Matt Rulli

Solving the Space Debris Crisis: How One Generation’s Trash Became Another’s Tragedy

Abstract

This paper examines the history and proliferation of the space debris problem and attempts to analyze the proposed solutions for cleaning up the environments of low, middle, and geostationary earth orbits. Since the beginnings of human spaceflight in the late 1950’s, the deposition of waste materials like spent rocket stages and assorted mission debris has reached a crisis point. Damage to operating communications and global positioning navigation satellites, not to mention the hazard posed to crewed spacecraft like the International Space Station, from impacting high-energy orbital debris represents a clear and present danger to current and future space operations as well as people on the ground. Mitigation and collision avoidance are simply not effective enough for a sustainable future in space, and this paper serves to offer a comparative analysis of the proposed solutions and a recommendation for action based on currently available data.

Keywords: space debris, space trash, space waste, active-removal, low earth orbit debris

The modern word “disaster” comes from the Latin dis meaning ‘bad’ and aster meaning ‘star’ because the ancients believed that “shooting stars” were signals of troubled times ahead, and they might not have been too far off the mark. The continuously increasing threat posed by space debris to human safety and the global communication and navigation infrastructures has reached a critical point and requires immediate remedial action. Attempts to mitigate further deposition of waste in orbit around the planet have been ineffectual at best, and without stricter international oversight, humanity’s utilization of low earth orbit may be rather short-lived.

Mitigation alone is simply a continuation of the same “band-aid on a bullet-wound” approach to problem-solving that allowed the current crisis to develop in the first place, making active removal of the debris the only viable course of action. Additionally, while there may not be any singular system capable of resolving the issue in its entirety, it is without a doubt that a sustainable future in space will only be possible with a well-funded international partnership dedicated to correcting the problem.

Goals

The goals of this paper are to discuss the history of human spaceflight and the negligent attitude regarding waste that led to the current crisis state. Additionally, this article will examine in detail the current methods of tracking orbital space debris as well as analyze and compare the proposed solutions to the problem. Once the analysis is complete, a final recommendation for remedial action will be presented for the reader’s consideration followed by a summary of the article’s findings.

Background

Definition

According to the International Academy of Astronautics (IAA), the definition of orbital debris is, “…any man-made object which is non-functional with no reasonable expectation of assuming or resuming its intended function, or any other function for which it is or can be expected to be authorized, including fragments and parts thereof.” (Schildknecht, 2007). While that may sound relatively benign considering the incomprehensible vastness of space, the area of Low Earth Orbit (LEO), or the environment immediately surrounding our home planet, is becoming increasingly cluttered with these artifacts. Even something so small and seemingly innocuous as a frozen paint chip can become a remarkable hazard if it collides with a functional spacecraft in orbit, not to mention a threat to the lives of those brave individuals who dare to live and work in space.

History

Since the late 1950’s, human beings have been traveling to and operating in the areas of low, middle, and geostationary earth orbits. Back then, to us, space was an expanse of emptiness sprinkled with mystery and wonder. Every rocket launch was newsworthy, every mission was a fascinating adventure, and it captured the imaginations of an entire generation. However, little did we know that with every one of those launches, we were laying a minefield of headaches and worry for ourselves and our future in space. According to a report from the Embry Riddle Aeronautical University, after the initial Mercury missions in the early 1960’s, the odds of an orbital debris collision with the Gemini 8 spacecraft (piloted by none other than Neil Armstrong) were 2.3 x 10-9 (or a .0000000023% probability) during its 10.7-hour orbital flight (Hall, 2014). Ten years later, in 1976, it was estimated that that probability had jumped to a 1.3% probability of a collision, which equates to roughly one impact every 77 years (Hall, 2014). Data from the same report suggests that by the end of 1997, the odds that a piece of space debris coming within the space shuttle’s maneuvering area during a 9.7-day flight in orbit had a probability of 86%. Additionally, the likelihood that an onboard window would need to be replaced upon returning to Earth was 60% for every space shuttle mission (at a low cost to the American taxpayer of $50,000 per window).

In July of 1962, the first commercial communications satellite, Telstar 1, was launched into orbit to supplement communications between ground stations that were beyond each other’s line of sight. Since that launch, there have been upwards of 4,900 launches and over 6,600 satellites placed into orbit about the Earth, and every single one has deposited its small share of debris to the cloud. Of those satellites, more than half are still in orbit while only about a third (roughly 1,300) remain active and controllable (Gupta et al., 2018). While this may not seem like a staggeringly large number of objects, considering the average size of a satellite is about that of a minivan and moving at speeds that can be difficult to fathom, even one collision (and the subsequent cloud of debris that would result) could mark the beginning of an unrecoverable situation.

Physics – Putting Velocity in Perspective

It can be difficult to fully comprehend the velocities of high-energy orbital debris as there is nothing in our day-to-day lives that moves even remotely close to the speeds being discussed in this article. Even the speed of a high-powered rifle bullet is relatively slow by comparison. The first step in really understanding the destructive power of space debris is to understand energy. Simply put, the larger an object is, the more energy is required to put that object into motion. Once that object is moving, Newton’s Laws of Motion dictate that it will remain in motion until another force acts upon it. When it comes to objects in flight within the atmosphere, atmospheric drag, or rather friction between the object and the air it’s moving through, causes the object to lose energy and fall back down to the ground. However, once an object has been put into orbit where there is a negligible atmospheric drag effect, that object could stay in orbit for hundreds or even thousands of years, and it could do so without losing much of its initial energy. So how fast are these bits of trash really going?

Imagine an Olympic shooting competition where a woman is standing on the firing line ready to “take her shot” at a gold medal. She looks down her sights and sees the target blur as she focuses on the crosshairs. A slow exhale escapes her lips as her finger settles over the trigger and begins to squeeze. Then, bang! The hammer falls onto the cartridge’s primer throwing sparks into the grains of gunpowder. As the powder ignites, the resultant gas expands and creates overwhelming pressure inside the chamber. The pressure builds forcing the chunk of lead in its path through the barrel where it continues gathering speed before making its repercussive exit. The moment the projectile leaves the muzzle, it is traversing a distance of 990 meters for every one second of time that elapses. To put that into perspective, the bullet is traveling at about 2,214 miles per hour as it leaves the barrel of the gun (which is about thirty-four times faster than you’re allowed to drive on the average American highway). That speed is about three times slower than the slowest pieces of orbital debris while the fastest pieces can exceed that velocity by over eighteen times.

So how much damage can something traveling that fast possibly do if it hits something? Below is a chart that details the relative magnitudes of energy associated with an impact at the speeds with which we’re discussing. As you can see, a small object traveling at high velocity could have a devastating effect on something as fragile as a solar panel and high-resolution camera-laden weather satellite. The possibilities are terrifying to imagine when considering the result of an impact on a crewed spacecraft which makes the need for urgent remedial action only more pressing.
Proliferation

Between the first launches in the middle of the 20th century and today, there have been three major collision incidents in space resulting in tremendous amounts of space debris being produced and almost 300 other less severe incidents. The earliest and possibly the most disastrous of those is the explosion of the STEP II upper rocket stage fuel tank that was left in orbit after its separation from the launch payload. The tank had a relatively small quantity (roughly 10kg) of hydrazine rocket propellant remaining when the stage was separated, and pressure build-up from solar heating caused the fuel to ignite (Carns, 2017). When the stage exploded, it produced an estimated 700 pieces of mid-to-large sized pieces of debris that will remain in orbit for decades to come (Carns, 2017). While this incident signaled a need for change in the policies regarding how spent rocket stages were dealt with post-launch, it would only mark the beginning in a long succession of disastrous events.

The next significant instance occurred in 2007 when the Chinese government targeted and destroyed one of their own weather satellites using an Anti-Satellite (ASAT) missile system. The strike was designed to test the feasibility of destroying an enemy satellite in orbit; a feat often considered to be as difficult as “shooting a bullet with a bullet” considering the relative velocities involved. After the satellite’s destruction, which produced thousands of individual debris pieces, it was estimated that 15% of existing space debris at the time was a result of that single event (Carns, 2017). Fortunately, the subsequent international outcry of protest for polluting one of the most heavily traveled regions of LEO led to a significant decrease in the testing of shrapnel-based ASAT weapons.

The third, and probably most famous, incident of space debris deposition was in 2009 when a non-operational Russian communications satellite (Cosmos 2251) collided with and rendered inoperable an American communications satellite (Iridium 33). A report conducted in 2010 states that the majority of the resulting debris cloud is still in orbit today, and the Space Surveillance Network (SSN) in the United States estimates that over 1,600 pieces of debris larger than 10cm2 continue to pose a threat (Wang, 2010). The same report suggests that 70% of the remaining debris will fall through the region where the ISS maintains its orbit by the year 2030. This scattered debris will pose a very serious hazard to not only the station itself but also the international crew of astronauts and cosmonauts who live onboard.

An additional factor that compounds the existing problem is the issue of satellite disintegration. As older satellites fail and become unresponsive, their orbits gradually begin to decay. While this can take decades or even hundreds of years, it wouldn’t be much of a problem if they were to stay together as one whole piece that can be easily tracked and avoided, but that is seldom the case for satellites that spend more than a few decades in orbit. Atmospheric drag, micrometeorite impacts, and vibration damage eventually cause larger space objects like satellites to break apart into ever smaller, but equally dangerous, pieces increasing the overall amount of debris.

Tracking the Problem

Current Tracking Capabilities

There are currently numerous systems and methods in use to track and catalog orbital debris. One of the most common methods is computer-aided optical sensors, such as those used by the U.S. Space Command, where large pieces of space debris can be identified and tracked (Bakhtigaraev, 2015). Another system that is in wide use by several government space organizations is ground-based radar detection systems such as such as the inverse synthetic aperture radar (ISAR) and the single-range Doppler interferometry (SRDI) projects (Schildknecht, 2007). These types of observation and tracking methods are capable of spotting and cataloging objects as small as 10cm2 (roughly the size of a softball), and the technology is continuously improving to track smaller and smaller objects (Li, 2014). Often times simple maneuvers out of the debris path can be conducted to avoid what might be a potentially deadly threat. The more precisely those objects can be cataloged and tracked means more time to plan those maneuvers and continue the mission as planned.

In addition to ground-based tracking capabilities, there are numerous projects underway to expand space-based tracking systems as well. Systems like optical cameras and laser-based radar (LADAR) mounted on spaceborne vehicles have been proposed as options for more precise observation of debris. These systems might also allow for better planning of avoidance maneuvers for especially sensitive space-based telescopes such as the Hubble (which has suffered several impacts such as the one pictured below).

Tracking Limitations

Other tracking systems such as Lockheed’s Space Fence system, which is set to become operational sometime in 2021, offer ever-improving means of tracking smaller and smaller pieces of debris at ever-greater distances, but being able to see more debris alone doesn’t solve the problem(Lockheed, 2018). Unfortunately, as it stands now, we are currently only capable of tracking objects larger than 10cm2, and while these pose the greatest threat from impact damage, the threat of smaller debris cannot be discounted, especially since the numbers of small particles far exceed those of the larger objects.

Current Estimates

According to the NASA’s official website, there are currently over 500,000 pieces of orbital debris roughly the size of a marble or larger (NASA, 2018). According to the same data source, there are about 15,000 objects larger than 10cm2 that are currently cataloged and tracked by various U.S. space agencies. The European Space Agency (ESA) published a report in 2017 that indicates that there are upwards of 29,000 debris objects larger than 10cm2, more than 670,000 pieces larger than 1cm2, and over 170 million individual pieces of debris larger than 1mm2 currently in the areas between low earth and geosynchronous earth orbit (ESA). However, due to the limits of ground-based observations and radar, it is not currently possible to actively track objects smaller than 10cm2, but Lockheed’s Space Fence system is expected to decrease that size when the project becomes operational.

Future Projections

Kessler Syndrome is the term that has been coined to describe a catastrophic cascade of collisions that would essentially make it impossible to sustain an operational constellation of satellites in LEO without a massive cleanup initiative being undertaken. It begins with a relatively small piece of debris (let’s say the size of a baseball) left over from one of the earliest crewed missions of the 1960’s. The object is traveling at a velocity almost ten times the speed of a modern military rifle bullet, and it collides with a non-operational satellite tumbling in low earth orbit. As the object impacts the old satellite, it shatters the main body of the spacecraft and sends new debris flying in all directions. So, what was once a single piece of debris is now hundreds of all shapes, sizes, and speeds ready to go off and do some damage of their own. As the cloud of debris travels around the planet, it eventually comes in contact with another satellite and annihilates it like a blast from a shotgun. As the cloud of debris grows and spreads, a cascading effect begins to snowball out of control until the region of low earth orbit is nothing short of a shooting gallery.  As far-fetched as it may sound, it may have already begun. As stated earlier, the incident involving the collision of two whole satellites in 2009 may have been the spark that ignites the wildfire of a situation we are no longer able to control.

Solutions

Mitigation vs. Active-Removal

Every year, millions of dollars are spent, and hundreds of person-hours are consumed by the planning and execution of collision avoidance maneuvers for both satellites and the International Space Station (ISS). This practice is clearly prudent for crew safety reasons, but it is only a matter of time until collision avoidance becomes an impossibility with the current rate of debris accumulation. One incident in 2015 forced the crew of the ISS to evacuate the station and seek shelter inside the Soyuz crew capsule because a cataloged piece of space debris was expected to come dangerously close to the station. The debris passed the station without inflicting any damage, but considering the debris was identified as a piece of a Soviet weather satellite originally launched in 1979, it only demonstrates the longevity of the threat and a perpetuation of the problem through lack of corrective action (O’Gara, 2015). That incident also marked the fourth time the ISS crew was forced to evacuate due to a potential space debris collision (O’Gara, 2015). While this practice of moving the space station to avoid collisions is becoming a more regular problem, as the cloud of debris continues to grow, it’s only a matter of time before avoidance isn’t an option. There may not be enough time to react, or they might not see the object coming at all. Either way, the possible results are terrifying. Actively removing the debris from orbit is the only way of preserving the orbital environment and ensuring the safety of those who brave the unknown wilderness of space.

Proposed Active-Removal Solutions

The following is a list of short summaries detailing various systems designed for the active removal of space debris from the orbital environment. The list is by no means comprehensive but is rather representative of the four main categories of systems that could serve as potential solutions.

Aero-drag. The first category is based on the concept of increasing an object’s area-to-mass ratio enough for light pressure (the physical influence sunlight has on an object in space) and atmospheric drag (friction caused by the interaction of materials with the upper-atmosphere) to cause the object’s orbit to decay (fall back to Earth).  Various iterations of this idea have been developed such as the aero-drag foam system, a project proposed by a team from the Royal Institute of Technology. The method essentially relies on launching a satellite system into orbit, closing the distance between the satellite and target debris, and then attaching a device to it. Once activated, the device will deploy a bubble of foam material to act as a sort of parachute. As the object’s surface area increases, the influence of light pressure and atmospheric drag become more pronounced and eventually cause the object to slow and fall back to Earth (Guerra, 2017). Once the object hits the thicker portion of the atmosphere, it will either burn up (like the satellite debris pictured above), or it will more than likely fall into the vast oceans.

While this idea has much in the way of promise for removing large pieces of debris like non-operational satellites or spent rocket stages, the cost of launching and maintaining new satellites to conduct debris removal operations is unlikely to be favored by those nation states that will be asked to foot the bill. Until a more cost-effective method for putting vehicles into orbit is commercially available for companies that would like to operate satellites, this solution stands out as one of the less likely to be endorsed in the short term.

Aero-gels. Another system, proposed specifically for the collection of very small pieces of space debris, involves using aerogel materials. Similar to a ballistics gel, these materials are excellent at absorbing energy from impacting projectiles and are currently being explored for the development of improved shielding. The method could also be employed on a larger scale for the active collection of debris by maneuvering through known clouds of small particulate objects. The idea for using aerogels was first tested in 1995 on the Long Duration Exposure Facility (LDEF – pictured above) experiment where two panels of aerogel material were installed and later collected for analysis after over 5 years in orbit (Colombel, 2013). If scaled up, this system could be utilized to essentially “sweep” large areas of orbit over time, but again the limitations imposed by cost remain a significant hindrance to the taking of action.

Nets and claws. Many of the proposed systems involve the use of large nets that can be fired from a satellite in close proximity to a piece of debris. Once captured, the satellite conducts a deorbiting maneuver, and both satellite and debris burn up in the atmosphere (NASA, 2018).

Often the simplest solution is the most likely to be successful; however in this case, again the limitation falls to the cost of launching new satellites. Not to mention intentionally causing those satellites to burn up after a single large item is collected.

Another method that has been suggested within this category is sending a very large ship into LEO and collecting pieces of debris by opening and closing the ships cargo hatch, much akin to Pacman eating dots. The idea was first mentioned by Elon Musk, the CEO of Space Exploration Technologies (SpaceX, 2016), during a presentation on a new concept rocket known colloquially as the Big <expletive> Rocket, or BFR. Unfortunately, to date, there has not been any new information published about this concept as the BFR project is still currently under development.

Lights and Lasers. This concept system uses laser pulses or focused sunlight to cause a piece of space trash’s orbit to decay prematurely. Laser ablation (burning away of material) is a process by which a small portion of space debris material is ablated, or “zapped” with a high powered laser, either from the ground or a space-based system in orbit. As the laser turns part of the material into an ionized gas, the ejected gas acts as a form of micro-propulsion causing the debris to fall into a decaying orbit where it will ultimately burn up due to air friction (Shuangyan). Configuring an aircraft with such systems is one of the more common proposals, or, if powerful enough, even ground-based lasers could be utilized to effectively remove small-to-medium sized pieces of debris.

Another light-based system that essentially works off of the same principle as the laser concept is a parabolic solar mirror system that utilizes concentrated sunlight to ablate space debris materials into a decaying orbit. While this may not sound quite as “cool” as blasting space trash with a laser, its functionality is based on a very simple design which is also relatively light-weight (Sandu, 2018). These two factors make it a significantly less expensive option than some of those others mentioned above. However, space-based systems have their drawbacks as well. The most significant of which is the fact that any anti-orbital debris system placed is inherently at risk of being struck by a piece of the very debris it was sent to bring down.

Analysis

Findings

Unfortunately, there is no singular system capable of removing all the different types and sizes of space debris currently in orbit. The reality of the matter is that it will take a combination of several active-removal systems and a multinational partnership of space organizations to effectively eliminate the threat that space debris poses to current and future space operations.

There is no question or debate that the threat exists; there is simply a lack of motivation to pay for its resolution. Based on the analysis of current methods proposed by numerous spacefaring organizations and governments, it becomes apparent that the most cost-effective solution is also the most likely to receive the necessary funding. Given this likelihood, a ground or aircraft based laser ablation system provides the best solution to the problem with currently available technology.

Conclusion

The risk to operating spacecraft and the lives of those who work around them by space debris is extremely evident. The problem has developed to a point where millions of dollars are spent avoiding collisions every year, and at the increasing rate of material deposition in orbit, it is a most certainly unsustainable. The only hope for alleviation of the threat is to raise public awareness, increase research funding for active removal systems, and impose stricter regulations on how space organizations handle mission waste. International cooperation has taken humanity far into the vast ocean of space, but only through continued partnerships can the security of future operations beyond our planet be ensured. One could even say that continued negligence of the problem spells nothing short of a disaster.

References

Bakhtigaraev, N. S., Levkina, P. A., Chazov, V. V.. (2015, March 30). Empirical Model of Motion of Space Debris in the Geostationary Region, Solar System Research. 2016, Volume 15, No. 2, p130-135

Black, S., Butt, Y.. (2010). The Growing Threat of Space Debris, Bulletin of Atomic Scientists, Volume 66, Issue 2

Carns, M.G.. (2017, Dec). Consent Not Required: Making the Case That Consent is Not Required Under Customary International Law for Removal of Outer Space Debris Smaller Than 10cm^2, Air Force Law Review. Volume 77, p173-232

Colombel, P., Duffours, L., Durin, C., Woignier, T.. (2013). Aerogels Materials as Space Debris Collectors, Advances in Materials Science and Engineering, Volume 2013, Article 484153, 6p

Dobritsa, D. B.. (2014, May). A Method for Calculating the Resistance of Spacecraft Design Elements under the Action of Space Debris Particles, Cosmic Research. Vol. 52, Issue 3, p229-234

ESA. (2017). Space Debris: The ESA Approach, European Space Agency (ESA) website, Retrieved from https://download.esa.int/esoc/downloads/BR-336_Space_Debris_WEB.pdf

Guerra, G., Muresan, A.C., Nordqvist, K.G., Brissaud, A., Naciri, N., Luo, L.. (2017, June). Active Space Debris Removal System. INCAS BULLETIN, Volume 9, Issue 2

Gupta, B., Roy, R. S., (2018). Sustainability of Outer Space: Facing the Challenge of Space Debris, Environmental Policy and Law, Volume 48, Issue 1, p3-7

Hall, L. (2014). The History of Space Debris, Embry Riddle Aeronautical University Scholarly Commons: Space Traffic Management Conference, 19

Li, N., Xu, Y., Basset, G., Fitz-Coy, N. G. (2014, Mar). Tracking the Trajectory of Space Debris in Close Proximity via a Vision-Based Method, Journal of Aerospace Engineering, Volume 27, Issue 2

Lockheed Martin Corporation. (2018). How to Keep Space Safe, Lockheed Martin website, Retrieved from https://www.lockheedmartin.com/en-us/products/space-fence.html

NASA. (2018). Space Debris and Human Spacecraft, National Aeronautics and Space Administration website, Retrieved from https://www.nasa.gov/mission_pages/station/news/orbital_debris.html.

O’Gara, E.. (2015). International Space Station Evacuated Due to Russian Debris, Newsweek Magazine, Retrieved from http://www.newsweek.com/iss-close-passnasainternational-space-stationissspacesoyuz-602152

Sandu, C., Brasoveanu, D., Silivestru, V., Vizitiu, G., Filipescu B., Sandu, R. C.. (2018). A Thermal- Solar System for De-Orbiting of Space Debris, INCAS Bulletin, Volume 10, Issue 1, p27-38

Schildknecht, T. (2007). Optical Surveys for Orbital Space Debris. Astronomy & Astrophysics Review, Volume 14(1), 41-111. DOI:10.1007/s00159-006-0003-9

Shuangyan, S., Xing, J., Chang, H. (2014) Cleaning Space Debris with a Space-Based Laser System, Chinese Journal of Aeronautics, Volume 27, Issue 4, p805-811

Wang, T. (2010) Analysis of Debris from the Collision of the Cosmos 2251 and the Iridium 33 Satellites, Science & Global Security, 18:87–118 http://scienceandglobalsecurity.org/archive/2010/06/analysis_of_debris_from_the_co.html

Annotated Bibliography

Black, S., Butt, Y.. (2010). The Growing Threat of Space Debris. Bulletin of Atomic Scientists, Volume 66, Issue 2

Samuel Black, a research associate at the Henry L. Stinson Center and former research assistant as the Center for Defense Information, along with Yousef Butt, a staff scientist in the High-Energy Astrophysics Division at the Harvard Smithsonian Center for Astrophysics, authored this article on the growing threat of space debris. The paper begins with a brief overview of the vulnerability of satellites to the threat of space debris. The introduction also discusses the possibility of not knowing whether satellite damage was the result of debris or an intentional act, adding to the political ramifications of the problem. The main body of the paper talks about two primary reasons for the proliferation of the problem. The first of which being the production and testing of high-velocity antisatellite weapons, and the second being a lack of international communication on a sustainable plan for operating in low earth orbit. The article concludes by touching on the political climate surrounding the problem of space debris as well as the existing and planned international agreements implemented to alleviate the threat. This is an excellent article that will provide strong evidence in favor of my paper’s argument for the necessity of urgent action.

Dobritsa, D. B.. (2014, May). A Method for Calculating the Resistance of Spacecraft Design Elements under the Action of Space Debris Particles, Cosmic Research. Vol. 52, Issue 3, p229-234

Dmitri Borisovich Dobritsa is a Candidate of Technical Sciences for the Lavochkin Scientific Research and Production Association and specializes in the mechanical physics of high energy ballistics. This highly technical article begins with a discussion on the difficulty of developing models to support the design of anti-meteorite protections and goes on to cite the many potential risks of high-energy debris impacting thin-walled spaceborne systems. The bulk of this article consists of a comparative analysis of the existing space debris impact models and the means of improving them. The paper then discusses methods of evaluating and mitigating the risk of impact from high-energy debris and improving the survivability of spacecraft materials. The paper concludes with a final argument for the need for improvement both for modeling but also for protective materials. This article offers supporting pieces of evidence for the argument that there will need to be more than one singular method of addressing the space debris problem (which will serve as my papers ultimate argument).

Guerra, G., Muresan, A.C., Nordqvist, K.G., Brissaud, A., Naciri, N., Luo, L. (2017, June). Active Space Debris Removal System. INCAS BULLETIN, Volume 9, Issue 2

This article was authored by a team of researchers from the KTH Royal Institute of Technology’s Department of Aeronautical and Vehicle Engineering in Stockholm, Sweden. This paper ultimately serves as a proposal for an active space debris removal system that employs the use of natural aerodynamic drag to cause the orbits of large space junk to decay more quickly. The paper begins with a brief description of what space debris is and how it came to be a problem followed with a short description of the team’s goals. The next section details the overall mission strategy and phases followed by another section which examines the components of the satellite system itself. The paper then explains the orbital mechanics involved in achieving an intercept orbit, the deployment of the system, and the subsequent decay orbit achieved by employment of a foam aero-drag device. A detailed discussion of the selected rocket engine’s performance specifications and intended employment is the next topic, and the main body of the article ends with several cost estimates. The paper concludes with an assessment of the system’s reliability and a final summary of the proposed removal system overall.

Colombel, P., Duffours, L., Durin, C., Woignier, T.. (2013, August). Aerogels Materials as Space Debris Collectors, Advances in Materials Science and Engineering, Volume 2013, Article 484153, 6p

Dr. Thierry Woignier, PhD, the Director of Research at the French National Centre for Scientific Research’s Institut National de Physique (INP) in Marseille, France, was the lead author on this report on the effectiveness and functionality of aerogel materials as space debris shielding. The paper begins with a detailed explanation of the chemistry involved in the production of the gel materials as well as their characteristics given certain chemical changes. The report then discusses how these chemical changes can affect the longevity and impact resistance of these materials. A discussion on the placement of two aerogel panels aboard the International Space Station follows, and a report based on the impacts sustained over the experiment period closes the main body of the article. The paper ultimately concludes by endorsing aerogel materials as an ideal candidate for use in collecting extremely small particles of space debris both on manned spacecraft and on unmanned orbital assets.

Carns, M.G.. (2017, Dec). Consent Not Required: Making the Case That Consent is Not Required Under Customary International Law for Removal of Outer Space Debris Smaller Than 10cm^2, Air Force Law Review. Volume 77, p173-232

Major Marc G. Carns is a Judge Advocate with the United States Air Force and serves as the Chief of Cyber Special Programs Law with the 24th Air Force JFHQ Command at Kelly Field in San Antonio, Texas. This report begins with a brief description of the history of space debris and the laws developed relating to space and the mitigation of the space debris. The paper then goes on to make an appeal to the reader based on presented evidence that mitigation efforts alone are not sufficient to thwart the problem long term. The author then discusses the difference between mitigation and active debris removal followed by the argument that nation-states must take immediate action in order to preserve present and future spaceborne assets. The report goes on to explain the current political climate regarding the issue and the difficulties of enacting meaningful resolutions through international laws and treaties. The paper concludes with a discussion on space debris as a national security threat, and then makes a final appeal to government officials in the United States to set an example, as a global leader in space exploration, by taking immediate measures to alleviate the threat space debris poses to future space operations of all nations. This article gives useful insight regarding the legal and geopolitical nature of the problem and reinforces the arguments for global cooperation and immediate action.

Bakhtigaraev, N. S., Levkina, P. A., Chazov, V. V.. (2015, March 30). Empirical Model of Motion of Space Debris in the Geostationary Region, Solar System Research. 2016, Volume 15, No. 2, p130-135

This report was authored by a team of scientists from the Institute of Astronomy at the Russian Academy of Sciences and the Sternberg Astronomical Institute at Moscow State University in Moscow, Russia. The article is based on a continuing program that observes, catalogues, and tracks the orbital trajectory and velocity of space debris specifically in the geostationary region of earth orbit (generally orbits that are higher than those considered to be “low earth orbit”) based at the Terskol Peak Observatory.  The report begins with a description of the observations made and the goal of generating a workable model for tracking smaller and smaller objects. The main body of the report discusses the variability of area-to-mass ratios of the debris and how their orbits are affected by a variety of factors such as light pressure and spin. The paper finally concludes with a summary of the report’s general findings and notes that additional observations and studies are required to better understand the influence of light pressure and spin on an object’s orbit. This article provides insight into the processes and capabilities of tracking small sized debris at ever greater distances and how that information can be useful in satellite avoidance or removal of space debris particles.

Gupta, B., Roy, R. S., (2018). Sustainability of Outer Space: Facing the Challenge of Space Debris, Environmental Policy and Law, Volume 48, Issue 1, p3-7

Biswanath Gupta is a Research Scholar at the Rajiv Gandhi School of Intellectual Property Law at the Indian Institute of Technology along with Rajrupa Sinha Roy who is also an Assistant Professor of Law at Adamas University in Kolkata. This article gives an interesting summary of the international laws in place that govern the use of outer space and our neighboring celestial bodies and how those laws deal with the growing problem of space debris. The paper begins with a brief history of space exploration and the deposition of space debris into low earth orbit. Following is a detailed discussion on the legal issues surrounding space debris and the problems that have occurred with even reaching an internationally agreed upon definition of what space debris is. The article goes on to discuss methods by which an international agreement might be reached through a continuation of the committees who enacted the five original international space treaties.  The conclusion gives a short summary of the threats to continued space activities and advocates for organization of the international community to work on agreements to minimize space waste.

Sandu, C., Brasoveanu, D., Silivestru, V., Vizitiu, G., Filipescu B., Sandu, R. C.. (2018). A Thermal- Solar System for De-Orbiting of Space Debris, INCAS Bulletin, Volume 10, Issue 1, p27-38

Constantin Sandu, PhD is a Project Manager for the National Research and Development Institute for Gas Turbines and the Industrial Application of Turboengines. This article serves as a proposal for a space-based system that concentrates sunlight onto orbital space debris through a series of parabolic mirrors causing their orbit to decay and fall back to Earth. The article begins with an introduction on what space debris is and classifies it into three distinct categories by size. The main body of the paper describes the components of the system as well as its planned implementation and operation. The paper goes on to describe the most effective materials for the mirrors based on their reflectivity and offers a plethora of diagrams and illustrations for the readers convenience. The article concludes with a very brief summary of the proposals findings and the steps involved in the implementation of the system. This article provides a good example of a proposed system that could be used to remove high-energy orbital space debris for relatively low cost.

Li, N., Xu, Y., Basset, G., Fitz-Coy, N. G. (2014, Mar). Tracking the Trajectory of Space Debris in Close Proximity via a Vision-Based Method, Journal of Aerospace Engineering, Volume 27, Issue 2

A team of researchers and associate professors from the University of Central Florida developed this proposal for a for an onboard vision-based debris tracking system that could support the planning of evasive maneuvers of an at-risk satellite. The paper begins with a statistical overview of the problem and details the variety of ways by which the international community currently tracks and monitors space debris. The paper goes on to enumerate the limitations of current tracking methods that are based at ground stations in turn making a case for the necessity of onboard tracking system development. The main body of the article is a highly technical read on the process of coordinating two satellites in orbit to use optical equipment as a means of triangulating the position of potentially hazardous space debris. The article goes on to detail the mathematical formulas the system will use to control the orbits of the two satellites and the tracking and logging of individual pieces of debris. Following is a highly detailed accounting of two modeled simulations complete with graphs and charts as visual aids. The paper concludes with a discussion on the limitations of the system as being a function of the limits of the associated cameras, and then an overview of the project along with the main technical challenges of the system. This is an excellent example of a reasonable solution that will probably not gain much traction simply because of the cost of launching and coordinating two separate satellite systems. Moreover, the system is not active-removal capable so its function is ultimately limited to tracking only and monitoring only, making it a very expensive option with not a lot of long term benefit.

Schildknecht, T. (2007). Optical Surveys for Orbital Space Debris. Astronomy & Astrophysics Review, Volume 14(1), 41-111. doi:10.1007/s00159-006-0003-9

Thomas Schildknecht is a Swiss astronomer who serves as the deputy director of the Astronomical Institute of the University of Bern and the director of the Zimmerwald Observatory. This report is a very well-structured survey of the issue of space debris and begins with a detailed explanation of what space debris is, where it comes from, and why it’s a problem for human space operations. The paper continues by discussing the methods of observation and tracking of space debris as well as the limits of ground-based optical telescopes for such operations. The paper then gives short summary of the U.S. organizations tasked with monitoring known space debris and the then current estimates.  Following is a short discussion on the European Space Agency’s efforts in observation and tracking of orbital space debris. The article concludes with a summary of the general topic and the numerous optical observation methods mentioned throughout the report. This paper, while a little dated, is still highly relevant to the subject today, and serves to iterate that the problem is not only known, but that it has been known for well over a decade. It will also serve as evidence that the problem has not only existed but that it has compounded and gotten worse by a significant magnitude since this report was originally published.