India's GSLVMKⅲIII III launch vehicle launched "Moon II".
"Patrol around the ground" detector
The GSLVMK rocket put the 3.85-ton Lunar Ship-2 probe into orbit, and it has been successfully launched for three consecutive times since 20 17. In this launch, GSLVMK rocket successfully sent "Yuechuan II" into the elliptical orbit of170 km× 45,000 km.
According to the data of the Indian Space Research Organization, the apogee of the orbit is about 6,000 kilometers higher than that of the earlier scheme, or the rocket capacity is increased by 15%. India's big rockets are playing very steadily, but the key and focus of the "Yuechuan II mission" has always been the detector. The design of "Yuechuan II" is quite complicated, and the design scheme of "circling and patrolling" was adopted for the first time in lunar exploration.
"Yuechuan II" was launched by a large Indian rocket at one time. The probe consists of three parts: lunar orbiter, vikram lunar lander and Prajian lunar rover. Compared with the simple lunar orbiter 1, the technical difficulty of the "patrol around the moon" scheme has greatly jumped, which poses a great challenge to Indian space.
"Lunar Spacecraft II" includes a lunar orbiter and a lunar lander.
"Yuechuan II" pioneered unmanned lunar exploration with the design of "patrolling around the circle", which reflected the enterprising spirit of Indian space. Although India is only a third world country as a whole, and its investment in the space field is not large, India's space industry has made many achievements and become a rare international business card for the country. One of the important reasons why Moon Boat II chose this difficult and complicated scheme is the publicity highlight of "the first time for mankind". Similarly, they also spent a lot of time in choosing the landing site of the probe.
Landing on the south pole of the moon for the first time
In the past decades, humans have launched more than 65,438+000 lunar probes, including less difficult astronauts and orbiters, as well as more complex landers and sampling return probes. Including six Apollo manned landings on the moon, humans made 20 soft landings on the moon. Among them, China's Chang 'e IV probe also achieved the first soft landing on the back of the moon.
Although there are many unmanned and manned lunar landers launched by humans, the landing area is limited to the middle and low latitudes of the moon. India's "Moon Boat II" will land at 70.9 degrees south latitude and 22.78 degrees east longitude. Located in the middle of ManzinusC and SimpeliusN craters, it is a relatively flat area.
In fact, "Yuechuan II" even planned to land at 85 degrees south latitude of the moon in the early days. The terrain here is extremely complex, soft landing is very difficult, and the solar altitude angle near the South Pole is very low.
Lunar rover working in polar regions needs to erect solar panels to ensure sufficient power supply. Although, after comprehensively weighing the landing difficulty and other factors, India chose the landing point of 70.9 degrees south latitude, the solar panel design of the lunar rover still remained and became the landmark design of the Indian lunar rover Pragyan. The solar cell of the vikram lander of "Yuechuan II" is installed on the side wall with a large angle, which is also to adapt to the lighting conditions in the polar regions of the moon.
Lunar rover carried by "Lunar II" lander
China's Chang 'e-4 probe once set a record for the first soft landing on the back of the moon, and the landing site was named Tianhe Base, while the Indian "Yuechuan-2" aimed at the south pole of the moon, which may also go down in history.
The South Pole of the Moon is a hot spot for future lunar exploration. There is a lot of water ice here, which can be used not only for lunar base and personnel, but also for producing hydrogen-oxygen propellant to feed back space activities. The low solar altitude angle in the polar regions has additional benefits. It is neither too hot during the moon nor too cold at night, which is more suitable for human activities than the middle and low latitudes of the moon. There are also permanent shadow areas and permanent illumination areas in the polar regions of the moon, which is a treasure house for building lunar bases and developing the moon.
If "Chandrayaan II" successfully lands, it will become the first spacecraft in the history of human spaceflight to land in the polar regions of the moon, and it will also be a milestone in human lunar exploration, which will give Indian space an unprecedented international reputation. No wonder Indians choose polar regions for their first soft landing.
Try to break through the detection load
Although "Yuechuan II" weighs 3.85 tons, 23.79 kg of it is orbiter, and the rest 147, 1 kg is lander and patrol. In addition to the complicated design of "circle patrol", the main reason is that the GSLVMK rocket has insufficient transport capacity, so it can't directly send the probe into the earth-moon transfer orbit, so it can only use the orbiter to handle the orbit change maneuver, which makes the orbiter bulky. At the same time, the lander is small and the lunar rover is light. Faced with such an unfavorable situation, Indian Aerospace still strives to make a difference in detecting loads.
India designed a huge orbiter for "Yuechuan II", with the size of 3.2×5.8×2. 1 m. Although this is a helpless move with limited rocket capacity, it can also carry more loads because of its large size. Lunar orbiter 2 will orbit around the moon at 100 km × 100 km. The design life of the orbiter is 1 year, the power supply is 1 kw, and there are eight detection loads. Among them, in addition to TMC terrain camera, soft X-ray spectrometer, L/S band SAR radar and other common loads, the biggest highlight is the high-resolution camera.
The camera can image the area of 12km× 3km at a time, and the imaging resolution is as high as 0.32m, which is higher than that of the LRO detector in the United States, while the track height of the LRO detector is 50km in high-resolution imaging. In other words, the actual resolution of Indian high-resolution orbiter camera is more than three times higher than that of American LRO camera.
In addition, India will first use this camera to shoot the predetermined landing area and obtain high-resolution images for the lander to avoid obstacles. After landing, the orbiter camera will be used for subsequent scientific investigation tasks.
As the camera with the highest resolution in lunar orbit, it will definitely be used for lunar "archaeology" to photograph the landing sites of Apollo and other landers. Maybe in the near future, we can see clearer pictures of Chang 'e and Yutu.
Pragyan, the lunar rover of Yuechuan II, weighs only 27kg and is the lightest and smallest lunar rover ever. Indian lunar rover adopts six-wheel design, solar panels can only provide 50 watts of electricity, and there is no cold-resistant design in moonlit night, so the design life is only 14 days, which is moonlit night. The speed of Indian lunar rover is 1cm/s, but it has no independent communication ability and can only contact the earth through the lander. The designed driving distance is 500 meters. After all, its life span is limited, and it will lose contact if it passes.
Even so, the Indian lunar rover has carefully designed its payload, which carries a particle-excited X-ray spectrometer (APXS) and a laser-induced breakdown spectrometer (LIBS). APXS is used to detect the material composition of lunar soil and lunar rocks, and LIBS can quantitatively measure the elemental composition of the lunar surface. In-situ detection of lunar rover by APXS and LIBS can more effectively analyze the substances and elements on the lunar surface quantitatively and qualitatively, and provide valuable first-hand information for the study of lunar geology and evolution.
It is worth mentioning that the Indian lunar rover is the second extraterrestrial patrol vehicle equipped with LIBS in the world, which is likely to provide more direct and sufficient evidence for the exploration of water resources in the polar regions of the moon.
Text/Zhang Xuesong
Editor/Yang (Intern)
Producer/Xu Bin