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

vehicle on the launch pad during the period of thrust
buildup.
launch umbilical tower
A frame platform upon which a steel towerlike structure,
used to support and service the umbilical arms, is
located. The tower also supports and houses equipment
needed to perform certain service and checkout functions
on the space vehicle prior to launch.
launch vehicle
The part of a space vehicle that supplies the propulsion
and guidance to reach the prescribed velocity, position,
and attitude required for injection into the desired trajectory.
Today’s launch vehicles consist of two, three, or
more propulsive stages, and can be classified in a number
of ways. One of these is according to launch capacity, as
shown in the table (“Launch Vehicle Types”). Further
classification is possible into expendable, or nonreusable,
launch vehicles and nonexpendable launch vehicles.
launch window
The period during which a spacecraft must be launched
to achieve its given mission trajectory.
launcher deflector
A device constructed of steel or reinforced concrete, or a
combination of both, that deflects the booster engine
flame in controlled directions.
L-band
See frequency bands.
LDEF (Long Duration Exposure Facility)
A package of 57 experiments placed in Earth orbit by the
Space Shuttle to study the effects of exposure to the environment
of space. The LDEF was supposed to have been
recovered after about one year. However, delays in the
Shuttle program meant that the package was not brought
back until January 1990, just a few weeks before it would
have reentered the atmosphere and been destroyed.
LDEF was designed to provide long-term data on the
Launch Vehicle Types
Leasat (Leased Satellite) 233
space environment, including micrometeoroid and radiation
bombardment, and its effects on materials and satellite
systems (including power, propulsion, and optics), as
well as the survivability of microorganisms in space. The
mission’s experiments included the participation of more
than 200 principal investigators from 33 private companies,
21 universities, 7 NASA centers, 9 Department of
Defense laboratories, and 8 foreign countries. Its planned
retrieval was temporarily postponed in March 1985, and
then indefinitely postponed following the Challenger disaster
in 1986. Finally, it was brought back to Earth by
STS-32 in January 1990. Many of the experiments benefited
from their extended stay in space; in particular, it was
found that many of the microorganisms onboard had survived,
shielded beneath a layer or two of dead cells.
Shuttle deployment
Date: April 8, 1984
Mission: STS-41C
Orbit: 344 × 348 km × 28.5°
Size: 9.1 × 4.3 m
Total mass: 3,625 kg
Le Prieur, Yves Paul Gaston (1885–1963)
A French naval lieutenant who invented a small solidfueled
rocket designed to be fired from French or British
biplanes against German captive observation balloons.
La Prieur rockets were used in France in World War I.
Leasat (Leased Satellite)
A series of satellites, launched in the 1980s and developed
as a commercial venture, to provide dedicated communications
services to the American military. The
program stemmed from Congressional reviews in 1976
and 1977 that advised increased use of leased commercial
facilities. Owned by Hughes Communications, the satellites
are designed to provide global UHF communications
to military air, sea, and ground forces. The system’s
primary user was the U.S. Navy, with some support also
provided to the Air Force and ground mobile forces. The
Leasats, along with the Navy’s FLTSATCOMs (Fleet
Satellite Communications satellites), have now been
Capacity (kg)
Launch Vehicle (LV) LEO GTO Examples
HLLV (heavy-lift) >10,000 >5,000 Ariane 5, Titan V, Space Shuttle, Zenit
LLV (large) 5,000–10,000 2,000–5,000 Ariane 4, Atlas IIAS, CZ-2E, H-2, GSLV
MLV (medium) 2,000–5,000 1,000–2,000 Delta 7925, CZ-3, PSLV, Molniya, Tsyklon
SLV (small)