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NASA Space Science Data Coordinated Archive Header



Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1996-05-30 to 2001-02-28


This description was generated automatically using input from the Planetary Data System.

Data Set Overview

This data set includes the complete set of NEAR SPICE data files (``kernel files''), which can be accessed using SPICE software. The 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, spacecraft orientation, and data needed for relevant time conversions. This data set was created by assembling the original NEAR SPICE data sets NEAR-A-SPICE-6-CRUISE1-V1.0 NEAR-A-SPICE-6-MATHILDE-V1.0 NEAR-A-SPICE-6-CRUISE2-V1.0 NEAR-A-SPICE-6-EARTH-V1.0 NEAR-A-SPICE-6-CRUISE3-V1.0 NEAR-A-SPICE-6-EROS/FLY/BY-V1.0 NEAR-A-SPICE-6-CRUISE4-V1.0 NEAR-A-SPICE-6-EROS/ORBIT-V1.0 NEAR-A-SPICE-6-EROS/SURFACE-V1.0 containing data for individual mission phases into a single data set containing data for the whole mission. Most kernels from the original data sets were included in this data set with the same names and without changing their data. The only exception was daily CK files that were merged into tri-monthly CK files to reduce the total number of kernels to increase the usability of the archive. But even in the case of the CK files the merge was done in such way that the original data was not altered. The comments in all kernels were changed slightly either by adding a copy of the new PDS label at the top or by replacing the copy of the old label with a copy of the new label.

Data Types (SPICE kernel types)

SPK kernels contain ephemerides for spacecraft, planets, satellites, comets and asteroids as well as for moving or fixed spacecraft and instrument structures. They provide position and velocity, given in a Cartesian reference frame. SPK files are located under the ``data/spk'' directory of this data set. PCK kernels contain certain physical, dynamical and cartographic constants for target bodies, such as size and shape specifications, and orientation of the spin axis and prime meridian. PCK files are located under the ``data/pck'' directory of this data set. IK kernels (Instrument description kernels) give descriptive and operational data peculiar to a particular scientific instrument, such as internal timing relative to the spacecraft clock and field-of-view model parameters. IK files are located under the ``data/ik'' directory of this data set. CK kernels describe pointing, containing a transformation traditionally called the C-matrix which is used to determine time-tagged pointing (orientation) angles for a spacecraft structure upon which science instruments are mounted. CK files are located under the ``data/ck'' directory of this data set. EK (Events) kernels are derived from the integrated sequence of events used to produce actual spacecraft commands. EK files are located under the ``data/ek'' directory of this data set. LSK (Leapseconds) kernels contain the leapseconds and the values of other constants required to perform a transformation between Universal Time Coordinated (UTC) and Ephemeris time (ET). LSK files are located under the ``data/lsk'' directory of this data set. SCLK (Spacecraft Clock) kernels contain on-board clock calibration data required to perform a mapping between Ephemeris time (ET) and spacecraft on-board time (SCLK). SCLK files are located under the ``data/sclk'' directory of this data set. FK (Frame Definitions) kernels contain information required to define reference frames, sources of frame orientation data and connections between these frames and other frames supported within the SPICE system. This includes mounting alignment information for each instrument. FK files are located under the ``data/fk'' directory of this data set.

Kernel File Details

A brief overview of the different types of NEAR kernels included in this data set is provided in the CONFIDENCE_LEVEL_NOTE section of this file while details specific to individual files are found in the ``*info.txt'' files in the corresponding data directory. The most detailed description of the data in each file is provided in metadata included inside the file -- in the description area of text kernels or in the comment area of binary kernels.


The SPICE Toolkit contains software modules needed to read SPICE kernel files. SPICE software is highly documented via internal headers. Additional documentation is available in separate ASCII text files called Required Reading files. For example, the S- and P- Kernel (SPK) Required Reading File, named SPK.REQ, describes use of the SPK kernel file readers and contains sample programs. The latest SPICE Toolkit for a variety of computer platforms such as PC, Mac, SUN, etc. is available at the NAIF Node of PDS electronically (via anonymous FTP and WWW servers). Refer to information in ``software/softinfo.txt'' for details regarding obtaining this software. Each version of the Toolkit is also archived at the NASA National Space Science Data Center.

Loading Kernel Files into a SPICE-based App.

The easiest way to make data from a collection of SPICE kernels available to a SPICE-based application is to list these kernels in a meta-kernel and load it into the program using the high level SPICE data loader routine FURNSH. This data set provides such meta-kernel(s) under the ``extras/mk'' directory. For more information about the NEAR meta-kernel(s), see the file ``extras/mk/mkinfo.txt''.

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names

  • NEAR-A-SPICE-6-V1.0


  • Ancillary: Ephemeris/Orbit/Attitude

Additional Information


Questions and comments about this data collection can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Mr. Boris SemenovGeneral ContactNASA Jet Propulsion
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