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inaccessible to those in local government and civil society who could most benefit from them. It is recognised in Brazil 
that “the financial benefits from sales can never compare with the public benefit of everyone using this kind of data” 
(Barbosa, 1999) whilst the Indian ISRO notes that “you can never recover the cost from sales, it’s the public benefit 
from improved decision making where the return on investment is obtained” (Rao, 1999). 
22 From data to information 
In a future where data will be abundant and information will be the key resource in the economy, such data policies will 
have to change. Landsat 7 ETM data are now available at dramatically reduced prices and ESA are changing their 
policy to maximise data use rather than revenue. Space Imaging, the operator of the first commercial very high 
resolution satellite, estimate that a $1 investment in information can be leveraged to produce a $10 benefit in the 
economy (Neer 1999). The US government recognises this economic fact in its policy for meteorological data, easily 
recovering costs from tax revenues from the value added industry (Friday et al 1996). Like Space Imaging, RapidEye, 
another private company planning to launch EO satellites, see themselves not as satellite operators but as information 
providers. 
; - 
3 EXPLOITING THE COMPARATIVE ADVANTAGES OF SMALL SATELLITES 
As a leading UK supplier of EO value added services has noted, the question is not whether EO can provide useful 
information but rather, is it good enough for specific purposes in comparison with other sources? The comparative 
advantages of earth resources satellites are their ability to provide regular repeat coverage of large “synoptic” areas, 
providing relative objective measurements under the same conditions, globally. However they also suffer from 
disadvantages such as the problem of cloud cover for optical sensors, and the already mentioned issues of cost and 
access. : 
Apart from such comparisons between EO and other sources of data, it is interesting to compare the relative merits of 
the three types of land application EO systems that are expected to operate in the near future: very high resolution 
commercial systems, high resolution public systems and medium to high resolution low-cost systems. The table 
compares these. 
  
Commerical VHR Public HR Small Satellites 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Examples IKONOS, EarlvBird SPOT, Landsat, IRS SunSat, KITSAT, UOSAT12 
Resolution Very high, 1-2m Pan, High 5-20m Pan, Medium to High, 30m pan and 
3-5m multispectral 10-30m multispectral multispectral 
Repeat cycle 14 days 14 days 10 days/n, n=number of 
satellites in constellation, ie if 
n=10, cvcle = | day 
Revisit cycle 1-3 days “near real time” due | 7-14 days, SPOT is steerable 10/n days 
to agility but programme request must be 
: made 30days in advance 
Continuity “Blue chip” financiers, but Politically uncertain. Unknown, but low costs are 
commercial viability to be positive factor 
demonstrated 
Reliability Operators maintain High dependence on operating | Simplicity means satellite 
contingency satellite ready satellites design life >5 vears. 
Ground segment High set up costs, major Dominated by centralised and | Potential for very low cost, 
capacity technical challenges to industry | monopolistic receiving distributed receiving stations. 
stations. 
Accessibility Near real time distribution to 15 days — 1 month + effective | Direct reception to low cost 
customers via bandwidth on delay between image ground stations operated 
demand acquisition and distribution via | directly by user or local service 
7A snail mail provider. 
Costs — satellites $20-150M / satellite $100M-$1Billion $2-6M/ satellite 
Costs - ground stations | $1M / ground station S10M / ground station $5-$100K / ground station 
Costs — operations Complex Tasking Costlv rchiving V low 
Image quality — 11-12 bit pixels Stable, 8 bits Unknown 
radiometric stability 
Image quality — 2-10m H/V, often includes 20-50 m Unknown 
eometric precision stereo capabilitv 
  
Table 2 — Comparison of operational satellite systems. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part Bl. Amsterdam 2000. 73