Jade Rabbit 2 was woken up on January 10 after lunch break. On November 11th, five years later, we saw the lander and the lunar rover clapping each other historically!
Change-4 lander and Yutu-2 patrol were working normally on the afternoon of November 11, with the support of the Magpie Bridge relay satellite. The ground receiving images were clear and intact. The scientific payloads at home and abroad were working normally, the detection data were downloaded effectively, and the scientific experiment project was carried out smoothly, reaching the projects established goal, marking the successful completion of Change-4 mission, Xinhua reported. u3002 So far, Chinas lunar exploration project has achieved the Five World Wars and Five Quicks.
Change 4 lander and Jade Rabbit 2 patrol camera each other (source: CCTV)
I. Scheduling of Change-4 after landing
On January 3, 2019, at 10:26 a.m., the Change-4 lunar probe landed smoothly in the von Carmen crater at 177.6 degrees east longitude and 45.5 degrees south latitude on the back of the moon, becoming the first successful soft landing probe on the back of the moon.
At 22:22 on January 3, the Lunar Vehicle Jade Rabbit II stepped on the back of the moon smoothly. It will succeed the Yutu Lunar Rover and become the rabbit that sees the most stars!
No (upper left) Change 4 landing camera photo matching LROCNAC image, source: LROC/ASU  (lower left) Feng Carmen impact crater location (right) Change 4 landing area. Source: The area on the right of LROCWAC/NAC/haibaraemily is about 3 *5 kilometers, which is the main range of motion of the rabbit on the back of the moon after landing.
From 22:22 on January 3 to 17:00 on January 4, Change 4 was completed:
Separation of Lander from Yutu 2 Patrol Vehicle
Change-3 and Change-4 release lunar rovers Yutu (left) and Change-4 release lunar rovers Yutu-2 (right), captured by their respective surveillance cameras C. Source: Lunar Exploration Project
Three 5-meter antennas of the low-frequency radio spectrometer on the lander are deployed in place
Start-up Test of German Lunar Neutron and Radiation Dose Detector (LND) on Lander
The landers topographic and topographic images were sent back to Earth through the relay star magpie bridge one after another.
Yutu-2 and relay satellite successfully established independent data link, completed environmental awareness and path planning.
Yutu-2 arrived at point A on the lunar surface as planned. The lunar radar and panoramic camera were on and working normally. Other payloads start up one after another.
The lander monitored the line taken by Camera C and reached Point A, Yutu II.
Here is point A of Jade Rabbit No. 2. A few days ago, Change No. 4 ushered in the high temperature test of the moon and day. In order to cope with the high temperature, Yutu 2 chose to enter the lunch break mode. The rabbit took a lunch break here.
Two. Three Major Events of Change IV on the Moons Back
Change 4s trip has three main objectives:
1. Explore the topography, landform and mineral composition of the inspected area on the back of the moon.
2. Explore the superficial structure of the back patrol area.
3. Using the unique radio astronomical environment on the back of the moon to carry out low-frequency radio astronomical observation.
To accomplish these goals, Change IV has brought a lot of scientific instruments with superb skills.
As the backup machine of Change No. 3, Change No. 4 inherits Change No. 3 to a large extent in both shape and carrying scientific instruments, each carrying eight scientific instruments, but according to the actual detection targets and changes in the detection environment, new adjustments have been made to the carrying scientific instruments [2-4].
1. Landing Camera (Lander): See the lunar surface during landing
The landing camera is located at the bottom of the lander. It is 116 x 100 x 70.4 mm in size and weighs about 0.5 kg. The hardware specifications of the landing camera are the same as those of Change 3.
The main task of the landing camera is to obtain landing area topographic and geomorphological data at different altitudes in different time periods during landing, so it will always point vertically to the lunar surface.
The lunar surface photographed by the landing camera behind the soft landing moon (right) and left during the power descent of Change IV. Source: China Aerospace Science and Technology Group, Lunar Exploration Project
These two lunar photographs were taken by Change 4 landing camera on January 3 . The specific landing area of Change 4 described in the previous section is based on these photographs.
Since the landing camera is only used during landing, its working time is very short, only a few minutes.
That is to say, as early as January 3, the landing camera has done a good job!
2. Landform Camera (Lander): See the landform near the landing area
The landform camera is located at the top of the lander. Its size is 92 *105 *118.9 mm and weight is about 0.64 kg. It can take color images in visible light band. Its hardware index is the same as Change 3 landform camera. It was developed by Institute of Photoelectric Technology, Chinese Academy of Sciences.
The main task of topographic camera is to take pictures of the lunar surface and lunar rover, which can take 360 degree panoramic pictures around the landing area.
This is a mosaic of panoramic photos taken on December 20, 2013 by Change 3 lander topography camera. You can see the solar panels and some components, the remote lunar rover Jade Rabbit, and the ruts left by Jade Rabbit.
Source: Chinese Academy of Sciences/Don Davis [6
On January 11, 2019, Change 4s topographic and topographic camera also brought us such magnificent scenery.
Panorama (Cylindrical Projection) of Lander Topography and Landform Camera of Change 4 (Image Source: NASA)
Panorama (azimuth projection) of landform and landform camera of Change-4 (image source: NASA)
3. Low Frequency Radio Spectrometer (Lander): Astronomical Observation
Low-frequency radio spectrum analyzer is a new instrument carried by Change-4 in order to make full use of the natural and non-interference radio astronomical environment on the back of the moon. Its mission is to observe the low-frequency radio characteristics of the sun and the radio environment on the lunar surface on the back of the moon, filling in the radio observation gap in the range of 0.1-40 MHz .
Three low-frequency radio spectrum analyzer antennas of 5 meters long are designed to receive three mutually perpendicular components of electromagnetic wave signals, which is also the most significant difference in appearance between Change 4 lander and 3 lander.
Source: China Lunar Exploration Project
Because of the blockage of the ionosphere, electromagnetic waves with a wavelength of more than 10 meters can hardly penetrate the atmosphere to the earths surface. To observe such low-frequency electromagnetic waves with longer wavelengths, it is necessary to leave the earths atmosphere - the back of the moon is an excellent observation site.
The electromagnetic window of the earths atmosphere. Source: Wikipedia
In fact, in addition to the ionospheric interference of the Earth, the low-frequency radio observation on the back of the moon can effectively shield the interference of human activities, which is called ultra-long wave (low frequency) in astronomy over 10 meters, but belongs to the short wave (high frequency) band in human social activities, which is the main frequency band of civil radio broadcasting.
On the other hand, the low-frequency radio spectrum instrument carried on the lander will cooperate with the low-frequency radio detector (NCLE) (0.1-80MHz) developed by the Netherlands on the Magpier Relay Satellite to verify and complement each other.
4. Lunar Neutron and Radiation Dose De (Lander): Detecting Lunar Radiation Dose
Developed in cooperation with Kiel University in Germany and carried on the lander, the objective is to measure the radiation dose and LET spectra of charged particles, gamma rays and neutrons on the lunar surface, as well as the fast neutron spectra and thermal neutron fluxes on the lunar surface.
The two boxes are the sensor head and the electronic unit of the lunar neutron and radiation dose detector. Source: [7
What can I do to measure these? The most direct objective is to detect radiation doses on the lunar surface in situ.
If we want to explore space, we must protect ourselves from all kinds of radiation in space. First of all, we can know how much radiation dose is in different places.
The radiation dose in low earth orbit can be measured directly by astronauts at the space station. What about the moon? So far, only two detectors have been measured - the RADOM on the Indian Lunar Ship 1, which is not Indias own, but is developed and carried by the Bulgarian Academy of Sciences and the CRaTER on the NASA Lunar Reconnaissance Orbiter (LRO), but both of which only measure the orbit around the moon (distance). The radiation dose on the lunar surface is 100 kilometers and 50 kilometers respectively.
So far, we havent detected the radiation on the lunar surface (including primary and secondary radiation) , which is exactly what Change IV will do. That is to say, Change-4 will measure the radiation dose of various particles on the lunar surface for the first time, providing data support for future manned landing safety activities and revision of the lunar surface integrated particle radiation model.
In addition to measuring lunar radiation, thermal neutron measurements can also help us estimate water content in the shallow surface of the landing area (hydrogen is actually detected, note that the water here is also a collective term for various forms of water, either water ice or hydroxyl). It should be noted, however, that the detection of water here is not the same as the possible exposure of water ice in the permanent shadows of the lunar polar region, where the permanent shadows are usually located at the polar regions above 70 degrees north and South latitudes, while the Von Carmen crater is only in the middle latitudes (45 degrees south latitudes), far from the permanent shadows.
5 Panoramic Camera (Inspector): Shooting the Lunar Rover along the way
Two panoramic cameras, 90 x 110 x 120 mm in size and weighing about 0.69 kg, were mounted on the rover (lunar rover). Panoramic cameras on Change 4 and Change 3 are twins, which were developed and manufactured by Xian Optical Machinery Institute of Chinese Academy of Sciences when Change 3 was manufactured.
The panoramic camera installed on the mast of the lunar rover can realize 360 degree black-and-white and color imaging of different survey areas along the lunar rover, and can also stereo image the target through two cameras.
This is a mosaic of panoramic photos taken at N205 by Jade Rabbit, a lunar rover on Change 3. You can see its low-frequency lunar radar antenna, its rutting, and its remote lander. Source: [7
6 Infrared Imaging Spectrometer (Inspector): Analysis of Mineral Compositions on the Moon Surface
The infrared imaging spectrometer is located in the front of the lunar rover. It is 255 *172 *162 mm in size and weighs about 4.69 kg. It has two channels: visible near infrared (450-950 nanometer) and near infrared short-wave infrared (900-2400 nanometer). Its hardware index is approximately the same as that of Change-3 infrared spectrometer. It is manufactured by Shanghai Institute of Technology.
Infrared imaging spectrometer mainly detects the minerals along the lunar rover and their distribution by measuring the spectrum of the target area and the absorption characteristics of the spectrum. Since the Change-4 lunar rover no longer carries the particle-excited X-ray spectrometer (and therefore does not need a robotic arm), the infrared imaging spectrometer has become the only instrument on the Change-4 for chemical composition analysis.
7 Lunar Survey Radar (Surveyor): Detecting the Shallow Surface Structure of the Moon
Developed by the Institute of Electronics, Chinese Academy of Sciences, we can actively transmit and receive electromagnetic signals to detect the shallow surface structure profiles of the lunar rover along the way, such as the thickness of lunar soil and the shallow structure of lunar crust, to help us trace the geological history of the inspected area.
The main principle of lunar radar is that the dielectric constant of different substances (which can be simply understood as the ability to attenuate electromagnetic waves) is different, so the time and intensity of electromagnetic waves reflected back from the interface of different substances will be different. In turn, by measuring the radar reception time and reflection intensity, we can deduce which different substances these radar signals pass through and how thick each layer of substance is.
The working principle of lunar radar. Source: IECAS
Like Change No. 4 and No. 3, Change No. 4 carries two lunar radar with different frequencies in order to take into account both the detection depth and the detection resolution:
The antenna of low-frequency lunar radar (the first channel) is located in the rear of the lunar rover, with a central frequency of 40-80 MHz and a low resolution (meter level), but it can detect deeper underground structures (> 100 meters).
The antenna of the high frequency lunar radar (second channel) is located at the bottom of the lunar rover with a central frequency of 250-750 MHz and a high resolution (<30 cm), but it can only detect shallow underground structures (>30 meters).
The red arrow points to two low-frequency lunar radar antennas. The high-frequency lunar radar is a butterfly antenna, which is placed at the bottom of the lunar rover. Adapted from: China Aerospace Science and Technology Group
8 Neutral Atomic Detector [Sweden] (Inspector): Detecting the Interaction Mechanism between Solar Wind and Lunar Soil
It was developed in cooperation with the Swedish Institute of Space Physics and carried on a lunar rover. The goal is to measure the energy neutral atoms and positive ions in the range of 0.01-10 keV along the lunar rover, so as to help us understand how the solar wind interacts with the lunar soil.
The neutral atom detector carried by Change 4 lunar rover. Source: IRF [8
Unlike the Earth protected by a magnetic field, charged particles in the solar wind drive directly into the lunar surface, reflecting and sputtering energetic neutral atoms (ENA) and other particles.
Indias Lunar Ship 1 probe has used the sub-kilovolt atomic reflectance analyzer (SARA) developed by ESA to make relevant observations, and has also studied the regional magnetic anomalies of the moon through these results.
But the preliminary results of Lunar Ship 1 left two mysteries [8,9]:1). Lunar Ship 1 only explored the lunar orbit 100 kilometers from the lunar surface, but what was the situation on the lunar surface? 2) Lunar Ship 1s detection results show that after the solar wind hits the lunar soil, up to 20% of the protons of the solar wind are reflected in the form of high-energy neutral atoms, which is much higher than previous theoretical estimates. Is this really the case?
These are the problems that Change 4 intends to explore and try to solve. These probes will help us further understand the interaction mechanism between solar wind and lunar soil.
It will also be the first time that humans have detected neutral atoms on the lunar surface.
9 Popular Science Load (Lander): Growing Potatoes and Raising Drosophila
In addition to the above eight scientific loads, the Change-4 mission also carries a popular scientific load developed by Chongqing University - the lunar micro-ecosphere. This is a cylindrical jar made of special aluminium alloy. It is 18 centimeters high, 16 centimeters in diameter, 0.8 liters in net volume and 3 kilograms in total weight. It is placed on the lander.
Potato seeds, Arabidopsis seeds, fruit flies, soil, water, air, cameras and information transmission systems will be placed in the pot to observe and verify the growth of animals and plants under natural sunlight and low gravity conditions on the moon.
Source: Zhang Xianchao_NN9310, Responsible Editor of China Popular Science Expo