David Fearn, the father of ION propulsion

David Fearn, who died on August 29 aged 68, was internationally recognised as the father of ion propulsion in spacecraft, which he developed at the Royal Aircraft Establishment, Farnborough (now QinetiQ); his work enables telecommunications satellites to be positioned more accurately and, by saving on heavy rocket fuel, has made feasible missions to deep space that were previously impossible.

Find here a SpaceUK directory of Rocket Propulsion before the ion drive

Until the development of ion propulsion, manoeuvring artificial Earth satellites and deep-space probes was only possible by using conventional rocket thrusters.

Although relatively simple, they were inefficient and required large amounts of fuel.

As the size of Earth satellites has increased, the efficiency of the manoeuvring thrusters has become ever more critical, leading to the need for larger, more costly launch rockets and, ultimately, limiting capabilities.

Many of these limitations have been overcome by ion thrusters, which use the inert and naturally occurring gas xenon.

Physicist David Fearn, who died aged 68 on 29th Sept 2007, was the driving energy behind their development in the UK, and was internationally recognised as a father of spacecraft ion propulsion.

In 1999 two ion thrusters were flown on the European Space Agency Artemis satellite when it was used in the successful spacecraft rescue following the failure of the launch rocket.

Two thrusters are used on the gravity and ocean circulation explorer satellite, which provides a new level of understanding of the planet's composition, climate change and the processes operating below the Earth's crust.

This ground-breaking mission would be impossible without the ion thrusters that compensate for the disturbances the spacecraft experiences as it speeds through the rarefied upper atmosphere five times faster than a rifle bullet.

The level of control is analogous to compensating for the disturbance experienced by a supertanker when a snowflake lands on the deck.

In 2006 ESA used electric propulsion on its Moon mission, SMART-1. Following that event, the European Space Agency (ESA) and the Australian National University (ANU) successfully tested a new design of spacecraft ion engine that dramatically improved performance.  

This new engine was over ten times more fuel efficient than the one used on SMART-1.

Dr Roger Walker of ESA’s Advanced Concepts Team, Research Fellow in Advanced Propulsion and Technical Manager of the project, said at that time: "Using a similar amount of propellant as SMART-1, with the right power supply, a future spacecraft using our new engine design wouldn’t just reach the Moon, it would be able to leave the Solar System entirely"

So, in line with continuing progress on ion drive development, larger thrusters, pioneered by Fearn, will also be used on the 2013 ESA BepiColombo mission to propel a spacecraft to Mercury.

The significance of Fearn's work is illustrated by his extensive list of publications - more than 250 technical papers and scientific articles.

Find here an article written by David Fearn about the Prospero4 /X5 spacecraft

He led teams from a number of UK government, academic and industrial organisations, as well as international collaborative work with the European Space Agency (ESA), United States air force (USAF) and the National Aeronautics and Space Administration (Nasa).

A recent ESA accolade described him as "the father of electric propulsion in the UK and one of the most influential and inspirational figures in the field of European spacecraft propulsion".

He was awarded a visiting chair at Surrey University and often acted as an external supervisor for postgraduate students. His enthusiastic and approachable manner was an inspiration to generations of young scientists.