electromagnetic spectrum where clouds are a barrier to observe 
the Earth surface. An alternative to this problem is to increase 
the temporal resolution of the system in order to increase the 
chance of obtaining cloud free images. 
THE BRAZILIAN ALTERNATIVE 
The Brazilian Complete Space Mission (MECB, Missäo 
Espacial Completa Brasileira) was conceived in the late 
seventies and included the construction of two meteorological 
and two remote sensing satellites along with a satellite 
launching system (VLS, Veiculo Lançador de Satélites). 
Nonetheless budget restrictions, the first Data Collecting 
Satellite (SCD-1, Satélite de Coleta de Dados) was 
successfully launched on February of 1993 and is still in 
operation. The SCD-2 shall be launched later this year. 
The characteristics of the remote sensing satellites of the 
MECB program were defined in the late eighties. The 
satellites should carry a sensor denominated Wide Field Imager 
(WFI) which would cover a large surface area. The revisit 
time at equatorial locations should be of four days and the 
spatial resolution was specified as ~260 m (an intermediate 
resolution between Landsat/TM and NOAA/AVHRR 
satellites). Recently launched satellites such as the Russian 
RESURS-] (160 m) and the Indian IRS-1C (188 m) have 
similar characteristics. This kind of  satellite/sensor 
combination will undoubtedly provide a great improvement in 
global change monitoring. 
Also in the late eighties, Brazil signed a cooperation with 
China for a space program called China-Brazil Earth Resources 
Satellites (CBERS). The program comprised the construction 
of two remote sensing satellites (with some characteristics 
similar to Landsat and Spot satellites) that are much more 
sophisticated than those from the MECB program. At that 
time, it was also decided to include the WFI sensor on board of 
CBERS-1 and -2. This, in turn, brought the MECB program to 
a recent new evaluation. 
The increasing relevance of the Amazon region in studies 
related to global change processes, and the demand for 
information to monitor this region on a systematic basis have 
promoted the redefinition of the MECB Remote Sensing 
Satellites (SSR, Satélite de Sensoriamento Remoto) to mcet 
some of the remote sensing applications for this important part 
of the world. The major limitation to obtain data from the 
optical spectral region, in the Amazon, are clouds. For 
instance, in some areas the presence of clouds is so intense that 
no more than a few useful Landsat images were acquired, over 
the last twenty years. Therefore, a satellite with a low 
equatorial orbit was chosen to allow several overpasses over 
the same area on a given day. However, this feature will 
confine the imaged swath to the latitudes between 5?N and 
15°S (figure 1). 
600 
noose 
  
-0* 
    
  
arash : 
EN CPI 
Figure 1. South America and imaged swath by the equatorial 
orbit of the Brazilian Remote Sensing Satellite (SSR). 
THE BRAZILIAN REMOTE SENSING SATELLITE 
Changes in the orbit, sensor, and data transmission system of 
the Brazilian Remote Sensing Satellite (SSR) are suggested in 
the new project (Bogossian et al., 1995; Rudorff et al., 1995; 
Santana, 1995). Two satellites should be launched with an 
expected lifetime of four years each. The SSR shall be 
launched by the VLS (satellite launching system), from the 
launching center in Alcántara, Maranháo State, Brazil. Each 
satellite shall have a mass of 230 kg, stabilized at three axes, 
and hydrazine propulsion. The mean altitude shall be at ~893 
km allowing a temporal resolution of less than two hours. This 
means that the satellite will cover a swath width of 2,200 km, 
having a spatial resolution of ~100 m close to the Equator and 
~200 m at the 15°S limit. These characteristics impose the use 
of 2 or 3 modular sensors. 
The greatest innovation on the SSR is the equatorial orbit, 
which will minimize the cloud cover problem on the images. 
Also, partially cloud covered images, acquired at different 
times or days, can be registered, resulting in a single cloud free 
or almost cloud free composed image. The sensor should use 
state of the art technology with four spectral bands (blue, red, 
near- and mid-infrared). Another great innovation of the SSR 
concerns the data transmission mode. It can be done directly to 
the users, from a relatively close area around their stations 
(500 x 500 km) as well as to a central receiving station located 
in Cuiabá, Mato Grosso State, for the whole swath that covers 
Brazil. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996