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Rosetta, an European space vehicle 15 years in development, will head for the short period comet 67P/Churyumov-Gerasimenko in February, 2004. In September 1969 S.Gerasimenko and myself went to the Alma-Ata Astrophysical Institute to conduct a survey of short period and new comets. Later that month, I examined an exposure of comet 32P/Comas Sola made on September 11.92 UT, 1969, and found a cometary...
A new suitable target comet had to be found for the Rosetta mission after its launch planned for mid-January 2003 was cancelled. As soon as 67P/Churyumov-Gerasimenko became a likely new target for Rosetta, an extensive monitoring of this comet started from ESO with the first observation on 11 February 2003. Therefore, a postperihelion characterization of this comet is now existing, which covers its...
Following the selection of comet 67P/Churyumov-Gerasimenko as the new target of the Rosetta/ESA mission, observations of this comet were performed at the 30-m telescope of the Institut de radioastronomie millimétrique in May–June 2003. Observations focussed on the CO J(2–1) and J(1–0) lines and dust thermal continuum at 1.2 mm in order to constrain the CO and dust productions at 3 AU from the Sun...
Comet 67P/Churyumov-Gerasimenko is a dusty comet. In a previous work (Weiler et al., 2004) it was found that the mean dust to gas mass ratio could be as high as 4.8. In this work we study the influence of such a high dust mass loading of the gas flow in the coma on the terminal dust velocities used to compute the dust production rates. It was found that the mass loading is not significant for determining...
Comet 67P/Churyumov-Gerasimenko was observed with the International Ultraviolet Explorer (IUE) satellite observatory on 7 November 1982, five days before perihelion. At the time of the observation the heliocentric distance was 1.307 AU and the geocentric distance 0.414 AU. Only two relatively short exposures were obtained, one each with the short (SWP) and long wavelength (LWR) cameras. In the LWR...
At the beginning of January 2003 the Rosetta launch was delayed and the primary target was changed. As soon as a new short period comet, Churyumov-Gerasimenko, was defined as the new target, we asked for observing time at the 3.5m Galileo Telescope (TNG) on La Palma. On February 20, 2003, we obtained images in the B, V, and R broad band filters, and a low resolution spectrum. Since the images showed...
The Solar Wind Anisotropies (SWAN) instrument is a scanning Lyman-alpha imager on board the Solar and Heliospheric Observatory (SOHO) spacecraft. Since becoming operational in January 1996 SWAN has been producing full sky Lyman-alpha maps which are primarily used to study the interaction between solar wind and the interplanetary neutral hydrogen. In addition to that SWAN images can be used to study...
The new scenario of the Rosetta mission to comet 67/P Churyumov-Gerasimenko (launch on February 2004), includes as baseline the fly-by of the asteroid 2513 Baetsle. Several other asteroids are possible fly-by candidates (single or double) within the available resources. Other candidates whose fly-bys require a larger Δv can be considered if the execution of the Rosetta interplanetary orbit insertion...
As follows from the visible-range spectrophotometric observations of 21 Lutetia and laboratory reflectance spectra of suitable analog samples, the asteroid is probably an M-type body covered with uneven layer of hydrated silicates
A new method for detecting and characterizing comets is presented. Theoretical calculations using CS2 as an example are presented to support the possibility of using this method to identify parent molecules in comets. Laboratory experiments are suggested that can be used to provide the kind of data that is needed to make this proposal successful.
Dust ejected from comet nuclei includes up to millimeter-sized highly porous and collapsed aggregates plus small pebbles with mass/size distributions and compositions defined by the hypothesis of hierarchical dust accretion based on collected interplanetary dust particles and meteor properties.
Observations of the linear polarization of light scattered by cometary dust (spatial variations, phase and wavelength dependences) provide unique clues to the physical properties of the dust particles. The polarization of 67P/Churyumov-Gerasimenko has, up to now, only been observed at its 1982/1983 return. Data suggest that the coma is rather dust poor, in agreement with the absence of any silicate...
We overview an ongoing program of three-dimensional, time-dependent, physically realistic simulation of the gas and dust coma of the comet, using both fluid equations and Direct Monte-Carlo Simulations.
Comet 67P/Churyumov-Gerasimenko passed its last perihelion on August 2002 and was well observed from fall 2002 to spring 2003. Its most prominent feature was a bright thin dust tail, which is best fitted by the Neck-Line model. Fits of the whole tail provide the dust environment of 67P during a year around perihelion, which is dominated by nucleus seasons. The dust mass loss rate appears constant...
The ESA Cometary Environment Model is applied to comet 67P/Churyumov-Gerasimenko (C-G). From observed gas and dust production rates the model allows us to determine the conditions in the inner coma of a comet. Assuming a spherical nucleus and an axis symmetric surface activity, the densities and velocities of the gas and of dust particles are calculated as functions of location in the coma. The model...
Recent measurements indicate the H2O production rate of comet Churyumov-Gerasimenko to be of the same order as for comet Wirtanen. From a plasma physical point of view, this classifies both comets as “weak comets”, i.e. the plasma structures known from larger comets differ much from the MHD picture. We present two 3D hybrid model simulation results for Churyumov-Gerasimenko for heliocentric distances...
Cometary dust environment modelling is required to make predictions for the European Space Agency’s Rosetta mission. Following results from pre-planetary dust aggregation experiments both on Earth and in space (CODAG), we have developed a code to generate and study the morphological properties of dust chains characterized by a fractal mass dimension Df∼1.3. We are now analysing the scattering...
The planning of planetary missions and the operations preparation of the instruments payload require a knowledge as much as possible accurate of the target. This knowledge cannot be obtained only from ground based observations and can be integrated by theoretical models. Comet 67P/Churyumov-Gerasimenko is the current selected target for the ESA ROSETTA mission. Presently, little is known about this...
Big (millimeter-sized) particles released from a comet are displayed in a comet trail rather than in the tail. A comet tail is an extended ephemeral phenomenon that is caused generally by sub-millimeter sized particles that were released during the ongoing apparition of the comet in the inner solar system. A dust trail is defined as a concentration of big (mm-sized) particles close to the orbit of...
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