The WebGeocalc tool (WGC) provides a web-based graphical user interface to many of the observation geometry computations available from the "SPICE" system. A WGC user can perform SPICE computations without the need to write a program; the user need have only a computer with a standard web browser. WGC is provided to the ESA SPICE Service by NAIF.

The WGC server is built upon the Toolkit code available from the NAIF server; it merely provides another kind of interface to that code.


The ESA Planetary Mission's WebGeoCalc instance is available here:


The instance currently contains operational and archived data as well as data for training purposes of for specific cross-mission scenarios. The data used is the latest available in the operational repository and from the latest archive increment published in the PSA. More concretely WGC includes all the meta-kernels avaiable for the ESA missions.

A RESTful (programmatic) interface to the tool, accessible from a script on your computer, is also available now. When using this RESTful interface there is no human interaction involved. There is API documentation describing how to use this RESTful interface, including some examples. This same documentation is also available via a link named "API Docs" seen at the top-right portion of each WGC2 page. This second version can also be used via GUI controls and is accessible here.

IMPORTANT: Understanding the origin of the data being used is paramount for a correct usage of WebGeocalc we highly recommend you to read this page. If you have any doubts about the data beyond what is described in the tool when selecting a given Data set please contact the ESA SPICE Service.


This WGC instance supports ESA planetary projects and planetary data research in several ways:

  • It opens up much of the SPICE computational capability to those unable to write programs
  • It offers a mechanism that scientists and engineers may use to help verify their own SPICE-based code
  • It provides a quick and easy means for peer reviewers of science data archives to spot check many of the observation geometry computations included in the archive
  • It opens the possibility to obtain a quick answer to a geometry question arising during a meeting

WGC makes the job of computing many kinds of observation geometry quicker and somewhat easier than if one has to write a program to do so. A modest amount of HELP information is provided within the tool. Nevertheless, the user must have some understanding of the concepts and terminology used in the field of planetary science, and in SPICE.


More information about WebGeocalc can be found here.  

A NAIF WebGeocalc Tutorial (PDF format) provides an introduction to this tool.

In addition NAIF provides two WebGeocalc instances for PDS Archived data for the latest SPICE increments for RosettaMars Express and Venus Express. This instance can be found here:

JAXA via DARTS provides a WebGeocalc instance for a selection of their missions: