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NASA Operational Simulator for Small Satellites

The NASA Operational Simulator for Small Satellites (NOS3) is a suite of tools developed by NASA's Katherine Johnson Independent Verification and Validation (IV&V) Facility to aid in areas such as software development, integration & test (I&T), mission operations/training, verification and validation (V&V), and software systems check-out. NOS3 provides a software development environment, a multi-target build system, an operator interface/ground station, dynamics and environment simulations, and software-based models of spacecraft hardware.

Known Issues

  1. Not all cFS delivered apps are included and supported at this time. Currently supported are: CI, TO, SCH, SC, HK, CFS_LIB
  2. CentOS support not included in this release These issues will be addressed in future updates


The best source of documentation can be found at NOS3, as well as a PDF Users Guide attached to this Release on Github


Each of the applications listed below are required prior to performing the installation procedure:


  1. Open a terminal
  2. Navigate to the desired location for the repository
  3. Clone the repository git clone
  4. Clone the submodules git submodule init and git submodule update
  5. Navigate to /nos3/deployment
  6. Run vagrant up and wait to return to a prompt
    • This can take anywhere from 20 minutes to hours depending on internet speeds and host PC specs
    • The VM will reboot multiple times in order to finish install packages for you automatically so wait for that prompt!
    • Sometimes ansible does not seem to install and there is an error like "Could not get lock /var/lib/apt/lists/lock". If this happens run vagrant provision to install ansible and provision.
  7. Login to the nos3 user using the password nos3123! and get to work!
  8. Try building and running following the instructions below

Getting started

It is recommended to share the nos3 repository into the virtual machine

  1. Open a terminal
  2. To build use the make command from the nos3 repo
  3. To run nos3 use the make launch command from the nos3 repo
  4. To halt nos3 use the make stop command from the nos3 repo

Directory Layout

  • /nos3/deployment contains the repository for generating the nos3 virtual environment
  • /nos3/fsw contains the repositories needed to build cFS FSW
    • /apps - the open source cFS apps
    • /cfe - the core flight system (cFS) source files
    • /components - the hardware component apps
    • /osal - operating system abstraction layer (OSAL), enables building for linux and flight OS
    • /psp - platform support package (PSP), enables use on multiple types of boards
    • /tools - standard cFS provided tools
  • /nos3/gsw contains the nos3 ground station files, and other ground based tools
    • /ait - Ammos Instrument Toolkit (Untested for 1.05.0)
    • /cosmos - COSMOS files
    • /OrbitInviewPowerPrediction - OIPP tool for operators
    • /scripts - convience scripts
  • /nos3/sims contains the nos3 simulators and configuration files
    • /cfg - 42 files and NOS3 top level config file
    • /_sim - a component simulator
    • /nos_time_driver - time syncronization for all components
    • /sim_common - common files used by component simulators
    • /sim_server - NOS Engine Server config and build files
    • /sim_terminal - terminal for testing on NOS Engine busses


If this project interests you or if you have any questions, please feel free to contact any developer directly or email

Reporting Issues

Please report issues to the tracking system on Github NOS3 Issues

Frequently Asked Questions

  • A GUI environment hasn't shown up after an extended period (> 1.5 hours), what should I do?
    • Stop the provision, delete the existing VM (if it was created), and try again
    • CTRL + C, vagrant destroy, y, vagrant up, wait, vagrant reload
  • What is the root username and password?
    • vagrant with password vagrant
  • Why doesn't the shared clipboard work?
    • You will most likely need to re-install / update the guest additions and reboot for this to function properly
    • In the VirtualBox menu select: Devices -> Insert Guest Additions CD Image...
    • Follow the instructions provided
  • How can I mount a shared folder so that I edit on my host and compile / run in the VM?
    • In the VirtualBox menu select: Devices -> Shared Folders -> Shared Folders Settings...
    • Select the folder with a plus sign to add your folder
      • Provide the path, name, mount point inside the VM
        • Select Auto-mount, Make Permanent, and OK
  • How can I run 42 without the GUI?
    • Edit the /nos3/sims/cfg/InOut/Inp_Sim.txt and set Graphics Front End to FALSE
  • NOS Engine Standalone server reports NOSEngine.Uart - close uart port failed error?
    • This isn't actually an error and is scheduled to be removed, proceed as usual.


We use SemVer for versioning. For the versions available, see the tags on this repository.


This project is licensed under the NOSA (NASA Open Source Agreement) License.


  • Special thanks to all the developers involved!