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3 A Brief History of Space Flight
(11) When the astronauts return to the CSM with the collected lunar samples and
investigated results, the ascent stage is separated from the CSM, and jettisoned
and gotten rid of the orbit. Finally, the ascent stage falls to the lunar surface.
(12) As the engines of the SM are fired, the CSM is put into the Moon-Earth
transfer orbit, and begins to back toward the Earth.
(13) Before the reentry into the Earth’s atmosphere, the SM is separated from
the CM and jettisoned, and the CM is rotated 180 degrees to reenter the
atmosphere with its cone-shaped bottom forward the Earth’s direction.
(14) Under the action of the atmospheric resistance, the CM is decelerated to fall
down, and in the period, the ionization blackout effect will be generated due
to aerodynamic heating.
(15) The parachutes are deployed and the CM is slowly splashed onto the Pacific
Ocean. Shortly thereafter, the astronauts will be rescued by the military
helicopters and escorted to the standby aircraft carrier.
The Apollo flight tests were carried out in four phases as follows.
In the first phase (1961.10−1965.7), a total of 10 Saturn I rockets were launched,
of which the first four were suborbital flight tests and the last six were orbital flight
tests. For the suborbital flight tests, the Saturn I rockets were the two-stage ones with
an S-I first stage, a dummy upper stage as the second stage, and a cone-shaped head
as same as the Jupiter rocket. The test purposes were to investigate the performance
of H-1 engines, multi-stage parallel technology and control system. For the orbital
flight tests, the Saturn I rockets included the up-rated S-I rockets as the first stages
and the S-IV rocket as the second stages, and equipped with the Apollo spacecraft’s
simulators as the payloads. The test purposes were to investigate the performance
of the second stage rocket engine RL-10, the coupling capability between the rocket
and the spacecraft and the aerodynamic characteristics. Meanwhile, fully using the
two-stage Saturn I rockets, several space science exploration satellites were put in
the orbits, such as the Pegasus satellites that were designed to detect micrometeoroid
hits.
In the second phase (1964.5−1966.1), four single-stage Little Joe II rockets were
launched, carrying the Apollo spacecraft’s simulator and the escape tower. For the
first two flight tests, the altitude of the rocket flight reached 5 km, whose purpose was
to investigate the performance features of the escape tower. For the third flight test,
the rocket exploded and ended in failure. For the fourth flight test, the rocket flight
altitude reached 22 km, whose purpose was to investigate the capability of rapidly
separating the escape tower from the rocket.
In the third phase (1966.2−1968.4), using four Saturn IB and two Saturn V rockets,
six unmanned spacecrafts, including three Apollo-Saturn combination (AS) series
and three Apollo series, were respectively launched to carry out the flight tests. On
February 26, 1966, the AS-201 spacecraft was launched by using the Saturn IB
rocket from the Kennedy Space Center, which was a suborbital flight test, with the
maximum altitude of 488 km and the flight duration of 37 min. The mission objectives
were to achieve structural integrity and compatibility of launch vehicle, to launch
payload, and to demonstrate various technical performances, such as coupling and
3 A Brief History of Space Flight
(11) When the astronauts return to the CSM with the collected lunar samples and
investigated results, the ascent stage is separated from the CSM, and jettisoned
and gotten rid of the orbit. Finally, the ascent stage falls to the lunar surface.
(12) As the engines of the SM are fired, the CSM is put into the Moon-Earth
transfer orbit, and begins to back toward the Earth.
(13) Before the reentry into the Earth’s atmosphere, the SM is separated from
the CM and jettisoned, and the CM is rotated 180 degrees to reenter the
atmosphere with its cone-shaped bottom forward the Earth’s direction.
(14) Under the action of the atmospheric resistance, the CM is decelerated to fall
down, and in the period, the ionization blackout effect will be generated due
to aerodynamic heating.
(15) The parachutes are deployed and the CM is slowly splashed onto the Pacific
Ocean. Shortly thereafter, the astronauts will be rescued by the military
helicopters and escorted to the standby aircraft carrier.
The Apollo flight tests were carried out in four phases as follows.
In the first phase (1961.10−1965.7), a total of 10 Saturn I rockets were launched,
of which the first four were suborbital flight tests and the last six were orbital flight
tests. For the suborbital flight tests, the Saturn I rockets were the two-stage ones with
an S-I first stage, a dummy upper stage as the second stage, and a cone-shaped head
as same as the Jupiter rocket. The test purposes were to investigate the performance
of H-1 engines, multi-stage parallel technology and control system. For the orbital
flight tests, the Saturn I rockets included the up-rated S-I rockets as the first stages
and the S-IV rocket as the second stages, and equipped with the Apollo spacecraft’s
simulators as the payloads. The test purposes were to investigate the performance
of the second stage rocket engine RL-10, the coupling capability between the rocket
and the spacecraft and the aerodynamic characteristics. Meanwhile, fully using the
two-stage Saturn I rockets, several space science exploration satellites were put in
the orbits, such as the Pegasus satellites that were designed to detect micrometeoroid
hits.
In the second phase (1964.5−1966.1), four single-stage Little Joe II rockets were
launched, carrying the Apollo spacecraft’s simulator and the escape tower. For the
first two flight tests, the altitude of the rocket flight reached 5 km, whose purpose was
to investigate the performance features of the escape tower. For the third flight test,
the rocket exploded and ended in failure. For the fourth flight test, the rocket flight
altitude reached 22 km, whose purpose was to investigate the capability of rapidly
separating the escape tower from the rocket.
In the third phase (1966.2−1968.4), using four Saturn IB and two Saturn V rockets,
six unmanned spacecrafts, including three Apollo-Saturn combination (AS) series
and three Apollo series, were respectively launched to carry out the flight tests. On
February 26, 1966, the AS-201 spacecraft was launched by using the Saturn IB
rocket from the Kennedy Space Center, which was a suborbital flight test, with the
maximum altitude of 488 km and the flight duration of 37 min. The mission objectives
were to achieve structural integrity and compatibility of launch vehicle, to launch
payload, and to demonstrate various technical performances, such as coupling and