By Maj. Bradley Townsend

Click Here for a Printable/PDF Version

Where does the advantage lie in space, with the offense or the defense? Why does it matter? Put simply, perceptions of the balance between offense and defense determine doctrine. Doctrine, in turn, drives acquisition, and what military space operators acquire further reinforces the existing perception of the offense-defense balance.

As a result, a nation’s military is equipped and prepared to fight based on its perception of whether the offense is stronger or the defense, not the reality. It’s only when war starts that a nation’s doctrine and equipment are tested against the reality of its perceptions. The wrong equipment and doctrine often determine the winner and loser in any conflict (see France in 1940). So accurately assessing the strength of the offense and defense before conflict even begins is one of the fundamental determiners of success in war.

In the space domain, it is generally accepted that offense has the advantage. This frequently cited “fact” appears in studies, newspaper articles and treatises on strategy, often with little analytical support. RAND studies cite it, as do prominent strategists such as Colin Gray who argues with some equivocation that “offense may appear to be the stronger form of war in space, given the absence of terrain obstacles, the relative paucity of capital assets (and targets), and the global consequences of military success or failure.”

Gray’s opinion also is shared by some senior U.S. policymakers. James Finch and Shawn Steen, in 2011 the director and deputy director respectively for Space Policy and Strategy Development within the Office of the Undersecretary of Defense for Policy, argued that the domain is offense dominant because “holding space targets at risk is far easier and cheaper than defending them.”1 With the notable exception of an article by John J. Klein using a complex Clausewitz-based argument, there are few serious attempts to refute the idea that space is offense dominant.2

Common Perception Is Wrong

The common perception is wrong.

How is that possible? Satellites are vulnerable creatures. They travel in predictable orbits, and every kilogram of mass devoted to their defense is one less available to perform actual missions. The attacker is under no similar limitation and can devote all its capabilities to defeating whatever safeguards the defender has.

In addition, with many military satellites taking nearly a decade to design and build, the day a satellite launches, its technology is already outdated.3 With another ten to 15 years of expected lifetime on orbit, that technology deficit only grows with no realistic way for improvements or upgrades to occur. As a result, the attacking platform or system almost always will be newer and more capable.

Even the traditional advantages of the defender don’t apply. There is no physical terrain to leverage in a defending satellite’s advantage. The defending satellite essentially is trapped in the orbit in which it is placed. Even if the satellite had the fuel to move, it loses its very purpose once it changes orbit, and the attacker has achieved its objective merely by threatening to attack. The attacker also chooses the time and place of the attack, which can occur when the defender has limited ability to observe or react.

Yet another traditional defensive advantage that fails in space is that of interior lines. Interior lines traditionally allow a defender to mass forces and reinforce more quickly than an attacker. In space both the attacker and defender suffer from the same physical restrictions on achieving orbit, thereby neutralizing any advantage to either side.

Finally, the destructive projectile is always cheaper than the target. Whatever form the attacker takes is optimized for a single function, destroying or disabling the target, and this will inevitably be cheaper than the function the target satellite is designed to do.

Making the Argument

With all of these disadvantages accruing to the defending satellite, how can any argument be made that the defense has the advantage in space? Because the individual satellite doesn’t matter. The military utility of space lies not in an individual satellite but in the ability to transmit information through it and to collect information from it.

Gathering information from space requires a platform. This is a situation where the loss of a platform could create a catastrophic loss of information-gathering ability, although this is changing rapidly.

True, the satellite is critical to this process; however, the paradigm is shifting. As recently as 15 years ago the number of satellites on orbit with service to any one region in any particular band was relatively limited. Therefore, the ability to transmit information through space and the health of the satellite were inextricably linked.

It is becoming very difficult for any nation to hide anything and even harder to prevent someone from gathering the information they need. There are simply too many commercial, scientific, or national systems imaging the Earth for any attacker to reasonably deny them the ability to image an area.

While much of the growth is coming from small satellites, there is significant growth in larger satellites as well. In mid-2017 there were 1,738 active satellites on orbit, up from around 500 in 2008, and we are on the cusp of the era of active small satellite constellations which will greatly increase that number.4  The space between orbital slots in the geostationary belt continues to shrink with multiple satellites now operating in the same slot.

With this many satellites on orbit, a hostile entity looking to interfere with a signal will first have to contend with finding the signal. Once found, whether the attacker uses kinetic means to threaten the satellite or non-kinetic means to target the signal will not matter. The signal can simply move elsewhere in a matter of moments, and the attacker is again left hunting for a needle in a haystack.

A competent defender will be ready for interference or attack and have a pre-planned alternate frequency just as happens with terrestrial radio interference. A clever defender will take things one step further by having a plan when threatened to further complicate the attacker’s search by switching bands or even moving from fixed satellite services to mobile satellite services.

Further Complication

The existing intermixing of military, civil and commercial signals from a variety of sources on commercial platforms creates a further complication for an attacker. Attacking the wrong signal or satellite can involve a third party in any conflict, an undesirable situation for any attacking entity. The level of entanglement involved in commercial platforms varies, but it creates another issue that any attacker must account for.

Further blurring the line between commercial and military systems is the Air Force Space and Missile Systems Center’s Protected Tactical Enterprise (PTES) acquisition effort which has the goal of bringing military-standard wave forms to commercial systems.5 The sheer number of signals on orbit makes any attack seeking to stop the transmission of information extremely difficult, though preserving the ability to gather information presents a more difficult problem.

The one area where no commercial system can yet compensate is missile warning. The satellites performing this mission are currently irreplaceable though these systems’ specific association with the nuclear deterrence mission provides them with their best protection. Any attack on these systems represents an attack on the U.S. nuclear deterrent with attendant consequences. However, the clarity of this distinction is fading as these systems shift toward non-missile warning conventional missions such as “battlespace awareness.” This shift represents a dangerous trend that makes these satellites legitimate targets in any conventional limited conflict.

What this article argues is that the defense has the advantage through the disaggregation and entanglement of signals and sources, not through the disaggregation of military platforms via hosted payloads or other approaches. Disaggregation is a subset of resiliency, which is the ability of a nation’s assets “to continue providing required capabilities in the face of system failures, environmental challenges, or adversary actions.”6 One of the easiest ways to achieve resiliency is by dispersing the capability to gather and transmit information across as many platforms as possible; the broad definition of the disaggregation that this article argues.

The implications of the advantage lying with the defense are that commercial transmission and information-gathering capabilities will become even more critical to military operations than they are today. In fact, given the technical and cost advantages of commercial satellite communications and the difficulties involved in targeting any one signal, spending the money to maintain a dedicated military satellite communications network begins to look questionable.

This is especially true as advances in encryption on civilian systems and advanced waveforms outstrip the military acquisition cycle’s ability to respond or adapt. Those funds are perhaps better invested in efforts like PTES or in developing more adaptable ground terminals that are refreshed more frequently to incorporate the latest advances.

Going a step farther, perhaps U.S. military contracts can act as anchor tenants for commercial systems that otherwise would have difficulty getting off the ground. After all, it was a NASA first-ever commercial contract to resupply the International Space Station, awarded to a struggling and nearly bankrupt SpaceX in 2008, that allowed the revolutionary company to become what it is today.7

Author: Maj. Bradley Townsend is a Ph.D. fellow at Air University, studying military strategy. He is an Army space operations officer.

1 See Forrest E. Morgan, “Deterrence and First-Strike Stability in Space: A Preliminary Assessment” (Santa Monica, Calif.: RAND Project Air Force, January 2010),, pg. 2; Colin S. Gray, Weapons Don’t Make War: Policy, Strategy and Military Technology (Lawrence: University Press of Kansas, 1993), pp. 14-15; James P. Finch and Shawn Steene, “Finding Space in Deterrence,” Strategic Studies Quarterly, vol. 5, no. 4 (Winter 2011), pg. 11; and Paul Scharre, “The US Military Should Not Be Doubling Down on Space,” Defense One (blog), Aug. 1, 2018,

2 John J. Klein, “Space Warfare: Deterrence, Dissuasion and the Law of Armed Conflict,” War on the Rocks, Aug. 30, 2016,

3 Cristina T. Chaplain, “Space Acquisitions: DOD Continues to Face Challenges of Delayed Delivery of Critical Space Capabilities and Fragmented Leadership,” testimony before the Subcommittee on Strategic Forces, Committee on Armed Services, U.S. Senate, GAO-17-619T (Washington: Government Accountability Office, May 17, 2017),, pg. 12.

4 Dauna Coulter, “Who’s Orbiting the Moon?” National Aeronautics and Space Administration, Science Mission Directorate, Feb. 20, 2008,; Union of Concerned Scientists, “UCS Satellite Database,” last revised Nov. 7, 2017,

5 GovTribe, “Protected Tactical Enterprise Service DRAFT RFP,” Dec. 8, 2017,

6 “Resiliency and Disaggregated Space Architectures,” white paper, Air Force Space Command, April 14, 2016, pg. 4,

7 Eric Berger, “Without NASA There Would Be No SpaceX and Its Brilliant Boat Landing,” Ars Technica, April 11, 2016,