# Educator's Guide to Spotting the Shuttle

Courtesy of the Jet Propulsion Laboratory

# Space Shuttle Observing

On some space shuttle missions, there are opportunities for observers in the continental United States and Hawaii to see the orbiter fly overhead. To determine if it will be flying within visible range of your location you will need three things. The first is a "SPARK," Shuttle Prediction and Recognition Kit. The second item is a Space Shuttle Mission Chart, which is a Mercator projection map of the world with the orbiter's orbits superimposed on Earth's surface.

The third tool is the location of your observing site in latitude and longitude which you can get from the mission chart or, more precisely, from a local area map. These materials and information should be assembled a couple of weeks before the scheduled launch. Once the launch date has been set, plan to watch the launch on television. If you have a stopwatch start it at the moment of launch ("T-0" or "Lift-off"). This clock will be keeping "Mission Elapsed Time," or "MET." If you do not start a MET clock you can make the conversion from MET to your local time as long as you know when the Shuttle actually lifted off. Launches are often delayed so you may not be able to use the scheduled launch date and time.

Once the Shuttle is on its way, get the times of sunrise and sunset for the days when the mission is under way. Missions can be as short as four days or as long as a month. You now have all of the material necessary to determine if the orbiter will fly over you and whether it will be visible.

Observers south of 28.5° north latitude lie within the band overflown by all Shuttle flights. Shuttles are launched from the Kennedy Space Center in Florida, which is at a latitude of 28.5° north. That means that for most missions the orbiter's path is a circle around Earth that is inclined (tilted) 28.5° relative to Earth's equator. Observers more than a little bit farther north than 28.5° will not be able to see the orbiter. It will never rise above their local horizon.

But for some missions the "orbital inclination" will be as high as 57°. That means that everyone in the band between 57° north and south of the equator has a potential Shuttle over-flight. Because of the height of the Shuttle's orbit, just about every spot in this band, and for several degrees to the north and south, will be within the field of view of the orbiter and above the horizon for ground based observers.

But even if the orbiter flies directly overhead, you will only be able to see it directly under just the right conditions. Conditions are suitable only when the orbiter is illuminated by the light of the Sun in an otherwise dark sky. This occurs only before dawn and after dusk. Sunlight illuminates the sky overhead before dawn and after sunset. Mountain peaks and tall clouds capture the light of the Sun after it has fallen below the horizon for low-lying areas.

At the Shuttle's altitude of around two hundred miles above Earth's surface the sky will have some sunlight shining through it for two hours before sunrise and after sunset. The SPARK will show you how to calculate when you can actually see the orbiter. You can also calculate when the astronauts can see your community from orbit during daylight passes!

SPARKs and Space Shuttle Mission Planning Charts are available by writing, on school letterhead, to:

SPARK
AP4
NASA Johnson Space Center
Houston TX 77058

### Correct a misconception!

Most illustrations of the Space Shuttle's flight path greatly exaggerate the altitude of the orbiter. To give students a true sense of the orbiter's relationship to Earth, use a pair of calipers or a paper ruler to measure approximately 320 kilometers (200 miles) on the surface of a globe. Distances between local landmarks will make the best impression on children. Then turn the calipers perpendicular to the globe so that they show altitude. You will see that Shuttle orbits just graze the globe. Also note that our atmosphere is less than 1/4 as high!

Lesson Plans and Activities

##### Views of the Solar System Copyright © 1997 by Calvin J. Hamilton. All rights reserved.