Satellite maneuver is an operational tactic that can be used by satellites fitted with chemical thrusters to avoid kinetic and some directed energy ASAT weapons. For unguided projectiles, a satellite can be commanded to move out of their trajectory to avoid impact. If the threat is a guided projectile, like most direct-ascent ASAT and co-orbital ASAT weapons, maneuver becomes more difficult and is only likely to be effective if the satellite can move beyond the view of the onboard sensors on the guided warhead.


Best Segment for Countermeasure Deployment

  • Space Segment

NIST Rev5 Controls

D3FEND Techniques

D3FEND Artifacts


ISO 27001

ID: CM0079
NASA Best Practice Guide:  MI-AUTH-01 | MI-AUTH-02 | MI-INTG-01 | MI-DCO-02
ESA Space Shield Mitigation: 
Created: 2023/04/22
Last Modified: 2024/06/11

Techniques Addressed by Countermeasure

ID Name Description
IA-0005 Rendezvous & Proximity Operations Threat actors may perform a space rendezvous which is a set of orbital maneuvers during which a spacecraft arrives at the same orbit and approach to a very close distance (e.g. within visual contact or close proximity) to a target spacecraft.
.02 Docked Vehicle / OSAM Threat actors may leverage docking vehicles to laterally move into a target spacecraft. If information is known on docking plans, a threat actor may target vehicles on the ground or in space to deploy malware to laterally move or execute malware on the target spacecraft via the docking interface.
.03 Proximity Grappling Threat actors may posses the capability to grapple target spacecraft once it has established the appropriate space rendezvous. If from a proximity / rendezvous perspective a threat actor has the ability to connect via docking interface or expose testing (i.e., JTAG port) once it has grappled the target spacecraft, they could perform various attacks depending on the access enabled via the physical connection.
EX-0017 Kinetic Physical Attack Kinetic physical attacks attempt to damage or destroy space- or land-based space assets. They typically are organized into three categories: direct-ascent, co-orbital, and ground station attacks [beyond the focus of SPARTA at this time]. The nature of these attacks makes them easier to attribute and allow for better confirmation of success on the part of the attacker.* *
.01 Direct Ascent ASAT A direct-ascent ASAT is often the most commonly thought of threat to space assets. It typically involves a medium- or long-range missile launching from the Earth to damage or destroy a satellite in orbit. This form of attack is often easily attributed due to the missile launch which can be easily detected. Due to the physical nature of the attacks, they are irreversible and provide the attacker with near real-time confirmation of success. Direct-ascent ASATs create orbital debris which can be harmful to other objects in orbit. Lower altitudes allow for more debris to burn up in the atmosphere, while attacks at higher altitudes result in more debris remaining in orbit, potentially damaging other spacecraft in orbit.* *
.02 Co-Orbital ASAT Co-orbital ASAT attacks are when another satellite in orbit is used to attack. The attacking satellite is first placed into orbit, then later maneuvered into an intercepting orbit. This form of attack requires a sophisticated on-board guidance system to successfully steer into the path of another satellite. A co-orbital attack can be a simple space mine with a small explosive that follows the orbital path of the targeted satellite and detonates when within range. Another co-orbital attack strategy is using a kinetic-kill vehicle (KKV), which is any object that can be collided into a target satellite.* *
EX-0018 Non-Kinetic Physical Attack A non-kinetic physical attack is when a satellite is physically damaged without any direct contact. Non-kinetic physical attacks can be characterized into a few types: electromagnetic pulses, high-powered lasers, and high-powered microwaves. These attacks have medium possible attribution levels and often provide little evidence of success to the attacker.* *
.01 Electromagnetic Pulse (EMP) An EMP, such as those caused by high-altitude detonation of certain bombs, is an indiscriminate form of attack in space. For example, a nuclear detonation in space releases an electromagnetic pulse (EMP) that would have near immediate consequences for the satellites within range. The detonation also creates a high radiation environment that accelerates the degradation of satellite components in the affected orbits.* *
.02 High-Powered Laser A high-powered laser can be used to permanently or temporarily damage critical satellite components (i.e. solar arrays or optical centers). If directed toward a satellite’s optical center, the attack is known as blinding or dazzling. Blinding, as the name suggests, causes permanent damage to the optics of a satellite. Dazzling causes temporary loss of sight for the satellite. While there is clear attribution of the location of the laser at the time of the attack, the lasers used in these attacks may be mobile, which can make attribution to a specific actor more difficult because the attacker does not have to be in their own nation, or even continent, to conduct such an attack. Only the satellite operator will know if the attack is successful, meaning the attacker has limited confirmation of success, as an attacked nation may not choose to announce that their satellite has been attacked or left vulnerable for strategic reasons. A high-powered laser attack can also leave the targeted satellite disabled and uncontrollable, which could lead to collateral damage if the satellite begins to drift. A higher-powered laser may permanently damage a satellite by overheating its parts. The parts most susceptible to this are satellite structures, thermal control panels, and solar panels.* *
.03 High-Powered Microwave High-powered microwave (HPM) weapons can be used to disrupt or destroy a satellite’s electronics. A “front-door” HPM attack uses a satellite’s own antennas as an entry path, while a “back-door” attack attempts to enter through small seams or gaps around electrical connections and shielding. A front-door attack is more straightforward to carry out, provided the HPM is positioned within the field of view of the antenna that it is using as a pathway, but it can be thwarted if the satellite uses circuits designed to detect and block surges of energy entering through the antenna. In contrast, a back-door attack is more challenging, because it must exploit design or manufacturing flaws, but it can be conducted from many angles relative to the satellite. Both types of attacks can be either reversible or irreversible; however, the attacker may not be able to control the severity of the damage from the attack. Both front-door and back-door HPM attacks can be difficult to attribute to an attacker, and like a laser weapon, the attacker may not know if the attack has been successful. A HPM attack may leave the target satellite disabled and uncontrollable which can cause it to drift into other satellites, creating further collateral damage.* *
DE-0009 Camouflage, Concealment, and Decoys (CCD) This technique deals with the more physical aspects of CCD that may be utilized by threat actors. There are numerous ways a threat actor may utilize the physical operating environment to their advantage, including powering down and laying dormant within debris fields as well as launching EMI attacks during space-weather events.
.01 Debris Field Threat actors may hide their spacecraft by laying dormant within clusters of space junk or similar debris fields. This could serve several purposes including concealment of inspection activities being performed by the craft, as well as facilitating some future kinetic intercept/attack, and more.

Space Threats Addressed by Countermeasure

ID Description
SV-CF-2 Eavesdropping (RF and proximity)  
SV-AC-5 Proximity operations (i.e., grappling satellite)  
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-1 Space debris colliding with the spacecraft  

Low-Level Requirements

Requirement Rationale/Additional Guidance/Notes
The [organization] shall protect documentation and Controlled Unclassified Information (CUI) as required, in accordance with the risk management strategy.{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}
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.
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.{AT-3,CP-2}
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.
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)}
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.
The [organization] shall develop an incident response and forensics plan that covers the spacecrafts.{CP-2,IR-1,IR-3,IR-3(2),IR-4(12),IR-4(13),IR-8,SA-15(10),SI-4(24)}
The [organization] shall employ techniques to limit harm from potential adversaries identifying and targeting the [organization]s supply chain.{CP-2,PM-30,SA-9,SA-12(5),SC-38,SR-3,SR-3(1),SR-3(2),SR-5(2)}
The [organization] shall coordinate contingency plan development, and testing of the plan, with organizational elements responsible for related plans.{CP-2(1),CP-4(1)}
The [organization] shall define policy and procedures to ensure that the developed or delivered systems do not embed unencrypted static authenticators in applications, access scripts, configuration files, nor store unencrypted static authenticators on function keys.{SV-AC-1,SV-AC-3}{IA-5(7)}
The [organization] shall maintain 24/7 space situational awareness for potential collision with space debris that could come in contact with the spacecraft.{SV-MA-1}{PE-20}
The [organization] shall develop policies and procedures to establish sufficient space domain awareness to avoid potential collisions or hostile proximity operations.This includes establishing relationships with relevant organizations needed for data sharing.{PE-6,PE-6(1),PE-6(4),PE-18,PE-20,RA-6,SC-7(14)}
The [organization] shall monitor physical access to all facilities where the system or system components reside throughout development, integration, testing, and launch to detect and respond to physical security incidents in coordination with the organizational incident response capability.{PE-6,PE-6(1),PE-6(4),PE-18,PE-20,SC-7(14)}
The [spacecraft] shall terminate the connection associated with a communications session at the end of the session or after 3 minutes of inactivity.{SV-AC-1}{AC-12,SA-8(18),SC-10,SC-23(1),SC-23(3),SI-14,SI-14(3)}
The [spacecraft] shall protect authenticator content from unauthorized disclosure and modification.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),IA-5,IA-5(6),RA-5(4),SA-8(18),SA-8(19),SC-28(3)}
The [spacecraft] encryption key handling shall be handled outside of the onboard software and protected using cryptography.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(1),SC-28(3)}
The [spacecraft] encryption keys shall be restricted so that the onboard software is not able to access the information for key readout.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(3)}
The [spacecraft] encryption keys shall be restricted so that they cannot be read via any telecommands.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(3)}
The [spacecraft] shall produce, control, and distribute symmetric cryptographic keys using NSA Certified or Approved key management technology and processes per CNSSP 12.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-9(6),SC-12,SC-12(1),SC-12(2),SC-12(3)}
The [spacecraft] shall use [directional or beamforming] antennas in normal ops to reduce the likelihood that unintended receivers will be able to intercept signals.{SV-AV-1}{AC-18(5)}
The [spacecraft] shall provide the capability to restrict command lock based on geographic location of ground stations.{SV-AC-1}{AC-2(11),IA-10,SI-4(13),SI-4(25)} This could be performed using command lockout based upon when the spacecraft is over selected regions. This should be configurable so that when conflicts arise, the Program can update. The goal is so the spacecraft won't accept a command when the spacecraft determines it is in a certain region.
The [spacecraft] shall restrict the use of information inputs to spacecraft and designated ground stations as defined in the applicable ICDs.{SV-AC-1,SV-AC-2}{AC-20,SC-23,SI-10,SI-10(5),SI-10(6)}
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)}
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.
The [spacecraft] shall implement cryptographic mechanisms to identify and reject wireless transmissions that are deliberate attempts to achieve imitative or manipulative communications deception based on signal parameters.{SV-AV-1,SV-IT-1}{AC-3,AC-20,SA-8(19),SC-8(1),SC-23(3),SC-40(3),SI-4(13),SI-4(24),SI-4(25),SI-10(6)}
The [spacecraft] shall implement relay and replay-resistant authentication mechanisms for establishing a remote connection.{SV-AC-1,SV-AC-2}{AC-3,IA-2(8),IA-2(9),SA-8(18),SC-8(1),SC-16(1),SC-16(2),SC-23(3),SC-40(4)}
The [spacecraft] shall not employ a mode of operations where cryptography on the TT&C link can be disabled (i.e., crypto-bypass mode).{SV-AC-1,SV-CF-1,SV-CF-2}{AC-3(10),SA-8(18),SA-8(19),SC-16(2),SC-16(3),SC-40(4)}
The [spacecraft] shall enter a cyber-safe mode when conditions that threaten the platform are detected, enters a cyber-safe mode of operation with restrictions as defined based on the cyber-safe mode.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-10(6),CP-12,CP-13,IR-4,IR-4(1),IR-4(3),PE-10,RA-10,SA-8(16),SA-8(21),SA-8(24),SI-3,SI-4(7),SI-13,SI-17}
The [spacecraft] shall provide the capability to enter the platform into a known good, operational cyber-safe mode from a tamper-resistant, configuration-controlled (“gold”) image that is authenticated as coming from an acceptable supplier, and has its integrity verified.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-10(6),CP-12,CP-13,IR-4(3),SA-8(16),SA-8(19),SA-8(21),SA-8(24),SI-13,SI-17} Cyber-safe mode is an operating mode of a spacecraft during which all nonessential systems are shut down and the spacecraft is placed in a known good state using validated software and configuration settings. Within cyber-safe mode authentication and encryption should still be enabled. The spacecraft should be capable of reconstituting firmware and SW functions to preattack levels to allow for the recovery of functional capabilities. This can be performed by self-healing, or the healing can be aided from the ground. However, the spacecraft needs to have the capability to replan, based on available equipment still available after a cyberattack. The goal is for the vehicle to resume full mission operations. If not possible, a reduced level of mission capability should be achieved.
The [spacecraft] shall enter cyber-safe mode software/configuration should be stored onboard the spacecraft in memory with hardware-based controls and should not be modifiable.{CP-10(6),CP-13,SA-8(16),SA-8(19),SA-8(21),SA-8(24),SI-17}
The [spacecraft] shall fail to a known secure state for failures during initialization, and aborts preserving information necessary to return to operations in failure.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-10(6),CP-13,SA-8(16),SA-8(19),SA-8(24),SC-24,SI-13,SI-17}
The [spacecraft] shall fail securely to a secondary device in the event of an operational failure of a primary boundary protection device (i.e., crypto solution).{SV-AC-1,SV-AC-2,SV-CF-1,SV-CF-2}{CP-13,SA-8(19),SA-8(24),SC-7(18),SI-13,SI-13(4)}
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)}
The [spacecraft] shall recover from cyber-safe mode to mission operations within 20 minutes.{SV-MA-5}{CP-2(3),CP-2(5),IR-4,SA-8(24)} Upon conclusion of addressing the threat, the system should be capable of recovering from the minimal survival mode back into a mission-ready state within defined timelines. The intent is to define the timelines and the capability to return back to mission operations.
The [spacecraft] shall provide or support the capability for recovery and reconstitution to a known state after a disruption, compromise, or failure.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-4(4),CP-10,CP-10(4),CP-10(6),CP-13,IR-4,IR-4(1),SA-8(16),SA-8(19),SA-8(24)}
The [spacecraft] shall have multiple uplink paths {SV-AV-1}{CP-8,CP-11,SA-8(18),SC-5,SC-47}
The [spacecraft] shall utilize TRANSEC.{SV-AV-1}{CP-8,RA-5(4),SA-8(18),SA-8(19),SC-8(1),SC-8(4),SC-16,SC-16(1),SC-16(2),SC-16(3),SC-40(4)} Transmission Security (TRANSEC) is used to ensure the availability of transmissions and limit intelligence collection from the transmissions. TRANSEC is secured through burst encoding, frequency hopping, or spread spectrum methods where the required pseudorandom sequence generation is controlled by a cryptographic algorithm and key. Such keys are known as transmission security keys (TSK). The objectives of transmission security are low probability of interception (LPI), low probability of detection (LPD), and antijam which means resistance to jamming (EPM or ECCM).
The [spacecraft] 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
The [spacecraft] shall implement cryptography for the indicated uses using the indicated protocols, algorithms, and mechanisms, in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards: [NSA- certified or approved cryptography for protection of classified information, FIPS-validated cryptography for the provision of hashing].{SV-AC-1,SV-AC-2,SV-CF-1,SV-CF-2,SV-AC-3}{IA-7,SC-13}
The [spacecraft] shall protect system components, associated data communications, and communication buses in accordance with: (i) national emissions and TEMPEST policies and procedures, and (ii) the security category or sensitivity of the transmitted information.{SV-CF-2,SV-MA-2}{PE-14,PE-19,PE-19(1),RA-5(4),SA-8(18),SA-8(19),SC-8(1)} The measures taken to protect against compromising emanations must be in accordance with DODD S-5200.19, or superseding requirements. The concerns addressed by this control during operation are emanations leakage between multiple payloads within a single space platform, and between payloads and the bus.
The [organization] shall describe (a) the separation between RED and BLACK cables, (b) the filtering on RED power lines, (c) the grounding criteria for the RED safety grounds, (d) and the approach for dielectric separators on any potential fortuitous conductors.{SV-CF-2,SV-MA-2}{PE-19,PE-19(1)}
The [spacecraft] shall be designed such that it protects itself from information leakage due to electromagnetic signals emanations.{SV-CF-2,SV-MA-2}{PE-19,PE-19(1),RA-5(4),SA-8(19)} This requirement applies if system components are being designed to address EMSEC and the measures taken to protect against compromising emanations must be in accordance with DODD S-5200.19, or superseding requirements.
The [spacecraft] shall be constructed with sufficient electromagnetic shielding to protect electronic components from damage to the degree deemed acceptable by the Program.{PE-9,PE-14,PE-18,PE-21}
The [spacecraft] shall have on-board intrusion detection/prevention system that monitors the mission critical components or systems.{SV-AC-1,SV-AC-2,SV-MA-4}{RA-10,SC-7,SI-3,SI-3(8),SI-4,SI-4(1),SI-4(7),SI-4(13),SI-4(24),SI-4(25),SI-10(6)} The mission critical components or systems could be GNC/Attitude Control, C&DH, TT&C, Fault Management.
The [spacecraft] shall implement cryptographic mechanisms that achieve adequate protection against the effects of intentional electromagnetic interference.{SV-AV-1,SV-IT-1}{SA-8(19),SC-8(1),SC-40,SC-40(1)}
The [spacecraft] shall provide the capability for data connection ports or input/output devices to be disabled or removed prior to spacecraft operations.{SV-AC-5}{SA-9(2),SC-7(14),SC-41,SC-51} Intent is for external physical data ports to be disabled (logical or physical) while in operational orbit. Port disablement does not necessarily need to be irreversible.
The [organization] shall use NIST Approved for symmetric key management for Unclassified systems; NSA Approved or stronger symmetric key management technology for Classified systems.{SV-AC-1,SV-AC-3}{SC-12,SC-12(1),SC-12(2)} FIPS-complaint technology used by the Program shall include (but is not limited to) cryptographic key generation algorithms or key distribution techniques that are either a) specified in a FIPS, or b) adopted in a FIPS and specified either in an appendix to the FIPS or in a document referenced by the FIPS. NSA-approved technology used for symmetric key management by the Program shall include (but is not limited to) NSA-approved cryptographic algorithms, cryptographic key generation algorithms or key distribution techniques, authentication techniques, or evaluation criteria.
The [organization] shall use NSA approved key management technology and processes.NSA-approved technology used for asymmetric key management by The [organization] shall include (but is not limited to) NSA-approved cryptographic algorithms, cryptographic key generation algorithms or key distribution techniques, authentication techniques, or evaluation criteria.{SV-AC-1,SV-AC-3}{SC-12,SC-12(1),SC-12(3)}
The [spacecraft] shall produce, control, and distribute asymmetric cryptographic keys using [organization]-defined asymmetric key management processes.{SV-AC-1,SV-AC-3}{SC-12,SC-12(1),SC-12(3)} In most cased the Program will leverage NSA-approved key management technology and processes.
The [spacecraft] shall protect the confidentiality and integrity of the [all information] using cryptography while it is at rest.{SV-IT-2,SV-CF-2}{SC-28,SC-28(1),SI-7(6)} * Information at rest refers to the state of information when it is located on storage devices as specific components of information systems. This is often referred to as data-at-rest encryption.
The [spacecraft] shall protect external and internal communications from jamming and spoofing attempts.{SV-AV-1,SV-IT-1}{SC-5,SC-40,SC-40(1)} Can be aided via the Crosslink, S-Band, and L-Band subsystems
The [spacecraft] shall monitor [Program defined telemetry points] for malicious commanding attempts.{SV-AC-1,SV-AC-2}{SC-7,AU-3(1),AC-17(1)} Source from AEROSPACE REPORT NO. TOR-2019-02178 Vehicle Command Counter (VCC) - Counts received valid commands Rejected Command Counter - Counts received invalid commands Command Receiver On/Off Mode - Indicates times command receiver is accepting commands Command Receivers Received Signal Strength - Analog measure of the amount of received RF energy at the receive frequency Command Receiver Lock Modes - Indicates when command receiver has achieved lock on command signal Telemetry Downlink Modes - Indicates when the satellite’s telemetry was transmitting Cryptographic Modes - Indicates the operating modes of the various encrypted links Received Commands - Log of all commands received and executed by the satellite System Clock - Master onboard clock GPS Ephemeris - Indicates satellite location derived from GPS Signals