NSSDCA ID: XXNO-00599
Availability: Archived at NSSDC, accessible from elsewhere
Time span: 2005-11-09 to 2015-02-06
This description was generated automatically using input from the Planetary Data System.
SPICE data contain geometric and other ancillary information needed to recover the full value of science instrument data. In particular, SPICE kernels provide spacecraft and planetary ephemerides, instrument mounting alignments and spacecraft orientation. Data needed for relevant time conversions is also included. SPICE was designed by the Navigation and Ancillary Information Facility (NAIF) to aid scientists and engineers with ancillary and engineering data. This data comes from a wide range of sources such as the spacecraft, the mission control center and the designers of the spacecraft and its instruments. The ancillary data comprises information on data acquisition; position and orientation of the spacecraft at the time of acquisition; information on the target, such as location, shape and orientation; reference frame specifications and time conversion data. The primary SPICE data sets are often called 'kernels' or 'kernel files'. These kernels are composed of ancillary information, which has been created in such a way as to allow easy access and correct usage by the space science and engineering communities. In addition to the kernels, there is software provided, known as the SPICE Toolkit, along with standards, documentation and software support. The SPICE Toolkit and documentation can be found at: http://naif.jpl.nasa.gov/naif/ The SPICE Toolkit was freely offered to the worldwide space science and space mission engineering communities at the time this data set was released. The few rules governing its use are posted on the ''Rules'' page of the NAIF website: http://naif.jpl.nasa.gov/naif/rules.html SPICE is used on a number of space missions, such as ESA's Mars Express, SMART-1, Venus Express, ExoMars2016, BepiColombo, Solar Orbiter and Rosetta missions, and all of NASA's solar system exploration missions. The SPICE system has been produced and is maintained by Caltech's Jet Propulsion Laboratory under contract to the U.S. National Aeronautics and Space Administration. For an additional explanation of the SPICE system, please consult SPICE_INST.CAT.
The Venus Express SPICE data set has been produced by Semenov, B. (NAIF/JPL) Diaz, J. (ESAC/ESA) Vazquez, J.L. (ESAC/ESA) Barthelemy, M. (ESAC/ESA) Heather, D. (ESAC/ESA) Costa, M. (ESAC/ESA) Escalante, A. (ESAC/ESA) and archived by Vazquez, J.L. (ESAC/ESA) Costa, M. (ESAC/ESA) Escalante, A. (ESAC/ESA)
The Venus Express SPICE data set consists of several SPICE kernels, organised as follows: * CK: These kernels contain information about orientation of the space vehicle or any articulating structure on it. More information on the CK kernels in this data set is provided in CKINFO.TXT. * EK: These kernels contain spacecraft and science instrument event related information. More information on EKs in this data set is provided in EKINFO.TXT. * DSK: These kernels contain information about the shape of the Venus Express spacecraft structures. More information on DSKs in this data set is provided in DSKINFO.TXT. * FK: These kernels contain definitions of and specifications of relationships between reference frames (coordinate systems). Among the frames kernels included, there are kernels that specify reference frames related to the earth, mission targets, and the spacecraft and its instruments. More information on FKs in this data set is provided in FKINFO.TXT. * IK: These kernels contain instrument information, such as field of view or internal timing specifications. There are IKs provided for most of the Venus Express spacecraft instruments. More information on IKs in this data set is provided in IKINFO.TXT. * LSK: These kernels contain a table with the leapseconds used to convert between ET and UTC. If there are multiple LSKs in this data set, the latest kernel supersedes the previous ones. More information on LSKs in this data set is provided in LSKINFO.TXT. * PCK: These kernels provide information about Solar System bodies orientation and shape, and possibly parameters for gravitational, atmospheric or rings models. The data set contains PCK kernels for the planets and their satellites. More information on the PCK kernels in this data set is provided in PCKINFO.TXT. * SCLK: These kernels contain data needed for conversion between ET and spacecraft clock. If there are multiple SCLKs in this data set, the latest kernel supersedes the previous ones. More information on SCLKs in this data set is provided in SCLKINFO.TXT. * SPK: These kernels contain ephemeris data (position and velocity) of the spacecraft and solar system bodies. The data set provides kernels with such information for the planets, the Sun, the Moon, Venus, ground tracking stations, and the Venus Express spacecraft. More information on SPKs in this data set is provided in SPKINFO.TXT. 3.1 - Origin of the kernels. a) Generic kernels such as PCKs, LSKs and some of the SPKs are provided by NAIF. - Frames kernels for ground stations. b) Other kernels provided by NAIF. - The Venus Express frames kernel has been created by B. Semenov, in collaboration with the ESA SPICE Service. c) Kernels generated with ESOC Ancillary 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. d) Kernels created by the ESA SPICE Service, alone or in collaboration with the instrument teams. These include: - The instrument kernels (IK) have been developed by the ESA SPICE Service, in collaboration with the instrument teams and NAIF. - Kernel with mission independent frames, created by the ESA SPICE Service. - CK kernels with orientation of the Venus Express s/c as defined by the quaternions provided by the housekeeping telemetry. - CK kernels with orientation of the Venus Express Solar Arrays. - Kernel with orientation of the MAG boom. - The digital shape kernels (DSK) have been developed by the ESA SPICE Service. e) Kernels from other sources. These include: - CK kernels describing the motion of the ASPERA scanner, produced by the ASPERA team. - CK kernels describing the motion of the VIRTIS scanner, produced by the VIRTIS team. 3.2 - Creation of SPK, CK and SCLK kernels from ESOC Ancillary Data.
In terms of orbital data, the mission can be divided in three different phases: cruise phase, nominal and extended. This data set covers the cruise and nominal phases. The ORVM product provided by Flight Dynamics covers the complete mission, from cruise phase to the end of mission. There is only one ORVM product.
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. Provided attitude data usually is predicted, although kernels with reconstructed data are present in the data set if needed (for time intervals for which the predicted attitude is known to be not accurate enough).
Time Correlation is one of the most critical pieces of information needed for the use of the SPICE system within the Venus Express mission. This information allows the conversion between the Venus Express S/C Clock time and UTC time. ESOC always provide predicted and reconstituted orbit data, but only predicted attitude data. These products are the source of the CK and SPK kernels. ESOC generated time correlation data records and stored them in the telemetry server. These records were the source for the SCLK kernel. An automated system, called ADCS (Automatic Data Conversion System) was responsible for the generation of CK, SPK and SCLK kernels from the ESOC flight dynamics data file products and telemetry server SCLK records. ADCS detected when a new product was generated or a new time correlation packet was available, and ran a series of processes in order to create the proper kernels. ADCS used the SPICE Toolkit in order to fulfill its task. It ran on a server physically located at ESTEC until December 2007; after that date, the server was located at ESAC. 3.3 - Using the SPICE kernels. At least a basic knowledge of the SPICE system is needed in order to use these kernels. The SPICE Toolkit provides versions in Fortran (SPICELIB), C (CSPICE), IDL (icy), Matlab (Mice), and Java (JNISpice) and the user can choose any one that suits him/her. The SPICE routine FURNSH can be used to load a kernel file into a SPICE-based application to make kernel's data usable with SPICE APIs. In the case when two or more kernel files contain data overlapping in time for a given object, for binary kernels, the file loaded last takes precedence. If two (or more) text kernels assign value(s) using the '=' operator to identical keywords, the data value(s) associated with the last loaded occurrence of the keyword are used -all earlier values have been replaced with the last loaded value(s). 3.4 - Meta-kernels A metakernel file, called 'VEX_Vvv.TM', can be found under the ``EXTRAS/MK/'' directory in this data set. This file can be used with a SPICE-based application running on a UNIX workstation to load Venus Express SPICE data provided in this data set together (note that the logical path provided in the PATH_VALUES keyword and pointing to the volume root directory should be changed to the actual path of the volume root directory on the system where the volume is mounted). When there are two or more kernels that cover the same time interval (as is the case here for the .BSP and .BC kernels) the last kernel loaded is the one used by the SPICE software for computations in the interval or overlap.
These data are available on-line from the Planetary Data System (PDS) at:
https://naif.jpl.nasa.gov/pub/naif/pds/data/vex-e_v-spice-6-v2.0/vexsp_2000/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Mr. Boris Semenov | General Contact | NASA Jet Propulsion Laboratory | Boris.Semenov@jpl.nasa.gov |