The aerospace engineering system is a system at the upper level of the spacecraft system, and if the spacecraft wants to play its functional role, it must be launched at the launch site with a carrier vehicle, and the carrier rocket and spacecraft must be measured and controlled through the ground measurement and control system, so that the spacecraft can enter the predetermined orbit, and the attitude and orbit of the spacecraft can be adjusted, and then, with the cooperation of the ground application system ( except for the retrievable satellite and the scientific test satellite ), the function of the spacecraft can finally be brought into play. Therefore, in addition to spacecraft, aerospace engineering systems also have launch systems (rockets, space shuttles, etc.) that send spacecraft into orbit.
There are launch sites for the assembly, testing, refueling and launch of launch vehicles and spacecraft before launch, ground measurement and control systems (measurement and control centers, measurement and control stations, measurement and control ships, etc.) for measuring and controlling carriers and spacecraft, and ground application systems that cooperate with spacecraft in orbit to play predetermined specific functions.
For deep space exploration and scientific research probes, the spacecraft system has one less real-time, continuously working application system than artificial earth satellites, but there is an application system for scientific research after the fact.
For manned spacecraft, spacecraft systems have several more systems than artificial Earth satellite (unmanned spacecraft) engineering systems, such as astronauts, escape lifesaving, and landing fields.
Spacecraft must cooperate and coordinate with carrier vehicles, launch sites and recovery facilities, ground measurement and control systems, and ground application systems to jointly complete space missions.
Spacecraft are the main components of the aerospace engineering system and the core of the aerospace engineering system.
The figure below is a typical satellite engineering system.
In aerospace engineering systems, systems other than spacecraft are all external environmental systems of spacecraft systems. When designing spacecraft systems, it is necessary to design the environment of other aerospace engineering systems other than spacecraft as constraints.
Let's look at the core spacecraft system
Spacecraft refers to the spacecraft that performs specific tasks such as exploration, development, and use of space and celestial bodies beyond the Earth, also known as space vehicles.
The specific classification of spacecraft is shown in the figure.
1. Classification of spacecraft
Spacecraft can be divided into unmanned spacecraft and manned spacecraft according to whether they are manned or not;
According to the use of spacecraft, it can be divided into civilian spacecraft and military spacecraft;
According to the spacecraft field, it can be divided into manned field, remote sensing field, navigation field, communication field, space science field, deep space exploration field and so on.
Different types of spacecraft, their supporting systems will be different.
1) Unmanned spacecraft
Artificial Earth satellites are the most numerous and widely used unmanned spacecraft, accounting for more than 90% of the total number of spacecraft launched. Artificial Earth satellites can be divided into scientific satellites, technical test satellites and application satellites according to their uses.
Science satellites are satellites used for scientific exploration and research, mainly including near-Earth space physical exploration satellites and astronomical satellites, and the hard X-ray modulation telescope satellites launched by China in 2017 belong to this category.
Technological test satellites are artificial satellites used for principled or engineering tests of space technology and space application technology. Some new technologies, new principles, new schemes, new instruments and equipment of spacecraft often need to be verified in orbit before they can be put into use.
For example, China's "Shijian Eighteen" and other new technology verification satellites.
Other experiments are done through entire spacecraft, such as rendezvous and docking of cooperative targets. Application satellites are artificial earth satellites that directly serve the national economy, military, culture and other fields. Application satellites have the largest number and the largest number of types of satellites launched in various types of artificial earth satellites, and can be divided into navigation satellites, earth resource satellites, marine satellites, reconnaissance satellites, communication satellites, meteorological satellites, etc. according to their uses, such as China's "Beidou-2" and "Beidou-3" series of satellites.
Space platforms are a new development of unmanned spacecraft, and they differ from satellites in that they repair, replace equipment, refuel, resupply consumables, or recover equipment or other items in orbit. Space platform requirements are easy to load, disassemble and replace, adapt to carry different payloads, adapt to different carrying launches, and can be reused.
Space probes mainly explore extraterrestrial space and celestial bodies, such as China's "Chang'e-1" satellite and "Chang'e-3" probe.
2) Manned spacecraft
In accordance with the way of flying and working,
Manned spacecraft are divided into four categories: space stations, manned spacecraft, space shuttles and aerospace aircraft.
The space station is a manned spacecraft that has certain test or production conditions, can be used by astronauts to live and work, and operates in orbit for a long time.
Manned spacecraft can ensure that astronauts perform space missions in space, and can enable astronauts to return to the ground landing spacecraft in the cockpit or return capsule. Manned spacecraft is a kind of space-to-earth round-trip transporter, which is divided into satellite manned spacecraft (for the space station to transport astronauts and items round-trip), lunar manned spacecraft and planetary manned spacecraft. China's Shenzhou series spacecraft are satellite-type manned spacecraft, and the American Apollo series spacecraft are lunar manned spacecraft.
The Space Shuttle is a part of a manned or cargo space vehicle that travels between the ground and space space and is partially reusable. At present, only the United States and the Soviet Union have developed and launched space shuttles.
Aerospace aircraft are a new generation of spacecraft that combines aviation and spaceflight, and a combination of launch vehicles and spacecraft that can be reused multiple times. In addition to using rocket engines, it uses aero engines to work with the help of air as an oxidant when launching ascent and re-entering the atmosphere.
2. The composition of the spacecraft
The spacecraft consists of several subsystems with different functions. In general, spacecraft can be divided into two parts: payload and spacecraft platform.
1) Payload
Payload refers to the instruments, equipment, personnel, test organisms and specimens loaded on the spacecraft that directly complete a specific space mission. The spacecraft payload is the most critical subsystem for the spacecraft to complete its space mission in orbit.
Payloads are the core of spacecraft, and the payload of spacecraft varies from mission to mission, so there are many kinds of them. Spacecraft payloads according to the purpose,
Remote sensing payloads refer to various remote sensors for Earth observation, including visible light remote sensors, multispectral scanners, infrared remote sensors, microwave radiometers, synthetic aperture radars, microwave scatterometers, etc. These remote sensors can obtain various information on the ground (water surface) or the atmosphere, space, etc.
Communication payloads refer to transponders and antennas, which can be used for satellite communications and occupy an extremely important position in various space activities.
Navigation payloads refer to various instruments and equipment that provide spatial and temporal references. Such payloads can be used for satellite navigation, such as high-stability atomic clocks, radio beacon machines, etc.
Scientific detection payloads refer to various instruments and equipment used for space environment detection, astronomical observation and space science experiments, including X-ray telescope spectrometers, solar optical telescopes, ion mass spectrometers, X-ray spectrometers and various space environment measurement and monitoring devices.
Other payloads mainly include two kinds of new technology test payloads and special payloads. The new technology test payload refers to some new spacecraft, subsystems and instruments and equipment and even components and other technologies that have not been tested in orbit, and are launched into a certain orbit by special new technology test satellites to verify their principles, schemes, feasibility, compatibility and reliability. Special payloads are non-technical payloads, such as space tourism (payloads are tourists), space memorabilia (payloads are envelopes, flags, etc.).
2) Spacecraft platform
A spacecraft platform is a satellite service (or support) system that can support one or several combinations of payloads.
The spacecraft platform can provide mechanical support, working power supply, attitude orbit control, condition monitoring, thermal environment protection, management control and other services for the normal operation of the payload.
Spacecraft platforms generally include attitude and orbit control subsystems, structure and mechanism subsystems, thermal control subsystems, power subsystems, measurement and control and digital tube subsystems.
The function of the attitude and orbit control subsystem (referred to as the attitude control subsystem) is to maintain or change the attitude and orbit of the spacecraft in operation.
In order to complete its special mission, each spacecraft has its specific nominal orbit and desired posture. However, due to the launch error, the attitude control subsystem needs to adjust the attitude or carry out orbital maneuvering; during orbital operation, due to the role of the external environmental interference force/torque, and the role of the internal electromechanical components interference force/torque, the spacecraft will deviate from the nominal orbit and the desired attitude, and the attitude control subsystem is responsible for attitude and orbit retention.
The structural and institutional subsystem includes the structural subsystem and the institutional subsystem.
The function of the structural subsystem is to provide the overall configuration of the spacecraft, provide support for the equipment on the spacecraft, and support the entire spacecraft during the launch of the launch of the launch vehicle (generally referred to as the active segment) and during the orbital maneuver, bear and transmit the load, and ensure that the entire spacecraft has sufficient strength and stiffness. The mechanism subsystem enables the spacecraft or a part thereof to complete the prescribed movement and places them in the required working state or working position. The general mechanism subsystem includes the unfolding and locking mechanism (such as the deployment and locking mechanism of the solar wing and the antenna, etc.), the separation and indentation mechanism (such as the connection and separation between the satellite and the launch vehicle, etc.), the driving mechanism (such as the solar wing to the sun directional drive mechanism and the antenna expansion or tracking of the driving mechanism, etc.), rendezvous docking mechanism, the door locking and unlocking mechanism, etc.
The task of the thermal control subsystem is to control the temperature of the instrument equipment and the structure of the star itself on the spacecraft during the flight of the spacecraft, and to ensure that the working temperature of each stage of orbit operation is within the required range, so as to ensure the normal operation of the spacecraft in orbit.
Power subsystems ( also known as power supply and distribution subsystems ) are designed to provide power to a satellite during its orbital operating lifespan , including during daylight and during shadow . Due to the long operating life of spacecraft in orbit, most of them use power sources that can be powered for a long time. The power subsystem should have functions such as power generation, energy storage, distribution, bus voltage regulation and battery charge and discharge control, and some also require the configuration of secondary power sources that transform and stabilize multiple voltages.
The function of measurement and control and digital tube subsystem is to realize the functions of satellite telemetry, remote control, orbit tracking and measurement, and data tube management under the cooperation of other subsystems and ground. The task of telemetry is to measure the working status, engineering parameters, environmental parameters and related data of the instruments and equipment of the satellite-related system. Remote control is to send instructions from the ground to control the working status of the instruments and equipment of the system and inject data or programs into the satellite. Orbit tracking and measurement is returned through the transponder transmitted by the ground radio waves through the satellite, and the satellite movement speed, distance and angle are measured according to the radio wave transmission characteristics, and finally the satellite orbit parameters are calculated by the ground. Data management is the use of satellite computers to carry out comprehensive management of satellite data.
The engineering architecture of the core spacecraft in the overall aerospace engineering is like this, and a simple functional introduction is made. I hope you have a macro concept.
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