In 1908, a flaming meteor fell through the Earth’s atmosphere and exploded above the Stony Tunguska River in the Siberian forest. The result was shocking: 80 million trees over 820 square miles were blown over like toothpicks and mankind began to fear destruction from outer space. A century later, it seems this fear should be focused not on natural objects from the heavens. Rather, a greater danger to man is the human-made debris orbiting the earth. This “space junk” threatens the Earth’s environment in several ways.
Destruction of the Ozone Layer
Ozone is a protective layer in the upper atmosphere that shields the Earth from the ultraviolet rays of the Sun. Environmentalists have long warned of the harmful effects of this layer by earth-based human activity. Some modern scientists believe that space activity may also adversely affect the ozone layer.
This destruction can happen in three ways. First, when rockets are launched, their emissions in the upper atmosphere may be harmful to the ozone. Though more research is needed, some experts like engineer Martin Ross of the Aerospace Corporation theorize that the rocket exhaust particles remain in the upper reaches of the atmosphere, increasing the temperature through their absorption of solar energy.
Second, as the orbits of human-made debris degrade, and re-enter the earth’s atmosphere, a shock wave occurs in the upper reaches of the layer of ozone. This physical stress on the area can be damaging to the protective buffer. Researchers have discovered that the impact of objects entering the atmosphere at high speed can produce nitric oxide during the rapid cooling that follows the splitting of oxygen and nitrogen. Nitric oxide is very destructive to the ozone layer.
Finally, though most of the debris that re-enters the earth’s atmosphere is vaporized due to the build-up of intense heat, the chemical residue of this material can also react with the ozone and deplete it.
Some scientists fear that erosion of the ozone layer may cause global climate change. They predict that these altered weather patterns could transform fertile farmland into deserts and threaten human life on the planet. Thus, the environmental effect of space debris on the ozone is of great concern to these experts.
Hampered Weather Prediction
Much of modern weather forecasting is powered by the score of satellites orbiting the earth that photograph storm systems as they form. These space-based tools have improved the accuracy of weather prediction, which has brought many benefits to society. Experts believe that ability to produce reliable weather forecasts results in many positive benefits. Henry R. Hertzfeld and Ray A. Williamson, researchers with the Space Policy Institute of George Washington University write that “…the benefits from earth observations from space have had a huge and significant impact on the economy.”
The growing clouds of outer space debris threaten this ability. Scientists estimate there are over 100,000 pieces of human-made objects littering the skies of Earth. In recent years, the clutter has increased dramatically. In 2007, the Chinese government intentionally destroyed an aging Chinese weather satellite in a missile test, which created a “cloud” of 2000 pieces of debris. In 2009, an abandoned Russian spacecraft collided with a U.S. satellite, resulting in a 3000-piece debris cloud. The combination of all these areas of polluted space reduces the visibility for good weather satellite images. This, in turn, hampers ground-based meteorologists in their efforts to forecast the weather.
Related: What happens to old spacecraft?
Collisions with Space Debris
Not only does “space junk” affect the Earth’s environment, but also creates a dangerous space environment as it falls back to earth. These millions of pieces of debris move at a tremendous speed, traveling up to 17,500 mph. Though most of these pieces of material are less than 1 centimeter in diameter, they can be very destructive due to their velocity. Even a small fleck of paint off of a spent rocket is dangerous. In 2017, a small piece of paint hit a window in the International Space Station and caused a 7mm crack. With 29,000 pieces that are the size of a softball or greater, there is the possibility of even more catastrophic collisions.
For this reason, several agencies across the globe keep track of space debris. The Department of Defense’s Space Surveillance Network (SSN) watches nearly 15,000 objects two inches or greater in size that are in a low orbit around the earth. Commercial businesses even help out, such as Exoanalytic. It has 150 telescopes around the world that are tracking space junk. It then shares its information with the SSN.
These efforts have proven to be effective in helping spacecraft avoid collisions with debris. In 2017, the SSN issued 655 emergency warnings to various agencies and governments about potential collisions between satellites and debris. Oftentimes these collisions can be easily avoided by moving the satellite to a higher orbit with a simple burn of the jet propulsion thruster.
Reduced Orbital Resource
The final impact of space debris on the environment is the reduction it causes in available areas of space open for new satellites. This area surrounding the globe is very valuable for “real estate,” especially with the advent of the Internet age. This year Boeing, OneWeb, and SpaceX
“Once you’ve been in space, you appreciate how small and fragile the Earth is,” said Russian female cosmonaut Valentina Tereshkova. With the growing number of pieces of human-made debris floating around above the earth, it may be that space is just as fragile.
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