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. There are different data sets available for each missions which are briefly described in WebGeoCalc.

The data used for each mission can be found here:

Mission Status Dataset Link to data
ExoMars 2016 Operational Default Metakernel
BepiColombo Study Default Metakernel
JUICE Study CReMA 3.2 - Consolidated Study Trajectory 141a Metakernel
JUICE Study CReMa 3.1 - SOC GCO500 and Europa Flyby-s Study  Metakernel
JUICE Study CReMA 3.1 - SOC Study for GCO500 and Europa Flyby Metakernel
JUICE Study CReMA 3.1 - Consolidated Study Trajectory c141 n45 Metakernel
JUICE Study CReMA 3.0 - Consolidated Study Trajectory 141a Metakernel
JUICE Study CReMA 2.0 - Study Trajectory 140 Metakernel
Mars Express Archived Default Metakernel
Rosetta Archived Default Metakernel
Venus Express Archived Default Metakernel
Chandrayaan-1 Legacy Default Metakernel

IMPORTANT: Understanding the origin of the data being used is paramount for a correct usage of WebGeoCalc 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 a WebGeoCalc instance for PDS Archived data for the latest SPICE increments for RosettaMars Express and Venus Express. This instance can be found here: