The mission of NASA's Cassini spacecraft, en route to become the first orbiter of the planet Saturn, will have to be redesigned to avoid losing data from the European Space Agency's piggyback probe, Huygens, which is to land on the Saturnian moon, Titan, in 2005.

A serious error in the design of the Huygens' communications equipment, discovered after launch, means that during the descent and landing, the Doppler effect due to the relative speeds of the two craft will change the frequency of the craft's communications with Cassini.

Source: Flight Daily News