After a 7-year journey of some 4 billion km aboard the Cassini spacecraft, Huygens is released on 25 December toward Titan. After coasting on a ballistic trajectory for nearly 3 weeks, the probe enters the moon’s thick atmosphere at a speed of 20,000 kph.
1st parachute opens
At an altitude of 180 km, the 1st parachute opens. The heat shield is jettisoned soon afterwards. The probe’s instruments are switched on and start collecting their 1st measurements.
First data transmitted to Cassini
Huygens cannot beam its data directly back to Earth, but rather relays them via the Cassini orbiter when it comes within range. Cassini then sends the data to Earth.
1st attempt to detect signal with radiotelescope
Although very weak (about 20 W), Huygens’ signal is picked up by several radiotelescopes in the United States, Australia and even Europe, confirming that the probe is alive and has successfully begun its descent through Titan’s atmosphere.
2nd parachute opens
Huygens lands on surface of Titan
After a descent lasting 2 h 27 min, Huygens touches down on Titan. Data will confirm later that it hit solid ground, an element that mission planners could not predict.
Last telemetry received by Cassini
1 h 10 min after the landing, Cassini passes over the horizon, like the Sun setting, and communications with the probe are cut off. Although Huygens is still transmitting 2 h after landing, Cassini can no longer receive its data. Only radiotelescopes on Earth continue to pick up Huygens’ weak signal. The Cassini orbiter then points itself at Earth to send back the data acquired.
1st data received at ESA control centre
The mission control centre in Darmstadt, Germany, receives the 1st data from Cassini. The principal investigators each receive their data for analysis.
Last data received at control centre
ESA unveils the 1st pictures of Titan’s landscape to the world