Orbital Organization: What is Up There?

Greetings #space enthusiasts! This week we are going to dive a bit more into the educational side and look at what exactly is in orbit around Earth and what all is included under the category of debris. To truly understand the bustling space economy, with all its ups and downs, and advocate for a safe orbital environment we need to understand what exactly is currently up in space and what do we mean when we use the term debris. I can promise you that it is a much more complex answer than you might expect! We throw this term around a lot when referring to Earth’s orbit and it is certainly an accurate categorization most of the time, but many people do not realize everything that it encompasses or what the various types of debris come from.

Fortunately, we are going to illuminate exactly what debris is, why so many different types of debris exist, and where it all comes from. Before we start diving in, I will clarify that this is focused on the category of debris or “dead” objects in orbit around Earth and is not focused on the various types of active satellites that are currently in orbit. That is an entirely different topic that would take multiple other articles to discuss, as there are satellites known as cube sats that are as small as 10 cubic cm all the way to the ISS.

To begin organizing debris, we need to start at the highest level of categorization; natural and artificial. For this, natural refers to any debris that was not created by humans and is of a naturally occurring material that ended up in Earth’s orbit through natural means. This refers to small bits of cometary or asteroidal material that have traveled through space and got close enough to Earth to be trapped in its orbit by Earth’s gravitational force. Artificial space debris, on the other hand, is the larger topic of discussion today and covers all objects, large and small, that are created by humans and are in Earth’s orbit due to actions taken by us. An interesting fact is that the very first piece of artificial space debris was put in orbit the first time we went into space when Sputnik-1 was launched and left the final stage of the rocket in orbit around Earth.

So, what all is included in the category of artificial space debris? This covers anything from a tiny paint chip to an entire, defunct satellite that is orbiting around the Earth at speeds up to 17,500 mph. Of course, none of these objects starts as orbital debris. Some might break up on launch and immediately become orbital debris, but nothing that is currently in the category of artificial space debris was created for that purpose. These are all objects or pieces of larger objects that had a purpose or a mission that they were either intended for or completed. For many spacecraft, especially the older ones, when they reach their end-of-life and are no longer operational they become debris that continues to travel around the Earth.

These “dead” satellites can of course be de-orbited, which is simply the process of bringing the object out of Earth’s orbit either by being slung into deep space or by coming back down into Earth’s atmosphere. This is the preferred option for satellites that are no longer functional. The goal is to have them brought down into?Earth’s atmosphere and created in a way where they can burn up in the atmosphere before every reaching the hard, rocky crust of the Earth where the small, fragile lifeforms known as humans reside. This is not always the case though and some satellites get stuck in orbit or only come down slowly through atmospheric drag (yes there is still drag in low-Earth orbit). If the satellite relies on purely atmospheric drag to de-orbit, then it could take decades to de-orbit depending on the orbital altitude of the spacecraft. Anything below 400 km in altitude could de-orbit in a year or less, naturally, but much of what is in orbit today is above this altitude. Satellites orbiting at 800 km or higher can take decades. This is determined by the objects ballistic coefficient, which I will not dive into here for the sake of more casual readers!

All of this is to say that objects in orbit can take a very long time to come down. Fortunate for us, the FCC has adopted a new ‘5-Year Rule’ that means satellite operators have to plan to de-orbit a satellite within five years of the end of its life. This is a substantial drop from the previous 25-year timeline that previously existed.?

The various other small pieces of spacecraft can be the byproduct of spacecraft collisions or the left-over parts of launched rockets, known as rocket bodies. For the former, this is a major problem right now that the space industry, and really all of us, are facing. When objects in orbit collide, even debris hitting other debris, they break apart into potentially thousands of other small pieces of debris that shoot off in all directions around the Earth creating even more debris that can hit more objects. This is known the Kessler Effect and is something I have spoken about in previous articles, so I won’t cover it too much here. Just know that this is a bad thing for our advancement into space!?

The pieces known as rocket bodies are from rockets launched into space that have break-away segments for the various stages that the rocket goes through during launch. Similar to a bullet firing from a gun where the actual bullet that hits a target is just the small tip of what you load into the gun. The bottom majority of the “bullet” is just the gun powder casing that holds the material needed to ignite and propel the bullet forwards. Rockets operate in a similar manner and, let’s be honest, are really just giant missiles being shot into space carrying really important things that are occasionally human lives. So, as the rocket reaches various stages of the launch the parts needed for the previous stages are no longer needed and are detached from the rest. These detached pieces are the “rocket bodies” that can occasionally end up in orbit around Earth if they are detached at a high enough altitude.

Fortunately, for many of the modern rockets that are being used this is not a problem (thank you SpaceX !). We now have rockets that are reusable and allow the base that is detached to land back on Earth for us to collect and use again. This was a huge step forward for rocket launches and space travel in general! Now, we “shouldn’t” be leaving left over rocket parts in Earth’s orbit anymore, but this sadly is not always the case. Reusable rockets are still a rather new concept and we still have a good ways to go.

You have likely gathered at this point that the paint chips that I referenced earlier are the pieces that can break off of spacecraft after a collision with another object in orbit. This can create a multitude of artificial debris depending on what is hit on the spacecraft. The complex satellites have components on them that have a wide range of material being used from various metals, glass, paint, plastic, and more. Any of this could be broken off or have fragments chipped off in a collision and sent hurdling around Earth’s orbit. In the worst case scenario, the collision is catastrophic, like the conjunction between an Iridium satellite and a defunct Russian communications satellite, and both objects are completely destroyed in the event and it results in thousands of pieces of debris being generated. The example listed is actually the first case of a satellite-on-satellite collision in space back in 2009 and involved a 689 kg satellite.

So, whether natural or artificial, there are a multitude of objects in orbit of all shapes, sizes, and materials that all pose a threat to the valuable, active satellites that are currently in orbit around Earth. Some items, like comets, ended up there naturally and are a normal part of our space ecosystem. Other objects tell a story of human exploration and our journey into the stars, whether for better or for worse. We cannot change the past actions that have left our orbital environment in the state that it is in, but we can work to rectify it and ensure we move forward with more sustainable space practices. I have spoken in past articles about the multitude of companies that are addressing the debris problem, either by removing debris or working with operators to ensure we are not adding any more. Knowledge is a tremendous first step though! It is essential to understand what is up there and how it got there to be able to make the proper steps to avoid making it worse.

Want to join a group of like-minded people to share knowledge on?#spacesustainability? Join the?Orbital Outpost?group on LinkedIn!

Send me a message over LinkedIn or to my?email?with any ideas you have for future articles. I love any suggestions you have for things you would love to know more about or questions you would like me to research and take a deep dive into!

Sources

[https://www.nasa.gov/mission\_pages/station/news/orbital\_debris.html]

[https://www.nationalgeographic.com/science/article/orbital-objects]

[https://www.nhm.ac.uk/discover/what-is-space-junk-and-why-is-it-a-problem.html]

[https://www.esa.int/Space\_Safety/Space\_Debris/Space\_debris\_by\_the\_numbers]

[https://www.esa.int/Enabling\_Support/Space\_Engineering\_Technology/The\_Kessler\_Effect\_and\_how\_to\_stop\_it]

[https://www.fcc.gov/document/fcc-adopts-new-5-year-rule-deorbiting-satellites]

[https://swfound.org/media/6575/swf\_iridium\_cosmos\_collision\_fact\_sheet\_updated\_2012.pdf]