References & products

Atlas - Icare

SolData measures ground and large structure deformations via satellite, using the ATLAS module or the ICARE channel.

The ATLAS module was developed in collaboration with the IGN (French Geographical Institute). ATLAS uses IGN and SolDatas' satellite and geodesic skills to create a new generation processing module for large-scale industrial applications. ATLAS monitors the evolution of large site deformations with better precision than those obtained by field topographic teams.

The ICARE channel processes existing images to determine the shifting of natural reflectors. Thanks to ICARE, and in particular the use of satellite image databanks from the European Space Agency (ESA), it is possible to observe an area’s settlement data from 1992 to present day.

The images processed by ATLAS and ICARE come from numerous radar satellites from different space agencies. The main satellites used are the following:

RADARSAT
RADARSAT is the first series of remote sensing satellites launched in Canada, with RADARSAT-1, launched in 1995, followed by RADARSAT-2, launched in 2007. These satellites focus on the use of radar sensors in order to observe the surface of the Earth in most atmospheric conditions, even darkness.

RADARSAT is equipped with an improved radar sensor called SAR (Synthetic Aperture Radar).
SAR is a powerful microwave instrument able to emit and receive signals allowing to ‘see’ the Earth regardless of the sky cover, the fog, the smoke or the darkness, and to obtain excellent quality images in all weather and all atmospheric conditions. RADARSAT’s SAR operates on the C band and is characterised by its ability to orientate its beam on a 500km band.
It provides users with a beam range able to scan corridor widths between 35 and 500 kilometres and to obtain images with a resolution included between 10 and 100 meters according to the corridor length. Its incidence angles also vary from less than 20 degrees to more than 50 degrees.
Moreover, RADARSAT is placed on a sun-synchronous orbit, allowing users to review a scene always at the same local time.

RADARSAT dawn orbit enables solar panels to be exposed almost continuously to sunlight. The main advantage of this type of orbit is that the SAR can be powered by sun energy rather than batteries. Because of that, it can offer an optimal number of shot occasions.

Moreover, RADARSAT does not transmit its data to Earth stations at the same moment as the other remote-sensing satellites, most of which transmit around midday.

The SAR collects data during a maximal period of 28 minutes per orbit to provide images of the Earth surface over a maximal area of 1.1 million square meters. In order to meet with commercial and international customers’ needs, data are transmitted downlink in real time or stored on one of the two system’s tape recorders, until the machine is seen by a receiving station.

ENVISAT
ENVISAT was launched on March the 1^st 2002 from the Kourou (Guyana) by an Ariane 5 rocket.

ENVISAT weights 8200 kg, 2050 of which are instruments and 300 are propellants, for an overall dimension of 10 m x 4 m x 4 m (bigger than a bus!). The solar generator is 14 m x 5m big and provides a 6.6 kW power, the energy being stocked in 8 cadmium-nickel batteries of 40 A.h each.

Orbital features:
ENVISAT moves about on a quasi-circular orbit at an average height of 800 km.
It is a polar orbit: the satellite almost flies over the poles due to the orbit’s tilt angle: 98° compared with the equatorial plane).

Besides, the ENVISAT orbit is SSO (Sun Synchronous Orbit): the trace of a sun synchronous satellite goes past a set latitude, always at the same time (in mean solar time). Its revolution period is 101 minutes.

Moreover, the satellite is synchronised: it goes past exactly the same area after a given number of revolutions. For ENVISAT, such cycle is 501 revolutions, which represents a 35 days orbital cycle.

ENVISAT satellite is a non-synchronous satellite. In effect, due to the Earth rotation, at each revolution, the satellite flies over a given parallel more western than the previous one. For example, at the Equator, 2800 km separate two consecutive traces.

Embedded Systems
ENVISAT carries ten instruments able to work simultaneously. Some of them are imaging sensors:

ASAR: all-weather day and night imaging sensor
MERIS: imaging spectrometer used to determine the “colour” of the ocean
AATSR: infrared radiometer used to measure the temperature of the sea surface
SCIAMACHY: atmospheric aerosol measurement instrument
GOMOS: Ozone layer measurement instrument
MIPAS : interferometer used to study Ozone concentration
RA-2 : altimetry radar used to measure the sea level
MWR : microwave radiometer which provides relevant changes to fine altimetry
DORIS : precise measurement systems of the satellite position on its orbit
LRR : laser reflector, facilitates DORIS measurements

Explored Spectral Bands:
The Earth resources monitoring satellite ENVISAT is used to acquire high resolution images on a large spectral band range.
The spectral areas concerned by the various embedded instruments cover different areas of the electromagnetic spectrum, from the microwaves to the ultraviolet.





ERS1 & ERS2
ERS (European Resource Sensing)
ERS satellites are part of a European Space Agency programme. They transport many sensors, the most famous of which is the SAR (Synthetic Aperture Radar), which was the first commercial radar sensor.

AMI Sensor (Active Microwave Instrument)
This instrument includes 2 different radar systems: an SAR (that can work on “Image Mode” or measure the waves’ height “Wave Mode”) as well as a Scatterometer to measure the wind (the radar measures the speed and the direction of the winds at the surface of the see). The great mastery of the orbits (precise positioning of the satellites known thanks to 2 embedded instruments) as well as the possibility to use 2 identical SAR, have converted ERS satellites into ideal tools for interferometry studies.

RA Sensor (Radar Altimeter)
This radar altimeter works in K-band (13.8 GHz) and measures altitudes vertically from the satellite with a maximal resolution of 10 m. It includes two measurement modes: "Ocean Mode" (measures the waves’ height, the altitude of the ocean’s surface and the wind speed on the surface) and "Ice Mode" (provides information on the topography of the areas covered with ice as well as on the kind of ice and the limits ice/sea).

ATSR Sensor (Along Track Scanning Radiometer)
This optical infrared sensor is used to measure the Sea-Surface Temperatures (SST) as well as the temperature at the top of the clouds. The version embedded on ERS-1 includes 4 bands (one of which is no longer operational) while the ATSR of ERS-2 is made of 7 bands. At the same time, another radar instrument (Microwave Radiometer - MWR) that works in 2 K bands (23,8 and 36,5 GHz) measures the steam content in the atmosphere, which increases the precision of the temperature of the sea surface as well as the altitude (RA sensor).

GOME Sensor (Global Ozone Monitoring Experiment)
This sensor, only present on ERS-2, enables to study the atmosphere. It enables to measure the ozone and to detect other gases, aerosols and micro-particles.

ICARE
SolData has developed the ICARE processing channel, a satellite subsidence monitoring module.
ICARE is based on a well-known "time deformation" measurement technique: satellite radar interferometry.

The satellite images processed with this method come from the different satellites equipped with SAR radars, such as ENVISAT. The deformation monitored over a given period corresponds to the monitoring of the Permanent Reflectors identified and selected during this period. Time reports and graphs resulting from this monitoring of the Permanent Reflectors can be consulted:
- on Geoscope Web and/or
- directly sent to you in the form of reports.

ATLAS
SolData and the IGN (French Geographical Institute) have developed ATLAS, a unique subsidence monitoring module by satellite.
ATLAS relies on a well known technique of deformation measurement over time: satellite radar interferometry.

The satellite radar images processed with this method come from the different working satellites equipped with SAR radars, such as ENVISAT, shown opposite.

Deformation follow-up over a given period corresponds to the follow-up of the Permanent Reflectors identified and selected on the satellite images collected during this period.

The ATLAS measurement channel includes a calibration with field measurements, which guarantees a +/-3mm precision on the monitored area.

Thus, SolData can provide a precise and reliable satellite monitoring.