The Apollo Program
Apollo 15 Facts
Apollo 15 Crew
Lunar Geologic Science
Lunar Roving Vehicle
Lunar Orbital Science
The Scientific Instrument Module (SIM) bay of the
Apollo J missions was located in Sector 1 of the Service Module. The SIM
shared this space with a third cyrogenic oxygen tank that was added after
the Apollo 13 incident.
Eight experiments were carried in the SIM bay:
- X-ray fluorescence detector
- gamma ray spectrometer
- alpha-particle spectrometer
- panoramic camera
- 3-inch mapping camera
- laser altimeter
- dual-beam mass specrometer
- a subsatellite
From Apollo 15 Press Kit
- X-Ray Fluorescence Spectrometer: Second of the geochemical
experiment trio for measuring the composition of the lunar surface from
orbit. Detects X-ray fluorescence caused by solar X-ray interaction
with the Moon. Analyzes the sunlit portion of the Moon under the spacecraft
Gamma-Ray Spectrometer: On a 25-foot (7.6 m) extendable boom.
Measures chemical composition of lunar surface in conjuction with
X-ray and alpha-particle experiments to gain a compositional "map"
of the lunar surface ground track. The device could measure energy
ranges between 0.1 to 10 million electron volts.
- Alpha-Particle Spectrometer: Measures mono-energetic alpha-particles
emitted from the lunar crust and fissures as products of radon gas isotopes
in the energy range of 4.7 to 9.3 million electron volts. The sensor
was made up of an array of 10 silicon surface barrier detectors.
- 24-inch Panoramic Camera (SM orbital photo task):
Gathered stereo and high-resolution (1 meter) photographs of the
lunar surface from orbit. The camera produced an image size of 11.4
cm x 114.8 cm with a field of view 11 degrees downtrack and 108 degrees
cross track. The rotating lens system could be stowed face-inward to
avoid contamination during effluent dumps and thruster firings. The
72-pound film cassette of 1,650 frames was retrieved by the command
module pilot during a transearth coast EVA. This camera worked in conjunction
with the 3-inch mapping camera and the laser altimeter to gain data
for construction of a comprehensive map of the lunar surface. About
8 percent of the lunar surface was covered by this mission.
- 3-inch Mapping Camera: Provided 20-meter resolution terrain
mapping photography on five-inch film with 3-inch focal length lens.
Also included stellar camera shooting the star field on 35mm film simultaneously
at 96° from the surface camera optical axis. The stellar photos
allowed accurate correlation of mapping photography by comparing simultaneous
star field photos with lunar surface photos of the nadir (straight down).
The stellar camera film was retrieved during the same EVA as the panoramic
- Laser Altimeter: Measures spacecraft altitude above the lunar
surface to within one meter. The instrument was boresighted with the
3-inch mapping camera to provide altitude correlation data. The laser
altimeter light source was a ruby laser operating at 6,943 angstroms,
and 200-millijoule pulses of 10 nanoseconds duration. The laser had
a repetition rate up to 3.75 pulses per minute.
Mass Spectrometer: Attempts to measure composition and distribution
of the ambient lunar atmosphere. The mass spectrometer was on a 24-foot
(7.3 m) extendable boom.
- Subsatellite: Ejected into lunar orbit from the SIM bay and
carried three experiments : S-Band Transponder, Particle Shadows/Boundary
Layer Experiment, and Subsatellite Magnetometer Experiment. The subsatellite
was 31 inches long, (78.7 cm) had a 14-inch (35.6 cm) hexagonal diameter
and weighed 78.5 pounds (35.6 kg).