* Astronomy

Tom Bogdan doesn't strike you as the nervous type but there is one thing that does keep him awake at night. His insomnia is caused by a 14-year-old satellite sitting between the Earth and the Sun some 1.5 million km away which he fears may one day suddenly die, so leaving the world without a vital early-warning system against a devastating solar storm.
Dr Bogdan is head of the US Space Weather Prediction Centre, the only civilian operation in the world dedicated to forecasting the size and timing of solar storms on a 24/7 basis. The satellite disturbing his sleep, the Advanced Composition Explorer, was designed with a lifetime of just two years - which is why, 14 years after its launch, Dr Bogdan gets worried.
 Read more   

Advanced Composition Explorer (ACE) is a NASA space exploration mission being conducted as part of the Explorer program to study matter in situ, comprising energetic particles from the solar wind, the interplanetary medium, and other sources. Real-time data from ACE is used by the Space Weather Prediction Center to improve forecasts and warnings of solar storms. The ACE robotic spacecraft was launched August 25, 1997 and is currently operating in a Lissajous orbit close to the L1 Lagrange point (which lies between the Sun and the Earth at a distance of some 1.5 million km from the latter).
 Read more