Revolutionary GOCE Spacecraft Benefits From QinetiQ Precision

LONDON - Ion Thrusters Provide Cruise Control for ESA Gravity Mission to be
Launched Today

QinetiQ’s (LSE: QQL) electric engines are playing a crucial role on a
revolutionary spacecraft to be launched today (Monday) from the Plesetsk
cosmodrome in Northern Russia. The electric engines(link:
www.qinetiq.com/home/defence/defence_solutions/space/ep.html), known
as T5 ion thrusters, are providing high-precision drag compensation for the
dart-shaped GOCE spacecraft being launched by the European Space
Agency (ESA) to map the Earth’s gravitational field.

To view the Multimedia News Release, please click:

www.prnewswire.com/mnr/qinetiq/37449/

GOCE (link: www.esa.int/SPECIALS/GOCE/) is the first spacecraft to
be launched as part of ESA’s living planet programme which is investigating
the impact that human activity is having on the Earth. By measuring the
Earth’s gravity, GOCE will contribute significantly to our understanding of
the Earth’s structure, ocean circulation and climate change. The strength of
the Earth’s gravitational field diminishes with altitude, so GOCE’s orbit
skirts the outer reaches of the atmosphere at just 200-300 kms (125-185
miles) above the Earth. As a result the spacecraft experiences small but
significant disturbances in its motion from atmospheric drag. QinetiQ’s
electric engines act as cruise control for the spacecraft, continuously
compensating for this atmospheric drag and quite literally preventing the
spacecraft from falling out of the sky.

“In order to achieve its very challenging mission objectives, the GOCE
spacecraft is based on cutting-edge technology, making it a jewel of
innovations,” commented Volker Liebig, Director of Earth Observation
Programmes at ESA. “It has been designed to fly at an extremely low orbital
altitude, just 250km (155 miles) above Earth. For this reason it has an
eye-catching aerodynamic shape and will actively compensate for the air drag
by using the finely controlled thrust of QinetiQ’s ion engine.”

QinetiQ’s T5 ion thrusters
(www.qinetiq.com/home/defence/defence_solutions/space/ep/t5_ion_thruster.Par.0008.File.pdf)
are around ten times more efficient than rocket
thrusters that have traditionally been used to propel spacecraft, requiring
only 40kgs of propellant for the whole 30-month GOCE mission. The thrusters
use the inert gas xenon as their propellant ensuring they are also more
environmentally friendly than conventional thrusters that use volatile
chemical propellant.

“This important space mission would not be possible without the precision
provided by the QinetiQ’s electric engines,” commented Mary Carver, Managing
Director of QinetiQ’s Integrated Systems business. “Our space engineers have
overcome a challenge that has been likened to compensating for the impact of
an insect landing on the windscreen of a car travelling at 100mph.”

Mary Carver added: “In the next few years electric propulsion could make
previously impossible missions into deep space a reality and extend the
operational life of commercial communications satellites, reducing costs.”

QinetiQ is currently working with partners to qualify its T6 thruster, an
even more advanced electric propulsion system that has been designed for use
on the ESA BepiColombo mission to Mercury.

About the GOCE mission

The GOCE (Gravity Field and Steady-State Ocean Circulation Explorer)
mission is dedicated to measuring the Earth’s gravity field and modelling the
planet’s geoid, essentially a gravitational contour map, with extremely high
accuracy and spatial resolution. It is the first Earth Explorer Core mission
to be developed as part of ESA’s Living Planet Programme and is scheduled for
launch from Plesetsk, Russia in March 2009.

A precise model of the Earth’s geoid is crucial for deriving accurate
measurements of ocean circulation, sea-level change and terrestrial ice
dynamics - all of which are affected by climate change. The geoid is also
used as a reference surface from which to map all topographical features on
the planet.

An improved knowledge of gravity anomalies will contribute to a better
understanding of the Earth’s interior, such as the physics and dynamics
associated with volcanism and earthquakes and also further our knowledge of
land uplift due to post-glacial rebound.

The prime contractor for the mission is Thales Alenia Space Italy, with
Astrium Friedrichshafen responsible for the spacecraft.

About the Ion Propulsion Assembly

The electric propulsion system is responsible for controlling and
maintaining the spacecraft’s orbit and as such is a vital GOCE subsystem.
Uniquely it also ensures the drag free attitude control in the flight
direction essential to allow the scientific objectives of the mission to be
achieved.

At the heart of the system is QinetiQ’s T5 ion thruster, mounted on an
adjustable alignment bracket to direct the thrust vector through the
spacecraft centre of mass. The thruster is extremely efficient requiring
dramatically less propellant than conventional rocket thrusters, allowing the
30-month mission to be achieved using only 40 kg of propellant. For
redundancy, two ion thrusters are mounted externally on the rear panel of the
satellite.

The propellant is the inert xenon gas which is continuously fed into the
10 cm diameter cylindrical discharge chamber. The xenon is then ionised by
electrons emitted by an internal cathode which both ignites and subsequently
sustains the plasma inside the thruster chamber. A weak variable magnetic
field is also applied which enhances the ionisation efficiency and also
allows the number of ions created, and therefore the thrust produced, to be
rapidly varied to precisely match the drag level.

In addition to providing the T5 thrusters, QinetiQ has produced control
software and algorithms for the GOCE propulsion system. QinetiQ has also
supported the testing of the Ion Propulsion Assembly.

Source: QinetiQ

Contact details: David Bishop, Head of External Communications, QinetiQ, +44-(0)1252-394573, +44-(0)7920-108675