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The Mars Simulation Project is a Java-based open source project that simulates the activities of the first generation of settlers on Mars with a higher fidelity of modeling and simulation details than a typical PC strategy game.


mars-sim is a general purpose simulator depicting the early development of human settlements on Mars. According to Encyclopædia Britannica, a computer simulation is the use of a computer to represent the dynamic responses of one system by the behavior of another system modeled after it. In essence, a simulation is a mathematical description, or model, of a real system in the form of a computer program.

mars-sim aims to integrate and incorporate as many research disciplines (such as physics, chemistry, biology, economics, psychology, and social science) as possible to simulate the dynamics and behaviors of people, social structure, physical and mechanical systems, and environment in the context of developing human settlements on Mars.

A settler will be a computer agent possessing certain prescribed attributes, dynamic properties and the external characteristics imposed on it. Each makes weighted decisions and interact with one another to produce unexpected results in a sandbox world.

For instance, each settler is assigned with a job, a role, having technical skills, personality traits, natural attributes, and preferences of tasks. They build relationship as they interact and work with one another. They are there to live, dream, explore, and settle Mars.

Operation Modeling

mars-sim adopts a rich set of scientific vocabulary from research journal and paper when it comes to defining operation paradigms and programming models based on the present day technologies that are applicable for the near-term human exploration and settlement on Mars.

For instance, the simulation assumes a low-pressure living environment that facilitates EVA and reduces structural requirements on buildings.

While at the Earth's sea level, the atmospheric pressure is 101 kPa (14.7 psi) and has 20.9% oxygen, in mars-sim, a low pressure atmosphere of 34 kPa (4.93 psi) is chosen for the settlement living with the composition of oxygen at 58.8%. However, inside a rover or an EVA suit, an even lower pressurized environment of 17 kPa (2.47 psi) is adopted for more optimal use of resources and design specifications. See Atmosphere wiki.

Each building has life-support system functions that continuously monitored and periodically replenished oxygen, carbon dioxide, and water moisture. These gases are produced via chemical systems such as Sabatier Reverse Water Gas (SRWG), and Oxygen Generation System (OGS), etc..

An example of operation modeling is the sequence of steps involving the ingress and egress of airlocks before and after an Extra-Vehicular Activity (EVA).

In mars-sim, to walk on the surface of Mars, a settler must come through an intermediate chamber called an airlock to exit the settlement. The airlock allows the passage of people between a pressure vessel and its surroundings while minimizing the change of pressure in the vessel and loss of air from it. One would find an airlock in Astronomy Observatory, any types of garage, all rovers, and any Hab (which stands for habitation module, usually cylinderical in shape) buildings such as Lander Hab, etc.

To perform a team EVA, one of will be selected as the airlock operator, who will ensure that proper procedures be followed before going out for an EVA or after coming back from an EVA.

In case of an egress operation, (1) the airlock would have to be pressurized. (2) The air would be heated so that the atmospheric pressure and temperature are equalized. (3) Then the airlcok operator would unlock and open the inner door. (4) The whole team would enter into the airlock. (5) After all have donned EVA suits, the operator will depressurize the chamber and the gases would be re-captured to match the outside air pressure. (6) At last, he/she would unlock and open the outer door and the whole team will exit to the outside surface of Mars.

Our third example is the Radiation Modeling, which account for how often the Galactic Cosmic Ray (GCR) and Solar Energetic Particles (SEP) would occur during EVA. The cumulative dose is closely monitored in 3 specific exposure interval, namely, the 30-day, the annual and the career lifetime of a settler. It would affect 3 different regions of our body, namely, the Blood Forming Organs (BFO), the Ocular Lens, and the Skin. The dose limits are measured in milli-Severt.

Settlement Development

Player may build numerous settlements spreading across the surface of Mars. Each settlement has a command structure and a development objective.

As mars-sim loosely follows the Mars Direct Mission Plan by Robert Zubrin, there are 6 types of settlement templates to choose from. A 4-settler initial base is called a Mars Direct Plan (MDP) Phase 1 template. A 8-settler base is constructed under MDP Phase 2 template. A 12-settler base is MDP Phase 3. A 24-settler base is designated as Alpha Base. Besides, players may build a Trading Outpost or a Mining Depot near sites with high mineral concentration.


In terms of economic modeling, mars-sim implements the Value Point (VP) system, which keeps track of the supply and demand on each good and resource. As there is no standard currency established on Mars yet, settlers barter trades with neighboring settlements by keeping track of the credits and deficit based on the VPs of the resources in exchange in each trading session.

Jobs and Missions

Settlers spend much of their time learning to live off the land. Assigning meaningful jobs to the settlers are vital to the health of the economy of the settlements. Settlers engage in various tasks such as maintenance, ensuring life support resources are well balanced, growing crops in greenhouses, making secondary food products, and manufacturing needed parts and equipment in workshops.

Settlers will also go out on field Missions to explore and study the surrounding landscapes, to prospect and mine minerals, and to trade with neighboring settlements, etc. They may even decide to migrate from one settlement to another.

Reliability and Malfunctions

The perils of living on Mars are very real. There are close to 30 types of Malfunctions that can strike. The failure rate, the Mean Time Between Failure (MTBF) and the reliability of parts are tracked real-time and updated dynamically based on field available data during the simulation.


Mars is a harsh world but is certainly less unforgiving than our Moon. Settlers come face-to-face with accidents, equipment malfunctions, illnesses, injuries, and even death. Survival depends on how well they work together, improve their survival skills and balance individual versus settlement needs. The reward of

As the settlers learn how to survive the hardship and build up their settlements, players are rewarded with the pure joy of participating in this grand social experiment of creating a new branch of human society on another planetary surface.


For a more detail description of this project, see our project website.


Supported Platforms


Check out the most recent build in the GitHub's Release Tab or in SourceForge Repo

Alternatively, you may use SourceForge's button below to automatically sense the correct platform. Download Mars Simulation Project

Getting Started


As of r5217 and afterward,

As of r4945 and afterward,

Before r4945,

Note 1 : Beginning Java 11, the JRE/JDK is decoupled from the graphic JavaFX API. 
For the JavaFX edition of mars-sim, make sure you also download and configure 
OpenJFK 11 SEPARATELY. See ticket #156 to read the discussions on how to set up
mars-sim to run it under Java 11 for JavaFX UI. 

For linux

  1. The debian edition of mars-sim comes with debian installer for quick installation. However, you will have to install, configure and properly update the JDK or openJDK binary in your linux machine in order to run mars-sim. Please google to find out the most updated instructions for your distro.

  2. To manage multiple versions of java with the use of a tool called SDKMan, see this DZone article.

For macOS

  1. The directory of JDK is at Library/Java/JavaVirtualMachines/jdk-12.jdk/Contents/Home. See DZone for more instructions.

  2. Enter /usr/libexec/java_home -V to find out which version of Java you have installed.

For Windows OS

  1. Start a command prompt and type this set PATH="C:\Program Files\Java\jre-12.0.2\bin";%PATH%.

  2. Alternatively, edit the JAVA_HOME and PATH in the Environment Variables in Control Panel. Add C:\Program Files\Java\jre-12.0.2\bin to the PATH variable.

    Note 2 : The order of precedence inside `PATH` is crucial. The first available folder having Java 
    executable inside will be the one to be loaded by Windows OS. 

    a. Set JAVA_HOME to a JRE or JDK's destination such as C:\Program Files\Java\jdk-12.0.2\bin\ or C:\Program Files\Java\jre-12.0.2\bin.

    b. Add %JAVA_HOME%; to PATH. Type "path" in a command prompt to double check the order of precedence when it comes to searching for the JDK.

    Note 3 : The BEST approach is to enable only one Java build (such as Java 12.0.2) 
    inside `PATH` and remove all other folders referencing other java versions/builds.
  3. Remove any path similar to C:\ProgramData\Oracle\Java\javapath; in PATH variable. It can interfere with the correct version of Java that you would like to use.

    Note 4 : Depending on the order of precedence in Path variable, 
    `C:\ProgramData\Oracle\Java\javapath` can load the undesired version of jre/jdk,
    instead of the java version you prefer.
  4. To test the version of Java that your machine is using, type "java -version" in a command prompt window.

  5. To check if a particular official version of Java is being enabled, start Java Control Panel in Windows's Control Panel as follows :


Feel free to provide your comments at our Facebook community. See also old/archived discussions


Help us by filling in the info below when submitting an issue

Describe the bug

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Note 1 : By providing the info above from the start, you help expedite the handling of the issue you submit.

Note 2 : if you double-click the jar file to start mars-sim and nothing shows up, it's possible that an instance of a JVM be created but it fails to load MainScene. In Windows OS, you may hit Ctrl+ESC to bring up the Task Manager and scroll down to see any "orphaned" instances of Java(TM) Platform SE binary running in the background. Be sure you clear them off the memory by right-clicking on it and choosing End Task.

How to contribute

We welcome anyone to contribute to mars-sim in terms of ideas, concepts and coding. If you would like to contribute to coding, see this wiki for developers. Also, we will answer your questions in our Gitter chatroom.

Official Codebase


This project is licensed under the terms of the GPL v3.0 license.