Viewing the guts of the earth from outer space

The European Space Agency's (ESA) Swarm mission will soon launch three satellites into space. Built in Germany, the satellites will research the earth's magnetic field, which acts as an invisible shield that repels energized particles from the sun and deep space. The ESA's Swarm mission, with a launch date in mid-2012, is intended to observe the Earth's geomagnetic field by measuring processes in the molten core, as well as on the mantle and crust of the planet. Information delivered can be used to determine whether the poles are shifting, and help predict space weather. Albert Zaglauer, a project director with the company Astrium in Friedrichshafen, explained the importance of the geomagnetic field. "Without the Earth's magnetic field, we wouldn't exist, as we'd be fully exposed to cosmic radiation," Zaglauer told DW. The Earth's magnetic field comes from movement of molten lava in the planet's core. And as measurements over the last 150 years show, the strength of the magnetic field has been steadily decreasing. Researchers also know that the magnetic poles of the Earth move, completely reversing about every half a million years. It may even be the case that the Earth's poles will soon be due to swap. The three satellites of the Swarm mission will, from their orbits of 460 to 530 kilometers (286 to 329 miles) above the Earth, measure the current state and ongoing development of the Earth's magnetic field to a more precise degree than ever before. Sensitive instruments on the satellites will investigate regional differences in magnetic characteristics of the Earth's crust, as well as how the magnetic field influences ocean currents. The mysterious processes occurring in the Earth's interior originate in outer space: The sun continuously beams charged particles of differing intensity to Earth. Sometimes these particles punch right through the Earth's magnetic field above the poles, causing the colorful phenomenon known as aurora borealis. Three satellites are necessary for making simultaneous measurements from different locations in order to follow quick changes in the magnetic field during solar storms. Nils Olsen, who is involved in planning the Swarm mission from the Danish National Space Center in Copenhagen, spoke enthusiastically about the project. "It's really astounding, all the things we can learn about the Earth and the sun through these quite small satellites," Olsen told DW. Each satellite weighs about 500 kilograms (1,102 lbs.) and measures about nine meters (30 feet) long. To keep drag to a minimum, the satellites have a streamlined form, and the sensitive measuring instruments lie at the end of a long arm that is extended once the satellites are in space. With a long neck and slim body, the satellites almost look like guitars, or flying broomsticks. At a cost of about 90 million euros ($117 million), technicians and engineers had to build the satellites such that the electronic devices onboard would minimally disturb the sensitive measuring instruments. That's why the main body of the satellites is made of carbon fiber, which doesn't influence the measurements of magnetic fields. Blast-off with an atomic rocket After some final tests in Germany, the satellites will be transported to Russia. Around the middle of July, the satellites will be put into orbit from the Plesetsk Cosmodrome, a space center some distance north of Moscow. Toward the end of the mission, the physicists will take measurements from only 300 km (186 miles) above the Earth. At this elevation, the magnetic field is far stronger and thus, easier to measure. The Swarm satellites will stay in orbit about four years. Due to friction in the extremely thin atmosphere, the satellite trio will gradually fall back to Earth, burning up upon re-entry. From : DW