The Growth of
Space Debris
Global Security Program
Union of Concerned Scientists
The Growth of Space Debris
Space debris is any human-origin object in space that no
longer serves a useful purpose.
The following slides show how the amount of space debris
orbiting around the Earth has increased since 1957,
when the first satellite—Sputnik 1—was placed in orbit
and the first pieces of space debris were created.
Source: http://www.secureworldfoundation.org/siteadmin/images/files/file_308.pdf
The Growth of Space Debris
Space debris can stay in orbit for a long time—decades in
orbits near the Earth, and essentially forever at very high
altitudes.
Over time, the amount of space debris has increased
dramatically, as these slides show. It has become dense
enough in some parts of space to threaten satellites,
which can be damaged or destroyed if they collide with
debris.
The Growth of Space Debris
In these slides, you will see debris in two main areas.
(1) The fastest growth is in orbits very close to the Earth,
where the first satellites were orbited. These appear to
form a fuzzy shell around the Earth in the slides.
This region is known as Low Earth Orbit, or LEO. It
contains roughly half of today’s active satellites and half
of the known space debris.
The Growth of Space Debris
(2) In the picture for 1970, debris in the Geo-stationary ring
(GEO) has become obvious.
In this special orbit, satellites orbit the Earth in 24 hours,
so a satellite orbiting above the equator will remain
above the same spot on the Earth. This is particularly
useful for communication and broadcasting.
Since these satellites must be above the equator, they
form a circle around the Earth rather than a shell.
The Growth of Space Debris
Constellations of satellites used for navigation, like the GSP
satellites, lie midway between LEO and GEO. Launching
these satellites is responsible for some of the debris
seen in that region.
The Growth of Space Debris
In LEO, space debris travels at roughly 17,000 mph—some
30 times faster than a passenger jet.
Because of its enormous speed, even small pieces of debris
can cause severe damage to a satellite in a collision.
Satellites cannot be shielded against collisions with debris
larger than about an inch in size. An object 4 inches in
size could completely destroy a satellite in a head-on
collision, which could produce thousands of additional
pieces of deadly space debris.
The Growth of Space Debris
The United States tracks active satellites as well as large
pieces of space debris. It keeps a list of those objects in
a debris catalog.
The following drawings are from NASA. They show a
“snapshot” of the cataloged objects over time (the debris
are not drawn to scale). The debris count on the slides
gives the number of objects in the catalog.
Today, only 5-6% of those objects are active satellites—the
rest are debris.
The Growth of Space Debris
The rest of the slides will
advance automatically.
Debris count: <100
Debris count: 1,000
Debris count: 2,700
Debris count: 3,800
Debris count: 5,400
Debris count: 6,500
Debris count: 7,300
Debris count: 8,700
Debris count: 9,500
Debris count: 10,000
Debris count: 14,000