Physics and Astronomy

New theory shows that high performance needn’t mean high risk.

For man-made systems such as machines and markets, catastrophe lurks somewhere between high risk and high performance. US physicists may have found a way to strike the optimal balance 1 .

This trade-off is familiar to the financial world. Brokers develop investment portfolios to provide the best returns within a specified level of risk. Mark Newman and co-workers at the Santa Fe Institute in New M

Chase a fast-moving comet, land on it and ’ride’ it while it speeds up towards the Sun: not the script of a science-fiction movie, but the very real task of ESA’s Rosetta spacecraft.

New observations with the European Southern Observatory’s (ESO) Very Large Telescope (VLT) provide vital information about Comet Wirtanen – Rosetta’s target – to help ESA reduce uncertainties in the mission, one of the most difficult ever to be performed.

Every 5.5 years Comet Wirtanen completes an o

The Sagittarius dwarf galaxy is our nearest neighbor. Yet it has been discovered only recently, in 1994, being hidden by the stars and dust in our own Galaxy, the Milky Way. It is however possible today to better know this companion galaxy, thanks to variable stars, the RR Lyrae, in which Sgr-dw is particularly rich. In a recent paper, Patrick Cseresnjes, from Paris Observatory, shows for the first time that Sgr-dw is not typical of other satellites of the Milky Way, but reveals instead striking simi

During the night of 28 February/1 March, Envisat, ESA’s most powerful and sophisticated Earth observation satellite, will be launched by an Ariane 5 rocket from Europe’s spaceport in Kourou at 22:07 hrs Kourou time (02:07 hrs CET).

Built by a consortium of 50 companies led by Astrium, Envisat is the successor to ESA’s ERS satellites. With an array of ten instruments to monitor land, oceans, atmosphere and ice caps, it will provide the most complete set of observations ever achieved, to hel

“Nuclear fusion” is the melting of light nuclei into heavier ones, a process that according to the laws of physics releases enormous amounts of energy. For the past 50 years many scientists have sought ways of harnessing this fusion reaction under controlled reactor conditions as a safe, clean and practically inexhaustible source of energy. Siegbert Kuhn and his team at the Institute of Theoretical Physics at Innsbruck University are making a major contribution to these efforts and positioning Austri

Thanks to ion propulsion, the Artemis mission is turning near-defeat into a success story. Nominal operations could start this summer, with ESA’s satellite, manufactured by Alenia Spazio as prime contractor (I), playing a significant role in the pursuit of high technology and advanced telecommunications.

On 12 July 2001, 30 minutes after lift-off from Europe’s spaceport in Kourou, French Guiana, it became apparent that the Ariane 5 launcher had propelled the Artemis satellite into a transf