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Capture Dynamics and Chaotic Motions in Celestial Mechanics by Edward Belbruno, Princeton University Press, 拢32.95/$49.95, ISBN 0691094802 Reviewed by Carl Murray

YOU have just launched a multimillion dollar com-munications satellite into space. A malfunction means your expensive cargo will not reach its required orbit. Who are you going to call?

A good choice would be Edward Belbruno, a celestial mechanician who seems to specialise in such lost causes. In 1991 he helped Japan鈥檚 ISAS Institute rescue its Hiten lunar spacecraft, and in 1998 he assisted in the recovery of a Hughes satellite that failed to achieve a sufficiently high orbit. In both cases he used the moon鈥檚 gravity field to save the day.

Belbruno has identified locations in space associated with a 鈥渨eak stability boundary鈥� and shown that orbits there tend to be chaotic. This allows relatively small changes in a spacecraft鈥檚 trajectory to result in dramatic changes to its orbit. Provided your satellite has enough fuel to reach one of these locations, it can be saved. These concepts are already being used to design complicated low-energy orbital tours for the next generation of planetary missions.

The trick is, of course, finding these regions. Capture Dynamics is the first book to describe the necessary theory in the context of the whole process of capture. It uses the mathematical language of dynamical systems theory and it is pitched at the graduate level or above. The result is a brilliant example of the application of chaos theory to practical problems.