Europe’s first mission to the Moon

• Launched 27 September 2003
• Entered Moon’s orbit November 2004
• Mission ended September 2006

The mission ended in dramatic fashion when SMART-1 underwent a controlled crash landing to reach its final resting place in the ‘Lake of Excellence’.

SMART-1 stands for ‘Small Missions for Advanced Research in Technology.’ The mission was designed to answer some fundamental questions about the geology and formation of the Moon. These include:

• What is the Moon made of?
• Does it have water?
• How was it formed?

Innovations on board SMART-1 included a British designed and built instrument, D-CIXS. This was used to examine the elemental composition of the Moon and the distribution of chemical elements. The spacecraft also proved the potential of ion propulsion.

Results from the mission are still being analysed and future missions will build on its achievements. An enhanced version of D-CIXS is to fly on India’s first mission to the Moon, Chandrayaan-1.

A long-term plan has been drawn up by a group of 14 space agencies to return to the Moon. ESA’s contribution to this strategy is the Aurora programme.

Mission facts

• The Moon is the fifth largest moon in the Solar System. It has a diameter of 3,476 km, around a quarter of the size of Earth.
  
  
• The far side of the Moon cannot be seen from Earth and is often known as the ‘dark side’ although it gets the same amount of Sun as the rest.
  
  
• The Moon has a direct physical effect on the Earth. Its gravity pulls the water in the oceans towards it, causing the tides. And, if we had no Moon, the Earth’s axis of rotation would wander chaotically. This would render the emergence and survival of life on Earth much more difficult.
  
  
• One of the major objectives of SMART-1 was to help scientists understand how the Moon was formed. The most widely accepted theory is that a Mars-sized object collided with Earth about 4.5 billion years ago and that the Moon was formed out of the debris. An alternative theory is that the Moon is a lump of rock ‘captured’ by the Earth’s gravity.
  
  
• SMART-1 demonstrated the advantages of the ‘express’ philosophy for space science missions. The spacecraft was developed and built in less time and at lower cost than traditional missions, without compromising on reliability or science.
  
  
• The decision to control the demise of SMART-1 with a controlled crash landing allowed the impact to be monitored from Earth. Astronomers observed a bright impact flash as the spacecraft hit the lunar surface. Analysis of the data was used to reveal the chemical composition of the rock and dust thrown up by the collision.

Technology

One of the principal tests of SMART-1 involved its solar electric propulsion technology or ‘ion engine’. The spacecraft’s solar panels generated electricity which was used to produce charged particles from xenon gas. These charged particles – known as ions – were then accelerated to very high speed before being neutralised and expelled from the spacecraft. The xenon atoms left SMART-1 at around four times the velocity of a conventional chemical rocket engine.

Ion engine technology has tremendous potential even though the thrust an ion engine produces is very small. It took SMART-1 almost 15 months to travel from the Earth to the Moon. This is a journey conventional rocket-powered spacecraft can manage in a matter of a few days. On the other hand, SMART-1 only used around 80 kg of xenon ‘fuel’ compared to around 500 kg of chemical fuel for a conventional rocket.

Unlike rockets, the advantage of ion engines is that they can work at very high efficiency for months on end. For longer journeys these types of thrusters would actually be quicker than conventional chemical engines. They would also be lighter and cheaper.

There were ten different instruments on board the SMART-1 spacecraft including monitoring equipment for the engine.

Innovations included the British designed and built D-CIXS (Demonstration of a Compact Imaging X-Ray Spectrometer) developed by a team at the STFC Rutherford Appleton Laboratory (RAL). This has been used to examine the composition of the Moon and the distribution of elements such as magnesium, aluminium, silicon, calcium and iron.

With experience gained on SMART-1, India’s national space agency, the Indian Space Research Organisation, is to use an enhanced version of the X-ray spectrometer – C1XS (pronounced ‘kicks’) – on its Chandrayaan-1 spacecraft.

The lunar mission is in co-operation with ESA and the C1XS instrument will be built at RAL. By flying at a lower and more constant altitude than SMART-1, C1XS will be able to spot elements at a much finer resolution.

SMART-1’s camera, AMIE, has also contributed significantly to our understanding of the Moon. By returning high-resolution images it has enabled more detailed maps to be produced of the lunar surface.

UK involvement

A team at UK’s Rutherford Appleton Laboratory near Oxford designed and built the D-CIXS instrument.

The following UK companies provided vital technology and expertise for the SMART-1 mission:

• Scisys Limited supplied mission control, system flight dynamics software and operations for the mission.
• E2V Technologies contributed to the design and manufacture of the D-CIXS X-ray detectors.
• Sea Group Limited helped to develop technology for the KaTE (Ka-band Telemetry Experiment) instrument on board SMART-1. KaTE was used to test new digital communications technology and featured very sensitive receivers. As missions get more and more ambitious, technology like this could be used to ensure two-way communication between spacecraft and the Earth.

The following UK institutions are all involved in analysing data from the D-CIXS experiment:

• STFC Rutherford Appleton Laboratory
• Southampton University
• Birkbeck College
• University College London (UCL)
• UCL’s Mullard Space Science Laboratory
• Queen Mary College, University of London
• Sheffield University
• Armagh Observatory