X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
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In article <15210@bfmny0.UU.NET> tneff@bfmny0.UU.NET (Tom Neff) writes:
>It seems to me this is a case where GEO would help. Deploying a few
>really BIG guidable antenna arrays in geosynchronous orbit, parked over
>dedicated ground stations, would allow tracking and commanding probes
>all over the solar system without usurping valuable observatory time.
Well, the DSN dishes are primarily for space communications; use of them
for things like interplanetary radar observations is secondary. (They
weren't originally built for it, but they do have ultra-low-noise receivers,
and they do have massive emergency transmitters for punching a signal into
the low-gain antenna of a tumbling planetary probe, and the combination
turned out to work pretty well for radar astronomy.) Normal radio
telescopes get dragged into it only for once-in-a-lifetime events like
the Voyager encounters, when it really pays to have most of Earth's total
big-dish area pointed in one direction.
JPL et al have looked at the idea of putting antennas in orbit. It would
have advantages and disadvantages. The decisive counterargument right now
is that it would be very expensive and there is not enough deep-space
traffic to justify it.
--
"The N in NFS stands for Not, | Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry henry@zoo.toronto.edu
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Date: Fri, 2 Mar 90 08:13 CST
From: GOTT@wishep.physics.wisc.edu
Subject: Lunar Comm.
Is there an accepted way for calculating how far away the horizon is for an
observer at a given height? I'm trying to figure out how many 500m relay towersit would take to link two bases 1000km apart. I tried using the radius of the
moon, triangles and trig., but... I don't think the accuracy is there i.e.
500m is pretty small compared to the Moons radius so the similar triangles are