Chang'e II 7 instruments will complete 4 tasks

The Chang'e II satellite currently orbiting the moon will complete four scientific goals within six months of its scheduled time: acquiring a moon surface 3D image with a resolution of better than 10 meters, detecting lunar material composition, detecting lunar features, and detecting land Monthly and near-month space environment. These four goals will be based on the results of the Chang'e-1 scientific exploration to obtain more abundant and accurate detection data, which will lay an important technical foundation for the follow-up lunar soft landing and deep space exploration missions, and deepen the human scientific understanding of the moon. .

The four sciences responsible for these four tasks are the payloads carried by the Chang'e II satellite - seven instruments and equipment for performing missions: TDI-CCD stereo cameras, laser altimeters, X-ray spectrometers, gamma-ray spectrometers, microwave detectors Solar high-energy particle detectors and solar wind ion detectors.

The TDI-CCD stereo camera is newly developed, and the remaining six types are also improved compared to those carried by Chang'e I. Their "weight" adds up to only 140 kilograms (the total weight of the satellite is 2480 kilograms, of which fuel is 1310 kilograms). After redesign and improvement, martial arts is even more powerful.

The stereo camera and laser altimeter acquire the three-dimensional image of the lunar surface. The "Chang'e I" stereo camera is an ordinary CCD camera. After being re-developed by the Xi'an Institute of Optics and Mechanics of the Chinese Academy of Sciences, this time it is a TDI-CCD camera that uses multiple cameras. The principle of multiple exposures of the linear array CCD to the same target can meet the requirements of the resolution increase to the exposure control of the camera. It is an important breakthrough for the relevant load research technology in China and is also used for the first time in the moon detection in the world. The altitude of the remote moon point of Chang'e II during the month of the month is 100 kilometers, and the height of the near-month point is only 15 kilometers. After the redevelopment, the TDI-CCD camera has increased the image resolution from 120 meters of the Chang'e I to 10 meters. About meters, it can even reach 1 meter on the 15km track.

On the moon, there are both several kilometers of mountains and several kilometers of deep valleys. The CCD stereo camera cannot accurately measure the height and depth of mountains and deep valleys. It requires laser altimeter power.

A laser altimeter is equivalent to a laser radar. It can shoot a laser beam to the surface of the moon and receive reflected light. In this way, by calculating the laser return time, the distance from the moon's surface to the satellite can be obtained. The height of the laser altimeter on Chang'e II has been improved. The frequency of detection is increased from 1 second in Chang’e 1 to 5 points in 1 second. This is equivalent to a detection point for satellites flying 300 meters around the moon. The density has increased by 5 times.

Using the TDI-CCD stereo camera to obtain a higher-resolution moon surface 3D image, combined with the moon surface topographic elevation data obtained by a laser altimeter, it is possible to obtain high-precision terrain data of the lunar surface, providing a basis for the subsequent landing area optimization; at the same time, The fine structure, fracture and ring structure of the geomorphic unit on the moon's surface are divided to provide original data.

After the X-ray spectrometer and the γ-ray spectrometer have been used to detect the moon's material composition to see the moon's appearance, the next step is to understand what elements are distributed on the moon and what the composition of the material is. The human eye uses visible light to distinguish objects by color. X-rays and gamma rays have much shorter wavelengths than visible light. These rays can be used to distinguish the types of elements.

The γ-ray spectrometer detects the crystal from the original cesium iodide, to a new material - cesium bromide, so that the detection sensitivity increased by more than 1 times; X-ray spectrometer spectrum, also from the original 10KeV- 60KeV, reduced to 25KeV-60KeV. In this way, it is possible to better detect the content and distribution characteristics of nine elements on the lunar surface—silicon, magnesium, aluminum, calcium, titanium, potassium, strontium, and uranium, and obtain an element distribution map with higher spatial resolution and detection accuracy.

Microwave detectors to detect lunar features to detect lunar features and estimate their thickness could have been radar. However, the radar consumes a lot of power and occupies a large amount of satellite resources. For this reason, the No. 1 and No. 2 carriers carry microwave detectors. It is actually a microwave radiometer that only receives microwave radiation from the moon's surface. Although the required energy is small, it can receive monthly microwave radiation of four frequency bands (3.0GHz, 7.8GHz, 19.35GHz, and 37GHz) and different microwave frequency bands. It can bring information on lunar or moon rock at different depths under the moon.

The Chang'e II microwave detector did not make much changes. However, since the Chang'e II flight path is lower than the Chang'e I, the coverage of the microwave detector antenna beam on the moon surface will be reduced, thus improving the spatial resolution of the detection. These new data can be combined with the data of the Chang'e-1 microwave detector to obtain more accurate information on the moon.

Solar high-energy particle detectors, solar wind ion detectors to detect the moon and space environment in front of any spacecraft to a new planet, we must understand the unknown environment in the space, especially the high-energy solar particles and solar wind, to protect their own safety . The charged energetic particles emitted by the sun and the solar wind, which is the charged low-energy particles emitted by the sun, will cause the satellite and its payload to fail.

The Chang'e II satellite is in the peak year of solar activity during orbital operations. It is a probe to study the events of solar high-energy particles, CME (a coronal mass ejection, that is, a phenomenon in which the material in the solar corona expands outward or outward), and the solar wind. And their best exploration period for the impact on the moon's environment. Using solar high-energy particle detectors and solar wind ion detectors, we can obtain the characteristics of flux, composition, energy spectrum, and time-and-space changes of interplanetary solar high-energy particles and solar wind ions, which are used to study solar activity and earth and moon space and the recent months. The interaction of the space environment. Provide environmental science data for the follow-up lunar exploration project.

It should be noted that on the Chang'e II satellite, there is a management system that works with these seven payloads to command, control, manage, and collect data for these seven instruments. The large-capacity memory is the newly developed device. Its storage capacity has been increased from the first 48GB to 128GB, and it has a higher throughput rate and faster processing speed. This will make the seven payloads more efficient and more reliable.