Space fly-by reveals new insights into Titan's life

10 October 2008

Cracking the secrets of the atmosphere of Titan, Saturn’s mysterious moon, and how planetary atmospheres evolve, have come a step closer after evaluation of data from a successful fly-by of its surface by the Cassini spacecraft.

Researchers and engineers on the Cassini project, which includes teams from UCL Space and Climate Physics and UCL Mullard Space Science Laboratory (MSSL), were also given a glimpse of how Titan, which has no magnetic field of its own, holds onto remnants of Saturn’s magnetic field as it caught the big moon on one of its excursions outside Saturn's magnetosphere.

The Cassini spacecraft approaching Saturn

Cassini project team member Dr. Nicholas Achilleos, UCL Physics and Astronomy, said: “The news is significant from two points of view; firstly, from a discovery angle, it is the first time that Titan has ever been found in interplanetary space.

“Normally it is shielded from the charged particles in the solar wind by Saturn's strong magnetic field. However during the Cassini Titan T32 flyby last year, the solar wind pressure was unusually high which meant that the planet's field could no longer 'hold off' the solar wind flow at the distance of Titan's orbit.

“As a result Titan emerged from Saturn’s very compressed magnetosphere, the shielded region, into the solar wind and interplanetary space.”

He added: “This data opens up exciting new possibilities and approaches for studying the interaction between planetary magnetic fields and the satellites of those planets.”

Titan is the only known moon with a fully developed atmosphere that consists of more than just trace gases, with over 98 per cent of it nitrogen. The encounter showed that Titan’s atmosphere actually retains a memory of the magnetic field of the plasma that surrounds Saturn and the team believes this memory might last for as long as three hours.

Cassini’s prime mission ended in mid-2008, marking four years since its arrival at Saturn in July 2004. The mission has now been extende extended until 2010 and project members are hopeful of the mission being extended even further.

For more information on the Cassini mission, UCL MSSL and UCL Physics and Astronomy click on the links above.

Image shows the Cassini spacecraft approaching Saturn (courtesy of NASA).