The lunar module is used to transportastronautA means of transportation between spacecraft in lunar orbit and the surface of the moon.Since there is no air on the moon, the lunar module can only be pushed by a rocket engine and can be vertically lifted like a helicopter.When the lunar module is on the lunar surface, the ascending and descending segments are combined into one, but when it takes off from the lunar surface again, the ascending segment is kept for takeoff, and the descending segment is the launcher, which is left on the lunar surface after launching.
Chinese name
Lunar module
Foreign name
Lunar module
Composition
Rising section and falling section
Role
Carrying astronauts to and from the moon and the earth
The phase from take-off to orbit entry of the lunar module is called the power ascent phase, which can also be divided into vertical ascent phase and orbit entry phase.When the vertical takeoff takes place for a certain time or reaches a certain speed, the vertical ascent phase is transferred to the orbital entry phase and guidance is started.[1]When the lunar module is on the lunar surface, the ascending and descending segments are combined into one, but when it takes off from the lunar surface again, the ascending segment is kept for takeoff, and the descending segment is the launcher, which is left on the lunar surface after launching.The ascending section hasCrew compartment，air temperature24 ℃, the room is filled with 1/3 atmospheric pressure pure oxygen.The ascending section of the manned lunar module has two structures: bedroom and vertical.Compared with the vertical structure, the horizontal structure in the rising section has obvious advantages, which mainly reflects the following aspects: (1) Under the same volume, the horizontal structure can provide more floor space;(2) Horizontal structure can provide better perspective for astronauts;(3) It is easier for astronauts to stretch their limbs;(4) Provide the structure to bear the load of propellant tank (vertical structure is weak in one direction).The descent section is equipped with the reverse jet used by the lunar module to descend to the moon surface and deceleraterocket, rocket equippedFuel、Oxidant tank、waterandOxygen tankAnd the science of investigating the lunar surfaceinstrument。The descent phase mainly includes the propulsion system and propellant required for lunar orbit insertion, lunar surface landing and lunar landing.[2]
key technology
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Analysis on key technologies of stage separation
The ascending and descending segments of the manned lunar module are mechanically connected to form an integral structure. When the ascending segment returns, it will be disconnected from the descending segment.Although the third phase of China's "Chang'e" lunar exploration will break through the return mission of the re-entry module, in addition to the mechanical connection between the ascending and descending phases of the manned lunar module, there are also connecting cables closely related to the astronauts' mission, which are used to transmit the water and oxygen stored in the descending phase to the gas and liquid channels of the environmental control system, and provide the circulation circuit of the coolant.Therefore, before returning, when separating the ascending section from the descending section, it is not only necessary to remove the mechanical connection, but also to cut off the connecting cable, gas and liquid connection channels, and to seal the liquid channel section.[2]
Generally, the interstage separation technology includes three aspects: (1) the key technology of mechanical connection disconnection between the ascending section and the descending section.Explosive bolts are widely used to disconnect the mechanical connection between stages, and explosive bolts are used to disconnect the mechanical connection in China's "Chang'e" Phase III and "Apollo" projects.Generally, four explosive bolts are used to connect the ascending and descending sections of the lunar module. The explosive bolts have the advantages of large bearing capacity, simple structure, reliable operation and convenient use;(2) The key technology to disconnect the connecting cable between the ascending section and the descending section.In addition to the above mechanical connection disconnection, the separation between the ascending and descending segments of the lunar module also includes the connection cable and gas liquid channel disconnection technology closely related to astronauts.Based on the previous manned moon landing and China's manned spaceflight research achievements, in general, the interstage cable disconnector can be used to disconnect the connecting cables between the lower levels, and the gas-liquid channel disconnector can be used to disconnect the interstage gas and liquid channels;(3) Key technology of automatic sealing of gas-liquid channel section in ascending and descending sections.After the cables, water supply channels, oxygen supply channels, etc. in the ascending and descending sections of the manned lunar module are disconnected, the automatic sealing device at the fracture must be highly reliable, or the life safety of astronauts will be seriously threatened.For lunar landers, the disconnection surface of the gas-liquid channel is generally located at the separation mechanism. The rising section and the falling section are connected through the separation mechanism with explosive bolts. During separation, the explosive bolts detonate. The separation mechanism is disconnected along the separation surface. The separated gas-liquid channel end faces should be automatically sealed as required to avoid gas and liquid leakage.The automatic sealing device has the characteristics of simple structure, stability and reliability. Apollo adopts a compression type double seal package.[2]
Key technologies of soft landing
Achieving soft landing on the lunar surface and ensuring the safety of astronauts is one of the most critical technologies in the whole lunar exploration mission. Whether the lunar module can land stably and safely on the lunar surface is directly related to the success or failure of the entire exploration mission.There are many ways for spacecraft to achieve soft landing, and the buffer methods used for spacecraft soft landing are mainly as follows: parachute, landing buffer rocket, buffer airbag, mechanical buffer, compression energy absorption buffer.In the unmanned lunar probe launched by the United States and the former Soviet Union, the mechanical buffer and the compressed energy absorption buffer are combined as the soft landing system, while in the Apollo manned lunar landing program, the lunar module soft landing system uses the compressed energy absorption buffer.In the new round of lunar exploration, various countries have applied MR buffer, oil-gas buffer, metal rubber buffer, etcLunar soft landingFeasibility study.With the emergence of new buffer materials, especially the mature application of semi-active buffer technology, breaking through the traditional aluminum honeycomb buffer device and finding simple, controllable and reliable buffer materials is the development trend of the future manned lunar soft landing field.[2]
Cushioning performance analysis and crashworthiness design
There is constant exchange of momentum and momentum moment between spacecraft and astronauts, and this interaction is random, uncertain and highly coupled in terms of action form, action scale, action intensity, action position and scope, action time and time.Must be in a manned spacecraftdynamic model The role and influence of astronauts should be taken into consideration.[2]
The domestic research on lunar landers mainly focuses on unmanned landers, without considering the participation of astronauts and crash characteristics.For the final landing process of manned lunar landing, various unexpected situations may occur. The lunar module may overturn or crash. Whether the main structure of the lunar module is not fatally damaged, and whether astronauts can use the ascending module to return, are extremely important issues.Therefore, it is necessary to conduct crash analysis and crashworthiness design research on the lander.The research in this field in China is still in its infancy, lacking relevant experience in crash test and simulation analysis of the whole aircraft, and even less relevant design standards and test standards.[2]
Design technology of flexible hinge for soft landing mechanism
Since the lunar surface is not flat, when the lunar module lands on the sloping lunar surface, the lunar module also has a slope relative to the horizontal plane at the landing place. For manned lunar module, if the lunar module is not horizontal after landing, it will cause a lot of inconvenience. Flexible hinges can be used for self leveling design of the lunar module.Flexible hinges are used for each landing leg, and the flexible hinges are optimized to keep the lunar module nearly horizontal within a certain range of landing slope.The weight of the lander and the resistance moment of the flexible hinge work together to make the lunar module achieve static balance.The key of lunar module flexure hinge design is how to derive the rotational stiffness of the flexure hinge, and optimize the flexure hinge and mechanism parameters.In view of the early use of trial and error method in flexometer technology, systematic analysis and design methods based on topological structure are now widely used.It mainly includes: rigid body replacement method (pseudo rigid body model method, structural matrix method), continuity method (topology optimization method, homogenization method, basic structure method, window function method, level set method), constraint design method, topology synthesis method based on screw theory, module method, etc.[2]
Key Technology of Asymmetric Manned Lunar Module Design
The lunar module generally has two types of symmetrical layout and asymmetrical layout.Symmetrical layout has been adopted in the lunar exploration field.However, relevant research shows that on the basis of the same reliability and stability, the asymmetric lunar module can reduce the structural mass by about 10% compared with the symmetric lunar module.[2]
The advantages of asymmetrical lunar module compared with symmetrical lunar module are summarized as follows: (1) The asymmetrical distribution of landing legs is conducive to balancing the position of the center of gravity of the lunar module, facilitating the arrangement of mechanisms, simple structure, convenient for carrying and easy to adapt to the loading requirements of transport space;(2) The lunar module with asymmetrical distribution of landing legs can improve the landing stability of the lunar module. Research shows that the asymmetrical four leg landing structure, compared with the symmetrical four leg landing structure, extends the two legs on one side of the asymmetrical four leg structure outward, increasing the distance between the foot pad and the axis of the body by 33%, which greatly improves the landing stability.At the same time, the asymmetric lunar module can adapt to other mission requirements.[2]
Although symmetrical lunar module is still the mainstream choice for lunar exploration, China's "Chang'e" Phase II and Phase III use symmetrical lunar module layout.However, due to the excellent landing performance of asymmetric lunar module, its relatively light weight is also suitable for large-scale lunar module, especially manned series. Foreign research has been widely carried out, and its research has also achieved phased results.[2]
Development overview
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First manned
Apollo 9
On March 3, 1969, the first manned mission of the lunar module was carried outApollo”The launch of No. 9 was successful.The basic purpose of this mission is to conduct flight appraisal for this part of the whole spacecraft system.In addition, it is also necessary to prove whether the lunar module can complete its task under the condition of weightless flight with the cooperation of command and service module.This work does not require flying to the moon, so the Apollo 9 mission was carried out in Earth orbit.According to the plan, during the flight, astronauts will enter the lunar module under three different conditions. First, a large number of procedures and other items will be checked. Second, the lunar module will be started and closed many times.It is the only time that the lunar module is powered on and powered off more than once in flight.The purpose of this is to find out what may go wrong, refine the program developed in the simulation process, and complete the task more accurately.
First moon landing
Apollo 11
July 21, 1969（US Eastern Time）At 4:17:40 p.m., American astronautsArmstrongandAldrinThe lunar module of Apollo 11 landed safely atMoon“Sea of Tranquillity”This is the world's first lunar module to land on the surface of the moon.They erected on the moonFlag of the United States, collected lunar surface rock samples, placed seismometers and laser reflectors, and conducted lunar surface detection.At 21:36:20, they lit the rocket in the ascending phase of the lunar module and flew away from the moon.Then another astronautCollins They are flying around the moon in the command module. After meeting and docking with the command module, Amstellian and Aldrin moved the collected data into the command module through an 80cm "tunnel", and then the ascending section of the lunar module was thrown away.About two and a half days later, at 12:50:35 on July 24, 1969 (US Eastern Time), the command module carrying three astronauts splashed down safelythe pacific oceanWe ended their 195 hours, 18 minutes and 35 secondsMoonsail.Since then, the United States has "Apollo 12, the lunar module 14-17 carrying two people eachastronautThey landed on the surface of the moon and carried out a lot of activities and scientific exploration in the central part of the moon, from which they obtained a lot of valuable information.
For every lunar mission, the soft landing support of the lunar module is undoubtedly one of the most critical devices.The soft landing support can ensure that the lunar module can land on the moon surface safely and smoothly, so that astronauts can exit the module and carry out lunar surface exploration activities smoothly.At the same time, the soft landing support also acts as the launching frame of the lunar surface raiser, ensuring that astronauts can reliably enter the lunar orbit from the lunar surface with lunar samples, and finally safely return to the earth.The design of the soft landing support for the Apollo lunar module has the following characteristics:;(2) The design adopts four groups of "cantilever" landing legs, retractable and deployable configuration, which is the comprehensive optimization result of fully considering the factors such as mass, landing stability, carrier envelope requirements, and various adverse working conditions;(3) The aluminum honeycomb is used as the buffer element, which has high energy absorption efficiency and light weight. It is an effective, reliable and simple method for the disposable lunar module soft landing support;(4) The spring driven deployment locking mechanism is simpler in system design and can be relatively independent compared with motor driven, hydraulic driven, fire operated and other modes.The key problem is to solve the motion optimization of the mechanism, without interference and dead point, and to ensure the repeated operation accuracy of the mechanism.[3]
Robot lunar module
On February 14, 2024, the US space exploration company SpaceX and Intuition Machine Company will launch a private lunar exploration mission, code named IM-1.The mission sent the robotic lunar module "Odysseus" developed by Intuition Machine Company to the moon from Cape Canaveral Space Base, Florida, at 12:57 a.m. EDT on February 14 (05:57 GMT) via the Falcon 9 rocket of SpaceX Company.SpaceX said that Odysseus will try to make history on February 22. If successful, it will become the first private spacecraft ever to soft land on the moon surface[4]。
