Core Concepts

This guide introduces the essential concepts you’ll encounter throughout the VALAR platform. Understanding these fundamentals will help you effectively plan missions, analyze orbits, and manage spacecraft operations.

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Spacecraft

The spacecraft is the primary asset in VALAR. Every operation begins with selecting a spacecraft. Before you can perform any orbital analysis, maneuver planning, or conjunction assessment, you must first register your spacecraft with proper international identifiers (NORAD ID and COSPAR ID). Spacecraft properties such as mass, dimensions, and drag coefficient directly affect orbit computations and propagation accuracy. The platform tracks spacecraft lifecycle status (Active or Archived), which determines visibility throughout the interface. Each spacecraft serves as the parent object for all related data: state vectors, maneuvers, conjunctions, and ephemerides.

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Identifiers

International catalogs track space objects using two standard identifier systems. These identifiers are required for receiving conjunction data from monitoring networks like EU SST and Space-Track, and they enable correlation with external tracking measurements. NORAD ID is a numeric catalog number assigned by the U.S. Space Force (example: “25544” for the International Space Station). COSPAR ID follows the format YYYY-NNNX, where YYYY is the launch year, NNN is the launch number, and X identifies the piece (example: “1998-067A” for ISS). Both identifiers appear in TLE format and are essential for linking your spacecraft to public catalogs and external tracking systems.

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Thrusters

Thrusters are the physical propulsion units that execute maneuvers. Their properties directly constrain what maneuvers are feasible for your spacecraft. Key thruster characteristics:

• Thrust: Force output measured in Newtons. Determines spacecraft acceleration capability.
• Specific Impulse (ISP): Fuel efficiency measured in seconds. Higher ISP means less propellant consumed per unit delta-V.
• Maximum Burn Time: Hardware constraint limiting continuous operation duration
• Position: Thruster location (X, Y, Z) relative to spacecraft center of mass. Affects angular momentum.
• Direction: Thrust vector orientation (X+, X-, Y+, Y-, Z+, Z-)

Chemical thrusters provide high thrust but lower efficiency (lower ISP), while electric propulsion offers high efficiency but low thrust. The platform uses thruster properties to validate maneuver feasibility and compute propellant consumption.

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State Vectors

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Cartesian Representation

A state vector defines a spacecraft’s position and velocity at a specific moment in time, the foundation for all orbital analysis. Think of it as a snapshot of where the spacecraft is and how fast it’s moving. Cartesian representation expresses state as:

• Position components: X, Y, Z (typically in kilometers)
• Velocity components: Vx, Vy, Vz (typically in km/s)
• Epoch: The precise timestamp when this state is valid
• Reference frame: The coordinate system used (GCRF, EME2000, TEME, ITRF)

Every state vector includes an originator field identifying the data source, whether generated internally by your orbit determination process or received from external providers. Understanding originator helps you assess data authority and accuracy. Covariance data accompanies state vectors to quantify position and velocity uncertainty. This uncertainty information is critical for collision assessment. You can’t reliably compute collision probability without knowing how confident you are in each spacecraft’s position.

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Keplerian Representation

While Cartesian representation provides precise position and velocity, Keplerian elements offer an intuitive description of orbit shape and orientation. These six classical parameters uniquely define an orbit:

• Semi-Major Axis (SMA): Controls orbit size and period. The primary target for altitude maintenance operations.
• Eccentricity (e): Describes orbit shape, where 0 represents a perfect circle and values less than 1 indicate elliptical orbits
• Inclination (i): The orbit’s tilt relative to Earth’s equator
• Right Ascension of Ascending Node (RAAN, Ω): Defines where the orbit crosses the equator heading northbound
• Argument of Periapsis (ω): Orients the ellipse within the orbital plane
• True Anomaly (ν): Identifies the spacecraft’s current position along its orbit

VALAR derives Keplerian elements from Cartesian state vectors and uses them as targets for maneuver planning. When you plan an altitude adjustment, you’re specifying a target semi-major axis; the platform calculates the required velocity change to achieve it.

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Reference Frames

Reference frames define how positions and velocities are interpreted. Using the wrong frame or mixing frames causes major errors in orbital mechanics. Understanding reference frames is critical for correct data interpretation. The platform supports several standard frames:

• GCRF (Geocentric Celestial Reference Frame): An inertial frame fixed relative to distant stars. The most common choice for orbit propagation.
• EME2000: Mean equator and equinox of epoch J2000.0. Functionally similar to GCRF for most applications.
• TEME (True Equator Mean Equinox): The reference frame used in TLE (Two-Line Element) format.
• ITRF (International Terrestrial Reference Frame): Earth-fixed frame that rotates with the planet. Essential for ground station locations.
• RTN (Radial-Tangential-Normal): A local orbital frame used for expressing covariance and relative motion.

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Covariance Matrices

Covariance quantifies orbit uncertainty and is essential for reliable conjunction assessment. Without knowing how uncertain each spacecraft’s position is, you cannot compute meaningful collision probabilities. A covariance matrix is a 6×6 mathematical structure capturing:

• Position uncertainty: Standard deviation (σ) in X, Y, Z directions, measured in meters.
• Velocity uncertainty: Standard deviation in Vx, Vy, Vz, measured in m/s.
• Correlations: How uncertainties in different directions relate to each other.

Covariance can be expressed in different reference frames, typically RTN (local orbital frame) or XYZ (inertial frame). Larger uncertainty means less confident orbit knowledge. Covariance naturally grows over time as prediction uncertainty accumulates, but shrinks when you incorporate new tracking measurements through orbit determination.

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Maneuver Operations

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Maneuvers

Maneuvers are orbit adjustments performed to maintain trajectory, avoid collisions, or reach target orbits. Each maneuver is characterized by its delta-V (ΔV), the velocity change measured in meters per second, which directly indicates fuel cost. Maneuvers have a planned execution date and duration. Longer burn durations can reduce accuracy due to gravitational changes during the burn. The platform tracks maneuver status as either PLANNED (future operations) or EXECUTED (historical telemetry from completed burns). Each maneuver references a specific thruster device that performs the burn. The standard format for importing and exporting maneuver data is OCM (Orbit Comprehensive Message). Executed maneuvers affect all future state vector predictions. The platform automatically accounts for them during orbit propagation.

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Safety and Risk Management

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Conjunctions (Close Approaches)

Conjunctions represent potential collisions and are the highest operational priority in spacecraft management. When two objects’ predicted trajectories bring them dangerously close, the platform generates conjunction assessments to evaluate collision risk. Critical conjunction parameters:

• Time of Closest Approach (TCA): The moment when objects reach minimum separation.
• Miss Distance: Physical separation at TCA, measured in meters.
• Probability of Collision (Pc): Statistical risk estimate ranging from 0 (no risk) to 1 (certain collision).
• Relative Velocity: How fast the objects approach each other, measured in km/s.

The platform classifies conjunctions as HIGH_RISK, MEDIUM_RISK, or LOW_RISK based on configurable thresholds. Conjunction data arrives in CDM (Conjunction Data Message) format from external sources like EU_EUSST or USA_SPACETRACK, identified by the originator field.

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Orbit Analysis

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Orbit Determination (OD)

Orbit determination is the process of estimating your spacecraft’s true orbit from tracking measurements. Think of it as solving a puzzle: you have noisy observations from ground stations, and you need to find the orbit that best explains those observations. The OD process requires:

• Measurements: Input observation data (ranges, angles)
• A priori state: An initial orbit guess to start the estimation
• Integrator: Numerical method for propagating orbits forward and backward in time
• Convergence criteria: Rules defining when the solution is “good enough”
• Parameter estimation: Deciding what to solve for. Position and velocity certainly, but also drag coefficient, solar pressure, or unmodeled maneuvers.

The quality indicator for OD solutions is residuals, the difference between predicted and actual measurements. Small residuals indicate the estimated orbit accurately explains observations. Better measurements lead to better orbit knowledge, which enables better maneuver planning and collision assessment. VALAR supports automated orbit determination through scheduled OD runs. Configure periodic processing to maintain up-to-date orbit knowledge as new measurements arrive.

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Tracking Measurements

Tracking measurements are raw observational data from ground sensors and serve as the input to orbit determination. Different measurement types provide different information about spacecraft motion:

• RANGE: Direct distance measurement from sensor to spacecraft (kilometers)
• AZEL: Azimuth and elevation angles defining spacecraft direction (degrees)
• RADEC: Right ascension and declination, angular position in celestial coordinates (degrees).
• PVT: Position-velocity-time from GPS or similar systems

Each measurement includes the sensor or station identifier that collected it, along with quality indicators. Measurements may have systematic errors called biases, consistent offsets that can be estimated and removed during orbit determination.

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Ground Stations and Sensors

Ground stations and sensors are physical locations that track spacecraft, defining when observation opportunities occur. Station properties directly affect tracking geometry and measurement quality. Essential station characteristics:

• Location: Latitude, longitude, and altitude determine what spacecraft can be observed
• Elevation mask: Minimum observable elevation as a function of azimuth. Accounts for terrain obstructions like mountains or buildings.
• Sensor type: GROUND_STATION for radio tracking, TELESCOPE for optical observations
• Provider: Operating organization responsible for the station
• Measurement capabilities: Which types of observations the sensor can collect
• Systematic biases: Station-specific measurement errors

More stations with diverse geographic distribution provide better orbit determination geometry and tracking coverage.

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Trajectory Prediction

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Ephemerides

Ephemerides are predicted spacecraft positions over time, essentially a table showing where the spacecraft will be at regular intervals. Think of an ephemeris as a detailed itinerary for the spacecraft’s future path. The platform generates ephemerides by propagating the current orbit state forward in time using orbital mechanics. Key parameters include:

• Time step: Granularity of predictions, typically ranging from 30 to 1800 seconds
• Coverage: The time span of predictions
• Export format: OEM (Orbit Ephemeris Message) is the CCSDS standard

Ephemerides support orbit visualization and conjunction screening. However, accuracy degrades over time as perturbations, unmodeled forces, and especially untracked maneuvers introduce errors. Regular orbit determination updates and incorporating executed maneuvers maintain ephemeris accuracy.

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Time in Space Operations

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Time Systems and Epochs

Precise time is fundamental to orbital mechanics. Position and velocity only have meaning when you know exactly when they’re valid. The platform uses several time concepts: UTC (Coordinated Universal Time) is the standard civil time system, including leap seconds to maintain synchronization with Earth’s rotation. All user-facing timestamps appear in UTC unless configured otherwise. Epoch is the specific moment when a state vector is valid, expressed in ISO-8601 format (example: “2025-01-15T14:30:00.000Z”). Orbital mechanics requires sub-second time precision. Errors of even a few seconds translate to kilometers of position uncertainty. Time range filters appear throughout the platform for querying historical data. Specify start and end dates to retrieve tracking measurements, orbit solutions, or maneuvers within a specific period.

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Data Standards and Provenance

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File Formats (CCSDS Standards)

VALAR uses industry-standard CCSDS (Consultative Committee for Space Data Systems) formats for data exchange, ensuring interoperability with other space operations systems:

• OPM (Orbit Parameter Message): Exchanges a single state vector with associated metadata
• OEM (Orbit Ephemeris Message): Time series of state vectors representing a trajectory
• OCM (Orbit Comprehensive Message): Comprehensive format including maneuver planning data
• CDM (Conjunction Data Message): Close approach warnings from collision monitoring services
• TLE (Two-Line Element): Legacy format offering compact representation but reduced accuracy

Using standard formats enables seamless data exchange with launch providers, tracking networks, and space situational awareness organizations.

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Originator (Data Source)

The originator field identifies who produced orbital data, an organization name like “VALAR,” “SpaceX,” or “18SPCS” (the U.S. Space Force’s Combined Space Operations Center). Different originators have different accuracy levels based on their tracking capabilities and processing methods. The platform allows filtering data by originator, essential when you receive multiple orbit solutions for the same spacecraft from different sources. Data provenance helps you select the authoritative source and maintain data quality.

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Platform Operations

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Asynchronous Job Processing

Computationally intensive operations run asynchronously to keep the user interface responsive. Long-running tasks like orbit determination or maneuver plan generation can take 30 seconds or more. Waiting synchronously would freeze the interface. The platform tracks asynchronous jobs with states: RUNNING → SUCCESS or FAILED. Each job has a unique identifier following the pattern {type}_{orgId}_{timestamp}. You can navigate away from the triggering page and check job status later through the process monitor, which polls for updates at regular intervals. Operations using asynchronous processing include SMA maintenance plan generation, automated orbit determination schedules, and large ephemeris generation requests.

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Authentication and Permissions

VALAR uses Auth0 for authentication and implements fine-grained access control through permission scopes. Your available operations depend on assigned scopes, which follow the pattern {operation}:{resource}. Operations include: read, write, delete, create, update, approve Resource categories include: tracking, ephemeris, maneuvers, orbit, spacecraft, conjunctions For example, the scope write:maneuvers grants permission to create and modify maneuvers, while approve:maneuver-plans enables approving automated maintenance plans. The interface only displays features you have permission to use, and the API enforces scope validation on every request. Access control operates at the organization level. Your permissions apply to all spacecraft within your organization.

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Next Steps

Now that you understand these core concepts: