Project Cyclops, A Design... - Department of Earth and Planetary ...

THEAUXILIARYOPTICALSYSTEM
Althoughnot studiedin anydetailby theCyclops
team,it is obviousthat theCyclopsystemshould
includeseveral opticaltelescopes. These could be used
independently or be slaved to look at the same area of
sky as the antenna array or subarrays.
One of these telescopes, probably a I-m diameter
aperture Schmidt, equipped with the proper instrumentation,
would be used to survey the sky for likely target
stars. Target star coordinates would be automatically
recorded in the master computer data file for subsequent
use. This same instrument, or another, used at high
magnification could provide visual confirmation of the
tracking accuracy of the computer program. Indeed,
tracking corrections might be automatically introduced
into
the system.
The advantages of being able to obtain simultaneous
optical and radio observations of source should appeal to
the astronomer. Pulse radio and optical emissions are
known to correlate. Do the pulsar "starquakes" cause
optical phenomena? Do the optical and radio emissions
of flare stars exhibit correlation? Improved instrumentation
always facilitates research and sometimes opens
up whole new and unsuspected areas of research.
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IO I
RANGE
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/ / / I000 MW BEACON
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m I0 m I00 m I km IO km
CLEAR APERTURE DIAMETER
Figure 7-2. @clops range capahility.
CAPABILITY
Figure 7-2 shows the range at which the Cyclops
system could detect a IO00-MW beacon, assuming an
observing time of 1000 sec per star. With a 1-Hz
resolution in the optical analyzers the range is simply
100 light-years per kilometer of antenna diameter. Going
to 0.I-Hz resolution increases this range by a factor of
1.6. Tire dashed curved marked /V '= 10 -3 is tile performance
of a system in which tile receiver is matched to
the observing time of 1000 sec. Its range is a factor of
three greater than the 1-Hz system, but to achieve this
performance the Doppler drift rate would have to be less
than 10-6 Hz/sec, which is completely unrealistic.
THE COST
OF CYCLOPS
The next four chapters contain cost estimates of the
major subsystems of Cyclops. At this early stage, many
of these estimates are quite crude. Accurate cost
estimates cannot be made until detailed designs have
been evolved, and even then are difficult unless production
experience with similar systems is available. Nevertheless
these estimates give a rough idea of the cost of
Cyclops and how the cost divides among the various
systems.
In Figure 7-3 the various costs have been plotted as a
function of the effective clear aperture diameter of the
array to permit easy comparison against the range
performance curves of Chapter 1. The clear aperture
diameter is about one-third the physical diameter of the
array, since the antennas are spaced by about three times
their diameter.
Many of the hardware costs are roughly proportional
to the number of antenna elements and therefore to the
square of the clear aperture diameter. This is true for the
tunneling, the receivers, the IF delay, and the imager.
Aside from a fixed added amount it is true for the power
system (where a half million dollars was added to
account for other power uses) and for the antenna
structures (where $200 million in initial plant and
tooling was added). The cost of the IF transmission
system varies as the 3/2 power of the number of
antennas and therefore as the cube of the clear aperture
diameter. This is because the array size increases as the
square root of the number of antennas, and the average
IF cable length increases accordingly.
The cost of the coherent signal detector depends
principally on the IF bandwidth and the search time per
star and is independent of the array size. We show a
fixed figure of $160 million, which assumes optical
analyzers with a 10 7 time-bandwidth product and 1000
sec observation time per star. If we were to use analyzers
with a 10 6 time-bandwidth product and 100 sec
observation time per star, this figure would drop to $45
million.
A rough guess of $ I O0 million is shown lbr engineerhag
costs. Building costs are shown at $10 million and
the companion optical system at $2 million. Road and
utility costs are highly site dependent and have not been
included.
For apertures larger than a few hundred meters the
cost of Cyclops is dominated by the antenna structural
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