This is the web home for SPICE data for Mars Express. For information about the mission operations, go to the Mars Express Science Operations web. For information about the scientific data, go to the Mars Express PSA web.

MARS EXPRESS SPICE KERNELS SET

The ESA SPICE Service (ESS), in collaboration the Mars Express SGS and the Instrument Teams, produces a SPICE Kernel Dataset (SKD) for the Mars Express mission. A complete description including naming convention and an index of the contents of the Mars Express SKD can be found in the description of the Mars Express repository.

The Mars Express SPICE Kernels dataset consists of several SPICE kernels, organised as follows:

The SKD has the following directory structure:

  • root directory (named after the mission: MARS-EXPRESS)
    • kernels
      • ck: Kernels that contain orientation for the spacecraft and some of its structures, (solar arrays, for instance).
      • fk: Kernels that define reference frames needed for the Mission.
      • ik: Kernels for the instruments on board the spacecraft.
      • lsk: Leapseconds kernel.
      • mk: Meta-kernel files (a.k.a "furnsh" files) that provide lists of kernels suitable for a given mission period in the appropiate order.
      • pck: Kernels that define planetary constants.
      • sclk: Spacecraft clock coefficients kernels.
      • spk: Orbit kernels, for the spacecraft and other solar system bodies.
      • dsk: Digital Shape kernels for extended bodies such as the MEX spacecraft
    • misc
      • release notes: Includes the Release Notes of the SKD.
      • cosmo: The SPICE-enchanced configuration for the Mars Express mission.
      • other: different directories of interest.

OBTAINING THE KERNELS

The complete Mars Express SPICE Kernel Dataset can be obtained from the ESA SPICE Service FTP or the ESA SPICE Service HTTP.

In order to obtain the latest operational kernels we recommend you to download the kernels listed in the metakernel. 

The latest version of the SKD's operational sub-set -including only the latest kernels listed on the metakernel- can be obtained either via:

The Release notes of the latest version of the Mars Express kernel collection can be seen here. 

Origin of the kernels

Generic kernels provided by NAIF

NAIF generates kernels that are mission independent. Some of them are used by ESA missions:

  • Binary and text PCK and LSK kernels.
  • Some SPK kernels with ephemeris of the solar system bodies.
  • SPK kernels for ground stations.
  • Frames kernels for ground stations.

Other kernels provided by NAIF

NAIF collaborates with the ESA SPICE Service and the Intrument Teams to create instrument and frames kernels for the different ESA Missions:

  • The instrument kernels (IK) have been developed NAIF, the intrument teams and RSSD/ESA.
  • The Mars Express frames kernel has been created by NAIF, in collaboration with RSSD/ESA. 

Kernels generated with ESOC Ancillary Data

 

Orbit, clock and attitude kernels are created from ESOC data:

  • ESOC ancillary data are the main source of information required to create SPICE kernels for attitude (CK), orbit (SPK) and time (SCLK) information for the Spacecraft.
  • Also, ESOC ephemeris data are used in the creation of SPK kernels for martian satellites. See below for a more detailed explanation on how these kernels are generated.

Kernels created by the Mars Express SGS (Science Ground Segment), alone or in collaboration with the intruments teams

These include:

  • CK kernels with orientation of the Mars Express Solar Arrays.
  • RSSD frames kernel.

Kernels from other sources

These include:

  • Ephemeris kernels provided by Royal Observatory of Belgium. They contain spacecraft position information, calculated independently of ESOC ancillary data.
  • CK kernels describing the motion of the ASPERA scanner, produced by the ASPERA team.

Creation of SPK, CK and SCLK kernels from ESOC Ancillary Data

Orbit Data

In terms of orbital data, the mission can be divided in three different phases: cruise phase, nominal phase and extended phase. The FTP repository provides the most up to date orbit kernels for Mars Express.

Several different types of data products are provided by ESOC: ORHM and ORMM. The ORHM product covers the cruise phase from launch to the Mars Insertion, and provides the orbit data as heliocentric states. There is only one ORHM product. During the nominal and extended phases, new ORMM files are provided on a regular basis (typically once a week), each of them covering a month period. The orbital data contained in these files provide the state of Mars Express with respect to Mars.

MARSAT_ESA products are created using ESOC ephemeris, and give ephemeris information for the martian satellites, from 2004 until the end of 2007. Creating MARSAT_ESA kernels for further dates is not foreseen.

Attitude Data

Attitude data for the spacecraft are provided for all mission phases except for safe modes, for the past and the near future. The attitude is provided in several records, called segments, each covering a specific time span. These segments have no overlap, but there may be gaps between the segments, and even gaps in the segments. The available attitude data is usually predicted, although kernels with reconstructed data are present (for time intervals for which the predicted attitude is known to be not accurate enough).

Time Correlation Data

Time Correlation is one of the most critical pieces of information needed for the use of the SPICE system within the Mars Express mission. This information allows the conversion between the Mars Express S/C Clock time and UTC time. ESOC delivers time correlation data which are the source for the SCLK kernel.

Note: ESOC always provide predicted and reconstituted orbit data, but only predicted attitude data. Only SPK kernels with reconstructed data are archived.

An automated system, called ADCS (Automatic Data Conversion System) is responsible for the generation of CK, SPK and SCLK kernels from the ESOC flight dynamics data. ADCS detects when a new product was generated or a new time correlation packet is available, and run a series of processes in order to create the corresponding kernels.

ADCS uses the SPICE toolkit in order to fulfill its task. It runs in a server physically located at ESAC.

WEBGEOCALC

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 browse. 

Access to the WebGeocalc here.

For more information on WeGeoCalc go to the NAIF WebGeocalc description.

STAYING TUNED

If you want to receive updates and notifications for SPICE for Mars Express you might join the SPICE_MEX mailing list here.

Notifications from the ESA SPICE Service can also be obtained via twitter.

You can also join the #SPICE channel in the OpenPlanetary Group in Slack. You can access using this link.