Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) is the major instrument on the

Soil Moisture and Ocean Salinity satellite Soil Moisture and Ocean Salinity (SMOS) is a satellite which forms part of ESA's Living Planet Programme. It is intended to provide new insights into Earth's water cycle and climate. In addition, it is intended to provide improved weather forecas ...

(SMOS). MIRAS employs a planar antenna composed of a central body (the so-called hub) and three telescoping, deployable arms, in total 69 receivers on the Unit. Each receiver is composed of one Lightweight Cost-Effective Front-end (LICEF) module, which detects radiation in the

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...

L-band The L band is the Institute of Electrical and Electronics Engineers (IEEE) designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz). This is at the top end of the ultra high frequency (UHF) band, at the lower en ...

, both in horizontal and vertical polarizations. The aperture on the LICEF detectors, planar in arrangement on MIRAS, point directly toward the Earth's surface as the satellite orbits. The arrangement and orientation of MIRAS makes the instrument a 2-D interferometric

radiometer A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, a radiometer is an infrared radiation detector or an ultraviolet detector. Microwave radiometers operate in the microwave w ...

that generates brightness temperature images, from which both geophysical variables are computed. The salinity measurement requires demanding performance of the instrument in terms of calibration and stability. The MIRAS instrument's prime contractor was

EADS Airbus SE (; ; ; ) is a European multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace products worldwide and manufactures aircraft throughout the world. The company has three divisions: '' ...

CASA Espacio, manufacturing the payload of SMOS under ESA's contract.''SMOS: The Challenging Sea Surface Salinity Measurement from Space'', J. Font, A. Camps, A. Borges, M. Martin-Neira, J. Boutin, N. Reul, Y. Kerr, A. Hahne and S. Mecklenburg,

Proceedings of the IEEE The ''Proceedings of the IEEE'' is a monthly peer-reviewed scientific journal published by the Institute of Electrical and Electronics Engineers (IEEE). The journal focuses on electrical engineering and computer science. According to the ''Journa ...

, vol. 98, no. 5, May 2010, pp. 649-665

LICEF

The LICEF detector is composed of a round

patch antenna A patch antenna is a type of antenna with a low profile, which can be mounted on a surface. It consists of a planar rectangular, circular, triangular, or any geometrical sheet or "patch" of metal, mounted over a larger sheet of metal called a g ...

element, with 2 pairs of probes for orthogonal linear polarisations, feeding two receiver channels in a compact lightweight package behind the antenna. It picks up

thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...

emitted by the Earth near 1.4 GHz in the

, amplifies it 100 dB, and digitises it with 1-bit quantisation.Operating Principles
SMOS Mission, ICM-CSIC (Spanish Institute of Marine Sciences –

Spanish National Research Council The Spanish National Research Council ( es, Consejo Superior de Investigaciones Científicas, CSIC) is the largest public institution dedicated to research in Spain and the third largest in Europe. Its main objective is to develop and promote res ...

), updated July 2008 Last batch of LICEF receivers delivered for SMOS

Living Planet Programme The Living Planet Programme (LPP) is a programme within the European Space Agency which is managed by the Earth Observation Programmes Directorate. LPP consists of two classes of Earth observation missions (listed below) including research missio ...

ESA , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

References

{{Satellite and spacecraft instruments Embedded systems Space imagers Earth observation satellite sensors