Risk from Space Rubbish Remains an Unknown Unknown
In the 50-odd years since Sputnik, the world has come to rely heavily on space. Roughly 1,200 satellites in orbit link global telecommunications networks, provide real-time positioning to our phones, and monitor the Earth for climate events and natural disasters. Space assets are also a critical enabler for the U.S. military. However, the increasingly heavy use of space has led to the creation of clouds of space debris numbering in the hundreds of thousands, which could deeply impact humanity’s ability to use space. The Cipher Brief’s Fritz Lodge spoke with Director of the Secure World Foundation, Dr. Michael K. Simpson, to learn more about the danger space debris poses, and how to clean up our orbits.
The Cipher Brief: What is space debris and can you outline the threat that it poses to satellites in orbit?
Michael Simpson: Space debris are uncontrolled pieces of material that are either in orbit because they are long left over pieces of former spacecraft that have exploded on orbit, or launchers that have fulfilled their responsibilities and are now just floating along orbital dynamics.
The most important threat from space debris is that it is not maneuverable. There is no way for it to get out of the way of anything. Therefore, controlled objects in space are left with the full responsibility to maneuver in the event that they detect a piece of debris approaching.
TCB: What are some of the problems with tracking these objects?
MS: Size is a huge part of the problem. We hope that when the new space fence is fully online, new sensors will potentially be able to see objects well below the size of five centimeters. Currently, we operate in an environment where we are limited to seeing objects about ten centimeters wide or longer. Ten centimeters is roughly the size of a softball, but it is a softball that is moving at 17,500 or more miles per hour—heck of a pitch. You can imagine that an object of this size traveling at that speed is going to cause very considerable damage to any spacecraft that it hits.
But the growing worry regards the pieces we can’t see. We think we can identify somewhere around 20,000 objects of space debris, but there may be as many as a half million objects, which go down to perhaps a centimeter in size. That is about the size of a .22 caliber bullet. Moving 17,500 miles an hour, you can imagine the amount of damage that could cause.
We increasingly worry that if the volumes of such objects in space were to continue to increase, we could have enough debris fields in space of objects moving at hyper velocity to diminish the use of space and subject it to enormous constraints. In an apocalyptic scenario, it might even become nearly impossible to use space. However unlikely that is in the near term, there is the potential for an exponential increase of debris at a certain point – as one piece of debris hits a larger object and creates more debris to hit more objects and so on and so forth.
The question now is how do we draw down on our creation of this kind of debris, which could curtail our ability to use space well into the future.
TCB: In that apocalyptic scenario, what are some effects that you can think of to U.S. – and global – security?
Simpson: The more crowded orbits get with debris, the harder it is to maneuver spacecraft that are particularly important to earth observation. The real challenge that we’re worried about right now is in low earth orbit, although there are certainly issues in polar orbits and we have a couple of really weird problems right now in the geosynchronous arc, where we have two satellites just completely adrift.
But obviously the militaries of the world are very concerned about being able to see things on the ground. Being able to distinguish between unusual activity and threatening activity, and being able to provide support to people who might be engaged in military operations. If it becomes difficult to maneuver spacecraft in low Earth orbit, that’s going to be a concern to any commander who wants to have a more perfect view of the battlefield. Low Earth orbit is where we like to place many optical sensors – it gives you a closer view with a higher resolution.
When you talk about debris in geosynchronous orbit, then you start to get into a national security concern on the part of anybody dependent on communication satellites operating from that orbit. That’s the preferred orbit from communications birds because they get to have a very large view of a very large portion of the Earth. Commanders always want to get beyond the fog of war, and good Earth observation and space-based communications are critical pathways to accomplishing that goal.
The ability to see the Earth clearly from low Earth orbit was also a significant factor in allowing the Soviet Union and the United States to back away from each other at times of tension and prevent nuclear conflict. It allowed both countries to distinguish real threats from unusual activity. The transparency that space provided enabled both the Soviet Union and the United States to take some important decisions to back off from what was a pretty tense period of time.
Space can facilitate a military conflict, but it can also – verifiably from history – prevent a military conflict.
TCB: What efforts are we taking to tackle this problem?
Simpson: The international effort is really focused around the activity of a group called the Interagency Debris Committee. This committee is an inter-governmental cooperative organization, which has come up with several guidelines about reducing debris.
I would say they’ve been the most effective in reducing launch debris. Guidelines that reduce the extent to which launchers spin off debris when they take off into space. In the early days, we used all sorts of techniques to separate the satellite from the launcher – explosive bolts, springs that just ended up floating in space, etc. – and this all left stuff in orbit because it was already moving at orbital velocity when it was created. But there are ways to make sure that you’re not just dumping bits and pieces into low Earth orbit every time you launch a satellite, and that’s very important.
We know that a significant part of the non-maneuverable and large pieces of debris in low Earth orbit are launch vehicles. The oldest piece of identifiable space debris is an American rocket body from the Vanguard program launched in 1958. Vanguard was a relatively unsuccessful launch program but apparently they got one of them blasted into an elliptical orbit and it’s still floating there. There are frequent jokes about funding the Smithsonian to go get it and put it on display, but this object really gives you a sense of how long these things can stay up there. It also underlines that we played a major part in creating this debris problem, in addition to other major producers of it like Russia.
TCB: Are there programs that are actively trying to clean up space debris?
Simpson: I would say that’s the Holy Grail of space debris. There are a number of technically possible active removal solutions that simply don’t have the funding. They are expensive and not yet proven, although of course they can’t be proven until they are tried.
But a long-term, economically sound system for debris removal has not yet been developed. We have not been able to optimize the technology or make it economical yet. There is a project in Switzerland – the S3 Corporation – where they have proposed using a co-orbiting de-orbiting device that would bring down a defunct Swiss satellite.
The European Space Agency has also hinted at a project to de-orbit Envisat, which is probably the largest piece of really challenging space debris in an important orbit. It’s over six metric tons so this is a problem. Their hope is to have it de-orbited sometime after 2022, but the full architecture of that mission isn’t really clear, but success here would really be a strong demonstration of the efficacy of this technology.
TCB: Last thoughts?
Simpson: As you look at the world of debris going forward, the real key will be to find some way to either de-orbit or capture un-maneuverable debris effectively.
This also helps when you think about the overcrowding issue in space. The biggest problem with some small satellites is not that they are small, not even that they’re numerous, it’s that they’re not maneuverable. If we can solve the maneuverability problem in small satellites, they cease to be debris because they can cooperate in avoiding a collision. I think you will see over the next several years, a lot of discussion about this issue of maneuverability. How do we build something to attach to a piece of debris and take it down successfully, and even more important, how do we make sure that new generations of satellites are maneuverable and can participate in avoiding collisions?
Then all we have to do is find a way to track all these objects, and we can manage them.
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