Redefining Space Key Terrain to Drive Decisions

Introduction 

Space Force doctrine does not provide terrain information relevant to commanders because the service has not fully defined what “key terrain” means for space. Key terrain is supposed to shape the development of courses of action and inform a commander’s decisions by establishing relative values of different physical locations within a domain.[i] Until the Space Force provides a definition of “key terrain,” and a process to identify and communicate it, service planners will not be fully integrated with the combatant commands. Key terrain in the space domain must serve the same purpose as key terrain in any other domain: to help commanders to prioritize their resources and shape their plans. But space has factors that make its terrain incomparable to other domains – namely, that the relative position of terrain features is in constant flux, due to orbital mechanics, including the rotation of the Earth. This paper provides an overview of key terrain from the joint perspective and makes recommendations for the Space Force to identify and depict key terrain in the context of space.

The Space Force’s Space Capstone Publication (SCP) established a doctrinal foundation for space operations and integration of space with joint and coalition partners.[ii] While the SCP recognizes that key terrain in space exists, it uses a framework that is at odds with the rest of the joint community, and that does not provide the details needed for a commander to make decisions. The SCP introduces the concept of “key topology,” composed of critical lines of communication (LOCs) and “key orbital trajectories” (KOTs).[iii] The service visualizes key terrain through LOCs and KOTs instead of using key terrain as the joint community knows it. In doing so, The Space Force does not fully capture the intent of key terrain, which is to prioritize portions of terrain in a way that enables a commander’s decision-making.

A main shortcoming of the key topology approach is its failure to scope the output to something that is understandable and actionable by a commander. The SCP lists “Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geosynchronous Earth Orbit (GEO), and sun-synchronous orbits” as KOTs.[iv] A space planner identifying key terrain using the SCP guidelines could follow the Space Force’s doctrine and decide that the key topology is all of space, from Earth to the GEO belt. While this may be accurate according to Space Force doctrine, it does not achieve the goal of prioritizing terrain features for a commander. This would be akin to a ground component planner identifying every mountain over 14,000 feet of elevation – be it in Nepal, Tanzania, Peru, or Switzerland – as key terrain, when preparing for a beach landing at Normandy.

The Space Force continued with the same key topology approach with its 2021 planning doctrine, Space Doctrine Publication (SDP) 5-0. There, the Space Force again identified LOCs and KOTs as the aspects of key topology.[v] This SDP did not list generic orbital regimes as examples of KOTs but also did not discount the standard established in the SCP.

By presenting full orbits (or worse, orbital regimes) as key terrain, planners both make the modifier “key” moot and render the operational goal of securing or denying an adversary access to key terrain impossible to accomplish. The KOT framework also encourages the idea that only the space segment matters, ignoring the electromagnetic (EM) and terrestrial factors that influence space operations. The invention of new terms, “key topology” and “key orbital trajectory,” further challenges space planners as they integrate with joint plans. The discordant terms and unfocused output prevent the concepts of KOTs and key topology from supporting joint operations. A different approach to defining and analyzing space key terrain is necessary. 

A Standard for Space Terrain

It is necessary to define the concept of “terrain” in space especially before defining “key terrain” in the context of space. This paper defines space terrain as:

A space terrain feature is based on a specific set of five criteria that together uniquely identify physical, electromagnetic, and temporal criteria that support the operation of a space system. The five criteria are system location, target location, system-to-target path, electromagnetic spectrum access, and the window of time when those factors are relevant.

See Figure 1 for a depiction of the five criteria of space terrain

Space terrain is best viewed through the physical, electromagnetic, and temporal dimensions. The physical dimension includes terrestrial sites, spacecraft, debris, other celestial bodies, and even notional locations that could support a specific space system effect. The electromagnetic dimension is the portion of the EM spectrum critical to the execution of specific space operations. As examples, the EM dimension could be a frequency for communications or a wavelength range for a sensor’s collection of infrared data. The temporal dimension is the period during which the terrain is relevant to the operation. This could range from an exact instant to an unbounded window.

Elements of terrain in space can be man-made. Spacecraft are mobile terrain factors that happen to host civil, commercial, or military capabilities. The positioning of those objects relative to targets on earth or to other space system objects enables payloads to conduct specific operations. The first two space terrain criteria define those relative positions. The first criteria is the space system location, whether in space or terrestrial-based, and the second criteria is the target location for delivery of effects.

The physical terrain is not just the locations of the object and its target. Space planners must consider the system-to-target path that connects the two nodes as the third criteria for space terrain. For example, a reconnaissance satellite could be overhead, but the adversary may use concealment to deny observation of the target. In another scenario, the adversary may rotate its spacecraft to place the body of the craft between a detecting sensor and a sensitive capability, which would prevent imaging. In these examples, the path is a straight line between the object and target, but this is not always the case. For instance, the path between a satellite in its initial (object) and final (target) positions may be a planned transfer orbit.

Space terrain is not limited to physical objects or locations. The fourth criteria addresses this category. Terrain extends into electromagnetic spectrum access because space operations are not possible without access to and control of portions of the EM spectrum. As an example, two satellites can occupy the same slot in geostationary orbit, sharing the same physical location, provided they operate on different frequencies. In another case, a reconnaissance asset that attempts to collect intelligence on an adversary can be in the right orbit for collection but may be “dazzled” by the adversary’s laser and is unable to image a target. In this scenario, the adversary denied the terrain by controlling the EM spectrum at that location.

The fifth and final criteria of space terrain is the window of time when the other factors are relevant. For a satellite in geostationary orbit, the time window might be unbounded. For a reconnaissance satellite in low earth orbit, transiting a target area, the timeframe might be a minute or less. Time is critical to the understanding of key terrain in space. Outside the window of time when the physical and EM factors combine to enable effects, the terrain is no longer “key.” When presenting space key terrain to a commander, planners must provide the context for when this key terrain is relevant.

A full combination of the five physical, EM, and temporal terrain criteria is a “criteria set.” The intent behind the identification of terrain is not to list out every possible combination of criteria sets. Instead, the five criteria would be used as a concept for visualizing the battlespace as planners consider candidates for key terrain, and to later communicate that terrain to the commander.

An Approach to Space Key Terrain

After developing a definition of space terrain, the next step is to establish a common definition for space key terrain. A proposed definition based on the joint definition of key terrain is: Space key terrain is a space terrain criteria set, the control of which affords a combatant a marked advantage in an operation.

Key terrain depends on the specific operation being conducted at the time of analysis and must be controlled to provide an advantage. In space operations, control requires placement of a space system object in a specific location and time with an unobstructed path to the target location for desired effects, In addition, it requires the ability to use the portion of the EM spectrum relevant to the mission. If any of these criteria are missing or denied, a combatant no longer controls the key terrain.

See Figure 2 for a depiction of key terrain denial in the space domain

Examples of Application

Space planners determine space key terrain criteria sets through analysis of the operation and assessment of friendly, enemy, and neutral space capabilities. The following vignettes on spacelift, satellite communications, and orbital warfare are provided as guides for specific space operations to assist planners in assessing their missions with this approach to viewing key terrain.

Spacelift:

Spacelift operations can be likened to a logistics resupply movement by ground forces. A ground element moves along a route (a LOC), transporting necessary supplies from one point to another. During this operation, the full LOC is not key terrain. Only the portions that have significance to the mission outcome are key terrain. For example, there may be a major intersection, or a portion of the logistics operation may depend on the use of a single route, with no alternative lines of communication if that one route is rendered impassable. The intersection and the section of the route with no alternatives would both be key terrain features for the logistics mission. Just as the logistics element identifies subsets of the terrain as key to the operation, a spacelift mission will identify subsets of the launch and orbital insertion as key.

In this spacelift example, a unit must conduct a launch into a specific orbital inclination and altitude. The unit manages the initial launch from the primary command and control site. Following launch, the unit analyzes telemetry and tracking data, enabling assessment of the space vehicle’s performance. Halfway through the first orbit, a secondary command and control node pushes an in-flight update to the vehicle, refining instructions for the spacecraft’s final burn and increasing the accuracy of the vehicle’s orbit. Planners might determine that there are three sets of space key terrain criteria in this scenario.

One set of space key terrain criteria during this mission will be while the space vehicle is on the launch pad. During the launch countdown (time), the primary command and control site (system location) must have a reliable communications link (path) and access to relevant communications frequencies (EM spectrum) between the command-and-control site and the launch site (target location) that facilitates a specific orbital inclination.

The second set of space key terrain criteria occurs during and in the first minutes following launch (time). During this period, the primary command and control site (system location) must track the progress of the space vehicle (target location), monitoring telemetry feeds (EM spectrum) from the space vehicle to the command-and-control center (path) to ensure the space vehicle is operating as planned and to facilitate destruction of the vehicle if it fails to perform as designed. The key terrain as viewed on a three-dimensional (3D) map has the shape of an arc because this data path goes between the fixed point of the primary command and control site and the moving space vehicle.

The final space key terrain criteria set is tied to the in-flight update. In this example, the secondary command and control node (system location) sends updated position data or system instructions to the space vehicle (target location). This information travels via radio frequencies (EM spectrum) during the specific window (time) when the command-and-control node has line-of-sight access (path) to the space vehicle. The criteria set meets the definition for space key terrain because the ability to use these factors provides a distinct military advantage. Like the key terrain during the launch, these criteria set would also project as an arc on a 3D common operating picture display.

Satellite Communications:

In this example for a satellite communications (SATCOM) mission, a ship attempts to send a message to an aircraft operating over the horizon. The communication path follows the simplest, non-direct route, with the transmission going up from the ship to a satellite, then returning down from that satellite to the aircraft. The SATCOM mission will have two space key terrain criteria sets, one for the near end and one for the far end.

The first key terrain criteria set, for the near end, would start with the ship’s wideband equipment (system location) that supports its ability to transmit to and from the satellite's communications payload (target). The criteria set would also include the path for data transfer between those locations (path), the portions of the EM spectrum used for the uplink and downlink messaging (EM spectrum), and the time windows when communications are critical (time). Viewed on a 3D common operating picture, this path could be a steady line, an arc, or a dynamically shifting line depending on the relative movement between the system and the target.

The second key terrain criteria set for this SATCOM mission would support the far end of the link. This criteria set would incorporate the satellite’s location (system location), the aircraft receiving the message (target location), the communications link between those locations (path), the uplink and downlink spectrum bands (EM spectrum), and the exact times when those relative positions exist (time).

This example used the simplest setup for SATCOM operations. The complexity of the system increases if two-way communication is necessary, or if other factors are at play. A more complex scenario would likely introduce additional criteria sets as considerations for key terrain.

Orbital Warfare:

For the orbital warfare example, guardians must attempt a rendezvous and proximity operation (RPO), maneuvering a friendly spacecraft to within a certain distance of a target spacecraft. An RPO is another example of a scenario with multiple, complementary space key terrain criteria sets. At its simplest, this operation requires two criteria sets.

In this scenario, the first space key terrain criteria set is from the perspective of the controllers of the friendly spacecraft. Relevant criteria are the ground control station (system location), the friendly spacecraft (target location), the communications link between them (path), the control frequencies (EM spectrum), and the engagement window (time). This criteria set is identical to the examples of a spacelift operation’s command and control node monitoring the launch, or to a ship transmitting a message to a SATCOM satellite.

Orbital warfare planners must also consider a second set of criteria--those from the perspective of the satellite conducting the RPO. This space key terrain criteria set contains the initial orbital elements of the friendly spacecraft (system location), the target satellite location (target location), the projected transfer maneuver (path), the frequencies related to the spacecraft sensors that are needed to successfully close with the target craft (EM spectrum), and the engagement window (time).

These vignettes provide some examples to shape a planner’s approach to determining space key terrain. Electromagnetic warfare, missile warning, space domain awareness, satellite control, and other space missions can be analyzed using the same fundamentals that stem from these definitions of space terrain and space key terrain.

Conclusion

The Space Force is developing its doctrine and searching for innovative ways to integrate into the joint fight. The service has yet to fully depict key terrain in the space domain. However, the Space Force has not locked itself into a false start because it can still modify seminal doctrine. Identifying and accounting for specific system location, target location, system-to-target path, EM spectrum access, and window of time factors as space key terrain allows planners to help their commanders to envision the critical criteria sets that influence the outcome of space operations. Identification of the key terrain supports future requests for reconnaissance or targeting related to these terrain features. Bringing discrete sets of space key terrain criteria to a commander, with the ability to visualize them in time and space via a common operating picture, provides space planners with the tools needed to discuss and weigh space key terrain decisions against those in other domains, enabling the commander to shape the fight in space and the other domains.

Lieutenant Colonel Nicholas Shaw, USSF, is the commander of the 4th Electromagnetic Warfare Squadron at Peterson Space Force Base. This paper represents solely the author’s views and does not necessarily represent the official policy or position of any Department or Agency of the U.S. Government. If you have a different perspective, we’d like to hear from you.

[i] Joint Guide, Joint Intelligence Preparation of the Operational Environment (Washington, DC: The Joint Staff, May 26, 2022), III-6, available at https://jdeis.js.mil/jdeis/JDN_pdf/jg_jipoe.pdf.

[ii] Space Capstone Publication,Spacepower (Headquarters United States Space Force, June 2020), 24, available at https://media.defense.gov/2022/Jan/19/2002924108/-1/-1/0/SPACE%20CAPSTONE%20PUBLICATION%20(10%20AUG%202020%20-%20AS%20RELEASED%20BY%20CSO).PDF.

[iii] Space Capstone Publication, Spacepower (Headquarters United States Space Force, June 2020), 24, available at https://media.defense.gov/2022/Jan/19/2002924108/-1/-1/0/SPACE%20CAPSTONE%20PUBLICATION%20(10%20AUG%202020%20-%20AS%20RELEASED%20BY%20CSO).PDF.

[iv] Space Capstone Publication, Spacepower (Headquarters United States Space Force, June 2020), 24, available at https://media.defense.gov/2022/Jan/19/2002924108/-1/-1/0/SPACE%20CAPSTONE%20PUBLICATION%20(10%20AUG%202020%20-%20AS%20RELEASED%20BY%20CSO).PDF.

[v] Space Doctrine Publication (SDP) 5-0, Planning (Space Training and Readiness Command, December 2021), 16-17, available at https://media.defense.gov/2022/Jan/19/2002924107/-1/-1/0/SDP%205-0,%20PLANNING%20(20%20DEC%202021).PDF.