Space Debris

  • March, 2020

More than 500,000 pieces of debris, or “space junk,” are tracked as they orbit the Earth. They all travel at speeds up to 17,500 mph, fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft.


Space debris (also known as space junk, space pollution, space waste, space trash, or space garbage) is a term for defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function. ...

Space debris comes in two types - Natural and Artificial.

Natural space debris

Natural space debris consists of small pieces of cometary and asteroidal material called meteoroids. We see these as meteors when they travel through the Earth's atmosphere.

Artificial space debris

Artificial space debris also known as space junk, space pollution, space waste, space trash, or space garbage is a term for defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function

Now that we know basic about this, let’s learn why and how it is harm full when it is in the sky …

Problems Created Because of Space Debris

  • In Space
    • Small pieces of space debris (less than 1/10 mm) are prolific enough to cause erosion of optical surfaces. This is like sandblasting, and can ruin telescope mirrors, and decrease the efficiency of solar cells.
    • Particles such as paint flakes (under 1 mm) can cause small craters in walls and windows. Almost 100 Space Shuttle windscreens have had to be replaced (as of 2008) due to pits caused by such impacts.
    • For Example : A 2mm space debris fragment colliding at 10 km/s is like being hit with a cricket ball at 100 km/hour
    • A 10 mm fragment at the same speed is like being hit by a large motorbike at 100 km/hour
    • Surprising high ? right? But Why?

  • Space Collision

      Velocities of objects in space are determined by the laws of physics and the gravitational field of the body around which the objects orbit. For the Earth , an object needs to be accelerated to a velocity of around 7 kilometres per second to stay in low Earth. Objects are in many different orbits around the Earth, some travelling in the opposite direction to others. With these high orbital velocities it is only natural that collisional velocities will be correspondingly high.
      In the case of natural space objects (meteoroids) that orbit around the Sun, these travel at even greater velocities. To remain in its orbit around the Sun, the Earth has to move at 30 km/sec. Other objects that come near the Earth may have relative velocities ranging anywhere from 11 km/sec to 72 km/sec. The average collisional velocity between a meteoroid and a satellite is about 20 km/sec.

    Falling into Earth

      It has been estimated that one piece of space debris may make it down to the Earth's surface almost every day. Most of these are very small and most will fall into the ocean or an unpopulated region of the Earth's surface. Very few are ever recovered, much to the disappointment of reentry scientists. Reason being most pieces of space debris will burn up as they enter the Earth's atmosphere.
      This ablation process starts around a height of 100 km and is usually complete by the time the object has descended to about 20 km. Very heavy or refractory pieces (and occasionally very light pieces) may not burn up completely, and some part of the object may make it down to the ground. However, even these objects have lost most of their "space" velocity and hit the ground at no more than 100 meters per second.
    Now let’s talk about solution of this Problem

    Ways to protect Satellite from Space Debris

      • Computer programs can search for possible collisions between large space debris objects and high value spacecraft. When they detect the likelihood of such a collision, the spacecraft is manuevred (by small thruster rockets) out of harm's way. Such manuevres are now being carried out for large spacecraft such as the International Space Station and the Space Shuttle. However, these operations are expensive and can disturb delicate experiments. Also, not every satellite has the ability to maneuvre.
      • Space tracking networks can only track space objects larger than about 100 mm. Since even a 10 mm object can severely damage a satellite it is obvious that collision avoidance will never be 100% effective.
      • Debris shieldscan be designed to provide additional protection for a spacecraft. One obvious way is simply to increase the thickness of the vehicle walls. However, this adds a lot of mass to the craft and makes it a lot more expensive to launch it into space. Specially designed shields take advantage of the fact that two thin walls separated by a space are more resistant to debris penetration than a single thicker wall. This type of design is called a Whipple shield after the astronomer Fred Whipple who came up with the idea in the 1950's. The outer wall absorbs a lot of the debris energy so that the inner wall is not punctured. This type of shield and modifications to this design are currently installed on the International Space Station. However, once again this does not offer 100% protection.

    A number of solutions to remove Space Debris

    • Objects in low altitude orbits (below about 500 km) are affected by atmospheric drag. This lowers their orbit until they re-enter the atmosphere and are thus naturally removed from orbit. The lower the orbit the faster it decays.
    • Space "tugs" could be employed to "catch" large space debris objects and either lower their altitudes for natural decay, or bring them back to Earth.
    • Giant "sponge" like objects could be deployed to "catch" or "soak up" small debris pieces. After a time, the sponge would be removed from orbit.
    • Attach tails or tethers to large pieces of space debris to increase the drag they experience and lower their orbits.
    • Use large ground based lasers to "push" small pieces of debris into lower orbits