Institute of Planetary Research

Asteroids and Comets Section

The Section Physics of Small Bodies was established in January 1997 to act as a focus for scientific activities in the fields of comets, asteroids and interplanetary dust, and for the institute's participation in the growing number of space missions to small bodies.The main objectives of the Section are to increase our knowledge and understanding of comets and asteroids by means of observations in the visible, infrared and radio regions and the modelling of associated physical processes, and by providing hardware and other support for international fly-by and lander missions.

For up-to-date details of research results, mission involvement, publications, and other activities of Section personnel, see the latest annual report:

Annual reports: 2007/6 2005 2004 2003 2002 2001 2000

The main activities of the Asteroids and Comets Section are:

In order to achieve our goals in these areas Section personnel are involved in various aspects of space missions, from initial mission concept studies, through hardware development, to data analysis and interpretation (e.g. ROSETTA, DAWN, NEOMAP), and carry out observation programmes with major optical and infrared telescopes, such as those at the Keck, IRTF, and ESO observatories. The development of complex computer models of asteroids and comets is also an important aspect of the work of the Section.

For some basic information on asteroids and comets read on:

Asteroids and Comets

Asteroids and comets are thought to be remnant material from the processes of formation and initial development of planets and therefore sources of information on the conditions in the early solar system. Through subsequent bombardment such bodies have significantly influenced the evolution of the terrestrial planets and may have contributed to the conditions needed for the development of life on Earth. Ironically, impacts of comets and asteroids on the Earth may also present one of the greatest threats to the long-term survival of mankind.


Most asteroids orbit in the so-called main belt which lies between the orbits of Mars and Jupiter. Collisions between asteroids in the main belt give rise to fragments, the orbits of which can evolve under the gravitational influence of the massive planet Jupiter and become highly elliptical. Such objects can become Mars- or Earth-crossers, meaning that their orbits bring them within the orbits of these planets.

The population of small bodies known as near-Earth objects (NEOs) consists mainly of such objects, together with (possibly) some nuclei of evolved or extinct comets. NEOs come close enough to the Earth to allow them to be studied in detail with groundbased and orbiting telescopes. Knowledge of the sizes, surface properties and compositions of NEOs is essential for investigations of their origins, their relation to main-belt asteroids, comets and meteorites, the role they have played in the development of the Earth and the threat they pose to civilization as potential impactors on the Earth.

Work carried out by the Section addresses these questions and provides crucial information for the preparation and planning of fly-by and lander missions to near-Earth asteroids.


Comets have physical and chemical properties that differ considerably from those of planets moons and asteroids. The low density and temperatures of the outer regions of the primordial planetary nebula, and the low relative velocities of the colliding building blocks during the accretion phase, determined the composition of comets and their fluffy, low density structure.

Comets are thought to contain unprocessed, virginal matter from the earliest phases of solar system formation. When a comet approaches the Sun, volatile material in the surface layer sublimates and ejects dust particles and small pieces of the surface. Due to the extremely low gravity at a comet's surface an extended cometary atmosphere, the coma, is produced. Interaction with solar radiation and the solar wind draws the coma into a long tail which may extend millions of kilometers.

Landing a spacecraft on a cometary nucleus, as planned during ESA's Rosetta mission, will greatly increase our knowledge of the origin and nature of comets.

The Section's activities include the preparation of hardware for the Rosetta mission, the theoretical modelling of the physical properties and activity of comets, and observations of comets with groundbased and spaceborne facilities.

Some examples of the type of work carried out by the Asteroids and Comets Section in past years is available via the links listed below.
A summary of NEO research activities in Germany as presented to the Scientific and Technical Subcommittee of the Committee on Peaceful Uses of Outer Space of the United Nations, 44th Session, Vienna 1223rd February 2007, is given in this report.
For up-to-date details of the activities of Section personnel, see the latest annual report.

Section personnel - see latest annual report



Extra-solar planetary atmospheres

Space missions

Technology transfer: forest fire warning system


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Related sites:

The Asteroids and Comets Section web pages are maintained by:

Dr. Alan Harris
alan.harris (at) dlr.de

DLR Institute of Planetary Research, Rutherfordstrasse 2, 12489 Berlin, Germany

Author: Asteroids and Comets Section, WWW-Author: Dr. Alan Harris
Last updated: Friday, 04-Apr-2008 17:38:09 CEST
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