[Illustration: 42. Lunar Orbiter.]
Directional Antenna
Velocity Control Rocket Engine
Fuel Tank
Nitrogen Gas Reaction Jets
Oxidizer Tank
Lenses
Micrometeoroid Detectors
Flight Programmer
Photographic Subsystem
Sun Sensor (located under equipment deck)
Solar Panel
Canopus Star Tracker
Inertial Reference Unit
Omni Directional Antenna
The Lunar Orbiter project was initiated in 1963 as part of the U.S.
Apollo program to land men on the Moon during the decade of the nineteen
sixties.
Lunar Orbiter’s primary mission was to take and transmit both wide-angle
and closeup images of the Moon. Lunar Orbiters photographed many areas
of scientific interest and provided general photographic coverage of
much of the moon’s surface. These pictures were then used to select the
best landing sites for the first manned lunar landings. Orbiters also
showed that the moon’s gravitational field permitted stable orbits.
_Lunar Orbiter 1_ was launched atop an Atlas-Agena D rocket on August
10, 1966. The last in the project, _Lunar Orbiter 5_, was launched on
August 1, 1967. All five missions were successful.
The first three missions were similar. After each launch, the Agena
stage’s booster engine was fired to send the spacecraft on a 90-hour
coasting trajectory to the Moon, about 386,160 kilometers (240,000
miles) distant.
As the spacecraft neared the Moon, its on-board engine was fired as a
retrorocket to slow the _Orbiter_ and permit it to go into orbit around
the Moon.
The closest approach to the Moon in each orbit was about 45 kilometers
(28 miles), and the spacecraft swung out to about 1850 kilometers (1150
miles) from the Moon.
Photography was conducted while the _Orbiter_ was near the lunar
surface. Lunar photography for the Apollo Program landing-site selection
was completed by the first three Lunar Orbiters. Each was then
intentionally crashed into the Moon to prevent it from interfering with
later missions.
The last two Lunar Orbiters were used for scientific photography of the
Moon. Both were placed into polar orbits so that they could photograph
all of the sunlit areas of the Moon.
Each Lunar Orbiter carried a camera with both a telephoto and a
wide-angle lens. The telephoto lens was capable of resolving objects on
the lunar surface as small as 91.4 centimeters (three feet) in diameter.
The wide-angle lens could resolve objects as small as 7.6 meters (25
feet) in diameter. The photographic images were converted to electrical
signals for transmission to Earth.
The Lunar Orbiter project was a complete success. All spacecraft
operated properly, photographing a total of more than 36-million square
kilometers (14-million square miles) of the moon’s surface.
Prime contractor for the Lunar Orbiter program was the Boeing Company.
Principal subcontractors were Eastman Kodak Company and RCA.
The Lunar Orbiter in the National Air and Space Museum’s collection was
used for thermal testing of spacecraft systems.
_Lunar Orbiter_ is from the National Aeronautics and Space
Administration.
Maximum span
Antenna booms 5.6 m. (18 ft., 6 in.)
Solar panels 3.7 m. (12 ft., 2 in.)
Height 1.68 m. (5 ft., 6 in.) without panels
Weight 385.6 kg. (850 lb.)
Power Electrical; four solar panels with a total area
of just over 4.8 sq. m. (58 sq. ft.) providing
375 w. to nickel-cadmium batteries
Velocity control A 45.4 kg (100 lb.) thrust engine burning a
system hydrazine mixture and nitrogen-tetroxide
oxidizer