SMART-1 leaves Earth on a long journey to the Moon

SMART-1, Europe’s first science spacecraft designed to orbit the Moon, has
completed the first part of its journey by achieving its initial Earth orbit
after a flawless launch during the night of 27/28 September.

The European Space Agency’s SMART-1 was one of three payloads on Ariane Flight
162. The generic Ariane-5 lifted off from the Guiana Space Centre, Europe’s
spaceport at Kourou, French Guiana, at 2014 hrs local time (2314 hrs GMT) on 27
September (01:14 Central European Summer time on 28 September).

42 minutes after launch, all three satellites had been successfully released
into a geostationary transfer orbit (742 x 36 016 km, inclined at 7 degrees to
the Equator). While the other two satellites are due to manoeuvre towards
geostationary orbit, the 367 kg SMART-1 will begin a much longer journey to a
target ten times more distant than the geostationary orbit: the Moon.

“Europe can be proud,” said ESA Director General Jean-Jacques Dordain, after
witnessing the launch from ESA’s ESOC space operations centre in Darmstadt,
Germany, “we have set course for the Moon again. And this is only the
beginning:
we are preparing to reach much further.”

The spacecraft has deployed its solar arrays and is currently undergoing
initial
checkout of its systems under control from ESA/ESOC. This checkout will
continue
until 4 October and will include with the initial firing of SMART-1’s
innovative
ion engine.

By ion drive to the Moon

“Science and technology go hand in hand in this exciting mission to the Moon.
The Earth and Moon have over 4 thousand million years of shared history, so
knowing the Moon better will help scientists in Europe and all over the world
to
better understand our planet and will give them valuable new hints on how to
better safeguard it” said ESA Director of Science David Southwood, following
the
launch from Kourou.

As the first mission in the new series of Small Missions for Advanced Research
in Technology, SMART-1 is mainly designed to demonstrate innovative and key
technologies for future deep space science missions.

The first technology to be demonstrated on SMART-1 will be Solar Electric
Primary Propulsion (SEPP), a highly efficient and lightweight propulsion system
that is ideal for long-duration deep space missions in and beyond our solar
system. SMART-1’s propulsion system consists in a single ion engine fuelled by
82 kg of xenon gas and pure solar energy. This plasma thruster relies on the
“Hall effect” to accelerate xenon ions to speed up to 16,000 km/hour. It is
able
to deliver 70 mN of thrust with a specific impulse (the ratio between thrust
and
propellant consumption) 5 to 10 times better than traditional chemical
thrusters
and for much longer durations (months or even years, compared to the few
minutes’ operating times typical of traditional chemical engines).

The ion engine is scheduled to go into action on 30 September. At first, it
will
fire almost continuously — stopping only when the spacecraft is in the Earth’s
shadow — to accelerate the probe (at about 0.2 mm/s2) and raise the altitude
of
its perigee (the lowest point of its orbit) from 750 to 20,000 km. This
manoeuvre will take about 80 days to complete and will place the spacecraft
safely above the radiation belts that surround the Earth.

Commissioning will be completed within 2 weeks, after which ESA’s control
centre
at ESOC will be in contact with the spacecraft for two 8-hour periods every
week.

Once at a safe distance from Earth, SMART-1 will fire its thruster for periods
of several days to progressively raise its apogee (the maximum altitude of its
orbit) to the orbit of the Moon. At 200,000 km from Earth, it will begin
receiving significant tugs from the Moon as it passes by. It will then perform
three gravity-assist manoeuvres while flying by the Moon in late December 2004,
late January and February 2005. Eventually, SMART-1 will be “captured” and
enter
a near-polar elliptical lunar orbit in March 2005. SMART-1 will then use its
thruster to reduce the altitude and eccentricity of this orbit.

During this 18-month transfer phase, the solar-electric primary propulsion’s
performance, and its interactions with the spacecraft and its environment, will
be closely monitored by the Spacecraft Potential, Electron & Dust Experiment
(SPEDE) and the Electric Propulsion Diagnostic Package (EPDP) to detect
possible
side-effects or interactions with natural electric and magnetic phenomena in
nearby space.

A promising technology, Solar Electric Primary Propulsion could be applied to
numerous interplanetary missions in the Solar System, reducing the size and
cost
of propulsion systems while increasing manoeuvring flexibility and the mass
available for scientific instrumentation.

In addition to Solar Electric Primary Propulsion, SMART-1 will demonstrate a
wide range of new technologies like a Li-Ion modular battery package;
new-generation high-data-rate deep space communications in X and Ka bands with
the X/Ka-band Telemetry and Telecommand Experiment (KaTE); a computer technique
enabling spacecraft to determine their position autonomously in space, which is
the first step towards fully autonomous spacecraft navigation.

Digging for the Moon’s remaining secrets

In April 2005 SMART-1 will begin the second phase of its mission, due to last
at
least six months and dedicated to the study of the Moon from a near polar
orbit.
For more than 40 years, the Moon has been visited by automated space probes and
by nine manned expeditions, six of which landed on its surface. Nevertheless,
much remains to be learnt about our closest neighbour, and SMART-1’s payload
will conduct observations never performed before in such detail.

The Advanced/Moon Micro-Imaging Experiment (AMIE) miniaturised CCD camera will
provide high-resolution and high-sensitivity imagery of the surface, even in
poorly lit polar areas. The highly compact SIR infrared spectrometer will map
lunar materials and look for water and carbon dioxide ice in permanently
shadowed craters. The Demonstration Compact Imaging X-ray Spectrometer (D-CIXS)
will provide the first global chemical map of the Moon and the X-ray Solar
Monitor (XSM) will perform spectrometric observations of the Sun and provide
calibration data to D-CIXS to compensate for solar variability.

The SPEDE experiment used to monitor Solar Electric Primary Propulsion
interactions with the environment will also study how the solar wind affects
the
Moon.

The overall data collected by SMART-1 will provide new inputs for studies of
the
evolution of the Moon, its chemical composition and its geophysical processes,
and also for comparative planetology in general.

Paving the way for future space probes

In addition to valuable lunar science, SMART-1’s payload will be involved in
the
mission’s technology demonstrations to prepare for future-generation deep space
missions.

For instance, the AMIE camera will be used to validate the On-Board Autonomous
Navigation (OBAN) algorithm, which correlates data from sensors and star
trackers to provide navigational data. It will also participate in a laser
communication link experiment with ESA’s optical ground station at the Teide
Observatory in Tenerife, Canary Islands, trying to detect an incoming laser
beam
from the ground.

Using both AMIE and KaTE hardware, the Radio Science Investigation System
(RSIS)
experiment will demonstrate a new way of gauging the interiors of planets and
their moons by detecting the well-known tilting motion of the Moon. This
technology can be used later by ESA planetary missions.

SMART-1 was developed for ESA by the Swedish Space Corporation, as prime
contractor, with contributions from almost 30 contractors from 11 European
countries and the United States. Despite its small size, the spacecraft carries
19 kg of science payload consisting in experiments led by Principal
Investigators from Finland, Germany, Italy, Switzerland and the United Kingdom.

Despite its relatively small budget and short development schedule, SMART-1
holds tremendous potential for future missions and is a clear illustration of
Europe’s ambitions in the exploration of the solar system, also highlighted by
June’s launch of Mars Express, which has now completed over the half on its
journey to Mars, and the launch of Rosetta, due in February 2004, to visit
comet
Churyumov-Gerasimenko.

For more information please contact:

ESA Communication Department

Media Relations Office

Paris, France

Tel: +33(0)15369 7155

Fax: +33(0)1 5369 7690

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/export/esaCP/SEMOJN0P4HD_index_1.html]
SMART-1 artist’s impression

Credits: ESA

[Image 2:
http://www.esa.int/export/esaCP/SEMOJN0P4HD_index_1.html#subhead1]
How an ion engine works. Electrons attracted into the discharge chamber collide
with xenon atoms from the propellant gas supply, making charged atoms (ions).
Current-carrying coils, inside and outside the doughnut-shaped discharge
chamber, sustain a magnetic field oriented like the spokes of a wheel. By the
Hall effect, ions and electrons swerving in opposite directions in the magnetic
field create an electric field. This expels the xenon ions in a propulsive jet.
Other emitted electrons then neutralise the xenon, producing the blue jet.

SMART-1 is the first of ESA’s Small Missions for Advanced Research in
Technology. It will head for the Moon using solar-electric propulsion and
carrying a battery of miniaturised instruments.

Credits: Illustration by AOES Medialab, ESA 2002

[Image 3:
http://www.esa.int/export/esaCP/SEMOJN0P4HD_index_1.html#subhead2]
Ariane 5G Flight 162 shortly before launch on the night of 27 September 2003,
with SMART-1 and two fellow passengers.

Credits: CNES – Arianespace

[Image 4:
http://www.esa.int/export/esaCP/SEMOJN0P4HD_index_1.html#subhead3]
How three remote-sensing instruments on SMART-1 will scan the Moon’s surface
during one pass. Repeated passes will gradually fill in the picture.

Credits: ESA 2002. Illustration by Medialab.