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Lander simulation · application of LunCoSim

Descent is a control problem.

A landing profile can look safe until propellant use changes the vehicle, terrain changes the approach and the controller can no longer correct the trajectory. LunCoSim keeps guidance, propulsion, vehicle condition and terrain in one descent study.

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Mission-first — start from the landing requirement Connected study — guidance, propulsion and environment together
ONE DESCENT STUDY · SEE THE CONTROL CONSEQUENCES Navigation IMU · altimeter star tracker · attitude ref Guidance powered descent gravity turn · limiter Thruster mapper accel demand → per-jet commands Propulsion tank · turbopump chamber · nozzle · reaction control mass flow · thrust Vehicle dynamics rigid body, dynamics changing mass & inertia state · contact Terrain site elevation data slope · touchdown sensing measured state closes the loop Burn propellant and the vehicle gets lighter, so the same valve command produces more acceleration — which the guidance only sees because navigation measured it, not because a script told it so.
The connected models keep the important descent assumptions visible. Change the vehicle, controller or site and see the effect without burying the vehicle behavior in a black box.
Mission question

Can the lander reach touchdown with margin?

A landing requirement is more than altitude and velocity. It includes touchdown conditions, payload delivery, propellant margin, recovery behavior and what the system can sense.

Start with the mission outcome: deliver the payload, reach the site and stay within the recovery limits. LunCoSim connects propellant use to system mass, thrust and motion, so the controller sees the consequences of its own decisions.

Use terrain data from the landing site and explicit touchdown sensing to test the approach you care about: uneven ground, an early leg contact or a vehicle arriving with less margin than planned.

What the study includes

Build the descent study around the decision.

Start with a representative lander and change the parts that affect the outcome. Keep the assumptions visible so the team can see why the result changed.

Guidance Compare guidance strategies against the same vehicle and terrain, then change the guidance logic when the mission needs a different descent behavior.
Actuation See whether the system can produce the acceleration and torque the descent needs. Change the thruster layout without rewriting guidance.
Propulsion See how propellant use changes mass and thrust during the descent. Tank, pump, chamber, nozzle and reaction-control behavior run in the same study.
Sensing Test whether the controller can land with the information it will actually receive. Inertial sensors, an altimeter, attitude reference and touchdown sensors are available with filtering.
Terrain Study the site that matters. Use real elevation data so the slope and approach geometry come from the place you intend to land.
Console See the variables that decide the outcome: altitude, rates, target offset, propellant, attitude, reaction-control activity and main-engine state.
Extended mission

Continue from landing into surface operations.

If a lander delivers a rover, delivery and surface operations are part of the same mission. Keep the handoff in one scenario instead of starting a second study after touchdown.

Deploy the rover, drive it off the ramp and continue the same run with the lander on the surface as a communications relay. The team can see what the lander, rover and link each experience during the handoff.

This connects the landing result to the surface operation that follows it, so a change in delivery or communications can be evaluated before the mission design is fixed.

See rover & surface mobility
From requirement to run

From a landing requirement to a controllable descent.

Build one representative descent, understand the margins, then repeat it across vehicle designs, sites and failure cases. The same command interface supports people, scripts and AI agents.

Translate the mission requirement

Choose the payload outcome, site condition, descent profile and recovery margin you need to understand. Keep the first model focused on the decision instead of rebuilding the whole mission at once.

Make the vehicle representative

Set dry mass, inertia, thruster layout and propellant behavior so the simulated vehicle carries the assumptions the design team is actually discussing.

Use the site that matters

Load the target elevation data and let slope, approach geometry and touchdown conditions come from the site instead of a generic flat pad.

Test expected and failure cases

Run the expected profile, then vary a sensor delay, valve behavior or approach angle. Find the cases the controller cannot recover from while there is still time to change the design.

Find the conditions the lander can handle

Vary initial mass, thrust margin, approach angle and site slope to see where the mission remains controllable and where it needs a new design choice.

Where to go deeper

Use specialist detail when it changes the decision.

This page focuses on descent studies. See the platform overview for the broader mission workflow.

Bring in the approach conditions you need

LunCoSim focuses on the descent and landing decision. Use a dedicated trajectory and orbit workflow to calculate the starting conditions, then bring them into the descent study.

Use specialist analysis for plume or surface physics

Use LunCoSim to understand how the landing system behaves at the mission level. Bring in CFD or soil analysis when plume impingement, erosion or detailed surface response changes the decision.

Add detail when it changes the landing decision

Start with the behavior needed to understand control and margins. Add physical detail when it changes the result you need to act on.

Qualification remains a separate step

Use LunCoSim to explore margins, compare designs and rehearse behavior, then use formal verification and acceptance testing for qualification evidence.

Next

Test the landing conditions that matter.

Start with the vehicle, site or failure case you need to understand. See how the connected descent behaves, then decide where higher-fidelity analysis is worth the effort.

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Want the operator's side of it? Our live crewed missions run on this simulator.