Apollo 11system modelDashboardMissionOperationsTimelineFunctionsPhysicalBudgetsRequirementsCostReview notesNavigator

Concept of operations

How the Apollo 11 mission unfolds: the sequence of mission phases, the criteria for leaving each phase, and the operations the crew, vehicles and ground perform in each one. It is the operational view a mission planner or flight director would review, and the bridge between the mission requirements (Requirements) and the functions that implement each operation (Functions).

13

mission phases

14

phase transitions

39

operations

41

operation steps across the phases

39 / 39

operations refined by functions

42 / 43

mission requirements traced to operations

Mission phase diagram

Product Mission phase diagram
The mission as a state machine: the 13 phases from prepare for mission to recovery quarantine, and the completion event (a notification accepted by the transition) that moves the mission from one phase to the next.
Use it to see the overall mission flow at a glance, and how many operations and exit criteria each phase has.

stateDiagram-v2
  direction TB
  state "Prepare For<br>Mission" as preparation
  state "Launch" as launch
  state "Trans Lunar<br>Injection" as tli
  state "Trans Lunar<br>Coast" as tlc
  state "Lunar Orbit<br>Insertion" as loi
  state "Lunar Orbit<br>Operations<br>Descent<br>Preparation" as lunarOpsDescentPrep
  state "Powered Descent" as poweredDescent
  state "Lunar Surface<br>Operations" as lunarSurfaceOps
  state "Lunar Ascent<br>Rendezvous" as lunarAscentRendezvous
  state "Trans Earth<br>Injection" as tei
  state "Trans Earth<br>Coast" as tec
  state "Reentry Landing" as reentryLanding
  state "Recovery<br>Quarantine" as recoveryQuarantine
  [*] --> preparation
  preparation --> launch
  launch --> tli
  tli --> tlc
  tlc --> loi
  loi --> lunarOpsDescentPrep
  lunarOpsDescentPrep --> poweredDescent
  poweredDescent --> lunarSurfaceOps
  lunarSurfaceOps --> lunarAscentRendezvous
  lunarAscentRendezvous --> tei
  tei --> tec
  tec --> reentryLanding
  reentryLanding --> recoveryQuarantine
  recoveryQuarantine --> [*]

#	Phase	Completion event	Operations	Exit criteria
1	Prepare For Mission	PreparationPhaseCompletedNotification	2	1
2	Launch	LaunchPhaseCompletedNotification	3	4
3	Trans Lunar Injection	TransLunarInjectionPhaseCompletedNotification	2	4
4	Trans Lunar Coast	TransLunarCoastPhaseCompletedNotification	4	4
5	Lunar Orbit Insertion	LunarOrbitInsertionPhaseCompletedNotification	1	3
6	Lunar Orbit Operations Descent Preparation	LunarOrbitOperationsDescentPreparationPhaseCompletedNotification	3	5
7	Powered Descent	PoweredDescentPhaseCompletedNotification	3	5
8	Lunar Surface Operations	LunarSurfaceOperationsPhaseCompletedNotification	7	6
9	Lunar Ascent Rendezvous	LunarAscentRendezvousPhaseCompletedNotification	5	5
10	Trans Earth Injection	TransEarthInjectionPhaseCompletedNotification	1	3
11	Trans Earth Coast	TransEarthCoastPhaseCompletedNotification	3	4
12	Reentry Landing	ReentryLandingPhaseCompletedNotification	4	4
13	Recovery Quarantine	RecoveryQuarantinePhaseCompletedNotification	3	4

The flow is strictly linear: no phase has more than one outgoing transition; every phase ends when its completion notification is received. No phase or operation models an abort (abort appears only in 4 requirements: AbortSequenceExecutionTime, CountdownAbortRequirement, CrewAscentAbortRequirement, LaunchAbortThresholds). What sets the timing of the phases is the trajectory, below.

The lunar landing mission profile as NASA charted it for the Apollo missions, deliberately out of scale: the same flight as the phases above, broken into its numbered events, from liftoff and Earth parking orbit through lunar orbit, descent and ascent, to reentry and splashdown. Open the image for a legible version of the legend. NASA, public domain.

Phase exit criteria

Product Phase exit criteria
For each phase transition, the conditions that must hold before the mission moves on, as documented on the transition.
Use it to review go/no-go conditions per phase, and spot gates that are thinly specified.

From phase	To	Exit criteria
Prepare For Mission	Launch	all preparations concluded successfully
Launch	Trans Lunar Injection	Successful insertion into stable Earth parking orbit All spacecraft systems verified 'nominal' or 'go' for TLI Astronauts report systems nominal and ready for TLI Ground stations confirm accurate tracking and TLI burn parameters
Trans Lunar Injection	Trans Lunar Coast	Successful S-IVB TLI burn Mission Control confirms free-return trajectory to Moon Successful CSM separation, transposition, docking, and LM extraction S-IVB stage successfully targeted for disposal
Trans Lunar Coast	Lunar Orbit Insertion	Spacecraft reaches precise LOI burn point All CSM systems (SPS engine) verified 'green' and ready for LOI Final navigation updates confirm precise trajectory and burn parameters Astronauts completed pre-LOI checklists
Lunar Orbit Insertion	Lunar Orbit Operations Descent Preparation	Successful LOI burn, achieving stable lunar orbit Mission Control confirms planned lunar orbit Post-LOI checks confirm no anomalies
Lunar Orbit Operations Descent Preparation	Powered Descent	Astronauts transferred into LM and systems activated LM successfully undocked from CSM (visual integrity confirmed) Landing site deemed acceptable by crew and Mission Control Final navigation updates confirm precise descent trajectory and targeting Mission Control gives final 'GO' for Powered Descent
Powered Descent	Lunar Surface Operations	LM descent stage makes soft landing ('The Eagle has landed!') LM integrity confirmed (upright, stable, systems nominal) Astronauts safe, healthy, and ready for surface operations Adequate consumables remain for abort or planned ascent Crew provides initial observations of landing site
Lunar Surface Operations	Lunar Ascent Rendezvous	All planned EVA activities successfully completed Both astronauts safely re-entered LM LM cabin successfully repressurized All LM ascent stage systems confirmed ready for launch Sufficient power and propellant for ascent and rendezvous Lunar orbital mechanics align for rendezvous
Lunar Ascent Rendezvous	Trans Earth Injection	LM ascent stage successfully launched and achieved stable lunar orbit LM ascent stage successfully rendezvoused and docked with CSM Armstrong, Aldrin, and lunar samples transferred back into CSM LM ascent stage successfully undocked and jettisoned CSM (with all three astronauts) confirmed ready for TEI burn
Trans Earth Injection	Trans Earth Coast	Successful TEI burn, achieving trans-Earth trajectory Mission Control confirms proper return path to Earth SPS engine is permanently shut down
Trans Earth Coast	Reentry Landing	CM positioned correctly for atmospheric re-entry (separated from SM) Final navigation updates confirm precise re-entry trajectory and landing zone All Command Module re-entry systems verified 'go' Recovery forces in position and landing zone clear
Reentry Landing	Recovery Quarantine	CM splashes down safely in targeted recovery area Astronauts report safe and healthy in capsule CM flotation systems active and stable Recovery forces have visually acquired CM
Recovery Quarantine	Mission complete	Astronauts extracted to MQF, CM retrieved Lunar samples secured and transferred to MQF Preliminary health checks of astronauts nominal 21-day quarantine period officially begins

• The most demanding gates are Lunar Surface Operations → Lunar Ascent Rendezvous (6 conditions), Lunar Ascent Rendezvous → Trans Earth Injection (5 conditions), Powered Descent → Lunar Surface Operations (5 conditions), Lunar Orbit Operations Descent Preparation → Powered Descent (5 conditions).
• Prepare For Mission closes on a single condition: all preparations concluded successfully.

Trajectory and timing drivers

Most phases follow the trajectory: the time spent in them is set by orbital mechanics more than by the operations. Two numbers drive the schedule: the period of the orbits the spacecraft waits in (set by the chosen altitudes) and the time of the transfer between Earth and Moon (set by the transfer's geometry and energy). The Δv each maneuver needs, which sizes the rocket, comes from the same geometry (the technical budgets carry it through to propellant and mass).

Product Trajectory and timing drivers
The mission phases placed on a schematic Earth–Moon trajectory, the maneuver that drives each phase with the Δv the model requires for it, and the orbit periods and transfer times that set the phases' timing, computed from the trajectory parameters in the model's Δv analysis.
Use it to see why the mission takes the time it does, and which trajectory choices drive the design.

88 min

Earth parking-orbit period

118 min

lunar-orbit period

119 h

Hohmann transfer to the Moon

73 h

translunar coast as flown

18,389 m/s

total required Δv (model)

#	Phase	Driving maneuver	Flown by (model's Δv analysis)	Required Δv (model)	Timing driver
1	Prepare For Mission	—	—	—	— (no timing driver in the model or on this page)
2	Launch	Ascent to Earth parking orbit	sic (stage1), sii (stage2)	9,400 m/s	Parking-orbit period 88 min: TLI waits for the right point in orbit (flown: 1.8 revolutions between S-II separation and TLI)
3	Trans Lunar Injection	Translunar injection burn	sivb (stage3)	3,135 m/s	— (no timing driver in the model or on this page)
4	Trans Lunar Coast	—	—	—	Transfer geometry: a Hohmann transfer takes 119.5 h; flown: 73.0 h (TLI complete → LOI)
5	Lunar Orbit Insertion	Lunar orbit insertion burn	sm (serviceModule)	883 m/s	Lunar-orbit period 118 min: burns, undocking and rendezvous are timed to revolutions
6	Lunar Orbit Operations Descent Preparation	—	—	—	Lunar-orbit period (flown: 29 revolutions from LOI to TEI)
7	Powered Descent	Powered descent to the surface	lmds (lunarModuleDescentStage)	2,100 m/s	— (no timing driver in the model or on this page)
8	Lunar Surface Operations	—	—	—	— (no timing driver in the model or on this page)
9	Lunar Ascent Rendezvous	Ascent to lunar orbit	lmas (lunarModuleAscentStage)	1,870 m/s	Lunar-orbit period: liftoff is timed so the LM meets the CSM
10	Trans Earth Injection	Transearth injection burn	sm (serviceModule)	1,000 m/s	— (no timing driver in the model or on this page)
11	Trans Earth Coast	—	—	—	Return transfer geometry; flown: 58.5 h (TEC start → reentry)
12	Reentry Landing	—	—	—	— (no timing driver in the model or on this page)
13	Recovery Quarantine	—	—	—	— (no timing driver in the model or on this page)

Trajectory parameters of the model's Δv analysis (the arguments it passes to its calculations)

Calculation	Parameter	As written in the model	Value (SI)
calculateTliDeltaV	mu_Earth	3.986E14 ['m³⋅s⁻²']	3.986e+14 m³/s²
calculateTliDeltaV	r_leo	6563 ['km']	6.563e+06 m
calculateTliDeltaV	r_apoapsis	384400 ['km']	3.844e+08 m
calculateLoiDeltaV	v_inf	1000 ['m⋅s⁻¹']	1,000 m/s
calculateLoiDeltaV	mu_Moon	4.9E12 ['m³⋅s⁻²']	4.9e+12 m³/s²
calculateLoiDeltaV	r_periapsis	1839 ['km']	1.839e+06 m

Timing, computed by this page from the model's parameters (Kepler's third law)

• Earth parking orbit (r = 6,563 km): period 88 min.
• Lunar orbit (r = 1,839 km): period 118 min.
• Minimum-energy (Hohmann) transfer from the parking orbit to the Moon's distance (384,400 km): half an ellipse of semi-major axis 195,482 km, 119.5 h (5.0 days).
• Flown (the model's execution record): 73.0 h from TLI complete to LOI (3.0 days) and 58.5 h back from TEC start to reentry.

The Δv analysis assumes a Hohmann transfer that the model's own flight record contradicts

• calculateTliDeltaV is documented as Calculates the required Delta-V for a Hohmann-like Translunar Injection: its required TLI Δv (3,135 m/s) is for a minimum-energy transfer, which would take 119.5 h; the model's own record shows Apollo 11 reaching the Moon in 73.0 h, 39% sooner. A faster transfer needs a higher-energy trajectory and so more TLI Δv than the model requires (orbital mechanics, not a model value).
• 4 of the 6 required Δv values are written as constants with no derivation in the model: dv_required_ascent = 1870 ['m⋅s⁻¹'], dv_required_landing = 2100 ['m⋅s⁻¹'], dv_required_leo = 9400 ['m⋅s⁻¹'], dv_required_tei = 1000 ['m⋅s⁻¹'].
• The model types the gravitational parameter mu_Moon as ISQ::force, though its value is written as 4.9E12 ['m³⋅s⁻²'] (m³/s²).
• The model types the gravitational parameter mu_Earth as ISQ::force, though its value is written as 3.986E14 ['m³⋅s⁻²'] (m³/s²).

What the concept does not yet state

• No nominal duration or time window per phase or operation: the only timing in the model is the mission's plannedDuration and the as-flown record.
• No abort or off-nominal paths: the phase machine is strictly linear, so the launch escape system and the abort requirements have no operational context (the free-return trajectory appears only as an exit criterion of Trans Lunar Injection).
• The mission timeline is one example trace through this nominal plan: the timings above are its drivers.

Phase operation sequences

Product Phase operation sequences
The ordered operations performed within each phase, from the mission preparation to the recovery of the crew.
Use it to walk through what happens in each phase and in which order.

flowchart TB
  classDef phase fill:#2a78d6,stroke:#2a78d6,color:#fff,font-weight:bold
  subgraph nPrepareForMissionPhase[" "]
    direction LR
    nPrepareForMissionPhase_label["Phase 1<br>Prepare For<br>Mission"]:::phase
    nPrepareForMissionPhase_loadConsumablesAndPropellants("Load Consumables<br>And Propellants")
    nPrepareForMissionPhase_transferCrewToVehicle("Transfer Crew To<br>Vehicle")
    nPrepareForMissionPhase_label --> nPrepareForMissionPhase_loadConsumablesAndPropellants
    nPrepareForMissionPhase_loadConsumablesAndPropellants --> nPrepareForMissionPhase_transferCrewToVehicle
  end
  subgraph nLaunchPhase[" "]
    direction LR
    nLaunchPhase_label["Phase 2<br>Launch"]:::phase
    nLaunchPhase_performPreLaunchCountdown("Perform Pre Launch<br>Countdown")
    nLaunchPhase_executeLaunchSequence("Execute Launch<br>Sequence")
    nLaunchPhase_monitorAscentTrajectory("Monitor Ascent<br>Trajectory")
    nLaunchPhase_label --> nLaunchPhase_performPreLaunchCountdown
    nLaunchPhase_performPreLaunchCountdown --> nLaunchPhase_executeLaunchSequence
    nLaunchPhase_executeLaunchSequence --> nLaunchPhase_monitorAscentTrajectory
  end
  nPrepareForMissionPhase ==> nLaunchPhase
  subgraph nTransLunarInjectionPhase[" "]
    direction LR
    nTransLunarInjectionPhase_label["Phase 3<br>Trans Lunar<br>Injection"]:::phase
    nTransLunarInjectionPhase_executeTLIBurn("Execute TLI Burn")
    nTransLunarInjectionPhase_performTranspositionDockingExtraction("Perform<br>Transposition<br>Docking Extraction")
    nTransLunarInjectionPhase_label --> nTransLunarInjectionPhase_executeTLIBurn
    nTransLunarInjectionPhase_executeTLIBurn --> nTransLunarInjectionPhase_performTranspositionDockingExtraction
  end
  nLaunchPhase ==> nTransLunarInjectionPhase
  subgraph nTransLunarCoastPhase[" "]
    direction LR
    nTransLunarCoastPhase_label["Phase 4<br>Trans Lunar<br>Coast"]:::phase
    nTransLunarCoastPhase_conductMidCourseCorrections("Conduct Mid Course<br>Corrections")
    nTransLunarCoastPhase_monitorSpacecraftSystems("Monitor Spacecraft<br>Systems")
    nTransLunarCoastPhase_communicateWithMissionControl("Communicate With<br>Mission Control")
    nTransLunarCoastPhase_manageCrewRestPeriods("Manage Crew Rest<br>Periods")
    nTransLunarCoastPhase_label --> nTransLunarCoastPhase_conductMidCourseCorrections
    nTransLunarCoastPhase_conductMidCourseCorrections --> nTransLunarCoastPhase_monitorSpacecraftSystems
    nTransLunarCoastPhase_monitorSpacecraftSystems --> nTransLunarCoastPhase_communicateWithMissionControl
    nTransLunarCoastPhase_communicateWithMissionControl --> nTransLunarCoastPhase_manageCrewRestPeriods
  end
  nTransLunarInjectionPhase ==> nTransLunarCoastPhase
  subgraph nLunarOrbitInsertionPhase[" "]
    direction LR
    nLunarOrbitInsertionPhase_label["Phase 5<br>Lunar Orbit<br>Insertion"]:::phase
    nLunarOrbitInsertionPhase_executeLOIBurn("Execute LOI Burn")
    nLunarOrbitInsertionPhase_label --> nLunarOrbitInsertionPhase_executeLOIBurn
  end
  nTransLunarCoastPhase ==> nLunarOrbitInsertionPhase
  subgraph nLunarOrbitOperationsDescentPreparationPhase[" "]
    direction LR
    nLunarOrbitOperationsDescentPreparationPhase_label["Phase 6<br>Lunar Orbit<br>Operations<br>Descent<br>Preparation"]:::phase
    nLunarOrbitOperationsDescentPreparationPhase_conductLunarOrbitCheckouts("Conduct Lunar<br>Orbit Checkouts")
    nLunarOrbitOperationsDescentPreparationPhase_prepareLMforUndocking("Prepare LM for<br>Undocking")
    nLunarOrbitOperationsDescentPreparationPhase_performLMUndocking("Perform LM<br>Undocking")
    nLunarOrbitOperationsDescentPreparationPhase_label --> nLunarOrbitOperationsDescentPreparationPhase_conductLunarOrbitCheckouts
    nLunarOrbitOperationsDescentPreparationPhase_conductLunarOrbitCheckouts --> nLunarOrbitOperationsDescentPreparationPhase_prepareLMforUndocking
    nLunarOrbitOperationsDescentPreparationPhase_prepareLMforUndocking --> nLunarOrbitOperationsDescentPreparationPhase_performLMUndocking
  end
  nLunarOrbitInsertionPhase ==> nLunarOrbitOperationsDescentPreparationPhase
  subgraph nPoweredDescentPhase[" "]
    direction LR
    nPoweredDescentPhase_label["Phase 7<br>Powered Descent"]:::phase
    nPoweredDescentPhase_executePoweredDescentBurn("Execute Powered<br>Descent Burn")
    nPoweredDescentPhase_monitorDescentTelemetry("Monitor Descent<br>Telemetry")
    nPoweredDescentPhase_performManualPiloting("Perform Manual<br>Piloting")
    nPoweredDescentPhase_label --> nPoweredDescentPhase_executePoweredDescentBurn
    nPoweredDescentPhase_executePoweredDescentBurn --> nPoweredDescentPhase_monitorDescentTelemetry
    nPoweredDescentPhase_monitorDescentTelemetry --> nPoweredDescentPhase_performManualPiloting
  end
  nLunarOrbitOperationsDescentPreparationPhase ==> nPoweredDescentPhase
  subgraph nLunarSurfaceOperationsPhase[" "]
    direction LR
    nLunarSurfaceOperationsPhase_label["Phase 8<br>Lunar Surface<br>Operations"]:::phase
    nLunarSurfaceOperationsPhase_conductLMPostLandingChecks("Conduct LM Post<br>Landing Checks")
    nLunarSurfaceOperationsPhase_prepareForEVA("Prepare For EVA")
    nLunarSurfaceOperationsPhase_performLunarEVA("Perform Lunar EVA")
    nLunarSurfaceOperationsPhase_collectLunarSamples("Collect Lunar<br>Samples")
    nLunarSurfaceOperationsPhase_deployScientificInstruments("Deploy Scientific<br>Instruments")
    nLunarSurfaceOperationsPhase_concludeEVA("Conclude EVA")
    nLunarSurfaceOperationsPhase_manageLunarSurfaceRestPeriod("Manage Lunar<br>Surface Rest<br>Period")
    nLunarSurfaceOperationsPhase_label --> nLunarSurfaceOperationsPhase_conductLMPostLandingChecks
    nLunarSurfaceOperationsPhase_conductLMPostLandingChecks --> nLunarSurfaceOperationsPhase_prepareForEVA
    nLunarSurfaceOperationsPhase_prepareForEVA --> nLunarSurfaceOperationsPhase_performLunarEVA
    nLunarSurfaceOperationsPhase_performLunarEVA --> nLunarSurfaceOperationsPhase_collectLunarSamples
    nLunarSurfaceOperationsPhase_collectLunarSamples --> nLunarSurfaceOperationsPhase_deployScientificInstruments
    nLunarSurfaceOperationsPhase_deployScientificInstruments --> nLunarSurfaceOperationsPhase_concludeEVA
    nLunarSurfaceOperationsPhase_concludeEVA --> nLunarSurfaceOperationsPhase_manageLunarSurfaceRestPeriod
  end
  nPoweredDescentPhase ==> nLunarSurfaceOperationsPhase
  subgraph nLunarAscentRendezvousPhase[" "]
    direction LR
    nLunarAscentRendezvousPhase_label["Phase 9<br>Lunar Ascent<br>Rendezvous"]:::phase
    nLunarAscentRendezvousPhase_executeLunarAscentBurn("Execute Lunar<br>Ascent Burn")
    nLunarAscentRendezvousPhase_performRendezvousManeuvers("Perform Rendezvous<br>Maneuvers")
    nLunarAscentRendezvousPhase_conductLMCSMDocking("Conduct LMCSM<br>Docking")
    nLunarAscentRendezvousPhase_transferCrewAndSamples("Transfer Crew And<br>Samples")
    nLunarAscentRendezvousPhase_jettisonLM("Jettison LM")
    nLunarAscentRendezvousPhase_label --> nLunarAscentRendezvousPhase_executeLunarAscentBurn
    nLunarAscentRendezvousPhase_executeLunarAscentBurn --> nLunarAscentRendezvousPhase_performRendezvousManeuvers
    nLunarAscentRendezvousPhase_performRendezvousManeuvers --> nLunarAscentRendezvousPhase_conductLMCSMDocking
    nLunarAscentRendezvousPhase_conductLMCSMDocking --> nLunarAscentRendezvousPhase_transferCrewAndSamples
    nLunarAscentRendezvousPhase_transferCrewAndSamples --> nLunarAscentRendezvousPhase_jettisonLM
  end
  nLunarSurfaceOperationsPhase ==> nLunarAscentRendezvousPhase
  subgraph nTransEarthInjectionPhase[" "]
    direction LR
    nTransEarthInjectionPhase_label["Phase 10<br>Trans Earth<br>Injection"]:::phase
    nTransEarthInjectionPhase_executeTEIBurn("Execute TEI Burn")
    nTransEarthInjectionPhase_label --> nTransEarthInjectionPhase_executeTEIBurn
  end
  nLunarAscentRendezvousPhase ==> nTransEarthInjectionPhase
  subgraph nTransEarthCoastPhase[" "]
    direction LR
    nTransEarthCoastPhase_label["Phase 11<br>Trans Earth<br>Coast"]:::phase
    nTransEarthCoastPhase_monitorSpacecraftSystems("Monitor Spacecraft<br>Systems")
    nTransEarthCoastPhase_communicateWithMissionControl("Communicate With<br>Mission Control")
    nTransEarthCoastPhase_prepareCMforReentry("Prepare CM for<br>Reentry")
    nTransEarthCoastPhase_label --> nTransEarthCoastPhase_monitorSpacecraftSystems
    nTransEarthCoastPhase_monitorSpacecraftSystems --> nTransEarthCoastPhase_communicateWithMissionControl
    nTransEarthCoastPhase_communicateWithMissionControl --> nTransEarthCoastPhase_prepareCMforReentry
  end
  nTransEarthInjectionPhase ==> nTransEarthCoastPhase
  subgraph nReentryLandingPhase[" "]
    direction LR
    nReentryLandingPhase_label["Phase 12<br>Reentry Landing"]:::phase
    nReentryLandingPhase_separateModules("Separate Modules")
    nReentryLandingPhase_guideReentryTrajectory("Guide Reentry<br>Trajectory")
    nReentryLandingPhase_deployParachutes("Deploy Parachutes")
    nReentryLandingPhase_conductSplashdownOperations("Conduct Splashdown<br>Operations")
    nReentryLandingPhase_label --> nReentryLandingPhase_separateModules
    nReentryLandingPhase_separateModules --> nReentryLandingPhase_guideReentryTrajectory
    nReentryLandingPhase_guideReentryTrajectory --> nReentryLandingPhase_deployParachutes
    nReentryLandingPhase_deployParachutes --> nReentryLandingPhase_conductSplashdownOperations
  end
  nTransEarthCoastPhase ==> nReentryLandingPhase
  subgraph nRecoveryQuarantinePhase[" "]
    direction LR
    nRecoveryQuarantinePhase_label["Phase 13<br>Recovery<br>Quarantine"]:::phase
    nRecoveryQuarantinePhase_retrieveCrewAndCM("Retrieve Crew And<br>CM")
    nRecoveryQuarantinePhase_initiateQuarantineProcedures("Initiate<br>Quarantine<br>Procedures")
    nRecoveryQuarantinePhase_secureLunarSamples("Secure Lunar<br>Samples")
    nRecoveryQuarantinePhase_label --> nRecoveryQuarantinePhase_retrieveCrewAndCM
    nRecoveryQuarantinePhase_retrieveCrewAndCM --> nRecoveryQuarantinePhase_initiateQuarantineProcedures
    nRecoveryQuarantinePhase_initiateQuarantineProcedures --> nRecoveryQuarantinePhase_secureLunarSamples
  end
  nReentryLandingPhase ==> nRecoveryQuarantinePhase

• Phases perform between 1 and 7 operations; the richest is Lunar Surface Operations (7 operations).
• Operations that recur across phases: Communicate With Mission Control (Trans Lunar Coast, Trans Earth Coast); Monitor Spacecraft Systems (Trans Lunar Coast, Trans Earth Coast).

Operations catalog

Product Operations catalog
The register of all operations with their description, the phases that perform them, how many functions refine them, and the mission requirements they contribute to (a satisfy in the model).
Use it to look up an operation and follow it up to the requirements it meets and down to the functions that implement it.

Operation	Phases	Refining functions	Mission requirements contributed to	Description
Load Consumables And Propellants	Prepare For Mission	1		The process of fueling the Saturn V rocket and loading all necessary consumables like oxygen and water into the spacecraft.
Transfer Crew To Vehicle	Prepare For Mission	1	HLR-R052	The operation where the flight crew moves from the crew quarters to the launch pad and ingresses the Command Module.
Perform Pre Launch Countdown	Launch	1	HLR-R068	The synchronized sequence of checks and configurations performed in the final hours and minutes leading up to liftoff.
Execute Launch Sequence	Launch	3	HLR-R046, HLR-R062	The automated and monitored sequence of engine ignitions, vehicle ascent, and staging events that propel the vehicle into orbit.
Monitor Ascent Trajectory	Launch	3		The continuous tracking of the vehicle's speed, altitude, and flight path during ascent to ensure it is following the correct trajectory.
Execute TLI Burn	Trans Lunar Injection	2	HLR-R003	The critical engine burn of the S-IVB third stage to propel the spacecraft out of Earth orbit and onto a trajectory to the Moon.
Perform Transposition Docking Extraction	Trans Lunar Injection	3		The complex maneuver where the CSM separates, turns around, docks with the LM, and extracts it from the S-IVB stage.
Conduct Mid Course Corrections	Trans Lunar Coast	2	HLR-R011	Small propulsive burns performed during the coast phases to refine the spacecraft's trajectory.
Monitor Spacecraft Systems	Trans Lunar Coast, Trans Earth Coast	2	HLR-R005, HLR-R026, HLR-R030, HLR-R057, HLR-R065, HLR-R067	The continuous monitoring of all onboard systems by the crew and Mission Control to ensure vehicle health.
Communicate With Mission Control	Trans Lunar Coast, Trans Earth Coast	2	HLR-R004, HLR-R048, HLR-R050, HLR-R063, HLR-R066	The two-way exchange of voice, telemetry, and command data between the spacecraft and ground stations.
Manage Crew Rest Periods	Trans Lunar Coast	1	HLR-R028, HLR-R054, HLR-R055	The scheduling and management of sleep, meals, and downtime for the crew to ensure their health and performance.
Execute LOI Burn	Lunar Orbit Insertion	2	HLR-R045, HLR-R061	The engine burn of the Service Module to slow the spacecraft, allowing it to be captured into a stable lunar orbit.
Conduct Lunar Orbit Checkouts	Lunar Orbit Operations Descent Preparation	1		A series of system health checks performed on the CSM and LM while in lunar orbit.
Prepare LM for Undocking	Lunar Orbit Operations Descent Preparation	1		The process of activating the Lunar Module's systems and configuring it for independent flight.
Perform LM Undocking	Lunar Orbit Operations Descent Preparation	1		The physical separation of the Lunar Module from the Command Module in lunar orbit.
Execute Powered Descent Burn	Powered Descent	1	HLR-R002	The continuous, throttleable engine burn of the LM Descent Stage to control the descent from orbit to the lunar surface.
Monitor Descent Telemetry	Powered Descent	1		The real-time tracking of the LM's altitude and velocity during the landing phase.
Perform Manual Piloting	Powered Descent	1	HLR-R047, HLR-R069	The manual control of the LM by the Commander during the final phase of landing to avoid hazards.
Conduct LM Post Landing Checks	Lunar Surface Operations	1		A series of procedures performed after landing to safe the LM's systems and verify its integrity.
Prepare For EVA	Lunar Surface Operations	1		The process of the crew donning their spacesuits and depressurizing the LM cabin for surface exploration.
Perform Lunar EVA	Lunar Surface Operations	2	HLR-R008, HLR-R009, HLR-R032, HLR-R033, HLR-R035, HLR-R036, HLR-R037	The extravehicular activity where the crew operates on the lunar surface to explore and conduct experiments.
Collect Lunar Samples	Lunar Surface Operations	1	HLR-R006, HLR-R038, HLR-R040	The task of gathering and storing rock and soil samples from the lunar surface.
Deploy Scientific Instruments	Lunar Surface Operations	1	HLR-R007, HLR-R059, HLR-R064	The setup of the Early Apollo Scientific Experiments Package (EASEP) on the lunar surface.
Conclude EVA	Lunar Surface Operations	1		The process of the crew re-entering the LM, stowing equipment, and closing the hatch.
Manage Lunar Surface Rest Period	Lunar Surface Operations	1		The scheduled rest and sleep period for the crew while on the Moon.
Execute Lunar Ascent Burn	Lunar Ascent Rendezvous	1	HLR-R049	The firing of the LM Ascent Stage engine to lift off from the lunar surface and return to orbit.
Perform Rendezvous Maneuvers	Lunar Ascent Rendezvous	2		A series of precise orbital maneuvers performed by the LM to match the orbit of and approach the CSM.
Conduct LMCSM Docking	Lunar Ascent Rendezvous	1	HLR-R053	The physical connection of the LM Ascent Stage with the orbiting CSM.
Transfer Crew And Samples	Lunar Ascent Rendezvous	1		The movement of the crew and collected lunar samples from the LM back into the Command Module.
Jettison LM	Lunar Ascent Rendezvous	1		The final separation from the LM Ascent Stage, leaving it in lunar orbit.
Execute TEI Burn	Trans Earth Injection	1		The engine burn of the Service Module to propel the CSM out of lunar orbit and onto a trajectory back to Earth.
Prepare CM for Reentry	Trans Earth Coast	1		Final checks and configurations of the Command Module in preparation for atmospheric entry.
Separate Modules	Reentry Landing	1		The pyrotechnic separation of the Command Module from the Service Module just before reentry.
Guide Reentry Trajectory	Reentry Landing	1		The controlled, lifting flight of the Command Module through the atmosphere to manage heating and target the landing zone.
Deploy Parachutes	Reentry Landing	1		The sequential deployment of drogue and main parachutes to slow the Command Module for a safe splashdown.
Conduct Splashdown Operations	Reentry Landing	1		The final water landing of the Command Module and the activation of its recovery systems.
Retrieve Crew And CM	Recovery Quarantine	1	HLR-R001	The location and recovery of the crew and capsule from the ocean by naval forces.
Initiate Quarantine Procedures	Recovery Quarantine	1	HLR-R010	The implementation of biological isolation protocols for the crew, capsule, and samples upon their return.
Secure Lunar Samples	Recovery Quarantine	1		The process of packaging and transporting the returned lunar samples to the Lunar Receiving Laboratory.

The Mission Operations Control Room in Houston during the Apollo 11 moonwalk, 20 July 1969. The flight controllers are the ground side of operations in the catalog such as CommunicateWithMissionControl and the monitoring of the onboard systems. NASA Johnson Space Center (S69-39593), public domain.

Operational coverage

Product Operational coverage
For each phase, how many of its operations contribute to mission requirements (the model links them with satisfy), and which mission requirements they contribute to.
Use it to find phases and operations that no mission requirement asks for, and check that each phase is justified by the requirements.

Phase	Operations	Operations contributing to a requirement	Mission requirements contributed to
Prepare For Mission	2	1	HLR-R052
Launch	3	2	HLR-R046, HLR-R062, HLR-R068
Trans Lunar Injection	2	1	HLR-R003
Trans Lunar Coast	4	4	HLR-R004, HLR-R005, HLR-R011, HLR-R026, HLR-R028, HLR-R030, HLR-R048, HLR-R050, HLR-R054, HLR-R055, HLR-R057, HLR-R063, HLR-R065, HLR-R066, HLR-R067
Lunar Orbit Insertion	1	1	HLR-R045, HLR-R061
Lunar Orbit Operations Descent Preparation	3	0	—
Powered Descent	3	2	HLR-R002, HLR-R047, HLR-R069
Lunar Surface Operations	7	3	HLR-R006, HLR-R007, HLR-R008, HLR-R009, HLR-R032, HLR-R033, HLR-R035, HLR-R036, HLR-R037, HLR-R038, HLR-R040, HLR-R059, HLR-R064
Lunar Ascent Rendezvous	5	2	HLR-R049, HLR-R053
Trans Earth Injection	1	0	—
Trans Earth Coast	3	2	HLR-R005, HLR-R063, HLR-R066
Reentry Landing	4	0	—
Recovery Quarantine	3	2	HLR-R001, HLR-R010

Coverage

• 18 of 39 operations contribute to at least one mission requirement (42 distinct requirements).
• Phases whose operations contribute to no mission requirement: Lunar Orbit Operations Descent Preparation, Trans Earth Injection, Reentry Landing.
• All 39 operations are refined by at least one function, so the operational and functional layers are fully linked.

Operations contribute to mission requirements; they do not satisfy them

• The model links 18 of the 39 operations to mission requirements with satisfy (47 links). But a mission requirement such as returning lunar samples to Earth is met only when the whole mission completes: collecting the samples on the surface is necessary, not sufficient.
• Read these links as contributes to: the operation performs functions that contribute to the requirement. The concept of operations is what explains how those contributions add up to satisfying it.

Operations without a mission requirement are where derived requirements belong

• 21 operations contribute to no mission requirement (table below). A reviewer would expect such operations to be governed by derived (functional) requirements rather than mission-level ones.
• The model bears this out: for 21 of 21 of them, the functions that refine the operation satisfy functional requirements (table below).

Operation	Phases	Refining functions	Functional requirements on those functions
Conclude EVA	Lunar Surface Operations	CompleteExtravehicularActivity	FLR-R061, FLR-R062
Conduct LM Post Landing Checks	Lunar Surface Operations	PerformPostLandingCheck	FLR-R051, FLR-R052
Conduct Lunar Orbit Checkouts	Lunar Orbit Operations Descent Preparation	PerformOrbitalSystemCheckouts	FLR-R040, FLR-R041
Conduct Splashdown Operations	Reentry Landing	PerformSplashdown	FLR-R083, FLR-R084
Deploy Parachutes	Reentry Landing	DeployDecelerators	FLR-R081, FLR-R082
Execute TEI Burn	Trans Earth Injection	ExecuteTransearthBurn	FLR-R075
Guide Reentry Trajectory	Reentry Landing	GuideAtmosphericEntry	FLR-R079, FLR-R080, FLR-R100
Jettison LM	Lunar Ascent Rendezvous	DiscardAscentStage	FLR-R073, FLR-R074
Load Consumables And Propellants	Prepare For Mission	PerformPropellantLoading	FLR-R001, FLR-R002, FLR-R093
Manage Lunar Surface Rest Period	Lunar Surface Operations	ConductSurfaceRestPeriod	FLR-R063, FLR-R064
Monitor Ascent Trajectory	Launch	AnalyzeLaunchTelemetryFromGround, GuideAscentTrajectory, ObserveAscentDataFromCockpit	FLR-R013, FLR-R014, FLR-R015, FLR-R016, FLR-R017, FLR-R018, FLR-R105
Monitor Descent Telemetry	Powered Descent	MonitorDescent	FLR-R047, FLR-R048, FLR-R097
Perform LM Undocking	Lunar Orbit Operations Descent Preparation	SeparateLanderFromOrbiter	FLR-R044, FLR-R045
Perform Rendezvous Maneuvers	Lunar Ascent Rendezvous	CalculateRendezvousManeuvers, ExecuteRendezvousBurns	FLR-R067, FLR-R068
Perform Transposition Docking Extraction	Trans Lunar Injection	ExecuteTranspositionManeuver, MechanicallyLatchModules, ProvideAttitudeControlThrust	FLR-R021, FLR-R022, FLR-R023, FLR-R025, FLR-R096
Prepare CM for Reentry	Trans Earth Coast	PrepareVehicleForReentry	FLR-R076
Prepare For EVA	Lunar Surface Operations	PrepareForExtravehicularActivity	FLR-R053, FLR-R054
Prepare LM for Undocking	Lunar Orbit Operations Descent Preparation	PrepareLanderForSeparation	FLR-R042, FLR-R043
Secure Lunar Samples	Recovery Quarantine	SecureReturnedSamples	FLR-R089, FLR-R090
Separate Modules	Reentry Landing	SeparateReturnCapsule	FLR-R077, FLR-R078
Transfer Crew And Samples	Lunar Ascent Rendezvous	TransferCrewAndMaterials	FLR-R071, FLR-R072

Modeling issues in the operational layer

• Phase exit criteria are written as prose in doc comments on 13 transitions (if "…" and "…"); no transition has a guard expression, so they cannot be evaluated or checked.
• The start and end of apollo11Phases are ordinary states named initial and final (typed by Initial and MissionComplete) instead of SysML's built-in entry and done.
• Nothing in the model sends the phase-completion notifications (0 usages outside the transitions' accept triggers), so what ends each phase is not modeled.

Produced on 07 Nov 2026 from the Apollo 11 SysML v2 model v0.0.1 with Modelware's Sysight tool, © 2026 Modelware.