978 
doubts about the viability of photogrammetry from 
space and particularly about non-photographic sys 
tems. Undeniably there are still many problems in 
the detection and mapping of important topographic 
features such as settlements and roads. Corrections 
for Earth curvature, although feasible in analytic 
al and digital restitution, are an additional com 
plication for classical analogue restitution. It is 
interesting to note that aerial photography has 
responded to the satellite challenge. New develop 
ments in survey photography have strenghtened the 
capabilities of optical systems. They include: 
Films: the high-resolution, grainless (but slow) 
Eastman Kodak 3412/2412 pana-tomic X Aerographic II 
film. 
Lenses: the Wild superaviagon 8.84 super wide 
angle lens and the Wild universal aviagon 15/4A and 
wide angle lens. 
Cameras: the Zeiss-Jena (Jenoptik) MKF-6 camera 
(1976) and the LMK camera of the same factory. 
The ITEK Metritek 21 camera is based on the LFC and 
meant for high altitude photography, giving 50 cm 
resolution at 12 km altitude! The Zeiss Oberkochen 
manufactures the IMC. 
Aircraft: stratospheric aircraft (Learjet, etc. ) 
offer new scope for high altitude photography. In 
addition, electro-optical systems have been devel 
oped such as used in the MBB MOMS (FRG) satellite 
and planned for the stereoscopic MEOSS (FRG) satel 
lite system and for the Mapsat satellite developed 
jointly by the U.S. Geological Survey and ITEK. 
Whether satellites or stratospheric aircraft 
should be preferred for purposes of photogrammetric 
mapping in scales of 1:50,000 to 1:100,000 is at 
the moment topic of hot discussion among the 
specialists. It is obvious that if or —rather 
should I say— as long as stratospheric aircraft 
perform better, they will get the market. However, 
the image data acquisition for them is more expens 
ive per km 2 and legal restrictions present taking 
images for several countries simultaneously. Further 
the great number of high altitude aircraft required 
to take imagery over large areas is unlikely to be 
available. It is also obvious that with improving 
photogrammetric performance of satellite systems 
these will in the future gradually gain importance. 
The space industry will, of course, stimulate this 
development by introducing optimal space platforms 
and increasingly sophisticated imaging hardware. 
TRENDS OF FUTURE DEVELOPMENTS IN SATELLITE REMOTE 
SENSING 
The spectral recording systems in the visible and 
near-infrared spectrum at present include: 
Multispectral sensing (MSS); probably the most 
widely used system when satellites are concerned: 
Landsat MSS and SPOT-3 band scanner. 
Multispectral photography (MSP) with multi-lens 
cameras or multispectral imaging with TV cameras; 
known from aerial survey and satellites such as 
Soyuz (MKF-6) and Landsat 1 and 2 (RBV-3). 
Panchromatic black and white imaging. Under this 
category come the RBV of Landsat 3, the linear ar 
ray, "pushbroom" SPOT configuration, and the long 
focal length photography of manned spacecraft, 
Stereosat and Mapsat. Air photography (panchro 
matic/colour) also comes under this heading. 
Multispectral sensing from satellites has a great 
promise for the future in studies of the Earth's 
cover. Panchromatic imaging from aircraft, orbiters 
and satellites will be the main field of interest of 
photogrammetrists. Earth scientists share with the 
latter the need for stexeoscopy, but their metrical 
requirements are of a lower level. 
In the microwave zont, the recording systems com 
prise side-looking aiiuorne radar (SLAR) and synthe 
tic aperture radar (SAR) systems used in orbiters. 
Because of the need for all-weather capacity, es 
pecially for purposes of monitoring and time-criti 
cal data-gathering, e.g., in the context of flood 
disasters, microwave recording will become increas 
ingly important. Once the technical problems have 
been solved, a great future exists for satellite- 
borne microwave observation. After the Seasat 
(1978) and the space-shuttle SIR-A and B (1981 and 
1984) new developments are eagerly expected, such 
as the ERS 2 satellite of ESA (1989), the Japanese 
MOS 1-3 satellites (19..) and the Canadian Radarsat 
(1992). Whether the —at present rather erratic— 
airborne microwave (SLAR) recording can compete 
with such operational satellite microwave systems 
is doubtful. 
Thermographic recording in the middle and far 
infrared, using aircraft as a platform, though very 
useful for specific purposes, has always been a 
rather rare bird in remote sensing. From satellites 
to the contrary, it has found wide applications in 
Landsat 3, the short-lived Seasat and particularly 
in the NOAA satellites (heat capacity mapping mis 
sion - HCMM). 
Since the technology for recording all usable 
parts of the electro-magnetic spectrum has already 
been developed, further perfections rather than 
spectacular new breakthroughs can be expected for 
the future, although, of course, the satellite sys 
tems will further evolve. 
The relief recording methods range from the con 
ventional but very important stereoscopic imagery 
radar altimetry and scatterometry and laser-altime 
try. The precision of the latter is such that defor 
mations of the sea surface caused by gravitational 
anomalies can be recorded and information about the 
submarine relief consequently can be obtained. The 
methods have been developed, but since this is a 
fairly recent occurrence further developments are 
likely. Stereoscopic imagery from space is in its 
infancy and will soon be widely applied, particular 
ly for purposes of earth sciences and photogram 
metry. Methodological developments in inter 
pretation, however, will be minor. 
The diverse requirements of the various users of 
satellite imagery make it likely that several types 
of sensors will be installed in future spacecraft 
in addition to dedicated satellites launched for 
specific purposes. These developments are, in fact, 
already underway and are rooted in the emphasis put 
on: 
Spectral characteristrics - for the study of 
vegetation, sea and ice. 
Relief characteristics - for earth science ap 
plications. 
Relief and high metric qualities - for photogram 
metric purposes. 
Temporal resolution - for monitoring. 
All-weather capability - for monitoring, disaster 
surveying, etc. 
Beyond doubt, a wide array of satellites having 
different configurations will be launched in the 
years to come! 
QUO VADIS? 
The cost involved in implementing satellite techno 
logy in the next few decades will be very high. In 
a recent report of the U.S. Commission or Space, 
entitled "Pioneering the Space Frontier", an annual 
U.S. expenditure of U.S.$ 20 billion is expected a- 
round the year 2000. The annual expenditure by the 
FRG is estimated at DM 1.6 billion, DM (approxima 
tely US.$ 0.75 billion. Adding to this the con 
siderable space efforts of the ESA and of countries 
like France, Japan, Canada, Brazil, etc., astro 
nomical figures are reached!. These figures assume 
continuous economic growth in the coming decades. 
Since this is quite uncertain, possibly less funds 
will in fact become available. 
Various countries would like to take the lead in 
space research 
stration. This 
countries want 
administrative 
the high tech 
their national 
such competit: 
this way will 
will yield opt 
operation wil] 
major inefficii 
The best so] 
of groups of 
important aspe 
nations togethi 
cannot be don 
job, I think, 
with the aim o: 
ment, "mother 
and to give t 
economic socia 
not pursue ted 
use for the 
life", a term 
periodical "Wc 
the costly eff 
be justified! 
aim. I wish yc 
in your work. 
1988!