Blue FCR Screen, originally uploaded by plemeljr

If you watch NASA TV the producers often put up a map (example above) showing the location and orbits of Station and Shuttle, with all sorts of additional lines overlaid on the map. Here’s an abridged list of what they are and mean:

• Yellow & Green Lines
  This represents the TDRS (pronounces Tee-dris) which is a series of nine geosynchronous satellites which handle space-to-ground communication. If Station or Shuttle is inside either the circle, they have to switch over from one system to the other (LOS or AOS). If Station and Shuttle are in the overlapped area (as is shown) then they temporarily lose strong communication to the ground
• White brackets at orbit line
  This represents the sunrise/sunset time and location for Station or Shuttle.
• Blue circles with acronyms
  This represents comms unavailability for various backup communication systems, mostly military.
• White polygon in South America with the acroynym SAA
  This stands for the South Atlantic Anomaly. This refers to the area where the Earth’s inner Van Allen radiation belt comes closest to the Earth’s surface leading to an increased flux of energetic particles in this region, exposing orbiting satellites to higher than usual levels of radiation. This location has to do with the off-axis rotation of Earth and the translation of the radiation belt. Station and Shuttle periodically go through this ever-changing anomaly during orbit, affecting communication, but also placing astronauts at higher risk of radiation requiring additional precautions.
  A diagram of the SAA is below:

This article continues my reporting of my junket NASAtweetup at the Johnson Space Center on 17 FEB 2010. For all articles, check out the NASA tweetup page and photos.