Data Set Overview :  This data set includes the complete set of Stardust SPICE data files (``kernel files'') for the primary (Stardust) and extended (NEXT) missions. These kernels files can be accessed using SPICE software. The SPICE data contains 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, spacecraft sequences of events, and data needed for relevant time conversions.  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 inter-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 Stardust 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. SPICELIB 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 Stardust meta-kernel(s), see the file ``extras/mk/mkinfo.txt''.

This volume contains SPICE kernel files created during mission operations and after mission data reconstruction and analysis. 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), accessible by using any available text file display tool such as a word processor, text editor, or the unix ``more'' or ``cat'' commands.  In some cases data accuracy information does not exist, or may be estimated after mission completion.  Where there are questions about data accuracy or ``confidence'' not addressed herein the reader is invited to examine subsequent SPICE archive releases associated with this data set (if such exist), or to contact the NAIF node of the Planetary Data System for possible further information.   SPK Files :  Majority of the SP-Kernel files included in this data set provide the trajectory of the Stardust spacecraft. These files also include ephemeris data for the primary mission targets -- Wild 2 and Annefrank -- and the NEXT mission target -- Tempel 1 -- along with ephemeris data for Earth, Moon, and Sun. The spacecraft trajectory stored in these SPKs was determined by the Stardust Navigation (NAV) and Optical Navigation (OPNAV) teams, both from JPL. According to the NAV Team post-Annefrank flyby trajectory release the converged B-plane solution -- B.R (b-plane radial), B.T (b-plane transversal), and CLTOF (closest approach time, ET) -- were -1249.9km (-+ 4km), 2813.4km (-+ 8.5km), and 2-nov-2002 04:51:20.8 (-+ 0.8sec). The flyby distance was 3078.5km (-+9km). For the Wild 2 encounter the most accurate spacecraft trajectory relative to Wild 2 was computed by the OPNAV team by fitting the NAVCAM image data. Based on this solution the closest approach time and distance for the encounter are 2004-01-02T19:21:32 UTC and 236.5 km. This solution is provided in a separate SPK file, covering just the two hour period around the encounter. While it, when used together with the adjusted spacecraft attitude CK file, provides the best geometry for processing of the image data, it does not provide an accurate representation of the heliocentric location of the spacecraft. The boundary discontinuity between this image-based solution and the primary radio navigation solution, which is more accurate in an absolute sense, is about 440 km. For the Tempel 1 encounter the most accurate spacecraft trajectory relative to Tempel 1 was also computed by the OPNAV team by fitting the NAVCAM image data. Based on this solution the closest approach time and distance for the encounter are 2011-02-15T04:39:12.417 UTC and 182.0 km. This solution was combined with the longer arc solution based on radio tracking data and delivered in the SPK covering the first four months of 2011. One additional SP-Kernel file included in this data set provides locations of the spacecraft's center of gravity and antennas with respect to the spacecraft reference frame origin. This file is included in the data set because it may be useful for the future radio science analysis. Additional information about SPK files provided in this data set is available in the file ``data/spk/spkinfo.txt''. CK Files :  C-kernel files included in this data set provide orientation of the spacecraft bus, Navigation Camera instrument, and dust collector grid. The former two kinds of CK files are produced from engineering telemetry downlinked from the spacecraft. As is often the case with spacecraft engineering telemetry-based measurements, considerable uncertainty exists as to the accuracy of such measurements, and, data quality (accuracy and completeness) can vary significantly. The latter kind of CK files is produced from commanded collector angle data.  Spacecraft Bus CK Files -----------------------  These CK files containing the orientation of the spacecraft bus (``the spacecraft'') are provided to support interpretation of data obtained by all science experiments. The spacecraft orientation CK file included in this data set were produced from the merged stream of orientation quaternions computed on-board and sent down in channelized telemetry, small forces packets, and NAVCAM image headers.  The fact that the NAVCAM instrument could successfully point to and track the desired targets (Annefrank, Wild 2, star fields, etc.) and that the targets were found close to the expected location in the images indicates that the accuracy of orientation information sent down from the spacecraft was within the mission requirements. At the same time it should be mentioned that at the time of this archive release there are no known reports assessing accuracy of the spacecraft orientation provided in these CK files.  For the Wild 2 encounter the most accurate spacecraft orientation was computed by the OPNAV team by fitting the NAVCAM image data. This attitude solution is provided in a separate CK file, covering just the 45 minute period around the encounter. When used together with the OPNAV-determined spacecraft trajectory SPK file, this solution provides the best geometry for processing of the close encounter data, predicting the Wild 2 center position in the NAVCAM images to within five to twenty pixels of the actual, seen position (for the unadjusted, telemetry-based spacecraft attitude CK this difference is tens of pixels.) For the Tempel 1 encounter the most accurate spacecraft orientation was computed by the OPNAV team by fitting the NAVCAM image data. This attitude solution is provided in a separate CK file, covering just 72 short intervals between to the exposure start and stop times of the 72 encounter images. When used together with the OPNAV-determined spacecraft trajectory SPK file, this solution provides the best geometry for processing of the close encounter data. Navigation Camera CK Files --------------------------  These CK files containing orientation of the NAVCAM instrument relative to the spacecraft bus are provided to support the NAVCAM image analysis. The orientation data in these files are comprised of a number of individual transformations implementing the NAVCAM pointing model defined and described in the Stardust Frames Kernel (FK) file. Some of these transformations have been computed from the NAVCAM mirror angle data contained in the image headers, others -- using the OPNAV team pointing correction tables provided in the NAVCAM IK file.  The original, type 1, NAVCAM CK files contain discrete data points corresponding to the exact times when the images were taken and cannot be used to compute the camera view direction for any other times. To get these exact times users interested in computing NAVCAM orientation using these CKs must start with SCLK values provided in the SPACECRAFT_CLOCK_START_COUNT keywords in the NAVCAM image labels and convert these SCLKs to other time system(s) to access SPICE data. Starting with UTC times from the NAVCAM labels will result in a small round off and the pointing will not be found.  The type 2 NAVCAM CK files prepared for the archive contain the same orientation as the original type 1 CKs but that orientation covers small windows, from exposure start minus 1 SCLK tick to exposure stop plus 1 SCLK tick, allowing computing NAVCAM orientation at any time within the image exposures and making these CKs more usable with high-level SPICE APIs. The mirror orientation stored in these files is constant during each of the exposure windows.  While OPNAV Team invested substantial effort in solving for correction to be applied to the ideal NAVCAM pointing model in order to estimate actual camera orientation, the correction that had been derived prior to the Annefrank flyby and used to compute orientation data for the NAVCAM CK files did not work well for all image sequences. Even with correction applied, computed pointing estimate had been off by as much as few tens of pixels for some of the images. Dust Collector CK File ---------------------- This file contains commanded orientation of the collector, computed from commanded collector position angles, because no direct indicators of the actual collector orientation were available in the spacecraft engineering telemetry. It covers both ISP collection period and the Wild 2 encounter.  Caution on Using CK Files -------------------------  While not a data accuracy issue, the CK user is nevertheless cautioned to understand and properly use the data found and tolerance arguments that are inputs to the CK reader provided in the SPICE Toolkit. Descriptions about how to read CK files are found in the CK reader routine headers (top of the source code files) and in the ``CK Required Reading'' document; these are contained in each SPICE Toolkit package.  Additional information about CK files provided in this data set is available in the file ``data/ck/ckinfo.txt''. PCK Files :  PCK files provide size, shape and orientation data for ``target'' bodies such as planets, satellites, comets and asteroids. A description of these data items and reference to their source is provided inside the PCK file, which is a simple text file that can be viewed using any word processor, text editor or text display utility.  This data set contains generic PCK files based on the official IAU/IAG/COSPAR values accepted in 1994 and 2006 and PCK files for Stardust mission targets -- Wild 2 and Annefrank, -- and NEXT mission target -- Tempel 1 -- that provide constants determined after the encounters. While the PCK files for Wild 2 and Tempel 1 contains both rotation and shape data, the file for Annefrank contains only the shape data because orientation of the asteroid was not determined from the flyby data. Additional information about PCK files provided in this data set is available in the file ``data/pck/pckinfo.txt''.  FK Files :  Frames kernel files provide specifications for how one reference frame is defined relative to another frame. The Stardust FK provided in this data set contains a complete set of frame definitions for the spacecraft, its structures such as antennas, and all of its science instruments. Meta information provided in the comments included in this file consists of the frame definitions, description of the frame relationships, source of and accuracy of the mounting alignment information, etc.  Additional information about FK files provided in this data set is available in the file ``data/fk/fkinfo.txt''.  IK Files :  Instrument kernel files provide specifications for the optical and physical instrument parameters and -- where applicable -- field-of-view size, shape and orientation for the named instrument. Metadata describing these estimates are provided in each IK file included in this archive.  Additional information about IK files provided 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). A SPICE SCLK file is made from a similar file -- SCLK/SCET file, or SCLKvSCET file -- produced by another mission entity. Each newly made SCLK file fully replaces the previous SCLK file.  For Stardust the time correlation accuracy provided in SCLK/SCET files is informally reported by the Lockheed Martin spacecraft team to be better than 20 milliseconds. (NAIF has not attempted to obtain or produce an independent corroboration of these LMA estimates.) The SPICE SCLK file has essentially the same accuracy as the SCLK/SCET file.  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. Additional information about SCLK files provided 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.  Additional information about LSK files provided in this data set is available in the file ``data/lsk/lskinfo.txt''. EK Files :  Two kinds of Events kernel (EK) files for the primary mission are included in this archive: Experimenter's Notebook EKs and Sequence EKs. No EK files were made during the NEXT mission.  Experimenter's Notebook EKs kernels are a digital analog to the traditional paper laboratory notebook. Hence Experimenter's Notebook entries represent truth only as seen by the author of the notes--there is no attempt made to independently validate any aspect of Experimenter's Notebook information.  Sequence EKs comprise a summary of the commands sent to the spacecraft as well as instrument state (status) summaries as modeled by the sequence generation tools. This data set includes Sequence EKs created from integrated sequence Predicted Events Files (PEFs) produced by the Stardust spacecraft team, LMA. As seen from the source product name these files contain predicted information -- background sequences, as should have executed by the spacecraft. Because of that the EK records have times different from the actual command execution times (although very close in most cases.) These EKs are also missing any commands that were not part of the background sequences (real-time commands). Additional information about EK files provided in this data set is available in the file ``data/ek/ekinfo.txt''.