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The SMART-1 multicolour micro-camera (AMIE)

Miniaturisation is an everyday feature of our daily lives. Whether it is in cars, dishwashers or home digital cameras, everything is increasingly more compact and incorporates automatic procedures. The economics of the approach play a part as, in space at least, smaller can mean smarter and cheaper. Optimising a small spacecraft is a requirement and the mass and size of a proposed instrument can be crucial when deciding if it qualifies for a place on a science mission.

Early prototype of the micro imager (AMIE)

Over recent years, the assessment of future space exploration missions, notably in the framework of ESA's Technological Research Programmes, has repeatedly demonstrated the desirability of highly compact, lightweight and rugged cameras. The AMIE experiment is SMART-1's opportunity to demonstrate such an instrument.

The Asteroid-Moon Micro-Imager Experiment, AMIE, is an imaging system derived from the current development efforts of ESA's Technological Research Programme and has been developed by the Centre Suisse d'Electronique et de Microtechnique (CSEM) in Neuchatel, Switzerland. The principal investigator is Jean-Luc Josset.

Lunar colour lightweight camera

The SMART-1 payload has to meet stringent mass constraints, so the AMIE unit is miniaturised as much as possible. It consists of two parts: the AMIE micro-imager camera unit and the dedicated AMIE electronics unit. The micro-imager is placed on one of the lateral panels of the spacecraft on the external side whereas the electronics unit is on the internal side of the same panel. The main functions of the system are:

  • to take images with colour information
  • to keep image data in a memory buffer
  • to perform some image processing (data compression, image subtraction)
  • to allow the downloading of the images by the on board computer

The AMIE micro-imager is a remarkably compact design, a package of dedicated optics, electronics and mechanical interfaces that weighs only 450 grams (all included). This feat has been achieved by using new microtechnology in terms of micro-mechanics, micro-optics and 3D-stack packaging. Ultra thin printed circuit boards are 'sandwiched' vertically and allow the highly dense integration into a single multi-chip module of everything required by the camera, from its CCD sensor to its connector, including all electronic components.

The AMIE electronics are composed of:

  • a microprocessor board (CSEM's microprocessor) for the management of the instrument
  • a micro Digital Processing Unit - DPU (IAS/CSEM) for the data compression
  • a spacecraft interface board (CNR/IAS).

The design of the AMIE camera naturally takes into account the vibration stress encountered during launch, the low power consumption and wide operating temperature constraints during a space mission.

The original AMIE concept foresaw a panchromatic, 1024 x 1024 pixel image with a medium field of view of 5.3 degrees by 5.3 degrees. The camera will provide a high spatial resolution, some 50 m/pixel. Data from the micro-imager is read out and stored in the AMIE electronics, from which it can be downloaded as required from the spacecraft.

Initially a technology demonstration of a miniaturised micro-imager, AMIE on SMART-1 now has significant science objectives, covering the study of the Moon's morphology, topography and surface texture. The science community realised the potential of such a camera operating in a multi-spectral mode. AMIE has thus been equipped with four filters, one in the red (750 nm), two in the infrared (900 and 950 nm), and one specific to the Laserlink experiment (850 nm). It will also operate in white light.

AMIE will be opening new ground in the field of multi-spectral lunar observation. Whereas the multi-spectral camera aboard the American Clementine mission had constant illumination conditions, SMART-1's orbit will offer multi-angular imaging. AMIE's views at different angles correlated with Clementine data of the same lunar areas will allow scientists to establish photometric models, allowing the interpretation of such spectral data. These photometric studies will further our knowledge of the lunar surface, but will also be helpful for future multi-spectral observation of other planetary bodies, such as Mercury.

The micro-imager will work closely in conjunction with the SIR and D-CIXS instruments. Its infrared filter overlaps and complements the SIR spectrometer (900 nm - 2400 nm) and will notably allow studies of the different lunar rock types. Information obtained by AMIE and D-CIXS will help establish abundance maps of the elements present on the lunar surface.

The AMIE team

In addition to the AMIE technical team at CSEM, co-investigators in France are Patrick Pinet at the Terrestrial and Planetary Dynamics Laboratory, Toulouse, Yves Langevin at the Institut d'Astrophysique Spatiale, Orsay and Antonella Barucci at Observatoire Paris Meudon.

Italy is equally involved with co-investigators and hardware responsibilities. The co-investigators are Dr Priscilla Cerroni and Dr Maria Cristina De Sanctis, both from IAS-CNR, Rome, whose scientific interests lie in the fields of planetary sciences, physics of small Solar System bodies, impact cratering, and who have specific experience in the remote sensing of planetary surfaces from space missions. The Italian contribution to AMIE will include the DC/DC power converter and spacecraft interface board, and the development of ground support equipment software for scientific support and for the spacecraft's assembly, integration and verification activities, under the supervision of the Technical Manager Dr Andrea Di Lellis, IAS-CNR, Rome.

Other co-investigators include the Director of the Helsinki Observatory, Karri Muinonen, for the modelling of the Moon scattering light. The Institut de Géologie de l'Université de Neuchâtel (CH) are also co-investigators and part of the AMIE team. In addition to support by the SMART-1 team and project scientist, ESA/ESTEC is participating in the instrument development: Patrick Plancke for the overall technical developments and Detlef Koschny for thermal analysis of the instrument.

AMIE is supporting three other SMART- 1 investigations: the Laser-Link experiment (led by Zoran Sodnik, ESA), an autonomous navigation algorithm OBAN (Finn Ankersen, ESA) that uses image processing, and a measurement of lunar libration in coordination with the radio-science experiment RSIS. AMIE will also provide a visual record of the mission for educational and science communication purposes.

Last Update: 16 August 2006

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