AEROSPACE

AEROSPACE

Aerospace

Aerospace refers to areas related to research and exploration of outer space, spacecraft navigation activities in space. The scientific community generally refers to navigational activities within the solar system as "aerospace and navigational activities outside the solar system as "aerospace."

According to the objects of spacecraft exploration, development and utilization, spaceflight includes orbiting the earth, sailing to the moon, sailing to other planets and their satellites in the solar system, interplanetary navigation (interplanetary navigation, interstellar navigation). According to the relationship or position of spacecraft with objects of exploration, development and utilization, space flight methods include flying (passing near celestial bodies), orbiting (flying around celestial bodies), landing (landing on celestial bodies), returning (away from celestial bodies, back to Earth).

Space activities that perform military missions (with military purposes) are called military aerospace; space activities that carry out civil missions (with non-military purposes) such as scientific research, economic development, and industrial production are called civil space; (Profit-making) aerospace activities, called commercial aerospace. Space activities of manned spacecraft are called manned spaceflight; space activities of unmanned spacecraft are called unmanned spaceflight.

The main purpose of spaceflight is space exploration, and its commercial use is mainly satellite communications, as well as the recent rise of space tourism. Other non-commercial uses include starry sky observation, spy satellites and earth observation.

History

The feasible space travel program can be traced back to Konstantin Tsiolkovsky, his most famous work ("Explore the Space with Reaction Facilities") published in 1903 at the earliest, he theoretically demonstrated that multi-stage rockets can overcome gravity and enter space, but this theoretical work at that time did not have a wide impact outside the Soviet Union.

Spaceflight became a viable project since 1919. Robert Goddard published the paper "The Way to Reach High Altitude"; which applied the Laval nozzle to the liquid rocket engine, and its enough power to make interstellar travel possible. He also proved in the laboratory that the rocket can work in a vacuum space, but it was not generally accepted at the time. This paper has a great influence on the key figures of later aerospace engineering, including Herman Obert and Werner von Braun.

1.      In June 1944, the German V-2 rocket reached an altitude of 189 km in a flight test, which was the first rocket to reach space.

2.      On October 4, 1957, the Soviet Union launched Sputnik 1, which was the first artificial satellite to enter Earth orbit.

3.      On April 12, 1961, Orient One carried Soviet astronaut Yuri Gagarin in an orbit around the earth once, which was the first manned space flight. Orient One was designed by Sergey Korolev and Klim Aliyevich Klimov.

Emission

Rocket launches are usually on the launch site, where there are a full set of test facilities and equipment to assemble, store, detect and launch spacecraft, measure flight orbits, send control commands, receive and process telemetry information. For noise and safety reasons, the launch site was chosen to be far away from human habitation. Most of the space launch sites are transformed from missile test ranges, and their component equipment and functions are basically the same.

The emission is usually limited by a certain emission window. These windows depend on the position of the celestial body and the orbit relative to the launch site. Once launched, the orbit is usually on a relatively fixed plane, which is at a fixed angle to the earth's axis, and the earth rotates in this orbit.

Space Flight Speed Requirements

Cosmic velocity is the general name of the four representative initial velocities for objects starting from the earth and moving in the gravitational field of celestial bodies. Depending on its mission, the spacecraft needs to reach one of these four cosmic velocities.

First Cosmic Velocity

The first cosmic velocity, also known as orbital velocity, refers to the minimum initial velocity required for an object launched on the earth to make a circular motion around the earth. At a flight altitude of 150 kilometers, its orbital speed is 7.8 kilometers / second.

Second Cosmic Velocity

The second cosmic velocity, that is, the escape velocity of the earth, refers to the minimum initial velocity required for an object launched on the earth to get rid of the gravity of the earth and fly away from the earth. If the spacecraft has reached the altitude of low-Earth orbit, the spacecraft's detachment speed is about 10.9 km / s.

Third Cosmic Velocity

The third cosmic speed, which is the speed of escape of the sun, refers to the minimum initial speed required for an object launched on the earth to get rid of the gravitational constraint of the sun and fly out of the solar system. Originally, in Earth's orbit, the initial speed required to deviate from the gravity of the sun was 42.1 km / s, but when the earth revolves around the sun, all objects on the ground already have an initial speed of 29.8 km / s. To launch, just add 12.3 km / s speed beyond the gravity of the earth.

Fourth Universe Speed

The fourth cosmic velocity refers to the minimum initial velocity required for an object launched on Earth to get rid of the galaxy's gravity and fly out of the galaxy. However, because people have not yet known the exact size and mass of the Milky Way, it can only be roughly estimated, its value is above 525 km / s. In fact, no spacecraft can reach this speed.

Landing

The spacecraft descended to an altitude of about 15km, and its speed has been reduced to subsonic speed. In order to ensure a safe landing, further deceleration measures are required. Ballistic reentry spacecraft often use parachutes as a means of deceleration

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