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OFFICE OF PUBLIC EDUCATION AND INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA. TELEPHONE 354-5011
FOR RELEASE MONDAY AM's FEBRUARY 15, 1965
The areas on Mars that are expected to be photographed
by the single television camera aboard Mariner IV have been
determined by the National Aeronautics and Space Administration.
Analysis of Mariner's flight path by engineers at the
Jet Propulsion Laboratory, operated by the California Institute of
Technology, pinpointed the areas.
The target areas were outlined in a notice requesting
amateur and professional astronomers to observe the areas with
ground-based telescopes. The areas can be seen a number of times
over the next several months before and after the closest
approach of Mars to earth in early March.
If the Mariner spacecraft is still operating normally
when it flys by Mars, it will photograph the planet on July 14.
Recording of the first picture will occur when the
spacecraft is approximately 8400 miles above the Martian surface.
The camera will sweep an area some 4000 miles long from the
northern hemisphere, where it will be Fall, down through the
southern hemisphere, where it will be Spring.
When the first of up to 21 pictures is taken, Mariner's
camera will be pointing at the northern Martian desert Amazonis.
The camera's coverage will then sweep southeast below the Martian
equator covering the Mare Sirenum, the southern desert Phaethontis,
Aonius Sinus and into the terminator or shadow line. The space-
craft will be about 6300 miles above Mars for the final picture.
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The picture taking sequence will begin about 8:25 P. M.
EST. Some 25 minutes later, the final picture will be taken and
after another 21 minutes, Mariner will reach its point of closest
approach to Mars at a distance of about 5,400 miles.
The maximum ground resolution will occur near the middle
of the photographic sequence when the camera is pointing nearly
straight down toward the Martian surface in the area of the Mare
Sirenum. At this point the photograph will cover an area approxi-
mately 150 miles on a side and the pictures should resolve
prominent surface markings as small as two miles across.
Not all of the 4000 mile strip to be photographed will
be covered by pictures since only a limited number of pictures
can be stored on the magnetic tape.
The photographs will be stored in digital form on the
tapes and played back to earth when Mariner has passed beyond
Mars. Each picture will consist of about 250,000 bits of data
and will be recorded at 10,700 bits per second.
Transmission rate is 8 1/3 bits per second so, during
the playback sequence, it will take about 8 hours and 20 minutes
to transmit each picture to earth. Each picture transmission will
be followed by 1 1/2 hours of engineering data on the condition of
the spacecraft and then the next picture will be transmitted. It
is planned to repeat the playback of the pictures at least twice.
Mariner IV was launched November 28, 1964, and the
general areas on Mars to be photographed were determined at the
-3-
time of the mid-course correction to Mariner's flight path on
Dec. 5. A requirement for the mid-course maneuver was to time
Mariner's encounter period with Mars to coincide with the
tracking period of the Goldstone Station of the Deep Space Net,
in the Mojave Desert to insure maximum communication and command
coverage.
It has taken a period of detailed analysis of tracking
data since the mid-course maneuver to determine precise target
areas.
The investigators for the TV experiment for NASA are
Dr. R. B. Leighton, Professor B. C. Murray and Professor R. P.
Sharp of the California Institute of Technology.
###
Release No. 17
2/10/65