Comets are thought to be remnant material from the processes of formation and initial development of planets. Since comets formed in the outer parts of the solar nebula in a cold environment, they contain volatile material that has been only moderately altered. Comets have conserved information on the conditions in the early Solar System and are, therefore, of great interest scientifically.As a result of gravitational disturbances comets can approach the Sun on highly elliptical orbits. Due to solar heating, the surface of the nucleus becomes active, volatiles evaporate, carrying small solid dust particles with them, which produce the comet's coma of gas and dust. The neutral gas species in the coma can be ionised by solar UV photons. The Sun's radiation pressure and solar wind accelerate dust grains and plasma, respectively, forming the dust and ion tails opposite the Sun. These large-scale structures (up to millions of kilometres) are the well-observed characteristic features of comets.
Work carried out by the Department addresses these questions and provides crucial information for the preparation and planning of space missions to comets. Activities of Department members include:
For up-to-date details of the activities of Department personnel, see the latest report (click on the link in the right menu bar).