Huygens pulled away from Cassini at less than 1 mile per hour. The separation maneuver also imparted a spin of seven revolutions per minute to Huygens to ensure its stability on the 3-week journey to Titan. The only instrument on Huygens that will operate during this coast phase is a system of alarm clocks designed to wake the spacecraft a few hours before it hits the fringe of Titan's atmosphere the morning of January 14.
When Huygens reaches Titan, instruments will study the atmosphere's temperature, pressure, density, wind speed, and composition during an expected 2.5-hour-long descent. Shortly before Huygens reaches Titan's surface, a camera will photograph the area around the landing site. Huygens should hit the surface at about 10 miles per hour and could survive for half an hour before its battery dies. A suite of instruments will determine the physical properties of the surface — whether the probe lands on solid ground or in a hydrocarbon lake.
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