The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

CERISE (Characterisation de l’Environment Radio-electrique par un Instrument Spatial Embarque) 71
exclusively in tandem with Atlas but was then adapted
for mating to the Titan III to boost heavier payloads into
Earth orbit and interplanetary trajectories. Today, when
combined with the Titan IV, it makes up the most powerful
expendable launch vehicle in the world. The Centaur
is manufactured by Lockheed Martin and powered
by two Pratt & Whitney restartable RL10 engines. It interfaces
with the payload via a forward adapter, where the
avionics, electrical, flight termination, telemetry, and
tracking systems are mounted. 200 See Ehricke, Krafft.
(See also table, “Centaur Rocket Stage.”)
center of mass
The point in a body at which its entire mass can be considered
to be concentrated.
center of pressure
The point at which the aerodynamic lift on a rocket is
centered. Half the surface area of a rocket lies on one side
of the center of pressure and half on the other side.
centrifugal force
A force that must be included in the calculation of equilibria
between forces in a spinning frame of reference,
such as that of a rotating space station. In the rotating
frame, the forces on a body of mass m are in equilibrium
(as evidenced by the body staying at the same place) only
if all forces acting on it, plus a “centrifugal force” mv 2 /R
directed away from the center of rotation at a distance R,
add up to zero.
centrifuge
A large motor-driven apparatus with a long arm at the
end of which human and animal subjects or equipment
can be rotated at various speeds to simulate the prolonged
accelerations encountered in high-performance
aircraft, rockets, and spacecraft. The earliest centrifuges
were set up in the World War II era, at a time when aircraft
were coming into use that were capable of such
Centaur Rocket Stage
high-g maneuvers that pilots could easily black out. It was
also realized that pilots who were less susceptible to the
effects of g-forces would be able to twist and turn their
planes more sharply and thereby outperform an enemy.
Centrifuges thus served a dual role: to study the medical
effects of high acceleration and to select individuals best
able to cope with such acceleration. A pioneer in this
field was Heinz von Diringshofen of Germany, who, in
1931, began research into the physiology of radial acceleration
forces and established the limits of tolerance to
g-forces that could be sustained for any length of time
without loss of vision or consciousness. Early centrifuges
were set up at two laboratories in Germany, at the Mayo
Clinic, at the University of Southern California, and at
Farnborough in England. Others were built after the war,
including the immense Johnsville Centrifuge, used to
test and train the first American astronauts.
centripetal acceleration
The acceleration associated with motion in a circle and
directed to the center of the circle.
centripetal force
The force that acts toward the center of a circle and makes
circular motion possible. To enable an object of mass m to
move with velocity v around a circle of radius R, a centripetal
force of magnitude mv 2 /R must be applied.
CERISE (Characterisation de l’Environment Radioelectrique
par un Instrument Spatial Embarque)
An experimental ELINT (electronic intelligence) microsatellite
built for the French arms procurement agency
DGA (Delegation Generale pour l’Armement). It is
notable for having suffered the first known accidental
collision between two independent orbiting objects. On
July 21, 1995, a piece of debris from the Ariane 1 third
stage that launched SPOT 1 in 1986 collided with
CERISE. During the impact, the upper portion of
CERISE’s gravity-gradient boom was snapped off. The
Version Diameter (m) Length (m) Engine Type Propellant Mass (kg) Thrust (N)
Centaur I 3.1 9.2 RL-10A-3A (x2) 13,900 147,000
Centaur II 3.1 10.1 RL-10A-3A (x2) 16,800 147,000
Centaur IIA 3.1 10.1 RL-10A-4 (x2) 16,800 185,000
Centaur IIIA (Atlas IIIA) 3.1 10.0 RL-10-4-1 (x1) 16,800 99,000
Centaur IIIB (Atlas IIIB) 3.1 11.7 RL-10-4-1 (x2) 20,800 198,000
Centaur G (Titan IV) 4.3 9.0 RL-10-3A (x2) 20,900 147,000