Require Much Less Propellant Than Conventional Thrusters
Electric engines that were designed, built and tested at
QinetiQ's space centre in Farnborough, UK are ready to play a
crucial role in the European Space Agency's (ESA) gravity mission,
following their successful commissioning onboard the GOCE
spacecraft this week.
GOCE's ultra-sensitive measurements of the Earth's gravitational
field depend on the ability of QinetiQ's engines to maintain the
spacecraft's orbit by finely controlling its altitude and
speed.
The strength of the Earth's gravitational field diminishes with
altitude, so GOCE's orbit skirts the outer reaches of the
atmosphere at just 160-175 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, providing tiny but continuous
levels of thrust to compensate for atmospheric drag without
disturbing the sensitive science payload -- literally, preventing
the spacecraft from falling out of the sky.
ESA mission manager Rune Flobererghagen said all systems on the
spacecraft had now been activated following the launch from Russia
on 17 March and that the mission will become fully operational in
the next few weeks. "Now we must learn to drive our
super-satellite," he said.
The full commissioning proved that the main and back-up engine
chains are performing precisely to specification across the full
thrust range, providing very stable thrust with no interruptions
and a perfect thrust vector.
"This is an historic moment for the QinetiQ space team –
the first real, in-orbit qualification for our ion engines," said
Neil Wallace, QinetiQ's chief electrical propulsion engineer. "You
work on these things for so many years that you should be cold and
confident that it will all work, but there is nothing better than
results from commissioning that show performance in space perfectly
matches the on-the-ground thrust results."
The QinetiQ T5 ion thrusters are around 10 times more efficient
than rocket thrusters that have traditionally been used to propel
spacecraft, according to the company... requiring only 40kgs of
xenon propellant for the whole 30-month GOCE mission.
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 next generation of deep space and
interplanetary science missions, such as the ESA BepiColombo
mission to the planet Mercury.