Macrocosm: The Biggest Threat to Space Exploration is Entirely Man-made

Pakin Songmor

Adding a drop of red dye to a bucket of white paint won’t make much of a difference. However, as you add more coloring, drop by drop, the paint will eventually look completely different. Since the late 1950s, countries across the globe have successfully completed thousands of space launches. Most of these rockets, spacecrafts, and satellites have become space junk, relics of past space exploration orbiting the planet. In the vast, inconceivable expanse of space what difference could a few pieces of space junk really make? Humans have found a way to transform every part of this planet into a landfill. While the sky always seemed off limits, that may no longer be the case.

What is Space Junk?

Far beyond the clouds, up to 621 miles past Earth’s surface and more than 70 times higher than a commercial airplane can fly, lies low Earth orbit (LEO). LEO is a space junk yard filled with more than 100 million pieces of debris exceeding 8,000 metric tons. Most of the junk is human-generated: parts of rockets, flecks of paint, inactive satellites, old spacesuits, nuts and bolts, a glove, and even a spatula.

Over 23,000 objects are larger than 10cm, or the size of a softball, and about 500,000 are between 1 and 10cm in diameter. As the commercial space industry expands and more satellites are launched, these figures are bound to multiply. Objects in orbit often collide and shatter to create thousands of smaller debris further exacerbating the situation.

Earth’s space junkyard isn’t all trash; critical satellites used for navigation, communication, and weather forecasting are interspersed within. LEO even houses the International Space Station (ISS). Less than 10% of the objects in LEO are active satellites, the rest is useless junk.

Kessler Syndrome

Debris in LEO circles the Earth at an average speed of 16,777 mph; during a collision, impact speeds can reach up to about 33,554 mph, 10 times faster than a speeding bullet. This makes even the smallest debris extremely dangerous. To put things into perspective, debris debris more diminutive than a marble (~1 cm), could disable an essential instrument or system on a satellite.  

As the junk yard becomes more crowded, one collision could cause other collisions, similar to a pile-up on the highway. This cascade of collisions is called “Kessler Syndrome”, named after the astrophysicists and former NASA scientist who first proposed the idea in 1978, Donald J. Kessler. If Kessler Syndrome sounds familiar, you may recognize it as the plot of the 2013 film, Gravity.

The Kessler Syndrome domino effect is most catastrophic when large objects are involved because their collision generates the most space debris and greatly increases the probability of subsequent collisions. If such a collision were to happen, the resulting band of debris circling the earth would make space travel and satellite launches impossible for centuries. Although a Kessler Syndrome event hasn’t occurred yet, we are already witnessing the impacts of hoarding space junk. For decades, junk in LEO has delayed and even halted space launches.

What Can Be Done?

Debris in LEO will lose altitude over time and eventually fall back to Earth’s surface. Upon reentry, most of it will burn up in Earth’s atmosphere; the rest will land in large bodies of water or uninhabited regions. The farther the object, the longer it will remain in orbit. Objects farther than 1,000 km will circle the planet for over a thousand years, posing the biggest threat.

Some countries have taken to using missiles to shoot down old, inactive satellites to prevent a Kessler Syndrome event, but this has often proven problematic. Just last year, India conducted “Mission Shakti”, an anti-satellite missile test targeting a satellite with an altitude of less than 300 km. The impact added countless debris to LEO and increased the risk of collisions with the ISS by 44% over a 10-day period.

Other plans for clearing space debris sound like they were conceived in a writer’s room in Hollywood. In 2025, the European Space Agency plans to launch a ‘chaser’, ClearSpace-1, into LEO. The satellite will use a quartet of robotic arms to capture space debris and pull it back to Earth’s surface so that it will burn up in the atmosphere. The list of emerging technologies has also included electronic whips, harpoons, slingshots, and plasma thrusters.

Until researchers develop technology to reduce space junk, our only realistic option is to monitor what is currently up there and stop accumulating more debris. The U.S military tracks large orbital debris using a global network of telescopes, the Space Surveillance Network. The population of small objects in space is detected by ground-based radars and estimated with statistics. International guidelines recommend that a satellite should remain in LEO no longer than 25 years after its mission concludes, the aptly named “25-year rule”. Although compliance with the rule is optional, the U.S. will not approve a space launch that violates it. The U.S. cannot solve this issue alone. In order to guarantee space exploration for future generations, all countries must make an effort to reduce and, maybe even one day, eliminate space debris.