Cassini-Huygens prepares for closest approach to Titan

UK scientists and industrialists involved in the NASA, ESA, ASI Cassini-Huygens space mission are eagerly awaiting the data to be received when the spacecraft makes its closest fly-by of Saturn’s largest moon, Titan, on 26th October.

At the time of the closest approach, which is scheduled to be at 5.44 pm BST (9.44 am PDT), the spacecraft will travel a mere 1200km (745 miles) above the surface of the moon at a speed of 6.1 km per second. Confirmation that the flyby has been successful and that all the data have been received will not take place until 2.30 a.m BST, 27th Oct (6.30 pm PDT 26thOct).

This close flyby will be looking at all aspects of Titan, which although it is the second largest moon in the solar system, after Jupiter’s Ganymede, we know relatively little about. The instruments on board Cassini will be looking at the moon’s interior structure, surface characteristics, atmospheric properties and interactions with Saturn’s magnetosphere.

Furthermore the studies will provide important information for ESA’s Huygens team, who will be using the data gathered to verify the atmospheric models developed for the separation and descent and landing of the Huygens probe on 25th December and 14th January respectively.

Further data from the imaging and radar instrumentation onboard Cassini should provide an indication of whether the likely landing surface for the Huygens probe will be solid or liquid material. The first images are expected at 2.30 am BST on 27th (6.30 pm PDT on 26th) and will be posted on http://saturn.jpl.nasa.gov/home/index.cfm

Professor John Zarnecki from the Open University who is lead scientist for the Science Surface Package on the Huygens Probe, is eagerly awaiting the results. “This first close-up look at Titan should enable us to find out just how precisely our atmospheric models fit with the real situation and of course we are excited about the prospect of discovering just what type of surface the Huygens probe will land on early next year. In other words we want to know if our instruments will land with a splash or a thud!”

Professor Michele Dougherty, from Imperial College, lead scientist for the Magnetometer instrument on Cassini added, “Titan’s atmosphere is similar to the very early atmosphere of the Earth and by studying its properties we can start to unravel some of the mysteries of the planet. The Cassini Magnetometer experiment will investigate Titan’s interior and variations in the magnetic field measurements could indicate the presence of an ocean contaminated by salty materials like in the Earth’s oceans and in the hypothesised oceans of Callisto and Europa in the Jovian System.”

UK scientists are playing significant roles in the Cassini Huygens mission with involvement in 6 of the 12 instruments onboard the Cassini orbiter and 2 of the 6 instruments on the Huygens probe. The UK has the lead role in the magnetometer instrument on Cassini (Imperial College) and the Surface Science Package on Huygens (Open University).

UK industry had developed many of the key systems for the Huygens probe, including the flight software (LogicaCMG) and parachutes (Martin Baker). These mission critical systems need to perform reliably in some of the most challenging and remote environments ever attempted by a man made object. For examples, the Huygens probe will hit the atmosphere of Titan at 6 km/sec. LogicaCMG’s software onboard the probe will be responsible for deploying the parachutes, separating the front and back shield with precise timings to achieve the required descent profile; reducing the velocity of Huygens before commencing the science experiments, and managing communications back to Cassini.