Satellite fleet lifts off to probe aurora

Five satellites flew into orbit on Saturday to investigate the most spectacular natural light show on Earth. The five probes lifted off together on one rocket - a record for a single launch by Nasa - from Cape Canaveral in Florida. They form the Themis mission which will carry out detailed observations and study of the aurora, or northern and southern lights. Scientists want to solve the mystery of what triggers so-called geomagnetic substorms that cause a sudden brightening of the aurora. Their results will be used to help protect astronauts and sensitive electronic instruments aboard commercial satellites. The five identical Themis probes - it stands for the Time History of Events and Macroscale Interactions during Substorms - lifted off atop a Delta II rocket. They will eventually line up between the Earth and the Sun to monitor events in different areas of space. The aurora lights up the sky when an invisible wind of electrically charged gas from the Sun buffets the Earth's magnetic field. During substorms, a protective shell called the magnetosphere gets over loaded by solar energy and snaps back like a slingshot, firing particles called electrons towards Earth. These particles, the same electrons that carry electric currents in TVs and mobile phones, stream down invisible lines of magnetic force, making the aurora shine brightly. During a two-year mission, the five satellites are expected to witness around 30 substorms. Principal investigator Vassilis Angelopoulos said: "The mission will make a breakthrough in our understanding of how Earth's magnetosphere stores and releases energy from the Sun. Substorm processes are fundamental to our understanding of space weather and how it affects satellites and humans." Photo: Nasa. ©PAUL SUTHERLAND, Skymania.com • For more space reading, plus other bargains, check out the Skymania store!