CubeSat proximity operations: The natural evolution of defensive space control into a deterrence initiative
by Capt. Michael Nayak, USAF
|There is a remarkable similarity between nuclear deterrence and direct-ascent ASAT deterrence. While both can denigrate an enemy’s ability to engage in combat, both are easily culpable and attributable, and bring sizeable socio-political consequences.|
Foreign policy analysts have not missed this Achilles heel either. Calling the United States’ dependence on space its “soft ribs,” one Chinese analyst writes, “for countries that can never win a war with the United States by using the method of tanks and planes, attacking the U.S. space system may be an irresistible and most tempting choice. Part of the reason is that the Pentagon is greatly dependent on space for [the success of] its military action.” It is therefore no surprise that countries such as China, Russia, and India have chosen to aggressively invest in counterspace capabilities.
Perhaps the most prominent example is China’s destruction of its own Fengyun-1C weather satellite with an anti-satellite (ASAT) device. This event had a much wider impact than the mere demonstration of China’s ability to field a direct-ascent kinetic weapon. Now widely viewed as the most severe fragmentation in 50 years of space operations, NASA estimates that the breakup of Fengyun caused over 950 pieces of space debris with a size of greater than 10 centimeters, each with a velocity in excess of 12 kilometers per second, spanning 200 to 3,800 kilometers above the surface of the Earth.
The mission risk and operational burden caused by such debris continues to this day. Six critical orbital debris events were noted on the International Space Station between April 2011 and March 2012, two of which resulted in the crew and operators retreating to escape Soyuz capsules due to insufficient time to perform collision avoidance maneuvers . Though statistics are not publicly available, this same risk similarly affects the operation of other imagery and other intelligence satellites in similar orbits to Fengyun. This one counterspace event continues to consume money and resources in military space operations, a recurring effect not lost on America’s enemies.
However, there is a remarkable similarity between nuclear deterrence and direct-ascent ASAT deterrence. While both can denigrate an enemy’s ability to engage in combat, both are easily culpable and attributable, and bring sizeable socio-political consequences. China is still facing backlash from the orbital debris community for the Fengyun demonstration. Strong condemnation from the United States and allies, combined with the surety of culpability, serves as a strong deterrent for both direct-ascent ASAT testing and action, making it a last resort tool in the arsenal of counterspace capabilities.
For this reason, multi-faceted counterspace capabilities are in development around the world, including in the United States, beyond the relatively blunt kinetic approach. As another Chinese analyst writes: “An effective active defense may require China to have an asymmetric capability against the powerful United States… China’s possession of a robust reconnaissance, tracking, and monitoring space system would be in line with China’s ‘doctrinal’ position.”
This article focuses on the exploding growth of so-called “cube-satellites”, their utility to the national space architecture, the imminent threat they can pose to the present-day military space enterprise as a counterspace tool, and effective deterrence strategies for this asymmetric threat.
There has been considerable progress over the last few years in the 10–50-kilogram satellite class thanks to the advanced state of miniaturization technology. However, the real strides have been in cubesatellite or “cubesat” sized spacecraft. A standard “1U” cubesat form factor is 10 x 10 x 10 centimeters in dimensions, 1 liter in volume, and has a mass of approximately 1 kilogram. The number of cubesat segments designates system size; a 10x10x30-centimeter system is a “3U” and a 10x20x30-centimeter system a “6U” cubesat, three and six liters in volume respectively. Developed in the 1990s to train students in real-world satellite integration and testing, cubesats have now been designed and launched by both government and private entities.
Hundreds of cubesats have been launched worldwide. Science requirements for sophisticated instruments, communications, propulsionl and three-axis stabilization have been demonstrated. Commercial utility of cubesats have also increased exponentially: an example is the firm Planet Labs, which has launched more than 100 3U cubesats called Doves for responsive Earth imaging. The explosive development of small satellites can be harnessed to create effective deterrence against counterspace threats.
“Our current satellites are marvels of modern engineering, but their suitability is critically dependent on the strategic balance of a foregone era.”
- Lt. General Ellen Pawlikowski, Commander Space and Missile Systems Center, 2012
As it stands today, an adversary with basic spacelift capability may be able to deny, disrupt, or degrade the American military enterprise by striking a few centers of gravity (COGs) of space power. These are space systems that fulfill a critical defense or military enabling function, such as missile warning, protected communications, or space-based position, navigation, and timing.
|The exploding growth of cubesats, which have a reputation for being low-cost and easily reproducible, has a natural place in a discussion centering around both the growing fiscal burdens of the national space enterprise and its vulnerability due to lack of disaggregation.|
Existing doctrine discusses how the threat of this might be accomplished. One way is through direct-ascent ASATs, as demonstrated with Fengyun. Another is a co-orbital ASAT, where a satellite is placed into a similar or intercepting orbit as its target, and then maneuvered into a collision course with it. This threat dates back to the Cold War, with the USSR’s Istrebitel Sputnikov program. Translated as “satellite killer”, the program focused on satellites that would be pre-positioned to execute a “kamikaze-style” takedown of US space systems if and when commanded, and were capable of large maneuvers to rendezvous with their targets.
Therefore, one immediate deterrent to hostile space action is to distribute the concentration of space power, lessening the reward for an adversary’s hostile action. Given current fiscal constraints, fielding duplicate, redundant systems to those in existence is unrealistic. Distributed or disaggregated systems, on the other hand, are intrinsically less vulnerable. A disaggregated system offers a natural resiliency and survivability. Since the capability is exerted through a larger number of redundant component parts, multiple component satellites can be lost before total system failure. The exploding growth of cubesats, which have a reputation for being low-cost and easily reproducible, has a natural place in a discussion centering around both the growing fiscal burdens of the national space enterprise and its vulnerability due to lack of disaggregation.
However, to properly lay the foundation for an argument surrounding cubesat deterrence, it is important to realistically consider their utility. While there are definite cost and size advantages to cubesats, they are also significantly less capable than larger spacecraft, particularly in military applications. Larger spacecraft can lose multiple components and still have backup functionality available. They host larger instruments better capable of fulfilling primary military functions. Cubesats are largely “single-string”—not robust to single-point failure—and are size and volume limited in the instrumentation they can host. While they can fill a complementary role in ground-based imaging and imagery intelligence collection, requirements like larger optics, wider wavelength bands, and the need for cryocooling will always point in the direction of larger spacecraft. Cubesats are simply not a factor in signals intelligence, hyperspectral collection, or protected, survivable secure communications.
The forte of cubesats to military mission sets appears to be in the numbers game. Even in the absence of direct conflict, a disaggregated system allows for cost and efficiency benefits in acquisition and operations. There are many challenges to consider in the move toward small-satellite disaggregation, including architecture integration, ground system operations, and mission assurance. However, these are dwarfed by the benefits: such systems are resilient by nature. A distributed systems architecture serves to eliminate the US dependence on finite COGs of space power: with multiple systems in play, the payoff for an attack lessens. Utilizing small spacecraft to create fractionation and disaggregation of space power is therefore an excellent first step to deterring hostile counterspace actions.
“War is an act of force... and there is no logical limit to the application of that force.”
- Carl von Clausewitz, On War
From a doctrinal and policy point of view, it is important to consider more than just benefits to the United States. Perhaps more critically, cubesat systems are far easier for nations with less sophisticated space programs to design, build, and launch. The price of failure in the smallsat industry is far less, making incremental growth more practicable. Combined with the elimination of a need for heavy spacelift and triple-redundant systems, it is almost certain that adversarial nations with smaller space programs will soon be able to assemble and field capabilities that they cannot today.
In less than a decade, space miniaturization technology has advanced enough that high school students are capable of designing, integrating, launching, and operating cubesat systems. Some university-designed systems boast sophisticated maneuvering and navigation capabilities and are capable of advanced military-relevant mission sets. It is feasible that within the next decade, we will see North Korea fielding a surveillance capability via a crude optical sensor on a cubesat in competition with South Korea, which is today developing a cubesat-based telescope system. Equally probable is Iran fielding a rudimentary missile warning system on board a vehicle similar to the “Promise of Science and Industry” satellite, recently built by Iranian university students and launched atop a modified long-range missile.
|In an environment where any small satellite in a similar orbit to a national security asset could be a potential ASAT threat, it becomes critical that American space policy ensurew that US military capabilities in this arena are not left behind.|
Though systems centered on smaller spacecraft may not be as reliable, these development efforts prove that the technology is both mature and accessible. Today’s clumsy student satellite feeds the next generation’s “wisdom of experience.” Today’s school-bus-sized communication spacecraft will tomorrow be the size of a shoebox. Combining easy fabrication with access to space via rideshares, it is clear that small satellites are becoming a force to be reckoned with. At the rate of current development, the United States might find some of its actions or objectives deterred by the capabilities of its adversaries in the near future.
In an environment where any small satellite in a similar orbit to a national security asset could be a potential ASAT threat, it becomes critical that American space policy ensurew that US military capabilities in this arena are not left behind. However, our military space acquisition policy and business practices are both behind the times. Consider the Air Force Space and Missile Systems Center (SMC), the center of excellence responsible for space acquisition, whose commander is also the Program Executive Officer for Space. Though policy papers by recent SMC leaders have leaned in favor of disaggregation, there has yet to be a push to implement this through leverage of cubesat technology. In fact, to date, SMC has acquired only one cubesat system, which was declared experimental. The Department of Defense Operationally Responsive Space (ORS) office, recently absorbed into SMC, has fielded several small-satellite space systems, but only one is considered for operational use, i.e., successfully transitioned from experimental R&D to tactical-level tasking that directly benefits the warfighter.
Organizations such as ORS and NASA’s Ames Research Center are leading the charge in the military and civilian space arenas, respectively. However, it is not apparent that either the Department of Defense or NASA has made a serious institutional investment in small satellite technologies. When the only US government organizations actively involved in cubesat development are either doing so for R&D or because of cost constraints, it becomes obvious that the resolve to make small satellites a part of our national space architecture is simply not present. Meanwhile, it appears these systems are set to become an integral part of every other spacefaring nation’s military capability, likely within the next generation.
Therefore, there is an immediate need for decisive leadership action to focus US space acquisitions and operations into smaller, more agile systems, and, more importantly, transition these capabilities into the mainstream operational space industry directly benefiting the warfighter. To drive leadership decisions that encourage the official development of small satellite technologies, United States space policy must support the transition to smaller, more numerous satellite systems. This will drive a strategic investment that will set our space enterprise on a path that directly reduces the risk to space COGs. It will also support direct integration of small satellite technology into the national space enterprise, both military and civilian. Deploying mature technologies in parallel with ongoing R&D efforts for further development can help the United States widen the conversation on possible proportional and reciprocal dissuasion of enemy counterspace action, and preserve the ultimate “high ground” of space.
“Reading (Carl von) Clausewitz permits individuals to predict what will happen in the future by extrapolating from the present and offers a guide for action.”
– Mackubin T. Owens Professor, Naval War College
The asymmetric advantage of space power and its utilization as part of the warfighting enterprise has revolutionized the way that the United States engages in conflict across the globe. Its position as the world leader in utilizing space power makes it naturally vulnerable to attacks on these capabilities. A natural question to consider is: what is the next revolution in space power engagement, and what action should the United States take to maintain its space superiority?
The convergence of miniaturization technology and its growing utility to spaceborne systems should lead us to believe that the next revolution in space power engagement will be in the realm of cubesats. However, as discussed earlier, the best utility of cubesats to the military space enterprise appears to be in aid of fractionation and disaggregation of currently concentrated COGs. While that is a definite benefit, one would be justified in being underwhelmed by the claim that this is a “revolution.” Rather, it seems like a logical next step, perhaps even justifying the space acquisition industry being somewhat behind the curve. However, this section discusses the application of cubesat technology to the realm of space control, and makes a case for the potential of cubesat technology to change the nature of all facets of space control. The need for a new, active deterrence strategy to effectively combat such threats is needed, and will be discussed.
“Space control has not been at the forefront of military thinking because our people haven’t yet been put at risk by an adversary using space capabilities.”
- Hon. Peter B. Teets, Former Undersecretary of the Air Force Air Force Association Symposium, November 15, 2002
The previous section addressed the benefits of cubesat distributed systems to prevent attacks on COGs of space power. However, an attack on a COG, similar to that demonstrated on Fengyun, would be an overt act of war. The United States has extended Article 51 of the United Nations Charter to space, declaring that any hostile action against a US spacecraft will be tantamount to a declaration of war.
|Small satellite usage in space control is not a near-future scenario; rather, it is today’s emergency.|
However, in reality, the distance of and limited access to space provides anonymity to offensive space actions, similar to cyberattacks. It is more likely that, in order to maintain regional superiority, adversarial nations would seek to develop a denial of service counterspace capability against the United States. Culpability, attribution, and, more specifically, retaliation, are complicated by the lack of borders or sovereign regions in space and the infeasibility of total space situational awareness (SSA) system. A satellite malfunction could be caused by space environment conditions, faulty or inadequate satellite design, or even orbital debris. This adversary may therefore be able to deny, disrupt, or degrade the American military space enterprise while maintaining plausible deniability. This casts the shadow of doubt over classic deterrence philosophies such as progressive retaliation.
“Space control” is defined as combat and combat support operations to ensure freedom of action in space, and when directed, deny the same to an adversary. A key component of deterrence against space control is the vigilant maintenance of SSA. However, SSA has known holes: it is simply not possible to monitor US satellites around the clock, let alone maintain total awareness of all space activity. If the United States today has difficulty with assigning attribution and culpability to hostile actions in space, consider the uncertainty involved if hostile cubesatellites are deployed as co-orbital ASAT devices. A low-velocity impact could be engineered to have just enough speed to shatter the impactor, cause disabling damage to the target, and leave very little debris.
However, this is the crudest use of cubesatellite technology as a counterspace tool. The realm of rendezvous and proximity operations (RPO) is the ultimate tool for space surveillance, advanced space-based space situational awareness, and even offensive action. In 2005 and 2007, respectively, the United States proved an experimental RPO capability with the Air Force Research Laboratory’s XSS-11 and DARPA’s Orbital Express. While Orbital Express weighed more than 1,000 kilograms and fielded two spacecraft that were aware of one another, XSS-11 was 150 kilograms and demonstrated advanced maneuvering with respect to its own spent upper stage. It demonstrated the capability to safely approach an “uncooperative” object in LEO, image it, and retreat to a safe distance. Small satellite usage in space control is not a near-future scenario; rather, it is today’s emergency.
A valid question to ask is whether cubesatellites are truly capable of performing the level of advanced precise maneuvers required for RPO around another object in space. China has made large capability advances in this arena, developing small satellites reputedly able to capture another satellite with a robotic arm and relocating it. Published work by authors at Embry-Riddle Aeronautical University in Florida discuss the concept and ongoing design of a cubesat-sized RPO mission, with precise attitude determination and control, pointing accuracy, and real-time maneuver commanding, as well as optimal trajectory design for docking applications from a future cubesat platform.
A satellite weighing 10 to 25 kilograms with optical sensors and agile maneuvering capability is a configuration that is easily achievable with today’s technology. This satellite would be in the 12U cubesat class. Such vehicles have a mass of less than 24 kilograms and a negligible radar cross-sectional area. Detection of such a vehicle in low Earth orbit would be at the edge of current ground-based SSA capabilities. In geostationary orbit, these vehicles would be completely invisible from the ground.
In addition, the delivery system for cubesats is easily configurable. Cubesats can be released from stowed configurations designed to ride-along with any launch vehicle. Launch options include hosted payload services, a quickly growing industry that has proven the ability of government payloads to act as secondary missions on commercial communications satellites. These provide numerous launch opportunities per year to any desired orbit regime. This has even expanded to the commercial sector: Space Systems Loral hosted payloads on Intelsat and SES Astra space vehicles, and has an established business model in place for government collaborations. International and commercial telecommunication satellites, as well as national security satellites, have demonstrated the capability to host cubesats.
As this technology becomes smaller and easier to launch, the detectability factor significantly decreases, allowing adversaries to take autarchic actions against the US space enterprise with lessened fear of retribution or discovery. One example in play today is the Russian object 2014-28E: initially thought to be drifting space junk associated with the launch of three Russian telecommunication satellites, this object has since been observed to be maneuverable, and made a close approach to the rocket stage that boosted it into orbit as recently as November 2014.
|Cubesats are poised to become the stealth aircraft of space technology. A nation capable of wielding a cubesat-based offensive space control capability creates a real and present threat to US space superiority.|
Another translation of Istrebitel Sputnikov is “satellite fighter,” istrebitel being the Russian word for “fighter aircraft.” The big push in next-generation fighter aircraft is stealth, and it is not unreasonable to refer to small satellites as the stealth aircraft of space. The existence of 2014-28E was not announced, and the object’s functions and capabilities are largely unknown, except that it appears capable of precise RPO.
While its maneuvering was seen from the ground, the smaller the spacecraft, the lower the chance of ground-based detection. If sensor avoidance techniques are employed during an approach, the target object may not ever detect another satellite near it. Cumulatively, this makes it harder to attribute space control actions, which may embolden an adversary to move past proximity surveillance to offensive actions from the cubesat platform. This is the textbook definition of counterspace capability: the ability to deny space capability to the adversary as situations require.
RPO-capable cubesats have the potential to be of critical importance to spaceborne intelligence gathering, and are capable of close approaches, surveillance, material characterization, and battle damage assessment, all with minimal fear of discovery and almost no counter-actions possible without prior warning. Even if discovered, close approaches are legal if they do not endanger the operation of the target body; socio-political ramifications are likely inside a certain approach distance for safety reasons, but this is a gray area without much legal precedent or policy backing.
This expanded reach of spaceborne space control is the true jump in capability presented by burgeoning cubesat technology. Never before has there been the capability for a force so large to be wielded from a body so small. Cubesats are poised to become the stealth aircraft of space technology. A nation capable of wielding a cubesat-based offensive space control capability creates a real and present threat to US space superiority.
The murkiness over classic deterrence philosophies with regard to adversarial space control actions only grows when considering cubesats, revealing a need for policy development in this arena. The next section discusses a threat-based deterrence strategy aimed at discouraging or denying adversarial nations from impinging upon US assets.