OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA. TELEPHONE 354-5Oll
FOR RELEASE
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.

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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
JULY 22, 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.

       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 conduct 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 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 kilograms) 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 slowing the spacecraft by about 3,250 miles-perhour (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 to insure 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.

       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 bitsper-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 contractor 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.

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7/21/71
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