Space debris is piling up around the Earth and collisions have become a hazard to spacecraft. Humans are in danger as well.
Space debris is the collection of man-made objects around Earth, like old-satellites, spent rocket stages, and pieces from disintegration, collisions, and erosion, which no longer serves a useful purpose.
A significant amount of debris does not survive the severe heating which occurs during re-entry. Components which do survive are most likely to fall into the oceans, other bodies of water, or onto sparsely populated regions like the Canadian Tundra, the Australian Outback, or Siberia in the Russian Federation. During the past 50 years, an average of one cataloged or tracked piece of debris fell back to Earth each day. No serious injury or significant property damage caused by re-entering debris has been confirmed.
How much debris is orbiting Earth?
On 5 July 2016, the United States Strategic Command found a total of 17,852 artificial objects in orbit above the Earth. Including 1,419 operational satellites. Still, these numbers are just for objects large enough to be found. On 2013, USSC estimates that more than 170 million debris smaller than 1 cm, about 670,000 debris 1-10 cm, and around 29,000 larger debris are orbiting Earth.
Where do old satellites go when they die?
Like every other machine, satellites do not last forever. Whatever their job is, eventually all satellites grow old and die. Right now there are two choices, depending on how high the satellite is. For the closer satellites, engineers will use its last bit of fuel to slow it down. That way, it will fall out of orbit and burn up in the atmosphere
The second choice is to send the satellite even farther away from Earth. For many of these high satellites, it takes less fuel to blast it farther into space than to send it back to Earth.
How long will orbital debris remain in Earth orbit?
The higher the altitude, the longer the orbital debris will typically remain in Earth orbit. Debris left in orbits below 370 miles (600 km) normally fall back to Earth within several years. It takes decades for scientists to measure orbital debris at altitudes of 500 miles (800 km). Above 620 miles (1,000 km), orbital debris normally will continue circling Earth for a century or more.
People have captured footage of space debris burning up in our atmosphere. But in reality, no one has been hurt here on Earth.
About 20 per cent of the objects are satellites (with fewer than 1/3 operational) and another 17 per cent are used rocket bodies and other objects from space missions. The remainder is debris from fragmentation.
ESA considers it as “catastrophic”, if an object larger than 10 cm collides at a speed of about 10 km/s in low-orbit. Catastrophic in space is something like the destruction of the spacecraft.
The bad news is that collisions create something called the Kessler Syndrome where it becomes a cascading effect: debris creates more debris and on and on it goes.