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It should be noted that the data in Tables .2 (a) and
(b) are for a 7-year period. hring the 21-y~ar total
period, three stages of complete space segment
replacement are expected to occur, which would allow
for an update for changes in traffic or other
requirements. For dual . frequency systems
development cost will be incurred at each stage.Single
frequency systems will not incur such costs since the
Same designs of spacecraft would be used throughout
the 21-year period: only the mix of EHF and SKF types
would change. Provided military components are used
in the design of the spacecraft it should be possible to
maintain full availabilty over the 21.year interval
t3.h examination of the data shows that:
....
P
For geostationary operations the cost of
interconnection of spacecraft is of the order of 3 % ,
and is not more than 4.5 % for the inclined orbits
(Tundra as the most expensive case).lnterconnection
provides significant Improvement in service availability
probability, ranging from 0.14 at the lower inherent
spacecraft probabilities to 0.04 at the high end.
Increasing the space segment availability by the
amount given in (a] above without. however, using
Inter-!Satellite Links ISL wou!d require launching more
satellites and this would increase the system cost by
about 25 %.
Operation in Inclined orbits costs about 50 % more
than the geostationary case for Ihe same sewice
availability, but gives full NATO coverage including the
polar region.
The geostationary case 1 corresponds lo the NATO IV
satellite as far as coverage and the nuniber of
satellitcs and reliability are cuncerned. It is interesting
to note, however, that the 7-year system cost of Case
1 and that 01 NATO N (about -M) are almost
identical even though Case t satellites have
considerably more capacity (in SHF and EHF) and
significantly greater resistance to jamming (on-board
signal procebsing in EHF and adaptive nulling
antennas).
The system cost changes signlficantly with the 7-year
service availabllity probability. How many Batelittes
would be needed for a 21- year period without having
excessive capacity would depend on this as well as on
what residual capacity would remain at the end of
each beven-year period and. how the change in
requirements is introduced; abruptly at each 7-par
period or progressively during the 21-year period. In
the latter case, some reduction in the total number of
satellites required and hence in total cost would be
expected.
14.The architectures which appear cost-affective and promising
ma ghn In Table -4.
The following comments can be made about theso
architectures:
a)
b)
An adequately wide range oef architectural options
are presented from which the architecture best suited
to the requirements, as they will be known nearer Ihe
date of system implementation. can be snlerted
Based on the assumptions made regardlng possible
future NATO requirements. reli&bilitles of future
electronic systems and wsts per kilogram of
Payloads. Spaceaaft Platforms and Launches which
have been used consistently for all of the candidate
architectures. it can be concluded that:
14-3
' i) Procided NATO can accept the coverage
provided by a geostationary only system of
satellites, Architecture A is the lowest cost
solution.
ii) If polar coverage obtained by leasing,from the
USA. costs less than Cost (H-A) or Cost (I-A)
then Architectures A or B plus Polar leasing
would provide the next .lowest cost options.
Option B gives improved availability and AJ
capability but at 33 % higher cost than the cost
of A.
iii) The lowest cost architecture which pidvides full
coverage is Architecture H at a cost increase of
50 %over geostationary only (Case B).
iv) For a further 5 % increase in cost, an
improvement from 0.95 to 0.98 in operational
availability and an enhanced AJ capability can
be obtained by using Architecture I. This
architecture is probably the most cost-effective
option of those considered. to all of the
assumed luture NATO requirements.
15.k is likely that cost will be the driving factor in determining the
hoice of a future SATCOM architecture and it is therefore
appropriate to consider the lhree dominant cost lactors (RBD.
replacement and launch costs) and indicate what steps could
bo taken to bring about cost reduction in each case.
Economy in R83 costs could be obtained through
NATO/National collaborgtion and by adopting a
modular approach to system diversilication. and
evolution. An effective way of achieving the latter
would be to devplsp at the outset separate SHF and
EHF spacecraft and use them, in GEO and TUNDRA
orbits alike, in a mix delermined by the changing
requirements.
The use of smaller spacecraft, even though more of
them may be needed, could lead to lower system
costs because of the economies 01 scale. Such
economies of scale would be further enhanced if the
same Spacecraft types are used at all stages of system
evolution over a period of, say, twenty years. They will
also be enhanced if the aame spacecraft types ate
bought for national as well as NATO use.
Launch wsts can be minimized by reducing
spacecraft mass. in particular through the exploitation
of new technology. tt is also important to maximize
compatibility with the largest possible range of launch
vehicles.
Interconnection of spacecraft increases system
reliability and therefore tends to reduce the tolal
number of spacecraft that need to be launched.
finally. long-term planning is the key to achieving
reductions in both RBD and recurring ccsts.
'.
t6.The NATO SATCOM systems sa far acquired have been
based on national d&elopments adapted to NATO
requirements and the %$tin& of service (not necessarily full
service ) has been obtai#f.ed. by sharing or borrowing capacity
Irom nntionsl sysleme. '?he national systems. In turn. have
relied for continuity 01 service on the availnbility of capncity on
the NATO system. Each procurdment has contained an
important element of R&D costs and since successive syster.is
have been developed almost independently of each other,
R&Dcosts have been. like the replacement cost, also recurring.
'-.