Space junk consists of over 500,000 objects surrounding the globe in low earth orbit. This threatens spacecraft and vital satellites, NASA says.
Ever since the space race was started by the successful Soviet launch of the Sputnik-1 satellite in 1958, humans have shot thousands of objects into space.
Every one of these events create new debris- or space junk – big and small, that orbit Earth. To combat collisions, NASA attempts to track all objects orbiting Earth. Below the altitude of 2000 km (1242 miles), there are more than 19,000 objects 5 cm (1.9 inches) or larger, and more than 500,000 objects of 1 cm or larger , according to a NASA FAQ.
There are also over 100 million objects smaller than 1 cm.[contextly_auto_sidebar]
While these space junk may seem tiny, NASA’s FAQ on the topic says orbital collisions occur at approximately 10 kilometers per second (6.2 miles per second) meaning “collisions with even a small piece of debris will involve considerable energy.“
An example of this comes from the space shuttle Challenger’s second mission 1983, as described in the book “Orbital Debris from Upper-stage Breakup” by astronomer Joseph Loftus. During the mission, impact with what is believed to be a flake of paint 0.2 mm wide caused a 5 mm-wide crater in the front window, pictured below, which the crew was forced to replace.
Photo courtesy of NASA via the agency’s website.
Space Junk Could Cause An Accidental War
Although the militarization of space is outlawed by The Outer Space treaty of 1968 , military communication and intelligence-gathering satellites proliferate. Some researchers speculate that during times of heightened fear, it is possible that a military satellite might become disabled or destroyed by space junk. Such an event, they speculate, could become the mistaken premise for retaliatory strikes that could result in a full-scale war.
More worryingly than impacts with individual spacecraft, however, the astrophysicist and former NASA scientist Donald Kessler proposed in 1978 a possible scenario in which the density of space junk objects in low Earth orbit (LEO) – 2000 km or below – would become high enough to cause a collision cascade, each collision producing further space debris, increasing the likelihood of more collisions until the density becomes high enough to render the LEO zone impassable.
To prevent this scenario, many solutions have been proposed, according to the European Space Agency including controlled re-entry down onto Earth, or lifting the satellites further up into a so-called graveyard orbit. While the former has been proposed for satellites in LEO, the latter is meant for craft in geostationary orbit, which is more than 35,000 km up, in order to prevent them from adding to LEO space junk.
Another proposed solution is a so-called “laser broom,” a laser beam projected from Earth that would target objects 1 to 10 cm in size, burning one end in order to shape it so it will plummet towards the ground and burn up in the atmosphere. The whole operation would cost around $200 million, according to a paper from 2000 by Colonel Jonathan Campbell of Air University, the academic wing of the U.S. Air Force.
Many NASA satellites, as well as the International Space Station and the now-retired space shuttle, also have the capability to maneuver away from space debris that ground sensors detect close to them, according to the 2009 report.
Still, with many space launches planned by NASA in the future, countries like North Korea and Iran eager to prove themselves by launching satellites, and private space travel on the rise, space debris in Earth orbit is likely to increase in the near future.