Scientific and Technical Subcommittee 2007

Near Earth Objects

Scientific and Technical Subcommittee 2007

The annual UN/COSPAR symposium in 2007 took place in Vienna, Austria.

"As a Federation of space organisations from around the world, the IAF appreciated the opportunity to organise, in collaboration with ourcolleagues in the Committee on Space Research, this workshop discussing the technical aspects of using the equatorial orbit.

We were particularly pleased that during the informal exchanges with delegates during our symposium, several opportunities for new international collaboration were discussed.

Bringing space organisations together to discuss cooperation is one of our Federation's main objectives".

James V. Zimmerman, IAF President

There is an infinite number of possible orbits. Some particular orbits have proven to be especially well suited for specific types of applications. Orbits can be classified according to various criteria. For example, according to their maximum altitude above Earth's surface we can distinguish between Low Earth Orbit (LEO, 200-1200 km), Medium Earth Orbit (MEO, 1000-36 000 km) or Highly Elliptical Orbit (HEO, 50 000-400 000 km).

Other distinctions can be made according to the orbit's inclination relative to a reference plane, with polar orbits having an orbit in the plane of the Earth's rotational axis, near-polar orbits having a non-zero inclination relative to the Earth's rotational axis and equatorial orbits lying in the Earth's equatorial plane.

A particular equatorial orbit is the circular Geostationary Orbit (GSO, 35.786 km). Satellites in this orbit maintain the same position relative to the Earth's surface and therefore provide an ideal vantage point for telecommunications and meteorological satellites, which can service an area as large as the visible surface of the Earth in their field of view. As the number of positions in the Geostationary Orbit is limited, it is a scarce natural resources which risks to be saturated and is therefore subject of deliberations in intergovernmental fora.

Equatorial Low Earth Orbit satellites at an altitude of 200-1200 km can, among others, be used for space science applications, satellite telecommunications and Earth-observations applications. In particular, remote sensing systems placed in an equatorial orbit, have the potential of providing higher temporal resolution for the monitoring of areas in the equatorial region. However, satellites in an Equatorial Low Earth Orbit are also subject to a very challenging illumination, thermal and radiation environment, which are reflected upon their technical requirements and require specific considerations during their development.

The Symposium addressed the use of the equatorial orbit for space science and space applications as well as its specific technical challenges. Jointly organised by the Committee on Space Research (COSPAR) and the International Astronautical Federation, the Symposium explored the status of the use of the equatorial orbit for space applications, its challenges and opportunities mainly focusing on the use of the Low Equatorial Orbit (LEO), and activities of countries already using this orbit for their space applications.

The chairs were Dr Jean-Louis Fellous (COSPAR) and Dr James V. Zimmerman (IAF).

Click here for Jim Zimmerman's opening address

The programme was as follows:-

The use of the equatorial orbit for telecommunications and navigation satellites

Dr Manfred Wittig

ESA/ESTEC, Directorate of Telecommunications and Navigations, The Netherlands

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Long-term, high-resolution observation of the extra-terrestrial solar out put from 150 to 2500 nm

Dr Mark Weber

Institute of Environmental Physics, University of Bremen, Germany

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The CNES/ISRO joint project on low inclination orbit to observe the low latitude water cycle