117.6 Kilobit Telemetry from Mercury-A Major Deep Space Telecommunication Advance

Abstract

For nearly eight hours on March 29, 1974, Mariner 10 transmitted imaging telemetry in real time at 117.6 Kbps from Mercury. During this time, 562 very high quality frames were received, even though the bit error rate was only about 1 in 40. The transmission of 117.6 Kbps from Mercury is a magnificent telecommunications achievement, which permitted an order of magnitude increase in imaging science data return. The Mariner 10 imaging scientists' requirements, simply stated, were to obtain maximum area coverage at highest spatial resolution. More precisely, they desired photomosaics which were equivalent to the best earth-based pictures on the Moon, i.e., about 1 km resolution. The purpose of this paper is principally to relate the methods by which these "desirements" were translated into measurable telecommunication system requirements and some of the attendant tradeoffs. Additionally, same of the steps taken to achieve their goal are recited.