Logiciel open source de calcul numérique

Passer au contenu principal

Use of Scilab for the Philae landing on comet Churyumov-Gerasimenko

By Thierry Martin, CNES & Romain Garmier, CS-SI

The Rosetta mission, an ESA space probe was launched in 2004 and reached after a 10 years journey comet Churyumov-Gerasimenko in august 2014.

The 12th November 2014, the small lander named Philae was released by Rosetta and successfully landed at the comet surface. The lander reached its targeted site but due to a failure of anchoring system it experienced 2 hours long bouncing and finally landed.

During 57 hours, 10 of 12 scientific instruments on board Philae realized in situ analysis. Unfortunately, as the lander was poorly illuminated, it failed to recharge its batteries and went into the hibernation mode waiting for more sunny days…

CNES, the French space agency, had a strong participation in the mission and is hosting the SONC (Science Operation and Navigation Center).

This center was tasking with:

  • Analysis of comet characteristics and descent trajectories to identify suitable landing sites for Philae based on data products of the Rosetta instruments.
  • Determining after landing the precise location and attitude of Philae as well as the communication opportunities and lander illumination.
  • Planning science operations of the Philae instruments and distributes de data among the instruments teams.

The Flight Dynamics team of SONC (SONC-FD), one the SONC team, was realizing the 2 first activities.

All the activities of SONC-FD were realized through the Flight Dynamics System. This entity covers all hardware and software used for the realization of the operations.

The Philae FDS was composed of:

  • Two PC computers and two laptops operated by Linux
  • Most of the FDS-software were developed in Fortran-90 and have C GUI. They were used for the core computation (computation of Philae trajectories, comet environment models …)
  • Scilab toolboxes for analyzing and visualization the various data (input, output…)

The two used Scilab toolboxes were:

  • Celestlab: this toolbox is developed by the French space agency and contains functions for space mechanics computations. This toolbox is generalist and distributed to the Scilab community,
  • Tracelab: this toolbox was specially developed for the FDS and contains various functionalities to process, plot and analyzed the data. It also included scilab GUI.

This presentation addresses the Rosetta/Philae mission and will also focus on how scilab/celestlab/tracelab were used during the operations.

Co-signed paper by Romain Garmier, Thierry Martin, Eric Jurado, Alejandro Blazquez, Elisabet Canalias, Thierry Ceolin - Centre National d’Etudes Spatiales and CS-SI.

CelestLab, Rosetta, Philae, space, interplanetary, flight dynamics, CNES