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Phasing changes one spacecraft’s position along its orbit relative to a saved reference. It accounts for the entry maneuver, drift, recovery and measurement coast together. The result must meet the phase target, terminal orbit and residual relative drift on the same assessed trajectory.

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Create and save an objective

In Operations → Planner → New Plan, select a spacecraft and thruster, choose Phasing, review Initial State to choose the operational TLE/state vector and mass, then continue to Phasing objective. Operations Flight plans can also link a saved Phasing intent to a phase. In Mission Analysis, select Add Phasing in the existing Flight plan editor. Choose a reference mode: Positive phase is ahead in the direction of travel. It does not prescribe the first burn direction. The authoritative observable is mean phase in degrees, not true anomaly, ground-track longitude or three-dimensional separation. Supply the phase tolerance, earliest burn and latest completion, temporary orbital excursion limits, terminal mean-orbit tolerances, permitted plane mismatch, residual drift bound and measurement-coast duration. Distances identify their representation: mean SMA and osculating perigee/apogee radii are different requirements. The selected catalog device supplies thrust, Isp and its maximum continuous firing duration. Declare remaining ignitions, minimum command, timing precision, restart gaps, propellant cap/reserve, rolling duty, sunlight eligibility and blackouts. Prograde and retrograde settings declare the ability to track those RTN directions throughout a firing. Identify the source of these command limits; the editor does not infer mission values. Save Phasing intent retains the target and reference. Select it from Saved Phasing intent when reopening. Computation uses the saved revision shown in the panel; save edits before computing them. Expand Saved reference state and resources to inspect the frozen GCRF/UTC state, its source, mass, and selected propulsion. Changing the controlled-state selection for a later computation does not replace the saved reference.

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Keep the target when replanning

A saved 10° correction with 4° already gained still targets 10°, leaving 6° to achieve. It does not request another 10° from the updated state. For a signed correction at a later entry epoch, provide continuous unwrapped phase history, the matching epoch and its evidence source. A wrapped state alone cannot prove completed relative laps, and a proposed burn is not evidence that it executed. Operations retains its existing future, whole-second planning-window requirement; history must be resolved to the selected planned-start state. Finite commands retain their finer declared timing precision. Select Explicitly replace the saved reference when revised intent should adopt a new anchor. A new correction or changed reference is explicit and versioned. Older proposals remain tied to their producing snapshots.

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References and terminal orbit

The default is an unmanoeuvred reference from the resolved selected state. Mission Analysis uses its explicit analysis initial orbit and frozen assets. The controlled spacecraft always enters a composed phase with the preceding phase’s achieved state, epoch and remaining mass. Advanced reference records use GCRF/UTC state data, source/version, model/data identity, coverage and maneuver assumptions. A leader ephemeris needs ordered knots, an interpolation-gap limit and declared thrust-free coverage of the measurement interval. Missing coverage is not extrapolated, and unknown future leader burns are not assumed. An unavailable saved model/data revision is reported rather than silently replaced. By default, the required terminal mean orbit follows the phase reference at arrival. A separate Terminal orbit reference can specify another return orbit. All authored phase, size/shape, plane and residual-drift requirements still apply together.

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Review the result

The review shows the saved target, selected branch/winding, achieved phase and error, residual drift, terminal orbit residuals, propellant used, remaining propellant and required reserve. Complete elapsed time includes coasts and the measurement interval; Total firing time counts only actual firings. Use the aligned charts to inspect unwrapped phase or selected-branch error, mean SMA, mean eccentricity and osculating perigee/apogee. Firing boundaries and authored limits remain visible. Phase tolerance is an endpoint condition; excursion limits hold along the full trajectory. Outcomes distinguish unsupported input/capability, conflicting requirements, an unsuccessful bounded search and insufficient numerical qualification. A verified candidate can remain usable when further optimization reaches its budget. Minimum propellant is the objective, not a promise of a global optimum. Operations approval uses the retained finite commands through the existing review lifecycle. Changed or unqualified proposals cannot be approved/exported. A coast-only achievement creates no artificial burns. Mission Analysis results remain isolated and cannot be approved as operational proposals. Initial and terminal mean orbits cover near-circular Earth LEO through 2,000 km mean-SMA altitude and eccentricity 0.01. Temporary excursions have separate authored bounds and model-applicability checks. Numerical achievement is modeled evidence; it does not establish indefinite spacing, rendezvous or conjunction clearance.