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1993-04-21
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OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA. TELEPHONE 354-5Oll
FOR RELEASE: THURSDAY, JULY 22, 1971
The Mariner 9 spacecraft is in its 53rd day of flight
today in its 167 day journey to Mars.
It has covered 88,600,000 miles in its 247 million mile
journey and is 9.5 million miles from Earth.
Both Earth and Mariner 9 are oving around the Sun
together with the spacecraft traveling faster and moving away fro
the orbit of Earth towards the orbit of Mars.
Since launch on May 30 this year, more than 600
commands have been sent to the spacecraft. Many of the commands
were routine, but one block of commands has programmed the
onboard computer for automatic insertion of the spacecraft into
Mars orbit on November 13th. In the event command capability
should be lost during the flight, the spacecraft, acting only on
internal commands, is capable of orbiting Mars and returning
scientific data.
Basic objective of the mission is 90 days in orbit and
mapping of about 70% of the Martian surface with two television
cameras. Other experiments will record atmospheric and surface
data.
***
7/21/71
OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA. TELEPHONE 354-5Oll
FOR RELEASE: FRIDAY, JULY 23, 1971
The Mariner 9 spacecraft is in its 54th day of flight
today and has traveled 90 million miles on its 247 million mile
journey to Mars.
Its distance from Earth is 9.7 million miles. Both
Earth and Mariner 9 are moving around away from the orbit of
Earth towards the orbit of Mars.
Since launch on May 30 of this year, more than 600
commands have been sent to the spacecraft. Many of the commands
were routine, but one block of commands has programmed the
on-board computer for automatic insertion of the spacecraft into
Mars orbit on November 13th. In the event command capability
should be lost during the flight, the spacecraft, acting only on
internal commands, is capable oriting Mars and returning
scientific data.
Basic objective of the mission is 90 days in orbit and
mapping of about 70% of the Martian surface with two television
cameras. Other experiments will record atmospheric and surface
data.
The objective of the Mariner mission is to study the
surface and atmosphere of Mars in detail and over a period of
time, to provide a broad picture of the history of the planet and
natural processes currently shaping the Martian environment.
-more-
Recurring phenomena such as dust storms, clouds and seasonal
changes in the appearance of the planet's surface have been
observed on Mars. The orbital mission will allow scientists to
study these phenomena daily at close range.
The Mariner carries a payload of instruments to
condduct six scientific investigations:
- Martian topography and variable features with two
television cameras, one with a wide-angle lens and one with a
telephoto lens;
- surface temperature measurements with an infrared
radiometer;
- composition and structure of the atmosphere with an
ultraviolet spectrometer;
- studies of the planet's surface and composition and
temperature of its atmosphere with an infrared interferometer
spectrometer;
- atmospheric pressure and structure with an S-Band
occultation experiment;
- and a more accurate description of Mar's gravity
field and the orbits of its two moons, and an improved ephemeris
of Mars (its position in its solar orbit at a given time).
The latter two experiments involve measurements of the
Mariner's radio signals back to Earth and do not require special
instruments on the spacecraft.
The scientific experiments have been teamed together to
provide a maximum correlation of the data they gather. The three
-more-
instruments on the scan platform, for instance, are boresighted
with the television cameras so that the photography can be
correlated with measurements of the Martian atmospheric and
surface characteristics.
Mariner 9 will orbit Mars once each 12 hours, inclined
65 degrees to the Martian equator, with a 10,700 mile
(16,090-kilometer) high point in the orbit (apoapsis) and a
750-mile (1,200-kilometer) low point (periapsis).
The spacecraft weighted approximately 2,200 pounds,
(1,000 kilomgrams) at launch, with about 1,000 pounds (454
kilograms) of fuel for the 300-pound thrust retro-engine. After
injection into Mars orbit, the spacecraft will weight
approximately 1,200 pounds (544 kilograms).
Orbit insertion will require about a 14-minute burn of
the retro-engine slowig the spacecraft by about 3,250 miles-per-
hour (1,450 meters-per-second). The spacecraft velocity relative
to Mars prior to the burn will be about 11,000 mph (4,920 m/sec).
The launch was direct ascent without a parking orbit.
The launch aiming point was away from Mars toinsure that neither
spacecraft nor the Centaur second stage would impact Mars in the
event of loss of control during the launch phase. The orbit of
the spacecraft is designed to guarantee that it will not impact
Mars for at least 17 years, to avoid contamination of the planet
before studies are conducted on the surface b landing spacecraft.
-more-
Following successful injection into solar orbit, a
midcourse maneuver was performed to correct the trajectory and
refine the aiming point. A second maneuver will be performed in
late October. The retro-engine is used for midcourse maneuvers.
The accuracy required to orbit Mars is unprecendented
in a flight into deep space. The aiming zone at the end of the
287-million-mile (462-million-kilometer) flight is an area about
435 miles (700-kilometer) on a side.
After insertion into Mars orbit, the spacecraft will be
tracked for a sufficient period to determine the orbital
corrections (trims) required to yield precise orbits. The trims
will be provided by the retro-engine.
The maximum data transmission rate will be 16,200 bits-
per-second when the spacecraft can transmit to the sensitive
210-foot (64-meter) antenna at the Goldstone station of the Deep
Space Network in the California Mojave Deser. Other stations
will receive at a maximum rate of 2.025 bits-per-second.
NASA's Office of Space Science and Applications assigned
project responsibility including mission operations and tracking
and data acquisiton to the Jet Propulsion Laboratory managed by
the California Institute of Technology. The launch vehicle is the
responsibility of the Lewis Research Center, Cleveland. The con-
tractor to Lewis is General Dynamic/Convair, San Diego.
Tracking and communications is assigned to the Deep
Space Net operated by JPL for NASA's Office of Tracking and Data
Acquisition.
Cost of the basic 90-day Mariner Mars '71 mission is
$129 million, exclusive of launch vehicles and data acquisition.
***
7/21/71
#586