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:
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!