PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = " 2001-09-06 JHU/APL:Taylor initial version; 2012-12-21 NAIF:Semenov update for the whole-mission data set; 2013-01-28 NAIF:Semenov changed reference to ACTON1996; 2013-02-08 NAIF:Semenov changed START_TIME and STOP_TIME; 2021-04-12 NAIF:Costa updated CITATION_DESC with DOI; " OBJECT = DATA_SET DATA_SET_ID = "NEAR-A-SPICE-6-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "NEAR SPICE KERNELS V1.0" DATA_SET_TERSE_DESC = " Navigation and ancillary data in the form of SPICE System kernel files for the NEAR spacecraft. " ABSTRACT_DESC = " 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. " CITATION_DESC = " Semenov B.V., H.W. Taylor, and C.H. Acton, NEAR SPICE KERNELS V1.0, NEAR-A-SPICE-6-V1.0, NASA Planetary Data System, 2012. https://doi.org/10.17189/1520103 " DATA_SET_COLLECTION_MEMBER_FLG = "N" START_TIME = 1996-05-30T23:58:58 STOP_TIME = 2001-02-28T17:14:46 DATA_SET_RELEASE_DATE = 2012-12-31 PRODUCER_FULL_NAME = "BORIS V. SEMENOV" DATA_OBJECT_TYPE = "SPICE KERNEL" DETAILED_CATALOG_FLAG = "Y" DATA_SET_DESC = " 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. Software ======== 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 Application =================================================== 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''. " CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= This volume contains SPICE kernel files created during mission operations only. No post processing has been done on these data except for merging daily CK files into tri-monthly CK files in such way that the original data was not altered. Some general information about this collection follows here, but the prospective user is also referred to extensive descriptions about each file that are stored inside each kernel file. These metadata provide detailed information regarding the information source from which the data were derived, the type of processing applied to the source data, applicability of the data, etc. Metadata are located in the ``comment area'' for binary kernel types (SPK, CK, ESQ), accessible using either the COMMNT or SPACIT utility program found in the NAIF Toolkit. Metadata are located after ``\begintext'' markers within the text kernel types (PCK, IK, FK, LSK, SCLK, MK), accessible by using any available text file display tool such as a word processor, text editor, or the unix ``more'' or ``cat'' commands. Where there are questions about data accuracy or ``confidence'' not addressed herein the reader is invited to contact the NAIF node of the Planetary Data System for possible further information. SPK Files ========= Three kinds of SPK files are provided in this archive: SPK files for the spacecraft orbit; SPK files for the Solar System planets and asteroids (Eros, Earth, Sun, etc); and SPK files with the DSN station locations. Each kind of file is briefly described below; more information is available in the file ``data/spk/spkinfo.txt''. Spacecraft Orbit SPK Files -------------------------- SPK files for the spacecraft were created by the NEAR Navigation team/JPL, NEAR Radio Science Team/JPL, and NLR Team/GSFC. The SPK files by NEAR Navigation team/JPL were specifically created for science users and distributed through the Science Data Center. These kernels were merged from series of final operational reconstructed OD solution SPKs. Combined, these SPKs cover the whole mission. The SPK kernels by the NEAR Radio Science Team/JPL and NLR Team/GSFC were created as a by-product of science processing of the Eros orbital data by these teams and cover only the Eros orbit part of the mission. Solar System Body SPK Files --------------------------- The solar system body SPK files were provided by the JPL Navigation team by way of the NAIF group. The accuracies for the bodies in each file can be obtained by inspecting the comment portion of each file. The asteroid SPK files were provided directly from the JPL Navigation team. The comment portion of the Mathilde and Eros SPK files provide detailed information regarding their usage and accuracy. Station Locations SPK Files --------------------------- The DSN station locations SPK file was provided by the NAIF group. It contains locations of the four tracking stations used by the NEAR mission. CK Files ======== C-kernel files provide orientation of the spacecraft. With the exception of NIS, the NEAR instruments have fixed orientation. MSI, NIS, XGRS and NLR all nominally are oriented along the spacecraft positive X-axis. The Solar panels and high gain antenna are nominally oriented in the positive z-axis. The small difference of instrument orientation from the X-axis are given in the instrument kernel (IK) files. The data CK files are taken directly from the attitude telemetry produced by the spacecraft Flight Computer (FC). The FC data is reformatted at full resolution into the CK files. More information about the CK files included in this data set is available in the file ``data/ck/ckinfo.txt''. EK Files ======== Events kernel files are often used to digitally represent an experimenter's notebook (ENB EKs) or to list a summary of all commands sent to a spacecraft, as is the case with Sequence EKs. In the case of NEAR, E-kernels are used in a very different way: to efficiently represent the shape of Eros. This representation is often referred to as a ``shape'' or ``plate'' model. There are two plate models of Eros in this delivery, one at a lower resolution, having only 1566 plates and another at a higher resolution, having 7516 plates. These plate E-kernels are specifically designed for use with the SPICE plate library, developed specifically for NEAR. This library is used to perform geometric calculations related to fields of view, observing geometry, etc. for shape models defined as a plate E-Kernel. More information about the EK files included in this data set is available in the file ``data/ek/ekinfo.txt''. PCK Files ========= PCK files provide size, shape and orientation data for ``target'' bodies such as Mathilde and Eros. A description of these data items and reference to their source is provided inside the text PCK files, which are simple text files that can be viewed using any word processor, text editor or text display utility, or in the comment areas of the binary PCK files. More information about the PCK files included in this data set is available in the file ``data/pck/pckinfo.txt''. IK Files ======== Instrument kernel files provide specifications for the mounting alignment and where applicable field-of-view size, shape and orientation for the named instrument. NEAR IKs also include the definitions of the spacecraft and instrument reference frames. Metadata describing these estimates are provided in each IK file included in this archive. Parameter values were determined from pre-launch measurements or from manufacturing blueprints. More information about the IK files included in this data set is available in the file ``data/ik/ikinfo.txt''. SCLK Files ========== Spacecraft Clock kernel files provide a tabulation of data needed for converting time measurements between ephemeris time (ET) and spacecraft clock time (SCLK). The SPICE SCLK file is produced by the NEAR Mission Operations Center. The time correlation accuracy provided in SCLK files is informally reported by the MOPS team to be better 20 milliseconds during orbital phases. This accuracy has been corroborated by independent estimates to within 500ms. SPICE software does not prohibit an SCLK file from being used for time conversions occurring for ``future times'' (or more accurately, for epochs that occur later than the epoch of the last telemetry data used in producing the last correlation coefficients found in the SCLK file). Such ``predict'' time conversions are likely to be inaccurate (changed somewhat) once the epoch of interest has been passed. More information about the SCLK files included in this data set is available in the file ``data/sclk/sclkinfo.txt''. LSK Files ========= Leapseconds kernel files provide a tabulation of ``leapseconds'' and some other terms used in converting time measurements between ephemeris time (ET) and Universal Time (UTC). ``Spacecraft Event Time'' (SCET) is the commonly used name for UTC events measured at the spacecraft. Metadata describing how the LSK data are obtained or computed is contained inside the LSK text file. The time conversion provided by SPICE LSK files is accurate to approximately 0.000030 seconds. More information about the LSK files included in this data set is available in the file ``data/lsk/lskinfo.txt''. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "NEAR EARTH ASTEROID RENDEZVOUS" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_TARGET TARGET_NAME = "433 EROS" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = "253 MATHILDE" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = NEAR INSTRUMENT_ID = SPICE END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ACTON1996" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END