On 15 October 1997, the Cassini-Huygens mission blasted off from Cape Canaveral bound for Saturn, with the aim of studying the planet’s rings and its moons.
The seven-year journey sent the 5.7-tonne craft swinging round the sun, passing Venus twice and Earth once, then shooting off into the outer solar system, passing Jupiter in December 2000, entering orbit around Saturn in July 2004.
After another seven months’ orbit, Huygens detached from Cassini on Christmas Day, 2014, and made a 21-day journey towards Titan. On this day in 2005, it came into contact with Titan’s atmosphere, and began its descent through the moon’s atmosphere. All the way down, Huygens was sending data back about its composition, the pressure, and any electromagnetic activity.
After the two and a half hour descent, Huygens landed successfully on Titan’s frozen surface, making it the first object from Earth to land on a planet in the outer solar system
Once there, it transmitted data for 72 minutes before contact was lost.
The data it sent back surprised scientists. The atmosphere was made up of nitrogen and methane, and it was discovered that large quantities of methane lay beneath the surface – which seemed to be composed of a soft, dry, sand-like substance. It also found river-like drainage networks similar to those on earth, and large dry lake beds.
The mission was a joint venture between America’s Nasa, the European Space Agency (ESA), and the Italian Space Agency (ASI) with Nasa providing the orbiter – Cassini, and the ESA providing the lander, Huygens.
Its total cost was $3.3bn, of which the US stumped up $2.6bn, the ESA $500m and the Italian Space Agency $160m.
The original Cassini mission was supposed to last just four years, but the orbiter is still there, sending back data, having twice had its mission extended. Its latest mission is planned to end in September 2017.
Also on this day
The government finally declared Britain’s foot-and-mouth disease crisis over on this day in 2002, almost a year after the first case had been identified. Read more here