Discovery and study of Comet 67P/Churyumov−Gerasimenko, the main target of the Rosetta space mission

Abstract

Rosetta, a European space vehicle, which was 15 years in development, headed for short-period Comet 67P/Churyumov–Gerasimenko in February 2004. In September 1969 S. Gerasimenko and the author went to the Alma-Ata Astrophysical Institute to carry out a survey of short-period and new comets. At a later date of that month, the author examined the exposure of Comet 32P/Comas Sola made on September 11.92 UT, 1969 and found a cometary object near the plate centre. The author assumed it to be the expected short-period Comet 32P/Comas Sola. Later explorations at the Kyiv University revealed that this comet’s position differed from predicted calculations for Comet 32P by 1.8°. It was a new comet. The comet had an apparent magnitude of 13 and the faint tail about 1 arcmin in length at a position angle of 280°. On the basis of the observations of Comet 67P obtained in Nizhny Arkhyz with the help of the 6-m BTA reflector of the SAO RAS, some physical parameters of the cometary plasma tail (coefficients of diffusion D||, D┴ and induction of magnetic field B) were determined (Jan. 12.105 UT, 1983: D|| = (5.07 · 10¹⁴ – 1.21 · 10¹⁵) cm²/s, D┴ = (5.73 · 10¹³ − 1.37 · 10¹⁴) cm²/s, B = (46 − 111) nT; Jan. 13.124 UT, 1983: D|| = (4.67 · 10¹⁴ – 1.14 ·10¹⁵) cm²/s, D┴ = (4.30 ·10¹³−1.05 ·10¹⁴) cm²/s, B = (55 − 134) nT). The author hope that the Rosetta space mission will obtain valuable data for solving the fundamental scientific problem on the origin and evolution history of the Solar System.