Space Debris: Wall-E’s Future is Real

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Yina is a startup founder and astrophysics enthusiast that enjoys blogging about space in her spare time.

She can be found at online at her website.

www.yinahuang.com

What is Space Debris?

Beyond similarities to a Pixar animated film, this image tells a compelling story: environmental sustainability is not contained to just Earth. Debris and man-made wastage can be seen everywhere, including environments such as space.

At first, space debris referred to the natural debris found in the Solar System: asteroids, comets, and meteoroids. However, that term has slowly expanded to include the debris leftover from the mass of defunct, artificially created objects in space, especially Earth orbit.

A lot of these “artificially created objects” are talking about satellites, which serve important functions for us down on Earth. They enable you to phone your overseas friend, check the weather if it’s raining, take that flight home during the holidays, and provide military and scientific data.

With all these functions, you can bet that satellite launches have become a dime a dozen. Per the United Nations Office for Outer Space Affairs (UNOOSA), 8,126 objects have been launched into space, with over 22% of these in the last eight years alone.

In 2017, there were over 453 objects launched — the highest record to date. Now, with the decline in space costs and the increase in human demand for the earth, this number is increasing year by year.

Space Debris and the Kessler Effect

This poses a concerning risk known as the Kessler Effect: where the sheer density of objects found in orbit is increasing to the point where collisions between objects could cause a chain effect of collisions that will render orbital space destroyed. A cascading Kessler syndrome increases in likelihood as satellites in orbit increase in number.

The simulated image above shows the current volume of “space junk” that exists in LEO — an estimated **128 million+ pieces of debris** smaller than 1 cm (0.39 in) as of January 2019.

Mind you, these pieces are floating around LEO travelling at 17,500 mph. At an orbital speed of 17,500 mph — these small pieces of debris are travelling fast enough that a collision would cause significant damage to a satellite or spacecraft.

For some context: even something as small as tiny paint flecks can damage spacecraft when travelling at these velocities. In fact: space shuttle windows often had to be replaced because of damage from collisions mid-flight. The risk of a catastrophic collision of the Space Shuttle with a piece of space debris was 1 in 300.

Space Debris Impact

What happens to space debris on impact? Pictured here is the end result when a 1/2 oz piece of plastic collides with a slab of aluminium at 17,500 mph (LEO orbital speed). For context, a 1/2 oz piece of plastic is about the size of a pencil eraser.

A wide variety of materials are used for satellites and rockets. To reduce energy output required to launch, they tend to be extremely light weight, usually made of materials such as titanium or aluminium as well as composites and alloys.

With the increasing amount of space debris, there is concern that large collisions could set off a chain reaction of destruction, rendering Lower Earth Orbit unusable.

Historically, this has already happened once — and will likely repeat again due to the sheer volume of debris that is floating around.

Space Debris Collisions of the Past

On February 10th, 2009, the first-ever collision between two satellites occurred in orbit. Kosmos-2251, a defunct Russian satellite, collided with and destroyed a functioning US Iridium commercial satellite, adding over 2,000 pieces of trackable debris to the growing collection of space junk orbiting Earth.

By 2011, many pieces of debris were in an orbital decay trajectory towards Earth, falling back towards the atmosphere, to burn up on reentry. However, as of 2016, 1,141 and 364 pieces of tracked debris remain in orbit for decades to come, posing future collision risk to other objects in Low Earth Orbit (LEO).

Space agencies invest considerable time and money towards building statistical models that dictate whether an impending collision is likely to happen and what actions should be taken from it (debris avoidance maneuver).

Events where two satellites approach within several kilometers of each other occur numerous times each day. Sorting through the large number of potential collisions to identify those that are high risk presents a challenge.

Precise, up-to-date information on current satellite positions is difficult to obtain — calculations made by CelesTrak had expected these two satellites to miss by 584 meters (1,916 ft).

It was not until Iridium 33 suddenly went silent, and the US Space Surveillance Network reported debris clouds in both Iridium 33 and Cosmos 2241 orbits that a collision was confirmed — via the orbital debris path.

Space Debris: Significance

The original risk of collision was one in 50 million, which was low enough to warrant no action. However, instances like these where reality defies data will only increase as the amount of space debris continues to climb and will pose a higher risk.

In summary, as the world continues to be more and more connected, we see how the volume of space debris continues to increase, which increases the risk of collision. At such fast speeds in LEO, and the sheer volume of millions of pieces of debris, incidents like the 2009 Iridium-Cosmos collision will likely occur again, and at an ever increasing rate.

To mitigate risks like this happening, we need to figure out more devices that can remove space debris from orbit, or be more strategic about allowing space debris to burn up upon re-entry into our Earth’s atmosphere.

Author: Yina Huang @yinadreamsofspace