A three-satellite mission to analyse the Earth's magnetic field has been selected for launch in 2009 by the European Space Agency (ESA). The Swarm mission will measure the field's strength, direction and variation from polar orbit to improve understanding of orbital radiation hazards, space weather and composition of the Earth's interior.
To be launched by the ESA's Vega small launcher or a Russian Soyuz booster, two satellites will be placed at 450km (280 miles) altitude and fly parallel 120km apart. The third will fly at 530km.
Roger Haagmans, a principal scientist in ESA's science and applications department, says: "In oil exploration they need to use directional drilling and use magnetic sensors for this. A better understanding of the magnetic fields means more accurate drilling."
The first two satellites will determine the gradient of the magnetic field, while the third, at a greater distance, will measure how the field changes due to solar radiation activity over time.
Last month NASA gave the go-ahead for its own satellite-constellation magnetic field mission, Themis (Time History of Events and Macroscale Interactions). Five satellites will be launched in October 2006 to study changes in the Earth's magnetosphere to improve understanding of space weather.
ROB COPPINGER / LONDON
Source: Flight International
