Among six Earth Explorer candidate missions, the European Space Agency (ESA) has chosen a 'Swarm' of satellites to look inside the Earth and to do the best survey ever of the Earth's geomagnetic field. The mission, scheduled for launch in 2009, will consist of three satellites released by a single rocket. Two will fly side-by-side 450 km above us while the third one will cruise at an altitude of 530 km. In "ESA to probe Earth's magnetic field," the Register also looks at this future mission which will lead to a better analysis of the Sun's influence in our solar system.
First, here is how the ESA describes the future mission.
The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by improving our understanding of the Earth’s interior and climate. The mission is scheduled for launch in 2009. After release from a single launcher, a side-by-side flying lower pair of satellites at an initial altitude of 450 km and a single higher satellite at 530 km will form the Swarm constellation.
High-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements, will provide the necessary observations that are required to separate and model various sources of the geomagnetic field. This results in a unique “view” inside the Earth from space to study the composition and processes in the interior. It also allows the analysis of the Sun’s influence within the Earth system. In addition, practical applications in many different areas, such as space weather, radiation hazards, navigation and resource exploration, benefit from the Swarm concept.
Below are two illustrations extracted from the About Swarm page at the ESA website and dating from July 2002.
||Here is a rendering of the Swarm constellation of three satellites (Credit: GeoForschungsZentrum Potsdam (GFZ)).|
||And here is an illustration showing the Earth's magnetic field which is mainly produced by a self-sustaining dynamo in the fluid outer-core (Credit: GeoForschungsZentrum Potsdam (GFZ)).|
The Register adds that our knowledge of the Earth's geomagnetic field is still limited.
The exact nature of the field is still something of a mystery, however. For instance, we know that the polarity of the field flips every million years or so. Some researchers think we may be seeing the beginning of a flip right now, but the debate is far from settled.
A better understanding of the field will allow for analysis of the Sun's influence in the solar system, and will provide insight into space weather and navigation.
Sources: ESA news release, June 3, 2004; Lucy Sherriff, The Register, June 4, 2004