Alternate Communications Paths

Establishing alternate communications paths for spacecraft and ground system operations reduces the likelihood that a single adversarial event, physical disruption, or technical failure will deny all mission communications. Reliance on a single communications pathway creates a single point of failure that adversaries can exploit through jamming, denial of service against ground infrastructure, physical disruption of a ground station, or compromise of network connectivity, any of which could result in complete loss of commanding and telemetry capability. Alternate paths must be assessed end to end for shared failure modes and operational dependencies. Differences in frequency, ground station, relay service, or network provider provide meaningful resilience only when the paths do not remain dependent on the same critical spacecraft, ground, management, or service infrastructure. The selection and configuration of alternate paths must be governed by the mission's concept of operations (CONOPS), which defines the conditions under which each path is used, the priority and switchover procedures between paths, and the minimum communications capability that must be maintained to satisfy mission safety and operational continuity requirements.

ID: CM0070

Tier: I

Ground CM

Created: 2022/10/19

Last Modified: 2026/08/06

Pre-Operations Government

Acquisition requirements should mandate alternate communications path capability as a mission resilience requirement, with specifications defining the minimum number of independent paths required, the diversity criteria that must be satisfied across paths to ensure they are not subject to common-cause failure, and the minimum communications capability that must be achievable through alternate paths alone when the primary path is unavailable. Requirements should address both the space segment and ground segment elements of each alternate path, ensuring that alternate path designs include independent ground station access, independent network connectivity to mission operations, and independent spacecraft radio or antenna configurations where feasible. Contract language should require that the alternate communications architecture be documented as a controlled system design deliverable subject to government review, including the switchover logic, the CONOPS for path selection and transition, and the testing approach for verifying alternate path operability. Evaluation criteria should assess offerors' proposed path diversity across frequency bands, geographic locations, and network infrastructure, and their experience designing and validating alternate communications architectures for space missions with similar operational profiles. Verification should include operability testing of each alternate path under realistic conditions, including switchover testing that confirms the mission can transition to and operate through alternate paths within defined timelines.

Pre-Operations Developer/Supplier

Alternate communications path architecture must be designed with genuine diversity as the governing criterion, distinguishing between redundant paths that share common infrastructure, frequency bands, geographic regions, or network providers, and truly diverse paths that are independent in their failure modes and susceptible to different threat scenarios. Ground station separation must be based on the mission’s assessed regional hazards, jamming threat, infrastructure dependencies, and required orbital coverage. Separation should reduce the likelihood that one regional event affects all available stations while still providing the contact opportunities needed to support the alternate-path CONOPS. Frequency band diversity should be considered where the spacecraft hardware and link budgets permit, as jamming and interference threats are band-specific and a path operating on a different frequency is more likely to remain available when the primary path is jammed or interfered with. The CONOPS must define whether path transition is automatic, operator-directed, or a combination of both based on mission timing and risk. Automated transition should be used only where path-failure detection, alternate-path authentication, transition logic, and recovery behavior have been validated and cannot be readily manipulated to force an unsafe or unauthorized switchover. Manual procedures must be documented and exercised. Network and ground system infrastructure supporting each alternate path should be assessed for shared dependencies, including shared internet service providers, shared facility power sources, and shared network equipment, with shared dependencies identified and eliminated or mitigated to maintain the independence of the alternate paths.

Sustainment & Maintenance Government

Operational alternate path maintenance requires that each path be exercised on a scheduled basis, with periodic full-path operability tests that confirm end-to-end connectivity from mission operations through the ground station or relay to the spacecraft, producing a verified readiness record for each alternate path. Path monitoring should include continuous or frequent health checks of the ground station infrastructure, network connectivity, and spacecraft receiver and transmitter configurations associated with each alternate path, enabling early detection of degradation before it results in loss of path availability during an incident. Any change to ground station equipment, network routing, or spacecraft configuration that affects an alternate communications path must be assessed for its impact on path operability and diversity before implementation, with operability validated through testing after implementation. Following activation of an alternate path, a post-incident review must assess the disruption, transition, and alternate-path performance. Restoration of the primary path should proceed when it has been shown safe and operationally necessary; corrective actions that do not require immediate implementation may be tracked through the configuration and corrective-action processes before the alternate path returns to normal readiness status.

Sustainment & Maintenance Developer/Supplier

Techniques Addressed by Countermeasure

ID		Name	Description
IA-0007		Compromise Ground System	Compromising the ground segment gives an adversary the most direct path to first execution against a spacecraft. Ground systems encompass operator workstations and mission control mission control software, scheduling/orchestration services, front-end processors and modems, antenna control, key-loading tools and HSMs, data gateways (SLE/CSP), identity providers, and cloud-hosted mission services. Once inside, a threat actor can prepare on-orbit updates, craft and queue valid telecommands, replay captured traffic within acceptance windows, or manipulate authentication material and counters to pass checks. The same foothold enables deep reconnaissance: enumerating mission networks and enclaves, discovering which satellites are operated from a site, mapping logical topology between MOC and stations, identifying in-band “birds” reachable from a given aperture, and learning pass plans, dictionaries, and automation hooks. From there, initial access to the spacecraft is a matter of timing and presentation, injecting commands, procedures, or update packages that align with expected operations so the first execution event appears indistinguishable from normal activity.
	.02	Malicious Commanding via Valid GS	Adversaries may use a compromised, mission-owned ground system to transmit legitimate-looking commands to the target spacecraft. Because the ground equipment is already configured for the mission, correct waveforms, framing, dictionaries, and scheduling, the attacker’s traffic blends with routine operations. Initial access unfolds by inserting commands or procedures into existing timelines, modifying rate/size limits or command queues, or invoking maintenance dictionaries and rapid-response workflows that accept broader command sets. Pre-positioned scripts can chain actions across multiple passes and stations, while telemetry routing provides immediate feedback to refine follow-on steps. Exfiltration can be embedded in standard downlink channels or forwarded through gateways as ordinary mission data. The distinguishing feature is that command origin appears valid, transmitted from approved apertures using expected parameters, so the first execution event is not a protocol anomaly but a misuse of legitimate command authority obtained through the compromised ground system.
EX-0013		Flooding	Flooding overwhelms a communication or processing path by injecting traffic at rates or patterns the system cannot comfortably absorb. In space contexts this can occur across layers: RF/optical links (continuous carriers, wideband noise, or protocol-shaped bursts); link/protocol layers (valid-looking frames at excessive cadence); application layers (command and telemetry messages that saturate parsers and queues); and internal vehicles buses where repeated messages starve critical publishers. Effects range from outright denial of service, dropped commands, lost telemetry, missed windows, to subtler corruption, such as out-of-order processing, watchdog trips, or autonomy entering protective modes due to backlogged health data. Secondary impacts include power and thermal strain as decoders, modems, or software loops spin at maximum duty, storage filling from retries, and control loops jittering when their messages are delayed. Timing matters: floods during handovers, maneuvers, or safing transitions can magnify consequences because margins are thinnest.
	.01	Valid Commands	Here the adversary saturates paths with legitimate telecommands or bus messages so the spacecraft burns scarce resources honoring them. Inputs may be innocuous (no-ops, time queries, telemetry requests) or low-risk configuration edits, but at scale they consume command handler cycles, fill queues, generate events and logs, trigger acknowledgments, and provoke downstream work in subsystems (e.g., repeated state reports, mode toggles, or file listings). On internal buses, valid actuator or housekeeping messages replayed at high rate can starve higher-priority publishers or cause control laws to chase stale stimuli. Because the traffic is syntactically correct, and often contextually plausible, the system attempts to process it rather than discard it early, increasing CPU usage, memory pressure, and power draw. Consequences include delayed or preempted legitimate operations, transient loss of commandability, and knock-on FDIR activity as deadlines slip and telemetry appears inconsistent.
	.02	Erroneous Input	In this variant, the attacker injects non-useful energy or data, noise, malformed frames, or near-valid messages, so receivers and parsers labor to acquire, decode, and reject it. At the RF layer, wideband or protocol-shaped interference drives AGC and clock recovery to hunt, elevates BER, and forces repeated acquisitions; at the link layer, frames with correct preambles but bad CRCs keep decoders busy while yielding no payload; at the application layer, malformed packets force parse/validate/deny cycles that still consume CPU and fill error logs. On internal buses, collisions or bursts of misaddressed traffic reduce effective bandwidth and reorder legitimate messages. Even though little of the injected content passes semantic checks, the effort of dealing with it crowds out real work and may trigger retransmission storms or fallback modes that further increase load. The hallmark is volumetric invalid activity, crafted to engage front ends and parsers just long enough, that degrades integrity and availability without relying on privileged or authenticated commands.
DE-0002		Disrupt or Deceive Downlink	Threat actors may target any point in the telemetry chain, onboard generation and transmission, the downlink path itself, or ground-side reception, processing, and display, to disrupt the operator’s visibility into spacecraft health and activity. This may involve denial-based attacks that prevent the spacecraft from transmitting telemetry to the ground (e.g., disabling telemetry links or crashing telemetry software), or more subtle deception-based attacks that manipulate telemetry content to conceal unauthorized actions. Since telemetry is the primary method ground controllers rely on to monitor spacecraft status, any disruption or manipulation can delay or prevent detection of malicious activity, suppress automated or manual mitigations, or degrade trust in telemetry-based decision support systems.
	.01	Inhibit Ground System Functionality	Threat actors may utilize access to the ground system to inhibit its ability to accurately process, render, or interpret spacecraft telemetry, effectively leaving ground controllers unaware of the spacecraft’s true state or activity. This may involve traditional denial-based techniques, such as disabling telemetry software, corrupting processing pipelines, or crashing display interfaces. In addition, more subtle deception-based techniques may be used to falsify telemetry data within the ground system , such as modifying command counters, acknowledgments, housekeeping data, or sensor outputs , to provide the appearance of nominal operation. These actions can suppress alerts, mask unauthorized activity, or prevent both automated and manual mitigations from being initiated based on misleading ground-side information. Because telemetry is the primary method by which ground controllers monitor the health, behavior, and safety of the spacecraft, any disruption or falsification of this data directly undermines situational awareness and operational control. Architectural limitations in ground station software can also enable deception without requiring direct compromise of the ground system. In publish-subscribe spacecraft architectures, ground tools typically attribute telemetry solely by Message ID rather than by producing application. This design assumes that Message IDs reliably identify the originating component. When a malicious onboard application publishes telemetry under a legitimate subsystem's Message ID, ground logs permanently record the spoofed data as genuine with no indication of the true source. Similarly, internal spacecraft bus commands may not be downlinked or logged by ground systems, rendering suppression events forensically invisible. This attribution gap allows onboard component impersonation to succeed without any ground system compromise: the ground infrastructure functions as designed, yet cannot distinguish authentic telemetry from architecturally valid spoofing.
	.02	Jam Link Signal	Threat actors may overwhelm/jam the downlink signal to prevent transmitted telemetry signals from reaching their destination without severe modification/interference, effectively leaving ground controllers unaware of vehicle activity during this time. Telemetry is the only method in which ground controllers can monitor the health and stability of the spacecraft while in orbit. By disabling this downlink, threat actors may be able to stop mitigations from taking place.
	.03	Inhibit Spacecraft Functionality	In this variant, telemetry is suppressed at the source by manipulating on-board generation or transmission. Methods include disabling or pausing telemetry publishers, altering packet filters and rates, muting event/report channels, reconfiguring recorder playback, retuning/muting transmitters, or switching to modes that emit only minimal beacons. The spacecraft continues operating, but the downlink no longer reflects true activity or arrives too sparsely to support monitoring. By constraining what is produced or transmitted, the adversary reduces opportunities for detection while other actions proceed.

Space Threats Addressed by Countermeasure

ID	Description
SV-AV-5	Using fault management system against you. Understanding the fault response could be leveraged to get satellite in vulnerable state. Example, safe mode with crypto bypass, orbit correction maneuvers, affecting integrity of TLM to cause action from ground, or some sort of RPO to cause S/C to go into safe mode;
SV-AC-1	Attempting access to an access-controlled system resulting in unauthorized access
SV-AV-1	Communications system jamming resulting in denial of service and loss of availability and data integrity
SV-MA-7	Exploit ground system and use to maliciously to interact with the spacecraft

Sample Requirements

SPARTA ID	Requirement	Rationale/Additional Guidance/Notes
SPR-7	The [organization] shall document and design a security architecture using a defense-in-depth approach that allocates the [organization]s defined safeguards to the indicated locations and layers: [Examples include: operating system abstractions and hardware mechanisms to the separate processors in the platform, internal components, and the FSW].{SV-MA-6}{CA-9,PL-7,PL-8,PL-8(1),SA-8(3),SA-8(4),SA-8(7),SA-8(9),SA-8(11),SA-8(13),SA-8(19),SA-8(29),SA-8(30)}	Spacecraft security cannot rely on a single control; layered defenses reduce the likelihood of catastrophic compromise. Documenting safeguard allocation across hardware, OS, firmware, and FSW ensures coverage across attack surfaces. This supports resiliency against both cyber intrusion and supply chain weaknesses. Clear documentation enables verification and independent assessment.
SPR-8	The [organization] shall ensure that the allocated security safeguards operate in a coordinated and mutually reinforcing manner.{SV-MA-6}{CA-7(5),PL-7,PL-8(1),SA-8(19)}	Independent controls that operate in isolation may create security gaps or conflicting behaviors. Coordinated safeguards ensure that encryption, authentication, partitioning, and monitoring functions reinforce each other rather than undermine availability or safety. This reduces bypass risk and improves fault/cyber response integration. Cohesive operation is essential for resilient mission assurance.
SPR-14	The [spacecraft] shall authenticate the ground station (and all commands) and other spacecraft before establishing remote connections using bidirectional authentication that is cryptographically based.{SV-AC-1,SV-AC-2}{AC-3,AC-17,AC-17(2),AC-17(10),AC-18(1),AC-20,IA-3(1),IA-4,IA-4(9),IA-7,IA-9,SA-8(18),SA-8(19),SA-9(2),SC-7(11),SC-16(1),SC-16(2),SC-16(3),SC-23(3),SI-3(9)}	Authorization can include embedding opcodes in command strings, using trusted authentication protocols, identifying proper link characteristics such as emitter location, expected range of receive power, expected modulation, data rates, communication protocols, beamwidth, etc.; and tracking command counter increments against expected values.
SPR-46	The [spacecraft] shall monitor [Program‑defined telemetry points] for malicious commanding attempts and alert ground operators upon detection.{SV-AC-2,SV-IT-1,SV-DCO-1}{AC-17,AC-17(1),AC-17(10),AU-3(1),RA-10,SC-7,SC-16,SC-16(2),SC-16(3),SI-3(8),SI-4,SI-4(1),SI-4(13),SI-4(24),SI-4(25),SI-10(6)}	Telemetry-based detection enables identification of anomalous command patterns, replay attempts, and injection attacks. Early detection allows rapid containment before mission impact escalates. Onboard monitoring is critical when ground latency limits intervention. This supports proactive defense.
SPR-74	The [organization] shall define the security safeguards that are to be automatically employed when integrity violations are discovered.{SV-IT-2}{CP-2,SA-8(21),SI-3,SI-4(7),SI-4(12),SI-7(5),SI-7(8)}	Predefined safeguards ensure consistent and timely response to detected integrity violations. Ad hoc response increases uncertainty and recovery time. Automated actions may include isolation, reconstitution from gold images, or transition to cyber-safe mode. Defined response paths improve resilience and reduce operator burden during crisis.
SPR-96	The [spacecraft] shall uniquely identify and authenticate the ground station and other spacecraft before establishing a remote connection.{SV-AC-1,SV-AC-2}{AC-3,AC-17,AC-17(10),AC-20,IA-3,IA-4,SA-8(18),SI-3(9)}
SPR-107	The [spacecraft] shall have multiple uplink paths {SV-AV-1}{CP-8,CP-11,SA-8(18),SC-5,SC-47}	Redundant uplink paths preserve command capability during jamming, interference, or subsystem failure. Availability is a core mission assurance objective. Diverse communication channels reduce single-point failure risk. This enhances resiliency in contested RF environments.
SPR-121	The [organiztion] shall maintain the ability to establish communication with the spacecraft in the event of an anomaly to the primary receive path.{SV-AV-1,SV-IT-1}{CP-8,SA-8(18),SC-47}	Receiver communication can be established after an anomaly with such capabilities as multiple receive apertures, redundant paths within receivers, redundant receivers, omni apertures, fallback default command modes, and lower bit rates for contingency commanding, as examples
SPR-229	The [organization] shall protect documentation and Controlled Unclassified Information (CUI) as required, in accordance with the risk management strategy.{SV-CF-3,SV-SP-4,SV-SP-10}{AC-3,CM-12,CP-2,PM-17,RA-5(4),SA-3,SA-3(1),SA-5,SA-10,SC-8(1),SC-28(3),SI-12}	Documentation may reveal architecture details exploitable by adversaries. Proper handling prevents leakage. Protection of CUI supports regulatory compliance. Information governance complements technical controls.
SPR-230	The [organization] shall identify and properly classify mission sensitive design/operations information and access control shall be applied in accordance with classification guides and applicable federal laws, Executive Orders, directives, policies, regulations, and standards.{SV-CF-3,SV-AV-5}{AC-3,CM-12,CP-2,PM-17,RA-5(4),SA-3,SA-3(1),SA-5,SA-8(19),SC-8(1),SC-28(3),SI-12}	* Mission sensitive information should be classified as Controlled Unclassified Information (CUI) or formally known as Sensitive but Unclassified. Ideally these artifacts would be rated SECRET or higher and stored on classified networks. Mission sensitive information can typically include a wide range of candidate material: the functional and performance specifications, the RF ICDs, databases, scripts, simulation and rehearsal results/reports, descriptions of uplink protection including any disabling/bypass features, failure/anomaly resolution, and any other sensitive information related to architecture, software, and flight/ground /mission operations. This could all need protection at the appropriate level (e.g., unclassified, SBU, classified, etc.) to mitigate levels of cyber intrusions that may be conducted against the project’s networks. Stand-alone systems and/or separate database encryption may be needed with controlled access and on-going Configuration Management to ensure changes in command procedures and critical database areas are tracked, controlled, and fully tested to avoid loss of science or the entire mission.
SPR-231	The [organization] shall distribute documentation to only personnel with defined roles and a need to know.{SV-CF-3,SV-AV-5}{CM-12,CP-2,SA-5,SA-10}	Least privilege and need to know should be employed with the protection of all documentation. Documentation can contain sensitive information that can aid in vulnerability discovery, detection, and exploitation. For example, command dictionaries for ground and space systems should be handles with extreme care. Additionally, design documents for missions contain many key elements that if compromised could aid in an attacker successfully exploiting the system.
SPR-232	The [organization] shall conduct a criticality analysis to identify mission critical functions and critical components and reduce the vulnerability of such functions and components through secure system design.{SV-SP-3,SV-SP-4,SV-AV-7,SV-MA-4}{CP-2,CP-2(8),PL-7,PM-11,PM-30(1),RA-3(1),RA-9,SA-8(9),SA-8(11),SA-8(25),SA-12,SA-14,SA-15(3),SC-7(29),SR-1}	During SCRM, criticality analysis will aid in determining supply chain risk. For mission critical functions/components, extra scrutiny must be applied to ensure supply chain is secured.
SPR-245	The [organization] shall define processes and procedures to be followed when integrity verification tools detect unauthorized changes to software, firmware, and information.{SV-IT-2}{CM-3,CM-3(1),CM-3(5),CM-5(6),CM-6,CP-2,IR-6,IR-6(2),PM-30,SC-16(1),SC-51,SI-3,SI-4(7),SI-4(24),SI-7,SI-7(7),SI-7(10)}	Predefined response procedures reduce reaction time. Clear escalation paths improve containment. Consistent handling prevents confusion during incidents. Preparedness strengthens resilience.
SPR-259	The [organization] shall develop an incident response and forensics plan that covers the spacecrafts.{SV-MA-5}{CP-2,IR-1,IR-3,IR-3(2),IR-4(12),IR-4(13),IR-8,SA-15(10),SI-4(24)}	A structured response plan enables coordinated containment and recovery. Forensics planning ensures evidence preservation. Defined procedures reduce confusion during crisis. Incident readiness enhances resilience.
SPR-292	The [organization] shall ensure that role-based security-related training is provided to personnel with assigned security roles and responsibilities: (i) before authorizing access to the system or performing assigned duties; (ii) when required by system changes; and (iii) at least annually thereafter.{SV-AC-4}{AT-3,CP-2}	Personnel must understand role-specific responsibilities. Tailored training reduces misuse. Continuous reinforcement maintains awareness. Human factors are central to defense.
SPR-293	The [organization] shall employ techniques to limit harm from potential adversaries identifying and targeting the [organization]s supply chain.{SV-SP-4,SV-SP-5,SV-SP-6}{CP-2,PM-30,SA-9,SA-12(5),SC-38,SR-3,SR-3(1),SR-3(2),SR-5(2)}	Adversaries often exploit supplier relationships. Protective measures reduce reconnaissance and manipulation. Supply chain resilience strengthens mission integrity. Proactive defense mitigates systemic exposure.
SPR-342	The [organization] shall test the plan for the transfer of essential functions to alternate processing sites for both the ground and space segment assets to familiarize personnel with the process and to evaluate the ability of the site to continue those functions.{SV-MA-5}{CP-4(2)}	Transfer testing validates ability to sustain operations during disruption. Ground and space segment continuity must be demonstrated. Exercises expose integration gaps. Preparedness supports mission survivability.
SPR-464	The [spacecraft] shall accept command and telemetry sessions from [organization]-authorized alternate ground or relay providers only when presented with valid cryptographic credentials and whitelisted link characteristics.{SV-IT-1,SV-AC-4,SV-MA-7}{AC-17,SC-23}	Accepting sessions only from authorized, cryptographically verified providers prevents rogue ground station compromise. Whitelisted link characteristics reduce spoofing risk. Strict admission control strengthens link-layer assurance. This supports TRANSEC alignment.
SPR-479	The [organization] shall define, baseline, and maintain the purposing of the space platform and link segment, including intended objectives, authorized capabilities, prohibited functions, and operational constraints, and shall use this baseline to bound requirements, updates, and on-orbit operations.{SV-AC-8,SV-MA-6}{PM-32,PL-8}	Defining authorized and prohibited functions prevents scope creep. Clear purposing bounds updates and operational use. Governance limits misuse potential. Structured baseline supports disciplined operations.
SPR-517	The [organization] shall correlate station/operator session activity with pass schedules and spacecraft mode, alert on off‑schedule access and command families invalid for the current mode, and retain results as audit evidence.{SV-AC-4,SV-AC-1,SV-AV-4}{AC-17,AC-17(1),SI-4,AU-6}	Off-schedule or mode-inconsistent commands signal compromise. Correlation across dimensions strengthens anomaly detection. Audit retention supports post-event review. Context validation strengthens mission assurance.
SPR-518	The [organization] shall require external stations/relays to complete an onboarding certification demonstrating operator/facility vetting, key custody and revocation practices, RF configuration discipline, time synchronization, and adherence to pass scheduling and emergency procedures, with periodic re‑certification.{SV-MA-7,SV-AC-4}{AC-17,AC-20,AC-20(1),SR-6}	Relay and partner stations expand trust boundaries. Certification ensures consistent security practices. Periodic re-validation prevents drift. External governance strengthens link integrity.
SPR-538	The [spacecraft] shall budget CPU/power/memory for security functions (crypto, logging, verification), implement graceful degradation (e.g., summarize logs, throttle verification) that preserves TT&C and safing, and expose telemetry showing throttling decisions and residual capacity.{SV-AV-1,SV-DCO-1}{PE-9,SA-8(8),SC-6,CP-2}	Security must not starve essential TT&C. Explicit resource budgeting ensures sustained enforcement. Graceful degradation preserves mission priority. Telemetry visibility supports oversight.

Alternate Communications Paths

Pre-Operations Government

Pre-Operations Developer/Supplier

Sustainment & Maintenance Government

Sustainment & Maintenance Developer/Supplier

NIST Rev5 Controls

D3FEND Techniques

D3FEND Artifacts

ISO 27001

NASA Best Practice Guide

ESA Space Shield Mitigation

Related MITRE EMB3D Mitigations

Related CSF 2.0

Related BSI Security Measures

Techniques Addressed by Countermeasure

Space Threats Addressed by Countermeasure

Sample Requirements