Huygens probe at Titan. Artist's impression of the main parachute of the Huygens probe opening in the atmosphere of Titan, the largest moon of Saturn. The heat-shield of the probe is still glowing after the atmospheric entry phase. Travelling at Mach 1.5 (1440 km/h), Huygens has just deployed its 8.3-metre diameter main parachute. Within 30 seconds, the probe's descent speed will drop to Mach 0.6 (580 km/h), and the heat-shield will be released. Huygens will then spend 15 minutes taking various measurements of Titan's nitrogen and methane atmosphere. Huygens is a European project, part of NASA's Cassini spacecraft, and will arrive at Titan on 27 November 2004.