The overall objectives of VEGETATION are to provide accurate and operational measurements of simple 
characteristics of vegetation canopies either for scientific studies or for operational programmes of vegetation 
productions prediction and management (Durpaire et al, 1992, Saint et al, 1993). 
VEGETATION/SPOT-4 system has been designed as a self-contained add-on system complete with its own 
imaging, recording and data transmission capability. The system includes its associated ground segment. The 
VEGETATION programme is a joint programme of the European Union, Belgium, Italy, Sweden and France. 
The main instrument characteristics are given in Table 2. 
The spectral bands B2, B3 and MIR are those of HRVTR. The simultaneity and collocation of comparable data 
will permit improved performances in radiometry and geometry and give the capability of a scale integration 
without any distorsion due to temporal variations of surface signatures or atmospheric effects. 
The data will be made available to users both through a global acquisition and local direct read out stations. 
The products are still under definition by the International Users Committee. The proposed general structure is 
shown in Figure 1. 
4.3 POLDER/ADEOS 
CNES also develops the POLDER (POLarization and Directionality of Earth Reflectances) instrument 
primarily designed for the study of interactions between aerosols, clouds and radiation and the impact of 
aerosols on the climate change. Another of his objectives is the monitoring of ocean colour and its relationship 
with ocean carbon absorption. Finally it will also permit to characterize the vegetation dynamics at low 
resolution and global scale. 
This CCD matrix instrument, whose principle is described in Figure 4 will measure the apparent reflectances of 
terrestrial targets under 12 viewing angles, in eight spectral bands , 2 of them specially for vegetation and the 
polarization in 3 of them (Table 3). 
Given the 102° field of view, 5 successive orbits are necessary to build a complete bidirectional reflectance 
function for a midlatitude pixel. 
The instrument developed by CNES will be flown onboard the Japanese platform ADEOS to be launched in 
1996. 
The POLDER standard products have been defined for each application. For vegetation studies, the level 2 
products will be the surface spectral reflectance (corrected from atmospheric contamination), bidirectional 
signature, vegetation index and albedo. They are defined on an equivalent sinusoidal projection at 6 km 
resolution. Level 1 to level 3 products (time or spatial composite of geophysical products at global scale) will 
also be produced for distribution by CNES to the international research community. 
4.4 IRSUTE 
IRSUTE for Infra Red Satellite Unit for Terrestrial Environment is proposed as a scientific mission for 
methodologic studies of surface fluxes determination with thermal imagery at high spatial resolution. It will 
serve to optimize the methods of atmospheric correction, decoupling surface temperature and emissivity and 
ultimately retrieve fluxes combining with information at lower resolution and better repetitivity from 
METEOSAT, AVHRR or ATSR. Other applications to geology, soil characterization, fire detection, thermal 
pollution are envisaged. 
This instrument is considered for a phase A study. Its main specifications are given in Table 4. 
The main adavantages of this instrument is its very spatial resolution (40m), an optimal combination of 
channels (3.7, 9.0, 10.5 and 11.5 pm), its capability to point 40° along the track. 
It is proposed to be embarked on a small platform. The optimal orbit for a revisit better than three days over 
around 20 experimental sites of 10 by 10 km and distributed over the world will be determined. The time pass 
specified is between 10 and 14 local time.