Vanguard 1[1], designed to test the launch capabilities of a three-stage launch vehicle as a part of Project Vanguard, and the effects of the space environment on a satellite and its systems in Earth orbit was launched by the USA on March 17, 1958, is the oldest piece of space junk. It stopped operating in 1964 but will continue orbiting Earth for 240 years.
Orbital debris, otherwise known as “space junk”, is a major concern. This massive cloud that orbits the Earth is the result of the many satellites, platforms, and spent launchers that have been sent into space over the years.
Collisions between these objects (as well as disintegrations and erosion) have created even more in the way of debris. To break the numbers down about 5250 launches have taken place since the beginning of the space age, which officially kicked off on October 4th, 1957, with the launch of the Soviet Sputnik 1 satellite. Of the many missions that have been launched since then, some 23,000 are still in orbit, while only 1200 are still operational. However, this accounts for only 6% of all the actual objects in orbit.
Another 38% can be attributed to decommissioned satellites, spent upper stages, and mission-related objects (launch adaptors, lens covers, etc.). All told, an estimated 94% of objects in orbit qualify as being “space debris” – a term used to describe objects which no longer serve any useful purpose. About 64% of these objects are fragments from the many breakups, explosions, and collisions of satellites or rocket bodies that have taken place over the past decades. There are an estimated 166 million objects in orbit that range in size from 1/32 inch to 13/32 inches in diameter.
There are also another 750,000 objects that range from 13/32 to 4 inches in diameter and about 29,000 objects that exceed 4 inches in diameter. The ESA (European Space Agency) and other space agencies around the world are responsible for tracking about 42,000 of the larger ones. All told, the total mass of all the objects orbiting the Earth is estimated at ~8267 US tons.
And between all this debris, a little over 290 break-ups, explosions, and collision events have taken place, resulting in the fragmentation of objects and the creation of many smaller pieces of debris. Each and every one of these is considered a serious threat due to the relative orbital velocities they have. Essentially, orbital debris can reach speeds of up to 34,796 mph due to the Earth’s rotation. At this speed, even a tiny piece of debris can seriously damage or disable an operational spacecraft.
[The debris cloud’s creation is] unacceptable. When one country does it, then other countries feel like they have to do it as well.
NASA Administrator Jim Bridenstine
Meanwhile, a collision with an object that is larger than 4 inches will lead to catastrophic break-ups, releasing more hazardous debris clouds that can cause further catastrophic collisions – a phenomenon known as “Kessler Syndrome[2]”. Space debris includes a glove lost by astronaut Ed White on the first American space walk (EVA), a camera lost by Michael Collins near Gemini 10, a thermal blanket lost during STS-88, garbage bags jettisoned by Soviet cosmonauts during Mir’s 15-year life, a wrench, and a toothbrush.
Sunita Williams of STS-116 lost a camera during an EVA. During an STS-120 EVA to reinforce a torn solar panel, a pair of pliers was lost, and in an STS-126 EVA, Heidemarie Stefanyshyn-Piper lost a briefcase-sized tool bag. Also floating are a spatula, camera lens caps, a screwdriver, and various nuts and bolts.
The United States Department of Defense monitors the debris with the Space Surveillance Network. The group is tasked with detecting, tracking, and cataloging the many human-made items swirling around the planet using a global network of telescopes.
While some of the junk will lose altitude over time and burn up in Earth’s atmosphere, there’s a lot of stuff up there. Even without new launches or major explosions, the space junk already in low Earth orbit is so abundant that it will likely continue to multiply over the centuries as orbiting pieces collide. Computer simulations of the next 200 years suggest that during that time debris larger than about 8 inches across will increase by 1.5 times. But the smaller particles will increase even more. Junk between 4 inches and 8 inches is expected to multiply 3.2 times and debris less than 4 inches will grow by a factor of 13 to 20.
In reality, the situation will undoubtedly be worse because spacecraft and their orbital stages will continue to be launched.
Review of the state of space junk published in Science Magazine
A piece of space debris can reach speeds of 4.3 to 5 miles per second. That’s nearly 7 times faster than a bullet and just about the equivalent of being hit by a bowling ball moving at 300 miles per hour.
Footnotes
- Vanguard 1 is an American satellite that was the fourth artificial Earth-orbiting satellite to be successfully launched, following Sputnik 1, Sputnik 2, and Explorer 1. It was launched on March 17, 1958. Vanguard 1 was the first satellite to have solar electric power. Although communications with the satellite were lost in 1964, it remains the oldest human-made object still in orbit, together with the upper stage of its launch vehicle. [Back]
- The Kessler syndrome (also called the Kessler effect, collisional cascading, or ablation cascade), proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) due to space pollution is high enough that collisions between objects could cause a cascade in which each collision generates space debris that increases the likelihood of further collisions. In 2009 Kessler wrote that modeling results had concluded that the debris environment was already unstable, “such that any attempt to achieve a growth-free small debris environment by eliminating sources of past debris will likely fail because fragments from future collisions will be generated faster than atmospheric drag will remove them”. One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges difficult for many generations. [Back]
Further Reading
Sources
National History Museum
Astria Graph
NASA
Wikipedia
National Geographic
Britannica
Rubicon
India Today
How It Works Daily
Universe Today
