Rosetta space mission to Comet 67P/Churyumov−Gerasimenko

On March 2, 2004 Rosetta space mission successfully started from the Kourou cosmodrom to Comet 67P/Churyumov–Gerasimenko. Upon entering orbit around the nucleus observations will be made as the comet becomes more active as it journeys towards the Sun. A lander, named Philae, will be deployed and attempt to make the first ever controlled landing on a comet. On its 10 year journey Rosetta will fly-by two asteroids, namely, 2867 Steins in September 2008 and 21 Lutethia in July 2010. Rosetta will be the first spacecraft to orbit a comet’s nucleus. It will be the first spacecraft to fly alongside a comet as it heads towards the inner Solar System. Rosetta will be the first spacecraft to examine from close proximity how a frozen comet is transformed by the warmth of the Sun. Shortly after its arrival at Comet 67P/Churyumov–Gerasimenko, the Rosetta orbiter will despatch a robotic lander for the first controlled touchdown on a comet nucleus. The Rosetta lander’s instruments will obtain the first images from a comet’s surface and make the first in situ analysis of the relict matter of the Solar System

On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002

Some spectra of Comet C/1999 S4 (LINEAR) are obtained with the UAGS spectrograph (long slit and CCD) installed on the 1-m Zeiss reflector of the SAO RAS (the Northern Caucasus, Nizhny Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Sophisticated identification of emission lines in the spectra of Comet C/1999 S4 (LINEAR) is made. Emission lines of the molecules C₂, C₃, CN, NH, CH, NH₂, CO⁺, H₂O⁺, and others were identified in the spectra of Comet C/1999 S4 (LINEAR) derived on July 22/23, 2000 before splitting the cometary nucleus. Analysis of the CCD spectra obtained on July 27/28, 2000 reveals very weak emission lines superposed on the solar reflection spectrum, unlike the case of spectra obtained with the same instrument on July 22/23. From analysis of the surface brightness profile of C₂ along the slit, the velocity of expansion of two secondary fragments (V = 10 km/hr) and energy of fragment expansion (E = 8.7 · 10¹⁵ erg) are estimated. The luminescence cometary continuum is detected by a level of 26% at 5000 Å in the spectra of the comet. Possible mechanisms of nucleus splitting are discussed

Exploration of spectra of periodic Comet 153P/Ikeya−Zhang

We present preliminary results of study of middle-resolution optical spectra of Comet 153P/Ikeya–Zhang obtained on May 5, 2002 with the help of the 2.12-m reflector of the Guillermo Haro Astrophysical Observatory. Emission lines of the molecules C₂, C₃, CN, NH₂, CO (Asundi and triplet bands), and H₂O⁺ are identified in these spectra. On the basis of the intensity distribution along the slit of the spectrograph in C₂, C₃, CN emission lines we determined the velocities expansion and life times of these molecules