a year later. Data will be recorded on board the spacecraft 
and downlinked to a central facility in Colorado. 
EarthWatch plans to retain ownership of all data 
collected, and sell both images and digital elevation data 
to customers through local area distributors. 
Each of the systems described will be capable of simultaneous 
panchromatic and multispectral imaging, and can acquire stereo 
coverage from each pass so that digital elevation data can be 
derived. They will have Global Positioning Systems and precise 
attitude sensors to provide exterior orientation to permit 
topographic mapping with no or minimum ground control points. 
Sophisticated processing algorithms will be required to assemble 
the numerous pieces of acquisition which make up a single stereo 
scene. All systems will provide a variety of products including 
radiometrically corrected, geometrically corrected, geocoded 
scenes, image mosaics, orthorectified scenes, multispectral 
composites, etc. Minimum time between tasking, acquisition, 
processing, and delivery are essential for all systems. Studies 
have predicted that the global market for these types of data will 
be about $8 billion annually by the early years of the next century. 
Some characteristics of the proposed systems are given in Table 
5, derived from information in (5). 
Table 5. COMMERCIAL SATELLITE SYSTEMS 
System CRSS Orbview-1 EarlvBird QuickBird 
Focal length 10 m 2.76 m 
Aperture 70 em 45 cm 
Altitude 680 km 460 km 470 km 470 km 
Inclination 98.1 deg 97.3 deg 97.3 deg TBD 
Detectors pushbroom — pushbroom — rect. array — pushbroom 
Res. pan Im land 2 m 3m 1m 
Swath, pan 11 km 8 km 6x6 km 36 km 
Scene, pan. 60x60 km 8x8 km 6x6km 36x36 km 
Res. MS 4m 4m 15m 4m 
Bands, MS 4 4 3 4 
Swath, MS 11 km 8km 30x30 km 36 km 
Scene, MS 60x60 km 8x8 km 6x6 km 36x36 km 
Repeat cycle 14 days 16 days 20 days 20days 
Revisit cycle 1-3days «3 days 2-3 days 2-3 days 
Two other commercial systems which have been announced are: 
GDE which will provide 0.7 meter resolution pan data and 2.8 
meter resolution multispectral images. 
Astrovision, Inc. which plans a geosynchronous spacecraft with 
a high definition TV camera providing images with 1 km 
resolution in real time. 
230 
All of these companies are struggling to develop 
commerciallyviable marketing arrangements and realistic 
pricing regimes for their products. These will obviously be 
controlled by the level of processing required, the size of areas 
to be covered, and the amount of repeat business to be 
expected. These questions will obviously be subject to intense 
negotiation between potential customers and commercial 
suppliers, and competition between suppliers of similar data sets 
will certainly affect the market. A critical point for many 
customers will be the fact that the U. S. government retains the 
right to turn off any collection at times of political or military 
stress. This may well result in agencies of foreign governments 
promoting the development of comparable systems by their own 
national organizations rather than buying data from a 
commercial supplier who may be required to cease operations 
at a most critical time. 
Nations have apparently concluded that secrecy and security are 
not necessarily synonymous, and the principle of open access to 
imagery by all nations seems to be accepted. So far as the 
application of commercial imagery to mapping and geographic 
information systems is concerned, it is apparent that imagery 
will be available with the technical ability to resolve most 
questions of significant importance. 
A revolution has begun in the way satellite imagery will be 
madeavailable to users, and it will be most interesting to see 
how it develops in the next few years. 
REFERENCES 
1. Richelson, Jeffrey - The KeyHole Satellite Program. Journal 
of Strategic Affairs, Vol. 7, No. 2, June 1984 
2. McDonald, Robert A. - CORONA: Success for Space 
Reconnaissance. ~~ Photogrammetric Engineering and 
Remote Sensing, Vol.61, No. 6, June 1995. 
3. CORONA: America's First Satellite Program. Center f or 
the study of Intelligence, Central Intelligence Agency, 
Washington, D.C., 1995. 
4. National Research Council - Useful Applications of Earth- 
Oriented Satellites. Vol. 6, Sensors and Data Systems. Vol. 
13, Geodesy-Cartography. National Academy of Sciences, 
Washington, D.C. 1969. 
5. Fritz, Lawrence W. - The Era of Commercial Earth 
Observation Satellites. Photogrammetric Engineering and 
Remote Sensing, Vol. 62, No. 1, January 1996. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996