Orbit Determination

For the complete documentation index, see llms.txt.

Orbit Determination (OD) enables you to compute precise spacecraft orbits by processing tracking measurements. Configure estimation runs, review residuals, and manage the resulting orbit solutions through an intuitive wizard interface. Route: /orbits/orbit-determination/solutions

Overview

Orbit Determination uses tracking measurements (range, angles, position/velocity) to estimate spacecraft state vectors with associated uncertainties. The platform supports:

• Batch Least Squares estimation from tracking measurements
• Maneuver estimation for thrust scale and pointing calibration
• Residual analysis for data quality assessment
• Maneuver-aware processing where detected maneuvers during the measurement arc are either estimated or considered

Refine an Orbit from its Residuals

Beside a saved solution’s Residuals, choose Refine orbit to select and stage rejection or restoration of multiple measurements. Use the Select points icon button at the top right of the chart to enable box selection; hover over or focus it for instructions. Selection and pending edits carry across residual components. Historical residuals without a source measurement link cannot be selected. Choose Apply and configure new run to save those changes and open a new OD configuration. It starts from the solution’s saved state vector and exact measured time span. Original run settings are not stored, so review the initial state, measurements and maneuvers before launching. Saving outlier changes does not launch OD; cancelling the subsequent configuration does not undo those saved changes. The original solution and residuals remain unchanged. Refinement is available after all residuals load and requires a saved state vector and a valid measured time span.

Review Saved Residual Checks

Open Residual checks in Solutions or choose Review saved OD result in Process Monitor. The link opens that process’s saved result, even outside the current date filter; some older jobs and dry runs have none. The summary shows whether the result was accepted and explains any failed checks. A residual is the difference between a measurement and the value predicted by the estimated orbit.

• Convergence: The calculation settled on a solution. This does not mean that the solution agrees with the measurements.
• Residual data: Confirms that the run recorded complete, usable residuals. Missing or invalid residual data prevent the remaining quality checks from being evaluated.
• Individual residuals: Each measured value is compared with the orbit prediction, allowing for the measurement’s stated uncertainty. A failure means at least one difference exceeds its allowed limit.
• Channel fit: Related measurements are checked together, such as repeated position measurements in one direction from the same sensor. The group can fail even when all individual differences are within their limits.

Comparisons shown in σ (sigma) describe disagreement relative to the measurement uncertainties, rather than a distance or speed. A converged result can still be Not accepted and excluded from operational use. For a failure, review the selected measurements, timing, frames, uncertainties and modeled dynamics before rerunning OD. Reopening shows the original outcome. Missing check details stay unavailable; they are not recreated from current data. Run OD again if you need a new assessment. On narrow screens, Toggle solutions list switches between the list and the result.

Approve a Result Despite Failed Checks

Approve use lets Operations users with orbit read and write access approve an eligible converged result without rerunning it. Confirming makes that exact result available to normal orbit selection and calculations. The checks stay Not accepted. Approved for use records who approved the result and when; it does not establish accuracy, approve future runs or waive other workflow requirements. Cancel to leave the result unapproved. Results without a usable saved orbit or complete check details cannot be approved; run OD again instead.

Page Layout

The Solutions page uses a split-view design with a solution list on the right and a details panel on the left.

Viewing Orbit Solutions

Solution List

The solution list displays orbit solutions with the following information:

• Solution ID: Unique identifier
• Status: Convergence indicator icon (green checkmark = numerically converged, red X = not converged, gray circle = unknown). Convergence alone does not establish residual acceptance; check the job outcome in Process Monitor.
• Measurements: Total measurement count used (hover for breakdown by type)
• Spacecraft: Colored satellite icon matching the spacecraft’s assigned color
• Created: Creation date in short format (hover for full UTC timestamp)

Filtering Solutions

• Spacecraft: Filter by one or more spacecraft using the spacecraft filter bar (empty shows all)
• Time Range: Filter by solution creation date
• Group: Group solutions by spacecraft or show as flat list

Solutions are paginated within each group (5 per page) with navigation controls.

Details Panel

Click a solution to view details in the left panel. Use the Previous/Next navigation buttons at the top of the panel to step through solutions without returning to the list. Overview Section:

• Spacecraft name with colored icon
• Creation date (UTC)
• Reference frame (GCRF, EME2000, TEME, or ITRF)

State Vector Section:

• Epoch (UTC)
• Mass (kg), or “From state vector” if mass was inherited
• Toggle between Keplerian and Cartesian tabs:
  • Keplerian: Semi-major axis (km), Eccentricity, Inclination (°), RAAN (°), Arg. of periapsis (°), True anomaly (°)
  • Cartesian: Position X/Y/Z (km), Velocity X/Y/Z (km/s)

Residuals Section:

• Arc time span (start and end epochs)
• Tabbed scatter plots by measurement type:
  • Range: Residuals in meters
  • RA/Dec: Right ascension and declination residuals in arcseconds
  • Az/El: Azimuth and elevation residuals in arcseconds
  • PV: Position (m) and velocity (m/s) residuals for X/Y/Z components
  • Doppler: Range-rate residuals in m/s
• Measurement count badge on each tab showing how many measurements of that type were used
• Sensor legend with dynamic color coding (up to 8 distinct sensor colors)
• Maneuver overlay toggle (flame icon button): Show or hide vertical markers at maneuver epochs on the residual plots. This helps identify whether residual patterns correlate with propulsive events
• Reference frame indicator: A small chip next to the chart title on the PV tab shows the frame the X/Y/Z position and Vx/Vy/Vz velocity residuals are expressed in (driven by the OD solution’s stored reference frame, e.g., GCRF). The other residual tabs (Range, RA/Dec, Az/El, Doppler) are non-frame-bearing and intentionally show no badge. Hover the badge for the full frame name; click Learn more to open the reference frame catalog.

Maneuvers Section: The maneuvers section shows how maneuvers during the measurement arc were handled. Maneuvers are split into two groups:

• Estimated maneuvers: Full cards showing thrust estimation results for each maneuver that was selected for estimation:
  • Normalized performance — thrust scale as a percentage of nominal (100.0% = nominal thrust). Color-coded: green (95–105%), orange (90–110%), red (outside 10% deviation)
  • Azimuth deviation — pointing offset in degrees from nominal thrust direction
  • Elevation deviation — pointing offset in degrees from nominal thrust direction
  • Execution epoch — when the maneuver was executed (UTC)
  • Individual fields show “N/A” when only partially estimated
• Considered maneuvers: Compact pills showing only the maneuver ID. These are maneuvers that occurred during the measurement arc but were not selected for thrust estimation. They are still accounted for in the orbit propagation (the OD process uses their nominal delta-V) but no thrust scale or pointing corrections are computed

When no maneuvers were present during the arc, a “No Maneuver Estimations” empty state is displayed. Activity Section: Timeline showing when the solution was created.

Running Orbit Estimation

Click New Orbit Determination in the toolbar to open the configuration wizard. The wizard guides you through the following steps to configure and launch an orbit estimation.

Step 1: Initial State

Configure the starting point for orbit estimation:

• Source Type: Choose between:
  • Public TLE — Automatically fetched from SpaceTrack using the spacecraft’s NORAD ID. The TLE is displayed read-only once loaded. Requires a NORAD ID to be configured on the spacecraft
  • State Vector — Select an existing state vector from the system (last 30 days, sorted by epoch)
• Mass: Spacecraft mass in kilograms. Choose between entering a manual override or inheriting mass from the selected state vector

Depending on the source type, configure the TLE or state vector parameters.

Step 2: Measurements

Configure which measurements to use for estimation:

• Spacecraft: Select the spacecraft (shown in wizard header)
• Time Range: Configure the measurement arc using one of two modes:
  • Rolling window: Last N days from current time (default 7 days). Adjustable via slider from 6 hours to 10 days in 6-hour increments
  • Custom range: Select a specific end date via date picker (up to 90 days in the past)
• Measurement Types: Select data types to include — RA/Dec, Az/El, Range, PV, Doppler. All available types are selected by default
• Data Sources: Select specific sensors from available sources. Only shown when sensors are associated with the measurement data
• Distribution Chart: Interactive chart visualizing measurement coverage, groupable by type or by sensor

Step 3: Maneuvers

Configure which maneuvers to include for thrust scale estimation during orbit determination. Three selection modes are available:

• All: Estimate thrust scale for every maneuver detected in the measurement time range
• None: Don’t estimate any maneuvers (maneuvers are still considered with their nominal delta-V)
• Above ΔV: Only estimate maneuvers with delta-V at or above a specified threshold (in m/s)

The maneuver list shows all detected maneuvers during the measurement period, each displaying its ID code, delta-V value (m/s), and execution epoch (UTC). Selected maneuvers are highlighted; unselected ones appear dimmed. When enabled, the OD process estimates thrust scale corrections for selected maneuvers, improving orbit accuracy across propulsive events. Unselected maneuvers are still propagated using their nominal parameters.

Step 4: Residuals Preview

Preview residual behavior before running the full estimation. This step shows pre-computation residuals as scatter plots, grouped by measurement type. Use the Select points icon button in the top-right corner of the chart to enable selection. Hover over or focus the button for instructions. Click individual observations or drag boxes around clusters. Each box adds to the selection; click a selected point again or hold Alt while dragging to remove points. Selection carries across component tabs, and each measurement is counted once even when it appears in multiple components. Choose Reject selected or Restore selected to stage changes without recomputing. Pending changes remain highlighted on the existing plots. Continue reviewing other clusters, use Undo to reverse the last edit, or Discard changes to clear unsaved edits. When ready, choose Apply and recompute to save the batch and refresh the preview once. Apply or discard pending changes before moving to another wizard step. If recomputation fails after saving, retry the preview; saved measurement changes remain in effect. Outlier changes update shared measurements and affect future OD runs that use them. They do not modify previously saved solutions. The Recompute button is also available to refresh the preview after other configuration changes.

Step 5: Review

Review all configuration settings before launching. The review page shows summary cards for:

• Initial State — Source type (TLE or State Vector), source details, and mass
• Measurements — Time span and selected measurement types
• Maneuvers — Selected maneuver codes displayed as pills, or “No maneuvers selected” when none are chosen

Each card has an edit button to jump back to that step and adjust settings. Click Launch Orbit Determination to start the process.

Estimated Parameters and Force Model

Regardless of which force model the platform applies during propagation, orbit determination always estimates the same dynamic parameters: a scalar drag coefficient (Cd) and a scalar reflectivity coefficient (Cr). Configuring an attitude profile on the spacecraft so that propagation runs in attitude-dependent mode does not add, remove, or rename estimated parameters. The OD setup, residual plots, and convergence reporting remain consistent; the estimated coefficients act as scaling factors over the underlying force model the propagator is using.

Monitoring OD Progress

After launching, the platform processes OD jobs asynchronously. Open Process Monitor for the job outcome and failure diagnostic; a queued request is not a successful fit. Notifications summarize failures and may shorten long diagnostics. Use the job details for the full explanation. You can navigate away and return later. A failed run may retain an audit solution, but it is not an accepted operational orbit. Solution status is indicated by icons in the solution list:

• Green checkmark: Numerically converged (still subject to residual acceptance)
• Red X: Did not converge (not a label for every OD failure)
• Gray circle: Unknown/processing

Troubleshooting

An OEM upload succeeding means its measurements were imported, not that OD will accept a fit. There are separate stages: configuration, measurement and initial-state preparation, propagation setup, residual preview, numerical estimation, residual acceptance, output preparation, persistence and background execution. A failed job is not necessarily a non-converged fit, nor proof that your measurements are invalid. Suspected causes in a diagnostic are possibilities to investigate, not confirmed diagnoses.

Find the diagnostic

• Before launch: read the initial-state lookup, configuration or launch error. Correct the indicated input; a job may not have been created.
• Residuals preview: read the inline error. Preview evaluates the selected starting orbit without fitting or saving an orbit solution; a successful preview does not certify the final fit. After correcting the cause, choose Recompute. Measurement rejection/restoration already saved with Apply and recompute remains saved even if recomputation fails.
• After launch: open Process Monitor, find the OD job and read its error, including the code (for example OD-7904). Notifications are summaries; open the job for unabridged evidence. Historical jobs retain their original messages and are not rewritten by a messaging fix.
• API: a 202 Accepted response confirms queuing, not estimation success. Read the job status afterward. Immediate errors can carry error and message, or Problem Details errorCode and detail, plus field errors. Preserve the code and diagnostic, not just the HTTP status. The legacy missing-tracking-config response can use Bad Request with [OS-4008] in the message. Internal enum names such as OD_7904 correspond to displayed codes such as OD-7904.

Non-convergence versus residual rejection

• OD-7901: “Numerical estimation did not converge.” There is no accepted orbit. Review initial-state epoch/quality, measurement coverage and geometry, and the Maneuvers step. Retry after making a justified change; repeatedly submitting identical inputs is unlikely to help.
• OD-7904: “Residuals check failed after numerical convergence.” The numerical fit converged, but its residual evidence did not pass acceptance. The result is rejected and must not be used as an accepted state vector or maneuver calibration. Inspect the diagnostic’s type/component, epoch, measurement ID (when available), residual value/unit, sigma and limit, or channel RMS/count. Compare nearby epochs in the residual preview and source measurements. Check timestamps/time system, declared reference frame, units, uncertainty provenance and modeled maneuvers. A discontinuity, measurement anomaly or unmodeled maneuver is possible. Correct erroneous data or explicitly reject a demonstrably bad observation using the residual selection controls; do not increase uncertainties merely to pass acceptance or discard valid observations solely to get a green result.
• OD-7902 / OD-7903: “Residual acceptance failed” for Right Ascension / Declination. Review that component, timing and maneuvers as above before retrying.
• Missing, empty, incomplete or invalid residual evidence: acceptance cannot be established. For missing/empty final evidence, retry once, then contact support if repeated. For invalid uncertainty or incomplete components, review the indicated measurement type and supplied data; if correctly supplied, contact support. Do not interpret missing evidence as a good fit.

A convergence icon in the solutions list describes numerical convergence only. Use the job outcome to establish whether the fit was accepted. Rejected runs may be retained for audit, but no accepted operational result should be inferred from their presence.

Error reference

The following codes are supported typed errors; some are specific to API-supplied configurations. Use the diagnostic alongside this table. The wizard does not expose optimizer trust-region settings, iteration limits, integrator steps, orbit representation or server data files. Do not try to change those internal controls; contact support when valid inputs still fail. Never relax numerical acceptance criteria.

Information to provide support

Include the exact displayed message and code, job ID/name (if created), UTC run time, spacecraft and workspace, measurement arc dates, types/sensors and source measurement ID/epoch/component from the diagnostic. Describe the selected initial-state source/ID and epoch, mass choice, maneuver estimation selection, whether the failure was during preview or a full run, and what changed between attempts. Include a screenshot or the API response’s correlation ID if available, plus whether a result appears in the solutions list. Share relevant source data only through your agreed support channel. Do not send passwords, API tokens, authorization headers, private server paths or raw stack traces.

Deleting Orbit Solutions

From the details panel header, click the ⋮ menu and select Delete Solution. A confirmation dialog will appear before deletion.

Related Pages

• State Vectors: Manage orbit solutions, import solutions (OPM, SpaceX OPM formats), and export ephemeris (OEM format)
• Measurements Data: View and manage tracking measurements
• Tracking Sensors: Configure measurement sources
• Force Model: How VALAR selects between isotropic and attitude-dependent drag/SRP