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The Need for Space Defence


With countries dependent on space systems for both their economic and military security, space defence is a priority. There is a UN outer space treaty (UNOOSA) and officially there is no sovereignty in space. But this doesn’t prevent there being both threats and conflicts. Space is still a contested domain.

In its early years, space exploration was quite competitive. Both the USA and USSR developed anti-satellite (ASAT) weapons. These were never used in conflict, but their development indicates the mood of the time.

The same principle of deterrence that prevented the outbreak of open nuclear hostilities on Earth also applied to outer space. However, many of the historical certainties of the late 20th century have dissipated or disappeared. Now the assurance of space-based deterrents is no longer certain.

At the same time, space communications and technology are playing a much more significant role in defence strategies and supporting economies.

One example is how counterterrorism operations depend on GPS and satellite communications systems to power drones for track and strike missions. These space-based communications are also used in surveillance.

The use of space technology has spread beyond purely military functions with a multitude of communications satellites orbiting the earth.

Now, around 90 per cent of the recently launched satellites represent commercial rather than government interests on a global scale.

The Threat of Disruption

Space is unregulated. The UN treaty does not prevent commercial and national interests from stretching regulatory boundaries.

An awareness of potential threats has seen more countries developing counterspace weapons. These are designed to disrupt or destroy satellites and satellite systems when in orbit. Consequently, there is need to be an emphasis on developing space defence technology. Broadly, the categories of threat in space are:

  • Kinetic physical – counterspace weapons such as warheads, but also orbital debris resulting from such attacks
  • Non-kinetic physical – weapons and devices that can disrupt satellites without making physical contact, such as lasers and high-powered microwave weapons
  • Electronic – weapons that disrupt the electromagnetic spectrum, blocking signals or creating fake signals
  • Cyber – cyberattacks on satellites can monitor data, erase it completely, or insert false data into systems.

Satellites ensure that the world is interconnected. But this also makes systems, networks and even whole economies increasingly vulnerable.

What forms of space defence will offer the protection global space-based assets need?

Defensive Counterspace Operations

Defensive counterspace operations aim to protect friendly space systems, whereas offensive counterspace operations aim to disrupt, degrade, or destroy adversary space systems.

According to CSIS Aerospace Security Project, space defence is divided into two broad categories:

  • Passive defences, and
  • Active defences.

Passive defences

Passive defences minimises the effectiveness of attacks on friendly space systems or make these space systems more capable of withstanding attacks.

Passive defences is further divided into three categories:

  1. Architectural defences
  2. Technical defences
  3. Operational defences.

Architectural Defences

  • Disaggregated constellations are satellites that operate in parallel with each other in mission-specific roles. This reduces the risk of having single mission-critical satellites that could be vulnerable to attack. It also throws doubt on which satellite the attacker should be focusing on to achieve their objectives.
  • Distributed constellations work in a system that ensures that the end-user is not dependent on any single satellite but uses multiple satellites instead. Essentially, it means not all their eggs are in one basket. GPS systems use distributed constellations, enabling the user to get a fix on time and position from any four satellites at a time.
  • Proliferated constellations use large numbers of the same type of satellites to duplicate functions. This provides more protection because it increases the number of satellites a hostile force would need to attack for this to be effective.
  • Diversified architectures use multiple systems to contribute to a common mission. These multiple platforms can use platforms and payloads that are in different orbits or domains. This makes it harder for an attack on any one of them to have a significant impact on the whole mission.
  • Mobile ground stations can provide a degree of architectural defence if they’re rapidly deployable in the event of an attack or natural disaster.

Technical Defences

  • Space Domain Awareness (SDA) includes the identification and tracking of space objects and predicting where these objects will position themselves in the future. It also involves monitoring the space environment and weather and analysing the characteristics and applications of space objects. Artificial intelligence can enhance SDA capabilities. SDA terrestrial-based systems include optical, infrared and radar. There are also space-based SDA systems using space situational awareness (SSA).
  • Radio Frequency Mapping involves the space-based mapping and analysis of radio frequencies that can impact terrestrial and space-based systems. RF mapping gives operators a clearer picture about the potential for jamming and spoofing attacks. The faster they can detect threats, the more valuable this information is.
  • Filtering and shuttering techniques protect satellites from laser dazzling and blinding. Filters only allow light from certain wavelengths through. Shutters block or divert all light towards a sensor after detecting anomalies or when the light reaches a certain threshold.
  • Jam-resistant waveforms can improve the resistance of communications systems to jamming and spoofing. Using a frequency hopping spread spectrum (FHSS) rapidly changes transmission frequency to make it harder for someone to interfere with or block signals. Interleaving divides and mixes the bits of transmitted data, making detection and interception more difficult.
  • Antenna nulling is a technical defence where satellites are designed with antennas that minimise, or null, signals from a specific geographic region.
  • Adaptive filtering uses antennas that block specific frequency bands regardless of where transmissions originate. This is useful where jamming occurs consistently within a frequency range.
  • Encryption offers some protection, but there can be vulnerabilities if the encryption keys themselves are compromised or lost.
  • Air-gapped systems are physically separate from the public internet, making it more difficult for anyone to infiltrate them.

Operational Defences

  • Rapid deployment of a new or expanded capability is one form of operational defence, providing the adversary is unaware of this capability. However, there are limitations on how fast you can launch a satellite, with practical factors to consider such as integration with launch vehicles and available launch windows.
  • Reconstitution is where you replace existing satellites rapidly with more advanced craft to bolster space communications or restore functionality.
  • Manoeuvrability is an operational defence tactic satellites use to minimise the risk of attack or disruption. One issue is that speed in manoeuvring a satellite can compromise its current operations. Also, the larger the satellite is, the more propellant power it will require.
  • Stealth works by incorporating evasive characteristics into space systems. This can involve smaller sized satellites or radar-absorbing coatings, for example. Stealth systems also have built-in radar-jamming and optimised manoeuvrability (see above).
  • The use of tactical decoys is an established operational defence tactic. These can confuse the sensors on weapons and detection systems. Tactical decoys can be as basic as inflatable devices that mimic the nature of satellites.
  • Other forms of deception include limiting information or making false announcements about launches, mission status and operational information.

Active defences

While passive defences seek to protect space systems from threats by making them harder to target or better capable of withstanding attacks, active defences target the threats to destroy or nullify them.

Active defences is further divided into two categories:

  1. Space-based defences
  2. Terrestrial-based defences

Space-based Defences

  • Jamming and spoofing disrupt sensors on incoming weapons to protect satellites from attack. This tactic works best in combination with evasive satellite manoeuvres.
  • Laser dazzling uses onboard laser systems to dazzle or blind missiles and other weapons sensors, similar to countermeasures used on aircraft to defeat heat-seeking missiles.
  • Some spacecraft can be equipped to physically dock onto or disrupt satellite systems, seizing them physically. This type of system can also collect and dispose of harmful orbiting debris.
  • Certain satellites can shoot back at incoming weapons, or use a laser or microwave beam to physically damage or destroy these weapons.

Terrestrial-based Defences

  • Cyberattacks can disrupt the command and control of antagonistic space weapons systems, or target information that will help prevent attacks. Cyberattacks on ground control systems will disrupt communications between counterspace forces, preventing the delivery of commands to weapons systems.
  • Jamming and spoofing can become defensive tactics, disrupting communications of counterspace forces and weapons systems.
  • Ground-controlled direct-ascent ASAT weapons can work defensively to neutralise threatening objects in space.
  • Defensive kinetic weapons that are land, sea or air-based can also provide terrestrial-based defences against space-based aggression. They may target ground-based centres of jamming activity or rocket-launch sites, for example.


There are ongoing and new threats to space operations. These may come from larger nations or rogue states. These threats have the potential to be seriously disruptive to military operations and defences and to entire economies. Fortunately, there is a range of defensive measures that space agencies can take.

However, these require testing and analysis to be effective. Having the necessary knowledge and insight can help space agencies devise and execute the most effective forms of space defence where there are constantly shifting scenarios.

Some of the most effective forms of testing and analysis involve advanced network modelling and simulation for space systems.

ST Engingeering Antycip partners with industry leaders in this field to provide cutting-edge capabilities in testing and analysis.

For more information, please contact us.


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