Probing Titan

The European Space Agency intends to send an unmanned probe to Titan - the largest of Saturn's moons - and TWI engineers have played a part in the project.

Part of the mission involves dropping a module, packed with measurement systems to the moon's surface to gather and relay information about atmospheric and surface conditions.

Engineers in the Microtechnology Centre at TWI have recently completed a project for the University of Kent who are producing the Surface Science package (one of six experiments on board). It explores preparation and welding techniques for one of the experiments where sensors will determine the thermal properties of either a gaseous atmosphere or a liquid if the probe happens to land in a 'sea'.

To allow for accurate signal transmission, the weld between platinum sensor wires of 10 and 25µm in diameter and the termination pins must not be distorted to less than the wire diameter as this would affect the sensor performance.

To solve this problem a laser beam was used to form a ball at either end of each wire, at least three times the wire diameter. This allowed a micro-resistance weld to be made without damaging the wire. The laser balling operation also served a second purpose - it cut the wires to tightly specified lengths, subsequently measured to an accuracy of +/-15µm.

To meet the strict wire positioning specifications TWI designed and manufactured specialist jigging.

In total, TWI assembled 20 capsules, two of each sensor wire size. Four of these capsules will form one of the experiments loaded on to the module itself.

Launch of the joint NASA/ESA Cassini/Huygens mission is planned for 8 October 1997 with a landing on Titan expected in late 2004.

For further details on the Microtechnology Centre, its facilities and expertise contact Chris Otter. E-mail: chris.cotter@twi.co.uk. Copyright © 2004 TWI Ltd