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

332 PSLV (Polar Satellite Launch Vehicle)
upgraded form of the Breeze-K currently employed as
the Rockot third stage—to increase geostationary transfer
orbit payload capacity by 25% to 5,500 kg.
PSLV (Polar Satellite Launch Vehicle)
A four-stage Indian launch vehicle capable of placing a
one-ton payload into polar orbit. Its development allows
India to launch its own IRS (India Resource Satellite)
missions, rather than relying on Russian launch services.
The PSLV uses a four-stage core vehicle surrounded by
six strap-on boosters of the type developed for the ASLV.
At liftoff only two of the strap-ons and the bottom stage
of the core vehicle are ignited. The other four boosters
are fired at an altitude of 3 km. The core vehicle is
unusual in having two solid-propellant stages (1 and 3)
and two liquid, hypergolic stages (2 and 4). The PSLV
was first launched on September 20, 1993, became operational
in March 1996, and has since successfully
launched several payloads, including IRS-P4 (Oceansat)
and two piggyback satellites, the Korean KITSAT and the
German TUBSAT, on May 26, 1999. See Indian launch
vehicles.
Total mass: 294 tons
Height: 44.4 m
Maximum diameter: 2.8 m
Payload to polar orbit: 1,000–2,000 kg
Thrust
First stage (+ 6 strap-ons): 8,600,000 N
Second stage: 725,000 N
Third stage: 340,000 N
Fourth stage: 14,800 N
pulse detonation engine
A rocket engine that works somewhat like an automobile
engine, by injecting fuel and oxidizer into long cylinders
and igniting the mixture with a spark plug. The explosive
pressure of the detonation pushes the exhaust out the
open end of the cylinder, providing thrust to the vehicle.
Pulse detonation technology is one of the approaches to
future low-cost launch vehicles being investigated at
Marshall Space Flight Center, which could lead to lightweight,
low-cost rocket engines. The pulse-jet and the
nuclear pulse rocket employ the same principle of
repeated controlled explosions.
pulse-jet
A type of air-breathing engine in which air is compressed
by a series of spring-loaded, shutter-type valves
located ahead of the combustion section. As in a ramjet,
compression is achieved without the use of a compressor;
however, whereas combustion in the ramjet is continuous,
in the pulse-jet it is intermittent. Air is admitted
through the valves, and combustion begins. This increases
the pressure and closes the valves, preventing backflow
through the inlet. As the gases expand through the rear
nozzle to produce thrust, the pressure in the combustion
section drops to the point where the valves open again to
admit fresh air, and the cycle is repeated. The basic idea
for the pulse-jet came from Paul Schmidt, of Munich, at
the start of World War I, but its most infamous manifestation
was the German V-1 “buzz bomb” (see “V”
weapons).
pulsed-plasma thruster (PPT)
A type of electromagnetic propulsion that has been
used on a number of satellites for station-keeping. The
Air Force’s LES-6 communications satellite, for example,
had four PPTs each producing about 12 million pulses
over the lifetime of the thruster. A PPT works by ablating
(see ablation) and ionizing material from a fuel bar (typically
made of a chlorofluorocarbon such as Teflon) with
the current from a discharging capacitor. The positive
ions released are then accelerated between two flat-plate
electrodes—one positive, the other negative—arranged in
the form of two long, parallel rails, which are connected
across the capacitor. Escaping from the spacecraft, the
accelerated ions produce a thrust of several hundred newtons.
The capacitor is then recharged from a power supply
and the pulse cycle repeated.
purge
To rid a line or tank of residual fluid, especially of fuel or
oxidizer in the tanks or lines of a rocket after an actual or
simulated test firing. It is done using a purging system that
introduces a noncombustible gas, such as carbon dioxide,
into the space above propellants to force out any
toxic or combustible materials.