335 
Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Monitoring of renewable resources in equatorial countries 
R.van Konijnenburg 
Netherlands Agency for Aerospace Programs (NIVR), Delft, Netherlands 
Mahsum Irsyam 
Indonesian National Institute of Aeronautics and Space (LAPAN), Jakarta 
ABSTRACT: Studies have been conducted on the feasibility of a joint Indonesian-Netherlands project for the 
development and operation of a dedicated Tropical Earth Resources Satellite (TERS) system. The studies confirm 
the need for an earth-observation system with a high temporal and geometric resolution to provide the capabili 
ty of monitoring the renewable resources in equatorial countries. The result of cloud studies indicates that 
the requirement for a high temporal resolution cannot be met by a satellite in polar orbit. An equatorial orbit 
however will enable to meet this requirement. In the course of the studies the user requirements for such a 
tropical earth-observation satellite were elaborated. Based on these requirements a baseline design was 
conceived. "Key applications" have been identified, which would typically need a TERS system and which are of 
sufficient importance from a benefits point of view. The two most important fields of application are agricul 
ture and forestry. Analysis of these key applications indicate profits in excess of yearly cost. It has been 
recognized that it will be necessary to ascertain that by the time TERS becomes operational an adequate 
infrastructure for the utilisation of such a system will be available. For that purpose the preliminary 
outlines of a rice production monitoring system and of a TERS utilisation preparation plan have been esta 
blished. 
1 INTRODUCTION 
An effective management of the renewable and 
non-renewable resources of a country requires up to 
date information where all the modern techniques and 
methods should be applied. After a hesitant start in 
the seventies, satellite remote sensing is gradually 
proving itself as a valuable tool for gathering such 
information. 
Satellite earth observation (remote sensing) is and 
will be an indispensable tool for the management of 
extensive countries like Indonesia, if the satellite 
systems are combined with the right groundsegment. 
The government can use the unbiased and timely 
information in an effective central management and on 
the other hand it will be possible to delegate the 
execution of its policy to the regions. 
Joint Indonesian-Netherlands studies have been 
performed on the concept of an remote sensing system, 
designed for the specific needs of the equatorial 
countries and Indonesia in special. 
2 SYSTEM CONCEPT 
The U.S. Landsat's 1, 2 and 3, which could provide 
imagery with a geometric resolution of about 80 m, 
provided for ample applications in the field of geo 
logy, vegetation classifications and acted as a very 
course substitute and complement to aerial 
photography. For various applications the LANDSAT 
satellites proved to have limitations as the details 
are sometimes too small to be observed and the 
problem posed by the long time between overpasses is 
amplified by the frequent cloud cover in certain 
regions. 
The problem of the coarse resolution is being 
solved in the new generation of satellites (Landsat 5 
and Spot). In the equatorial countries the problem of 
the long time between overpasses can be solved by 
using an equatorial orbit as to be used by the 
Tropical Earth Resources Satellite (TERS). In 
principle there are two ways to cope with the cloud 
cover problem. The first possibility is the use of 
microwave sensors (radar) which can penetrate the 
clouds. The application of radar for the monitoring 
of renewable resources however is still experimental, 
operational systems are a long way off and cannot be 
expected before the year 2000. A second way to solve 
the cloud cover problem is the use of sensors in the 
visible spectrum combined with an increased number of 
overpasses and the capability of selective viewing. 
Selective viewing can be implemented by using a could 
sensor and the pointing capability of either 
satellite or instrument. This latter solution is 
pursued in the TERS studies. 
The TERS concept is similar to an idea, which at an 
earlier date has been proposed by the Indonesian 
National Institute for Aeronautics and Space (LAPAN). 
The baseline for the TERS system was set in a 
workshop held in 1979 and basically consists of the 
following elements: 
-equatorial orbit resulting in four daytime 
passes per day 
-cloud detecting capability for selecting 
cloud-free regions 
-pointable multispectral optical instrument as 
payload 
Figure 1 shows the main elements of the concept.This 
concept has been studied into more depth to show the 
feasibility of the concept. 
The feasibility studies were started with an inven 
tory of the user requirements. A coverage pattern 
between latitudes of 10°N and 10°S in a true 
equatorial orbit of 1680 km altitude, with off-nadir 
pointing capability of the optical instrument could 
fulfil most of the identified Indonesian user 
requirements. Furthermore three spectral bands were 
specified in the the wavelength interval of 400-1000 
nm, which will enable identification and monitoring 
of most crops and green vegetation. 
A preliminary design study has established the 
configuration and the main parameters of the 
satellite system. The primary purpose of this study 
was to confirm the technical feasibility of the true 
equatorial orbit at 1680 km. At this altitude the 
proton radiation is quite severe, so normal optical 
glasses would be coloured and electronics would be 
damaged. It has been proved that it is possible to 
reduce the effects of this radiation to acceptable 
limits by shielding and the use of special radiation 
hardened materials and components. The design of the 
optical instrument posed also a challenge, because of 
the tight requirements for the geometric and 
radiometric resolution from an altitude of 1680 km.