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[[bold]]Chapter 6: The Shuttle's Orbit and Ground Tracks[[/bold]]

[[italic]]Objective: To understand the orbit of the shuttle around the Earth and the path it traces on the ground.[[/italic]]

In this chapter, we describe the shuttle's orbit and how to use maps of the shuttle's ground track during a KidSat flight (general concepts about orbits are given in an appendix at the end of this chapter). Students at the SMOCs will be using ground track maps before and during the mission to determine what parts of the world the shuttle will pass over, and therefore which areas can be photographed.

The description of orbits (other than the general concept) is not essential; it is critical, however, that the students be familiar with the concept of ground track, be able to read a world map with a shuttle ground track overlaid on it, and understand that the ground track changes from orbit to orbit (as the Earth rotates beneath the orbiting shuttle).


Essentials:
• The space shuttle orbits around the Earth. On KidSat flights:
- its altitude will range from about 160 miles (early in the flight) to 240 miles 
  (later on).
- one complete orbit around the Earth takes about 90 minutes.
- during each orbit, the shuttle is in daylight for about 45 minutes, and in night for 
  about 45 minutes.
- the inclination of the shuttle's orbit is 51.6 degrees.

• The ground track shows the locations on the Earth that the shuttle flies directly 
  over
- the shuttle's path along the ground track is from west to east (left to right on a 
  world map).
- the descending node of an orbit is where the ground track crosses the equator (going 
  south). Your students will be given an orbit's descending node in order to set up 
  their plastic ground track overlays ("slider maps", described in chapter 7).
- the northern-most and southern-most points on the ground track are at latitudes 51.6 
  N and 51.6 S. (determined by the inclination of the orbit). (i.e. your students will 
  not be able to photograph features at latitudes further north or south than about 52 
  degrees).
- the ground track shifts 22.5 degrees (at the equator) to the west with each 
  successive orbit (a result of the Earth's rotation).


Teachers' Handbook   Page 40