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Radio Telescope
It was Einstein who made the real trouble. He announced in
1905 that there was no such thing as absolute rest. After that there
never was.
--
Steven Leacock
The System: Now that the LNA has
been moved so that it is directly connected to the feedhorn, this
location change has caused a temperature stabilization issue that
can be solved in several ways.
- The LNA can be heated or cooled by running forced water or
antifreeze through copper tubing from a reservoir in the ground.
The copper tubing would be wound around the LNA, and insulation
then around the tubing. This would divert the thermal load into
the water, which would then be mixed with cool water below. Alternatively,
in the winter, the liquid in the ground would still be warmer
than the outside air, and thus would warm the LNA. This method
of temperature stabilization seems to be the easiest to construct
and the most economically viable solution.
- A second option is to use a Peltier device. This is a solid-state
device that heats with the current flow in one direction, and
cools when current is reversed. These have been known to use a
lot power and finding a way to mount it on the end of the spider
arm support can be tricky or just plain impossible. The weight
of the unit, box, and cables etc. can actually offset the feedhorn
and cause pointing inaccuracies.
Other options are available, but these two seem to be our best
options. Temperature stabilization is much more important to us
than intense cooling, because we simply need to have a predictable
baseline from day to day. The sensitivity of the front-end devices,
especially the LNA, rises as the temperature decreases, and falls
as temperature increases. Once we have these components stabilized,
weaker signals can be detected and the data will be cleaner overall.