Principles of ORaaS API

  • ORaas is a set of web services for flight dynamics computations based on the open source library Orekit.

    In the menu, click on a group to access to the documentation of each web service.

    • Flight Dynamics groups conversion tools.
    • Date/Time group is dedicated to the manipulation of dates.
    • From orbital data, the Propagation services compute the motion of objects and the occurrences of some events.
    • TLE services allow the generation of a Two Line Element from the propagation of an orbit bulletin, and the computation of orbital parameters from a TLE.
    • Orbit determination is the set of services necessary for the runs management. When a run is created, ORaaS immediately returns a unique id and launches the computation on the server. This id has to be stored for further requests about the run. Details can be found below.
    • Measurements Generation produces TDM or OEM files.
    • Enumerations give the possible values for input parameters.

    The available services are listed below.

    You can get help on how to use a REST API in our start guide.

    ORaaS uses configuration data which are published by Orekit. They can be downloaded there. Please note that a delay may be necessary before a new version is taken into account.

  • Format of the requests

    For most of the services, required parameters and algorithm configuration are organized in a single parameter called "json".

    • "json" parameter

      JSON is a way to structure objects in sets of key/values pairs. Further details about this format can be found there.

      For each request, the JSON schema is documented in a dedicated page where the request object is displayed in two views:

      • The main view lists all the parameters of the request with their descriptions and any details as expected type, format and default value.
      • To the left, a tree presents the root parameters. The objects are displayed in expandable nodes. Click on the link to scroll the main view to the parameter details. The simple parameters are just mentioned. Those which have a default value are displayed in green.

      As flight dynamics computations require precise configuration, each field has to be named precisely. To help your when writing your request, ORaaS may generate a skeleton with the name of each parameter. You can get it from the help page.

      You can also download the java classes used to parse a request (see our start guide).

    • Units and formats

      The decimal separator for the numbers is the point symbol, the digits are not grouped.

      All dates are expected in the ISO 8601 format but truncated representations are not supported. You can call our service Convert Date to get a formatted string from another representation of the date.

      Angles have to be expressed in radians.

      Distances have to be expressed in meters.

      Azimuth angles origin is the North direction at local point, they are counted clockwise, i.e positive towards the East.

    • Frames

      ORaaS expects frames to be designed by their Orekit name. Their list is returned by these dedicated web services: /enums/frame-name, /enums/ecef-frame-name or /enums/eci-frame-name. More information can be found there.

      ORaaS demos and tools can help you to choose a frame and get its name: go to the Frame Converter and click the button "..." at the right of the input. A popup is displayed where you select the frame and its available options (IERS date conventions and EOP interpolation).

  • Orbit determination services

    Orbit determination feature allows to estimate orbital parameters by fitting measurements. A request consists in:

    • a set of measurements: range, azimuth/elevation or position/velocity. They are uploaded in one or several files formatted according to OEM or TDM specifications. The meta-data associated are expected in the json request.
    • a guessed orbit,
    • the configuration of the algorithms,
    • a key which identifies your runs. Currently, the unicity of your identification is not checked by the server. This key is passed as a cookie named "guid".

    As the computation requires several successive iterations, it could take several minutes (depending on your run configuration). That is the reason why the algorithm is run asynchronously by ORaaS.

    When a request is received for a New Run, the configuration is checked and an identifier is returned. This id has to be stored and sent, along with your identification key, for any further request concerning the run:

    • get the estimated orbit,
    • consult the details (original request, result and report),
    • delete the run.

    A web socket is available to get feedback as your run progresses. Once connected, you will get messages at the end of each iteration of the orbit determination.

    The service Runs List returns the identifiers of the runs existing on ORaaS server which are associated to your key.

    Please note that, currently, runs data may be erased from the ORaaS server for maintenance purpose.

  • List of the ORaaS services

  • Input:
  • Output:
  • Errors: