The Huygens Probe was named after Christiaan Huygens, a Dutch astronomer who in 1655 discovered Titan, Saturn's largest moon. The probe was designed by the European Space Agency (ESA), to perform an in-depth study of the clouds, atmosphere, and surface of Titan.

Building the Huygens Probe

Traveling onboard the Cassini orbiter throughout the seven-year journey to Saturn, the probe underwent a series of in-flight tests and health checks to ensure that all of its instruments were working properly. This was essential, because the distance from Earth is too great to provide signals and commands directly to the probe. This means that the design and programming of the probe had to be such that it worked automatically so that valuable data could be communicated back to the orbiter and then back to Earth.

The 319-kilogram (703-pound) Huygens probe separated from the Cassini orbiter in December of 2004, and began a 20-day coast phase toward Titan. Remaining on the Cassini orbiter was the probe support equipment (PSE), which contained the electronics necessary to track the probe and to recover the data gathered during its descent. Then, in January of 2005, just four hours before reaching the atmosphere of Titan, timers woke up the Huygens probe.

As it finally entered Titan's atmosphere, three sets of parachutes acted to slow down the probe and provide a stable platform for scientific measurements. The fully instrumented robotic laboratory reached the surface of Titan two hours and 27 minutes later.

The Huygens probe plunged into a planetary atmosphere farther away from Earth than any other deep space probe has gone before. It was the first spacecraft to land on a moon in the outer Solar System.