Huygens’ entry and descent through Titan’s atmosphere—methodology and results of the trajectory reconstruction. Planet. Space Sci

The European Space Agency’s Huygens probe was separated from the NASA Cassini spacecraft on 25 December 2004, after having been attached for a 7-year interplanetary journey and 3 orbits around Saturn. The probe reached the pre-defined NASA/ESA in-terface point on January 14, 2005 at 09:05:52.52 (SCET-UTC) and performed a successful entry and descent sequence. The probe softly impacted on Titan’s surface on the same day at 11:38:10.77 (SCET-UTC) with a speed about 4.6 m/s. The probe entry and de-scent trajectory was reconstructed from the estimated initial state vector provided by the Cassini Navigation team, the probe housekeeping data, and measurements from the sci-entific payload. In this paper we present the methodology and discuss the results of the reconstruction effort. Furthermore the probe roll rate was reconstructed prior to the main entry phase deceleration pulse and throughout the entire descent phase under the main and drogue parachute