Chapter 3
A Brief History of Space Flight
Outer space (or simply space) is the expanse that exists beyond the Earth and
between celestial objects, and it is not completely empty but a hard vacuum containing
a low density of particles, predominant plasma of hydrogen and helium, as well as
electromagnetic radiation, magnetic fields, neutrinos, dust and cosmic rays. There has
not been a clear boundary between the Earth’s atmosphere and space while the density
of the atmosphere gradually decreases with altitude increasing. Conventionally, an
altitude of 100 km above sea level, also called Kármán line, was used as the start
of outer space in the Outer Space Treaty which entered into force in 1967. The
Kármán line was calculated by Theodore von Kármán (1881−1963), a HungarianAmerican mathematician, physicist and aerospace engineer because, at an altitude of
about 100 km, an aero-craft would have to travel faster than orbital velocity to derive
sufficient aerodynamic lift from the atmosphere to support itself. The altitude of 100
km is thereby used as a working definition for the boundary between aeronautics and
astronautics. Outer space is the common resource of mankind, and the exploration
and utilization of outer space is the unremitting pursuit goal of mankind.
Space flights (or astronautic flights) are various kinds of ballistic flight activities
of the spacecrafts into or through outer space, including orbiting the Earth, interplanetary space flight, interstellar space flight, flying around celestial objects, flying over
celestial objects, landing on celestial objects and returning from celestial objects.
The objectives of space flights are to explore, develop and use the resources of outer
space and celestial objects, and to benefit mankind on the Earth. Traveling in space
and exploring the universe has always been the oldest, simplest and most beautiful
dream of human beings. For thousands of years, a long and splendid human civilization has spread many wonderful myths and moving legends about space flights. At
the beginning of the twentieth century, the pioneers dedicated to studying modern
aerospace science had initially established a basic theoretical system of rockets and
space flights, which had been increasingly widely disseminated. The societies to
study space flights were successively built in many counties in the world, and they
promoted to develop the modern astronautic sciences and technologies. The first
artificial Earth satellite, Sputnik-1, was successfully launched by the Soviet Union in
© National Defense Industry Press and Springer Nature Singapore Pte Ltd. 2021
P. Shuai, Understanding Pulsars and Space Navigations, Navigation: Science
and Technology 11, https://doi.org/10.1007/978-981-16-1067-7_3
87
A Brief History of Space Flight
Outer space (or simply space) is the expanse that exists beyond the Earth and
between celestial objects, and it is not completely empty but a hard vacuum containing
a low density of particles, predominant plasma of hydrogen and helium, as well as
electromagnetic radiation, magnetic fields, neutrinos, dust and cosmic rays. There has
not been a clear boundary between the Earth’s atmosphere and space while the density
of the atmosphere gradually decreases with altitude increasing. Conventionally, an
altitude of 100 km above sea level, also called Kármán line, was used as the start
of outer space in the Outer Space Treaty which entered into force in 1967. The
Kármán line was calculated by Theodore von Kármán (1881−1963), a HungarianAmerican mathematician, physicist and aerospace engineer because, at an altitude of
about 100 km, an aero-craft would have to travel faster than orbital velocity to derive
sufficient aerodynamic lift from the atmosphere to support itself. The altitude of 100
km is thereby used as a working definition for the boundary between aeronautics and
astronautics. Outer space is the common resource of mankind, and the exploration
and utilization of outer space is the unremitting pursuit goal of mankind.
Space flights (or astronautic flights) are various kinds of ballistic flight activities
of the spacecrafts into or through outer space, including orbiting the Earth, interplanetary space flight, interstellar space flight, flying around celestial objects, flying over
celestial objects, landing on celestial objects and returning from celestial objects.
The objectives of space flights are to explore, develop and use the resources of outer
space and celestial objects, and to benefit mankind on the Earth. Traveling in space
and exploring the universe has always been the oldest, simplest and most beautiful
dream of human beings. For thousands of years, a long and splendid human civilization has spread many wonderful myths and moving legends about space flights. At
the beginning of the twentieth century, the pioneers dedicated to studying modern
aerospace science had initially established a basic theoretical system of rockets and
space flights, which had been increasingly widely disseminated. The societies to
study space flights were successively built in many counties in the world, and they
promoted to develop the modern astronautic sciences and technologies. The first
artificial Earth satellite, Sputnik-1, was successfully launched by the Soviet Union in
© National Defense Industry Press and Springer Nature Singapore Pte Ltd. 2021
P. Shuai, Understanding Pulsars and Space Navigations, Navigation: Science
and Technology 11, https://doi.org/10.1007/978-981-16-1067-7_3
87