KevinJamesNg

Traveling through time and space & Doing timey wimy stuff.

One year ago today 24th November 2020 Now it’s the 24th November 2021 , the Chang Zheng – Long March Five Carrier Rocket Launched away  in CNSA – China National Space Administration China Wenchang spaceport launch, Change Five  Lunar probe into orbit, opened up towards China – People’s Republic of China’s first celestial bodies sample return trip from Mons Rumker on the Lunar Surface.……  

Highlight 1: Narrow window launch The launch window is the ignition time period for the launch vehicle to meet the needs of the transfer to the moon. Due to the typhoon and strong tropical cyclone in Wenchang area, high-altitude wind, heavy rainfall, thunderstorms and other meteorological conditions are very complicated, it can be imagined. The narrower the window, the greater the risk of launching large cryogenic launch vehicles. There are many factors that determine the launch window, such as the relative position of the launch site and the target point, the safe landing zone of the rocket wreckage, the time of sunlight after the launch probe (satellite) enters orbit, the measurement and control arc, the lunar landing zone, and the lunar take-off time , Re-entry return time, etc. The more the launch constraint conditions, the narrower the launch window. In order to ensure the reliable implementation of the Chang’e-5 mission, it is necessary to solve the design difficulties of the multi-orbit moon launch scheme under the constraints of the range of launch, the safety of the landing zone, the measurement and control of the ascent section, and the rocket taxi time.

Aspect 2: During the two-stage taxiing process of the accurate low-temperature launch vehicle in the landing zone of the rocket, the quality of the propellant will decline with the passage of time, so the longer the taxiing time, the more unfavourable the startup of the low-temperature power system. For this reason, the rocket system has carried out a large number of ground tests, and the three flights of the Long March 5 have fully evaluated and verified the long sliding ability of the model. The rocket area of ​​the Chang’e-5 mission must fly over the Philippine Islands. The booster landing area is located west of the Philippines, the fairing landing area is located east of the Philippines, and the core landing area is located in the Pacific Ocean. Multi-ballistic launching has caused significant horizontal and vertical dispersion in the sub-level wreckage landing area. Therefore, if the mission permits, the range of the shooting direction and dispersion must be minimized to optimize the safety of the landing area. The scientific research team carried out multiple rounds of optimization design for the horizontal and vertical dispersion of the multi-ballistic trajectory to the moon with variable firing direction and variable glide time. In the end, the rocket wreckage landed exactly in the intended sea area. Aspect 3: Multi-trajectory, “moving target shooting”

A key technology in the launch phase of the Chang’e-5 mission is multi-ballistic launch, that is, within 3 consecutive days, there are 5 nominal trajectories with 10 minute intervals between take-offs every day, evenly covering the 50-minute launch window. The purpose of multiple ballistics is to achieve “mobile shooting” with different take-off points and the same destination during the relative movement of the earth and the moon. As long as the launch vehicle ignites within the launch window and sends the probe into a predetermined Earth-Moon transfer orbit, the probe can fly to the near-moon point at exactly the same time, altitude, incident angle, illumination, and measurement and control conditions. Through the detailed orbit design, the outstanding performance of the launch vehicle systems, and the concerted cooperation of various departments, the Chang’e-5 probe was sent into the scheduled orbit with very high accuracy, laying a solid foundation for the subsequent flight missions.

Aspect 3: Multi-trajectory, “moving target shooting” A key technology in the launch phase of the Chang’e-5 mission is multi-ballistic launch, that is, within 3 consecutive days, there are 5 nominal trajectories with 10 minute intervals between take-offs every day, evenly covering the 50-minute launch window. The purpose of multiple ballistics is to achieve “mobile shooting” with different take-off points and the same destination during the relative movement of the earth and the moon. As long as the launch vehicle ignites within the launch window and sends the probe into a predetermined Earth-Moon transfer orbit, the probe can fly to the near-moon point at exactly the same time, altitude, incident angle, illumination, and measurement and control conditions. Through the detailed orbit design, the outstanding performance of the launch vehicle systems, and the concerted cooperation of various departments, the Chang’e-5 probe was sent into the scheduled orbit with very high accuracy, laying a solid foundation for the subsequent flight missions.

Images and visuals are from Weibo and their respectives…. Of CNSA China National Space Administration …  

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