The Growth of Space Debris - Union of Concerned Scientists by fjzhangweiyun

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									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

								
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