Neutrals) - a small analyzer of neutral particles.



The protons and ions of the solar wind directly, without interference, affect the lunar surface, colliding with it, reflecting from it, creating energetic neutral atoms (ENA) and other particles.

Energetic Neutral Atom (ENA) is an energetic neutral atom (formed when "random" atoms from interstellar space collide with positively charged ions that move around the solar system at high speed. When colliding, active ions "take" the electrons from the atoms and turn into energy neutral atoms).

At the same time, sunlight leads to a positive charge on one side of the moon, and a plasma leads to a negative charge on the other side of the moon. At the junction of these effects, electrostatic force throws lunar dust into space.

Thus, the particles of lunar soil sprayed and reflected by charges leave the surface of the moon. The study of this process is of great importance for understanding the various mechanisms in the formation of the lunar layer, as well as similar layers on other space objects (asteroids and the like)



The main characteristics of the device ASAN:



But how are all these scientific instruments controlled, transmit data, receive power?

Communication schemes and data transfer of scientific equipment on the landing module "Chang'e-4":



Where:

- LFS - Low Frequency Spectrometer;
- LND - Lunar Lander Neutrons and Dosimetry;
- TCAM - Terrain Camera;
- LCAM - Landing Camera.

Schemes of communication and data transfer of scientific equipment on the rover "Yuuta-2":



Where:

- LPR - Lunar Penetrating Radar;
- ASAN - Advanced Small Analyzer for Neutrals;
- VNIS - Visible and Near-Infrared Imaging Spectrometer;
- PCAM - Panoramic Camera.

Comparative photographs taken by the LRO (NASA Lunar Orbital Probe) landing site of the Chang'e-4 mission on the far side of the Moon at different times (see the photo of the descent module and the rover moving farther from the landing site):





New data from the MCC mission "Chang'e-4" on the actual trajectory of the rover "Yuytu-2" - the map shows the depressions and craters with a slope, which the rover carefully avoids.



The ruts and marks on the surface of the moon from the wheels of the Yuytu-2 rover will remain intact there for at least hundreds of thousands of years.



Many problems that have already been solved on Earth at the design stage of devices for lunar missions could have become very complex and fatal if they interfered with the operation of equipment on the Moon.

And only people interested in space could foresee and understand what else needs to be done for the descent vehicle and the rover, so that they work in difficult lunar conditions without critical breaks, especially at the most crucial moments of the mission.

A team of engineers and employees of the Chinese Academy of Space Technology, participating in the Chang'e-4 mission: