The Huygens DCR at ESOC, Darmstadt, Germany, was calm yesterday as engineers count the minutes to the probe’s entry into Titan’s atmosphere, due 14 January 2005 at approximately 10:07 CET. Huygens is coasting in dormant mode after its release from Cassini last month.

“Huygens will be woken up for preheating by autotimers and send its first data to Cassini shortly after firing its parachute. By then, the probe will have been awake for 4 hours and 28 minutes,” said Martin Hermes, Huygens spacecraft operations engineer, speaking in the Dedicated Control Room while monitoring the Probe Data Relay System.

Huygens now coasting to Titan

Huygens started its three-week, independent coast to Titan on 25 December 2004 at 03:00 CET.

The separation from Cassini was achieved by the firing of pyrotechnic devices. Under the action of push-off springs, ramps and rollers, the probe was released at a relative velocity of about 0.3 metres per second with a spin rate of seven revs per minute.

NASA’s Deep Space Network stations in Madrid, Spain, and Goldstone, California collected telemetry data confirming the separation.

After entering Titan’s atmosphere, Huygens’ parachute system will be deployed for the approximately 2-1/2-hour descent, during which most of the scientific measurements will be made.

The probe will be suspended from a stabiliser parachute and pass through clouds, which are expected at around 20 km altitude. The descent will occur during daylight to provide the best illumination conditions for imaging the clouds and surface.

Once it has landed the probe may be able to gather additional data, directly characterising Titan’s surface for as long as the batteries can power the instruments and the Cassini orbiter is visible over the horizon at the landing site, i.e. up to 130 minutes.