Close Approaches
The Close Approaches tab provides a tool to calculate potential conjunctions between the satellite and other objects in orbit.
Understanding Close Approaches
A close approach (or conjunction) occurs when two space objects pass near each other. Monitoring close approaches is critical for:
- Collision avoidance - Identifying potential collision risks
- Situational awareness - Understanding the satellite’s orbital neighborhood
- Maneuver planning - Evaluating whether avoidance maneuvers may be needed
- Tracking analysis - Studying the behavior of nearby objects
The Close Approaches tab is disabled for satellites that have decayed, as position predictions are no longer possible.
Calculating Close Approaches
To calculate close approaches:
- Navigate to the satellite’s Close Approaches tab
- Configure the calculation parameters
- Select
CALCULATEto run the analysis
Calculation Parameters
| Field | Description |
|---|---|
| Time Range | How many hours into the future to search (1-24 hours) |
| Minimum Distance | Distance threshold in kilometers (1-100 km) |
Only approaches where the objects come within the minimum distance are included in results.
Running the Calculation
Select CALCULATE to find close approaches. The calculation propagates the orbits of the primary satellite and all cataloged objects to identify potential conjunctions.
Close Approaches Results
Results are displayed in a table showing all identified conjunctions:
| Column | Description |
|---|---|
| Time of Closest Approach (TCA) | When the objects are at minimum distance |
| Secondary Object | The other satellite or debris involved |
| Miss Distance | Minimum separation distance in kilometers |
| Relative Velocity | Closing speed at TCA |
Interpreting Results
- Very close approaches (< 1 km) - Warrant careful attention and may require action
- Moderate approaches (1-10 km) - Should be monitored as predictions evolve
- Distant approaches (> 10 km) - Generally low concern but useful for awareness
Secondary Object Details
Click on a secondary object name to navigate to its satellite detail page for more information about the approaching object.
Limitations
Close approach calculations are based on:
- Current orbital elements - Predictions are only as accurate as the available element sets
- Two-body propagation - Simplified orbital mechanics (perturbations may affect actual trajectories)
- Cataloged objects only - Untracked debris is not included in the analysis
Use Cases
| Scenario | Application |
|---|---|
| Active satellite operations | Monitor for potential collision risks |
| Debris tracking | Understand collision probability for debris objects |
| Constellation management | Track approaches between constellation members |
| Research | Study orbital dynamics and space traffic patterns |