THE RECORD OF MARINER
The performance record of Mariner II exceeded that of any spacecraft previously launched from Earth:
- It performed the first and most distant trajectory-correcting maneuver in deep space, firing a rocket motor at the greatest distance from the Earth: 1,492,000 miles (September 4, 1962).
- The spacecraft transmitted continuously for four months, sending back to the Earth some 90 million bits of information while using only 3 watts of transmitted power.
- Useful telemetry measurements were made at another record distance from the Earth: 53.9 million miles (January 3, 1963).
- Mariner II was the first spacecraft to operate in the immediate vicinity of another planet and return useful scientific information to the Earth: approximately 21,598 miles from Venus (December 14, 1962).
- Measurements were made closest to the Sun: 65.3 million miles away (December 27, 1962).
- Mariner’s communication system operated for the longest continuous period in interplanetary space: 129 days (August 27, 1962, to January 3, 1963).
- Mariner achieved the longest continuous operation of a spacecraft attitude-stabilization system in space, and at a greater distance from the Earth than any previous spacecraft: 129 days (August 27, 1962, to January 3, 1963), at 53.9 million miles from the Earth.
CHAPTER 6
THE TRACKING NETWORK
Thirty-six million miles separated the Earth from Venus at encounter. Communicating with Mariner II and tracking it out to this distance, and beyond, represented a tremendous extension of man’s ability to probe interplanetary space.
The problem involved:
1. The establishment of the spacecraft’s velocity and position relative to the Earth, Venus, and the Sun with high precision. 2. The transmission of commands to activate spacecraft maneuvers. 3. The reception of readable spacecraft engineering and scientific data from the far-ranging Mariner.
The tracking network had to contend with many radio noise sources: the noise from the solar system and from extragalactic origins; noise originating from the Earth and its atmosphere; and the inherent interference originating in the receiving equipment. These problems were solved by using advanced high-gain antennas and ultra-stable, extremely sensitive receiving equipment.