PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " 2003-10-15 NAIF:Semenov original; 2005-02-16 SBN:McLaughlin Fixed lien for errata.txt file; 2005-03-13 NAIF:Semenov Added missing keywords to DATASET.CAT; 2006-03-06 NAIF:Semenov added required DATA_SET_MISSION object; 2007-02-27 NAIF:Semenov update for addition of extras; 2007-06-11 NAIF:Semenov removed ARCHIVE_STATUS keyword; 2008-01-10 NAIF:Semenov set INSTRUMENT_ID to SPICE; 2013-01-08 NAIF:Semenov reset STOP_TIME; " RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "DS1-A/C-SPICE-6-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "DEEP SPACE 1 SPICE KERNELS V1.0" DATA_SET_COLLECTION_MEMBER_FLG = "N" DATA_SET_TERSE_DESC = " Navigation and ancillary data in the form of SPICE System kernel files for the Deep Space 1 (DS1) spacecraft. " ABSTRACT_DESC = " This data set includes the complete set of Deep Space 1 (DS1) SPICE data files (``kernel files''), which 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. " CITATION_DESC = " Semenov, B.V., L.S. Elson, and C.H. Acton, DEEP SPACE 1 SPICE KERNELS V1.0, DS1-A/C-SPICE-6-V1.0, NASA Planetary Data System, 2004. " START_TIME = 1998-10-24T09:00:00 STOP_TIME = 2001-12-18T20:51:43 DATA_SET_RELEASE_DATE = 2003-10-15 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 Deep Space 1 (DS1) SPICE data files (``kernel files''), which 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 Deep Space 1 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''. " CONFIDENCE_LEVEL_NOTE = " 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 ========= SP-Kernel files included in this data set provide the trajectory of the Deep Space 1 spacecraft. These files also include ephemeris data for the mission targets -- asteroid Braille and comet Borrelly -- along with ephemeris data for Earth, Moon, and Sun. The spacecraft trajectory stored in these SPKs was determined by the Deep Space 1 Radio Navigation (Radio NAV) and Optical Navigation (OPNAV) teams, both from JPL. The SPKs produced by DS1 Optical NAV team were created by processing images taken during the approach to and departure from the target. These solutions provide the best trajectory relative the specific target ephemerides that has been included in these SPKs to ensure that the s/c trajectory and that specific target ephemerides are always used together. These SPKs provide more accurate trajectory relative the target and, therefore, should be used to compute derived geometry during the encounters. The substantial difference between the DS1 trajectory provided by the OPNAV and Radio NAV solutions -- on average about 400 km for the Braille encounter and about 120 km for the Borrelly encounter -- can be attributed to the error in the knowledge of the target position. Since the OPNAV solution was done relative to the target and the Radio NAV was done relative to the Solar System ephemerides, the error is the target position became the main contributor to the difference between the two spacecraft trajectory solutions. Unfortunately the coverage of the OPNAV SPKs is relatively short, starting about a month before each encounter and ending shortly after it. For this reason the Radio NAN SPKs should be used wherever OPNAV SPK coverage is not available. 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 and its solar array. Both 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. 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 stream of orientation quaternions computed on-board and send down in channelized telemetry. The fact that the spacecraft could successfully point to and track the desired targets (Borrelly and Braille) 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. Attitude knowledge, represented by quaternions stored in the reconstructed s/c orientation CK files, ceased to be valid within a short time of the failure of the SRU on November 11, 1999. On-board knowledge (based on inertial celestial reference) was not restored until 01:00 on June 15, 2000. The reconstructed s/c orientation CKs provide no data during this period. Attitude knowledge was also subject to gyro drift inaccuracies during the following periods, in which our Science Camera/Star Tracker lost lock: 2000-07-16T20:00 until 2000-07-19T01:00 2001-03-13T16:00 until 2001-03-16T20:00 2001-07-15T20:00 until 2001-07-24T18:00 2001-08-16T12:00 until 2001-08-24T11:00 2001-09-13T17:00 until 2001-09-14T01:00 2001-12-02T16:00 until 2001-12-04T23:00 Although the magnitude of the inaccuracy is not known for each period, the reconstructed s/c orientation CKs provide data during these periods because the attitude was determined using real gyro measurements and may be, at least at the starts of the intervals, close to reality. This data set also includes a CK providing DS1 spacecraft predicted orientation for Borrelly encounter. Although the reconstructed orientation is available for the encounter, this file is included in the archive because its comments provide a a detailed description of the encounter attitude profile. Solar Array CK Files -------------------- These CK files containing orientation of the solar arrays relative to the spacecraft bus are provided to support the PEPE data analysis. The orientation data in these files was computed the solar array gimbal angles measured on-board and sent down in channelized telemetry. The validation of the data in these CKs involved computing the angle between the solar array normal direction from the spacecraft to the Sun and verifying that it was close to zero. While it was the case whenever the arrays were supposed to be tracking the Sun no formal reports assessing accuracy of the solar array orientation provided in these CK files were available at the time of archiving. Though a solar array CK file is provided for each year of the mission, the combination of all these files is lacking coverage from 1999-11-10 through 2001-09-08 (two little coverage windows in Dec 2000 and May 2001 are exceptions.) 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. The two PCK files provided in this data set are for the mission target -- asteroid Braille and comet Borrelly. Both files are were created around the times of encounters and contain preliminary size and orientation 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 Deep Space 1 FK provided in this data set contains a complete set of frame definitions for the spacecraft, its structures such as solar arrays, 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. While no formal report on the Deep Space 1 time correlation accuracy was available at the time of archiving, since the SCLK/SCET were created by the same process as the SCLK/SCET files for other JPL mission the accuracy can be assumed to be better than a few tens of milliseconds. 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. Note that this SCLK provides correlation for the main spacecraft on-board clock. While this clock was used to tag sequences up-linked to and all telemetry sent from the spacecraft, a different time was used to tag MICAS images (i.e. was included into the image headers.) That time was a count of ephemeris seconds past 1998 JAN 01 12:00:00 ET. Because this counter was also ``running'' on-board the spacecraft, it was not ``running'' at the true ET rate. Instead it was ``running'' at the rate of the main on-board clock and, therefore, was drifting from the true ET as time when on. To correct the drift, a special command was sent to the spacecraft every so often -- once every few weeks -- to synchronize the counter with the actual ET. If an image was taken long after the previous counter adjustment, the drift had usually accumulated into a substantial error, up to a few seconds. If an image was taken right after adjustment, the error have not yet accumulated and the counter value was very close to the true ephemeris time. Fortunately, the counter was adjusted right before both encounters and, therefore, the error between the counter value and the actual ET for in the encounter images is less than 0.1 second. The following small fragment of SPICE FORTRAN and C code illustrates how the 1998-based ET counter (IMGTIM/imgtim) provided in the MICAS image headers can be converted to UTC: FORTRAN: CALL STR2ET ( '1998 JAN 01 12:00:00 TDB', ETBASE ) ET = ETBASE + IMGTIM CALL TIMOUT ( ET, 'YYYY-MM-DDTHR:MN:SC.###', UTC ) C: str2et_c ( '1998 JAN 01 12:00:00 TDB', &etbase ); et = etbase + imgtim; timout_c ( et, 'YYYY-MM-DDTHR:MN:SC.###', utc ); This example does not take the drift into account; should it try to do that, the accumulated drift, in seconds, has to be estimated and added to the ET before converting to UTC. 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 ======== One kind of Events kernel (EK) files is included in this archive -- predicted Sequence EKs for target encounters. 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 predicted Sequence EKs created from integrated sequence Predicted Events Files (PEFs) produced by the Deep Space 1 Sequence team. 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''. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "DEEP SPACE 1" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_TARGET TARGET_NAME = "19P/BORRELLY 1 (1904 Y2)" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = "9969 BRAILLE" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = "DS1" INSTRUMENT_ID = "SPICE" END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = UNK END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END