Data Set Information
DATA_SET_NAME LRO LUNAR SPICE KERNELS V1.0
DATA_SET_ID LRO-L-SPICE-6-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview ================= This data set includes the complete set of Lunar Reconnaissance Orbiter 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, and data needed for relevant time conversions. This data set is contained on a single virtual volume, LROSP_1000, including data from all mission phases and covering from launch, 2009-06-18, through the end time of the latest spacecraft trajectory file supplied in the data set. Until the end of the spacecraft lifespan this data set is accumulating with new data added approximately every three to six months. 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 LRO 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.
DATA_SET_RELEASE_DATE 2025-09-15T00:00:00.000Z
START_TIME 2009-06-18T09:32:00.000Z
STOP_TIME 2025-06-15T12:00:00.000Z
MISSION_NAME LUNAR RECONNAISSANCE ORBITER
MISSION_START_DATE 2009-06-18T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME MOON
TARGET_TYPE SATELLITE
INSTRUMENT_HOST_ID LRO
INSTRUMENT_NAME SPICE KERNELS
INSTRUMENT_ID SPICE
INSTRUMENT_TYPE N/A
NODE_NAME navigation and ancillary information facility
ARCHIVE_STATUS
CONFIDENCE_LEVEL_NOTE This data set 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, 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 SP-kernel (SPK) files are provided in this archive: merged reconstructed spacecraft ephemeris SPK files, merged reconstructed reprocessed spacecraft ephemeris SPK files, and planetary ephemeris SPK files. The merged reconstructed spacecraft ephemeris SPK files were created at the time of archive preparation by merging together ``as is'' large sets daily LRO definitive spacecraft ephemeris SPK files (fdf29_???????_???????_???.bsp) to reduce the number of kernels provided in the archive. The daily LRO definitive spacecraft ephemeris files provided the definitive LRO spacecraft position and velocity relative to the Moon based only on S-Band tracking data. The spacecraft position and velocity vectors in these Type 13/degree 11 SPKs had sampling frequency of 1 minute. These SPKs were created by GSFC FDF on a daily basis and covered 24 hours of a single day with coverage endpoints matching exactly those of the SPKs for the previous and next days. The accuracy of the position in these daily SPKs was better than 500 meters. The merged reconstructed reprocessed spacecraft ephemeris SPK files were created at the time of archive preparation by merging together ``as is'' sets LRO reprocessed spacecraft ephemeris SPK files (fdf36_???????_???????_???.bsp) to reduce the number of kernels provided in the archive. The LRO reprocessed spacecraft ephemeris files provided the definitive LRO spacecraft position and velocity relative to the Moon based on LRO Orbit Determination (OD) reprocessing results which included both laser tracking measurements and LOLA OD and Improved gravity model products. The spacecraft position and velocity vectors in these Type 13/degree 11 SPKs had sampling frequency of 1 minute. These SPKs were created by GSFC FDF on an irregular basis and covered varying intervals of time with coverage endpoints of given SPK matching exactly the coverage endpoints of the previous and next reprocessed SPKs. The accuracy of the position in these SPKs was better than 500 meters. The DE421 planetary ephemeris SPK file included in this data set contains ephemeris data for the Solar System planet barycenters, Sun, Mercury, Venus, Earth, Moon, and Lunar. This version of ephemerides was officially used by the project during mission operations. The internal comments included this SPK file provide detailed accuracy information. More information about LRO SPK files (include file naming conventions)is available in the file ``data/spk/spkinfo.txt''. CK Files ======== Four kinds of C-kernel (CK) files are provided in this archive: merged reconstructed spacecraft orientation CK files, merged reconstructed High Gain Antenna (HGA) orientation CK files, merged reconstructed Solar Array (SA) orientation CK files, and merged reconstructed DLRE orientation CK files. The merged reconstructed spacecraft orientation CK files were created at the time of archive preparation by merging together ``as is'' sets of 9 to 11 daily LRO definitive spacecraft CK files (moc42_???????_???????_v??.bc) to reduce the number of kernels provided in the archive. The daily LRO definitive spacecraft CK files provided orientation of the LRO spacecraft bus relative to the inertial frame J2000. These daily CKs were created by LRO MOC by storing spacecraft attitude quaternions determined on-board at sampling frequencies up to 5 Hz. These daily CKs usually covered 24 hours of a single day with a few minute overlap with the next day. The accuracy of the attitude in these daily CKs was [TBD] radians. The ground system attitude reconstruction process used by the LRO project from the beginning of the mission up to 2015-042 could not correctly determine the spacecraft attitude at certain times when the spacecraft was offpointed. Because of that some of the ``v01'' spacecraft orientation CKs with coverages falling within the 2009-170 to 2014-349 range, added to the archive in releases 0001 to 0021, had incorrect spacecraft attitude during a small number of intervals lasting from a few to a few tens of minutes, with the errors at times reaching many tens of degrees. The complete list of these intervals is provided in ''errata.txt''. In February 2015 the project fixed the attitude reconstruction software and started producing spacecraft CKs with 10Hz samples with correct attitude at all times. For times after 2014-349, starting with release 0022, these CKs continued to be added to the archive as ``v01'' files. For times between 2009-170 and 2014-349, they were added to the archive as ``v02'' files, fully superseding the ``v01'' files already in the archive. The merged reconstructed HGA orientation CK files were created at the time of archive preparation by merging together ``as is'' sets of 9 to 11 daily LRO definitive HGA CK files (moc43_???????_???????_v??.bc) to reduce the number of kernels provided in the archive. The daily LRO definitive HGA CK files provided orientation of the LRO HGA relative to the LRO spacecraft bus. These CKs were created by LRO MOC by storing quaternions computed using the HGA articulation angles downlinked from the spacecraft at sampling frequencies up to 5 Hz. These daily CKs usually covered 24 hours of a single day with a few minute overlap with the next day. The accuracy of the HGA articulation angles used to produce these daily CKs was 10^-7 radians. The merged reconstructed SA orientation CK files were created at the time of archive preparation by merging together ``as is'' sets of 9 to 11 daily LRO definitive SA CK files (moc44_???????_???????_v??.bc) to reduce the number of kernels provided in the archive. The daily LRO definitive SA CK files provided orientation of the LRO SA relative to the LRO spacecraft bus. These CKs were created by LRO MOC by storing quaternions computed using the SA articulation angles downlinked from the spacecraft at sampling frequencies up to 5 Hz. These daily CKs usually covered 24 hours of a single day with a few minute overlap with the next day. The accuracy of the SA articulation angles used to produce these daily CKs was 10^-7 radians. The merged reconstructed DLRE orientation CK files were created at the time of archive preparation by merging together ``as is'' sets hourly reconstructed DLRE CK files (lro_div_????-??-??_??.bc) into monthly files to reduce the number of kernels provided in the archive. The hourly reconstructed DLRE CK files provided orientation of the DLRE gimbal frames relative to the corresponding gimbal reference position frames, allowing in combination with the other DLRE frames computation of the orientation of the instrument detectors relative to the spacecraft bus. These hourly CKs were created by the DLRE team using the DLRE gimbal angles downlinked in the instrument housekeeping telemetry. Each of these hourly CKs usually covered one hour with a few second overlap with the next hour. The accuracy of the DLRE gimbal angles used to produce these daily CKs was [TBD] radians. More information about LRO CK files (include file naming conventions)is available in the file ``data/ck/ckinfo.txt''. PCK Files ========= PCK files provide size, shape and orientation data for ``target'' bodies such as the Moon. 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 DE-421 based kernel file provide orientation of Lunar Principal Axis (PA) reference frame. More information about the PCK files included in this data set is available in the file ``data/pck/pckinfo.txt''. FK Files ======== Four kinds of Frame Kernel (FK) files are provided in this archive: LRO mission FK file, LRO instrument FK files, Lunar Reference Frames FK file, and Lunar Reference Frame Associations FK files. The LRO Mission FK file contains the complete set of frame definitions for the spacecraft, the solar array, and high gain antenna. Included are reference mounting angles and reference matrices for various spacecraft hardware and actuators, as well as the science instrument mounting alignments. 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. Multiple LRO groups provided inputs to create this file; those inputs were in the form of various project derived documentation. The LRO instrument FK files contain definitions of additional frames needed to compute observation geometry for a particular instrument. The Lunar Reference Frames FK file specifies lunar body-fixed reference frames associated with high-accuracy lunar orientation data provided by the JPL Solar System Dynamics Group's planetary ephemerides DE421. These reference frames realize the Lunar Principal Axis (PA) and Mean Earth/Polar Axis (ME) reference systems. The Lunar Reference Frame Associations FK files are used to associate a particular body-fixed frame with the Moon. Only one of these kernels (the one for the frame on interest) needs to be loaded at a time in order for some older SPICE APIs to perform computations in that frame. These kernels are not needed for the latest SPICE APIs. More information about the LRO FK files is available in the file ``data/fk/fkinfo.txt''. IK Files ======== Instrument kernel files provide specifications for geometric parameters and--where applicable--field-of-view size, shape and orientation for the named instruments. LRO did not levy any requirements on the individuals SOCs or instrument teams to create a corresponding Instrument kernel, which would provide the instrument field-of-view(s) size, shape and orientation. However, if the instrument teams or science centers created these files and forwarded them to the LRO MOC, the LRO MOC included them as part of the LRO SPICE archive. More information about LRO IK files 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 SCLK kernel is a cumulative file for the entire mission. The LRO spacecraft maintained time in a combination of both hardware and software. The LRO clock is formatted as a 32 bit seconds and 16 bit subseconds count. The C&DH flight software used the hardware counters, the MET, and the Spacecraft Time Correction Factor (STCF)(which included leap seconds) to represent one single value, the SC UT. The SC UT drifts because the clock oscillator frequency is not stable due to changing temperature and aging of the oscillator. Using an ultra-stable oscillator (USO) minimizes these effects. LRO has an Ultra Stable Oscillator (USO) 9500 and a USO 9600. The USO 9500 is a Double Oven Controlled Crystal Oscillator (DOCXO) while the USO 9600 is an Oven Controlled Crystal Oscillator (OCXO). The ovens keep each oscillator at a near constant temperature. The USO 9500 is the more accurate of the two clocks and therefore is the primary one used for operations. The USO 9600 is kept powered OFF unless needed due to a failure or anomaly with the USO 9500. Once LRO had launched it was determined that the spacecraft clock was drifting at approximately 6.7 milliseconds per day. The Project requirement is to keep the difference between the spacecraft clock and UTC on the ground to less than 100 milliseconds. Initially, LRO operations had decided to adjust the clock, should the difference reach 80 milliseconds. The drift rate experienced subsequent to launch required an adjustment approximately every 12 days. To reduce confusion and to standardize delivery of the SCLK files, constraints permitting, LRO operations decided to perform a routine clock adjust every Monday. However, instrument constrains may have delayed the actual execution of the adjustment. More information about the LRO SCLK files 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 is available in the file ``data/lsk/lskinfo.txt''. EK Files ======== The Events (E)-kernel store different kinds of the spacecraft and science instrument events related information such as spacecraft and instrument commands, status parameters, records of spacecraft activities, ground events, and so on, and to systematize and provide access to this data in relational database-like fashion. The means of an access to the EK data are provided via SPICE Toolkit APIs, calls to which can be integrated into user application programs. The information regarding how to obtain the SPICE system toolkit for a number of languages and computer platforms is located in the ``/software'' subdirectory of the main directory of this data set. To use E-kernels with INSPEKT program, a Leapseconds (LSK) is required. Refer to the ``ek.req'' and ``inspekt.ug'' documents provided with the toolkit to get more information on how to access E-kernel data. The Events Kernel is consists of the complete set of event sequences (in sequential time-order) when any instrument is not collecting science data, such as during spacecraft station keeping maneuvers. The LRO Event kernel is a Binary-formatted file that intended to provide current and future users of LRO science data information on events and activities that affected science data collection and that can assist in extracting the full value of the science data returned from the LRO mission. The events documented by the event kernel can be planned or unplanned. Some examples of planned events are: - halting data collection for slews or calibrations; - delta-v maneuvers; - loading a FSW patch; - recovery from non-nominal modes such as safe mode. Some examples of unplanned events might be: - an anomaly resulting in the orbiter transitioning to safe mode or powering down instruments; - instrument anomaly. The information for the event kernel came primarily from a single source: - The LRO telemetry and command (T&C) system event message log; - The spacecraft playback logs. The event kernel was generated by an automated process within the LRO Mission Operations Center (MOC). The LRO Event Kernel Utility ran once per week at 0000Z on Monday. The Utility scanned the T&C and spacecraft playback logs for appropriate information to be included in the event kernel. The LRO GS&O system engineering and mission operations team had the responsibility for determining which information is appropriate and configuring the LRO Event Kernel Utility accordingly. More information about LRO EK files is available in the file ``data/ek/ekinfo.txt''.
CITATION_DESCRIPTION Calk, W.H., Casasanta, R.T., Saylor, R.S., Waters, D., Tornabene L., Castro N., Myers D., Lanphear R. Wimbush R., Cooter, A., Burtnick J., Duff K., Johnson K., and Dickey B., LUNAR RECONNAISSANCE ORBITER SPICE KERNELS V1.0, LRO-L-SPICE-6-V1.0, NASA Planetary Data System, 2010. https://doi.org/10.17189/1520116
ABSTRACT_TEXT This data set includes the complete set of Lunar Reconnaissance Orbiter 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, and data needed for relevant time conversions.
PRODUCER_FULL_NAME KEEGAN OCONNOR
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