The National Aeronautics and Space Administration will launch two Mariner spacecraft, F & G, on fly-by missions to Mars in 1969. Project responsibility is assigned to the Jet Propulsion Laboratory of the California Institute of Technology. NASA's Lewis Research Center, Cleveland, is responsible for the launch vehicle. Tracking and communication will be provided by the Deep Space Net stations operated by JPL for NASA.

       The Mariner Mars '69 launch period falls between mid- February and mid-April. The spacecraft will arrive at Mars between the end of July and mid-August.

       The first spacecraft will be launched as early in the period as possible the second as late as possible. The arrival dates will not be less than five days apart.

       The launch vehicle for this mission is the Atlas/Centaur combination; the first time this combination has been used for planetary exploration. The spacecraft will weigh approximately 900 pounds compared with 575 pounds for the Mariner Mars '64 mission.

       All scientific experiments aboard the Mariner '69 are planet-oriented with particular emphasis on providing data on the atmosphere and surface of Mars. The experiments aboard Mariner '69 are as follows:

Infrared Spectrometer
Measure the infrared spectral energy from the lower atmosphere and surface at 1.9 to 14.7 microns.
Dr. G. C. Pimentel University of California Berkeley
Infrared Radiometer Measure thermally emitted energy from the surface in the regions of 8.0 to 12.0 and 18.0 to 25.0 microns. Dr. G. Neugebauer California Institute of Technology
Ultraviolet Spectrometer Detect the presence and scale height of atmosphere constituents by measurements in the 1100 to 4500 Angstrom region. Dr. C. A. Barth University of Colorado Boulder, Colorado
Television Photograph planetary disc and surface. Dr. R. B. Leighton California Institute of Technology
S-Band Occultation Determined atmospheric surface pressure and density and variations with height and latitude. Dr. A. J. Kliore Jet Propulsion Laboratory
Celestial Mechanics Refine accuracy of theEarth and Mars orbits,Mars Mass, Earth-Moon mass ratio and the astronomical unit. Dr. J. D. Anderson Jet propulsion Laboratory

       On currently designed trajectories the two spacecraft will fly-by Mars at a closest approach distance of approximately 2000 miles. In the 1964 mission the closest distance was 6000 miles. The extremely close approach, which will occur when Mars is about 62 million miles from Earth, includes a 30,000 to 1 probability that the spacecraft will not impact and contaminate the planet Mars.

       The two camera systems, wide-angle and narrow angle aboard each spacecraft will provide narrow angle photographs of the disc of Mars as it revolves in front of the approaching spacecraft during far-encounter, and both wide-and narrow-angle pictures of the planet's surface during the near-encounter fly-by.

       The best resolution of the full disc pictures will be about 1 1/2 miles; the resolution of the near-encounter pictures about 3000 yards for the wide angle camera and 300 yards for the narrow angle camera. The Martian moon Phobos may be visible in some of the approach pictures.

       A minimum of thirty-three TV pictures will be obtained by each spacecraft. At least eight of the pictures will be at a range which will show the entire disc of the planet (far-encoun- ter). (Optional sequences under consideration can provide additional far-encounter pictures).

       The remaining twenty-five pictures will be taken as the spacecraft fly past the planet, (near-encounter).

       The Infrared Radiometer (IRR), Infrared Spectrometer (IRS) and Ultraviolet Spectrometer (UVS) will scan the same areas photographed by the two cameras to allow correlation of data. They will also scan the planet's dark side. Data from the IRR, IRS and the UVS will yield information on temperatures in the atmosphere and at the surface and the composition of the upper and lower atmosphere.

       Mariner '69 design is based upon the successful Mariner missions to Venus 1962, Mars 1964, and Venus 1967. Comparison between 1964, and Venus 1967. Comparison between 1964 and 1969 reflect the growth and improvements in the Mariner class spacecraft.

Bits per second
Bits per picture
Record time per picture
Weight of Science Instruments
Closest approach
575 lbs.
10 watts
8 1/3
24 sec.
60 lbs.
6118 miles
900 lbs.
20 watts
270 and 16,200
42.24 sec.
141.18 lbs.
2000 miles

       Mariner 1969 has been designed to provide a number of options in the operation of the two spacecraft after launch if in-flight performance and the availability of ground tracking facilities permit. The options will allow enhancement of mission results.

       Encounter of the two spacecraft with Mars will be designed to allow one spacecraft to fly-by the Southern polar cap and the other near the Equator. The point of closest approach will occur over the tracking and communication station of the Deep Space Net Station at Goldstone, California.

       Program Manager for Mariner Mars '69 is N. W. Cunningham, of the Office of Space Science and Application, NASA, Washington.

       Harris M. Schurmeier, is Project Manager for the Mars mission for the Jet Propulsion Laboratory.