Daniel Leussler:

Satellites

The satellite that provides the majority of our coverage is called GOES-3 (pronounced like the word “goes”), an ancient weather satellite whose orbit became too wild to serve its original purpose years ago. Geostationary orbit is perfect for communications satellites, enabling them to be effectively stationary over one spot on the planet by orbiting over the equator fast enough that they complete an orbit in one sidereal day.  We’re as far as you can get from the equator here, so standard communications satellites stay well below our horizon, at least while they have sufficient fuel to maintain their position – once that runs out, the sun and moon tug the satellite out of their preferred spot, causing them to draw something like a figure-8 over the equator and allowing them to make contact with our dishes.

GOES-3 is old enough that it’s no longer useful to anybody, so we get it all to ourselves. This means that it’s nice and predictable, covering a little under 7 hours  of each day and beginning its pass 4 minutes earlier each day. Having a computer job, I get to enjoy its coverage while I’m at work, but others aren’t so lucky – if you’re working away from a computer, and GOES finishes around 2pm like it does currently, you might get 15 minutes over your lunch break to catch some satellite time. That’s where TDRS 3 and 4 come in, providing higher-speed passes later in the evening. They’re still viable satellites to NASA, so we buy time on them along with all their other clients, usually resulting in a few hour-long chunks around dinner time and later.