16. Physical Study of Planets and Satellites (Étude Physique de Planètes et Satellites)

The last three years have been marked by significant progress in the use of space probes to study Venus and Mars, and the new results from these have tended to dominate the field of our Commission's interest. The arrival of the U.S.S.R. orbiters, MARS 2 and 3, and the U.S. orbiter, Mariner 9, at Mars in the late summer of 1971 initiated a long period of intensive, close-up observation of that planet which has begun to equal that previously available only for our nearest celestial neighbor, the Moon. More recently, new information has been obtained on the characteristics of the dense atmosphere of Venus through the observations relayed back by the U.S.S.R. probe, Venera 8, in July 1972. While they have tended to be obscured by the more spectacular space missions, groundbased observations have also made solid progress in providing new data on the planets since the Brighton meeting in 1970. In keeping with the tradition established by J. S. Hall in the last triennial report and with the intent of brevity expressed by the IAU Executive Committee, this report will contain only short summaries of recent research and no comprehensive bibliography. A symposium on Planetary Atmospheres and Surfaces, jointly sponsored by the IAU, URSI and COSPAR, was held May 1972 in Madrid, and presented 52 papers touching on the chief scientific results obtained in this field in the last three years. The papers presented at this symposium are published in 4 successive issues of Icarus: Vol. 17, Nos. 2 and 3 (1972) and 18, Nos. 1 and 2 (1973). This report contains short summaries of progress in various aspects of planetary research followed by some notes of ongoing unpublished research at various centers, a report on the Planetary Data and Research Centers at Meudon and Flagstaff, a note on the International Planetary Patrol Program and a brief statement from the Working Group on Martian Nomenclature.