PVO Orbit SPK, JPL SSD Solution circa 1999 =========================================================================== Created by Boris Semenov, NAIF/JPL, July 21, 2014 Objects in the Ephemeris -------------------------------------------------------- This file contains ephemeris data for the Pioneer Venus Orbiter (PVO, Pioneer 12) spacecraft. The NAIF ID code for PVO is -12. Approximate Time Coverage -------------------------------------------------------- This file covers the following time interval: COVERAGE BEGIN TIME (UTC) COVERAGE END TIME (UTC) ------------------------- ------------------------ 1987-DEC-29 15:59:04.816 1988-JUN-01 01:59:03.815 Due to the way the source trajectory files were generated and the lack of good quality tracking data for some periods during the mission the trajectory coverage during the interval above is NOT continuous and has a few gaps ranging in size from an hour to a few hours. The complete list of covered time intervals is provided in Appendix 1 below. Pedigree -------------------------------------------------------- This SPK file contains PVO orbit reconstruction provided by Alex Konopliv of the Solar System Dynamics Group (SSD), JPL. This reconstruction was performed in 1998 as part of the Venus gravity work that involved reprocessing of PVO and Magellan data described in: Konopliv, A. S., W. B. Barendt, and W. L. Sjogren, "Venus Gravity: 180th Degree and Order Model", Icarus 139, 3-8, 1999, Article ID icar.1999.6086 @ http://www.idealibrary.com The trajectory data stored in this SPK was provided to NAIF as 22 NIO files each containing data for a single solution arc. The start and stop times for each of the arcs are provided in Appendix 3. The NIO files were converted to SPK format using NAIF's NIOSPK utility version 8.2.0 and merged together using using NAIF's DAFCAT utility version 1.0. Most arcs overlapped each other. The summary of discontinuities that exist at these overlaps is provided in Appendix 2. Contacts -------------------------------------------------------- If you have any questions regarding this data contact Alex Konopliv, SSD/JPL Alexander.S.Konopliv@jpl.nasa.gov or: Boris Semenov, NAIF/JPL, Boris.Semenov@jpl.nasa.gov Appendix 1: Trajectory Coverage =========================================================================== The coverage summary of this SPK file provided below was generated the BRIEF utility program Version 4.0.0: Start of Interval (UTC) End of Interval (UTC) ----------------------------- ----------------------------- 1987-DEC-29 15:59:04.816 1988-JAN-28 16:59:03.815 1988-JAN-28 17:59:03.815 1988-MAR-09 16:59:03.814 1988-MAR-09 17:59:03.814 1988-MAY-11 16:59:03.814 1988-MAY-11 20:29:03.814 1988-JUN-01 01:59:03.815 Appendix 2: Segment Boundary Discontinuity Summary =========================================================================== This SPK file contains a large number of SPK segments that came from original individual SPK files. Although, each segment provides continuous trajectory within the interval that it covers, in general a position and velocity discontinuity exists at the boundary of the segment and the segments whose coverage immediately precede and follow it. The times and magnitudes of these discontinuities are provided in the table included in this Appendix. The top portion of the table contains the name of this SPK file. All descriptive lines in the top portion of the file start with the ``#'' character to allow direct plotting of the data in the freeware ``gnuplot'' application. The table consists of 4 columns. The first column is the UTC time at which a segment boundary with discontinuity occurs. The last three columns (2..4) contain view coordinate frame components -- ``down track'' (this direction is parallel to the velocity vector), ``normal to plane'' (this direction is computed as cross product of position vector by velocity vector) and ``in plane'' (this direction is computed as a cross product of ``down track'' by ``normal to plane'') -- of the difference between the state vectors computed at that UTC time defining segment boundary at which a discontinuity exists. The units are kilometers. The pairs of segments and discontinuity times are determined using an algorithm that emulates the standard SPK loading priority -- ``last loaded segment takes precedence''. Therefore, the discontinuities summarized in the file are those which a user reading file would actually see. The difference components in the view coordinate frame were computed for each discontinuity using the following algorithm: -- A single state was computed from each pair of segment the J2000 frame at the time of discontinuity. -- For this pair of states, a position difference vector was computed by subtracting the state computed from the segment with higher priority from the state computed from segment with lower priority. Then, a frame transformation matrix rotating these difference vectors from J2000 to the view coordinate frame defined by the state obtained from the higher priority segment was computed, and the position difference vector was rotated to the view frame coordinates using this matrix. The segment boundary discontinuities for this file are: # # Summary of discontinuities at segment boundaries for # SPK file pvo_871229_880601_ssd1999.bsp: # # BOUNDARY TIME (UTC) DOWNTRK INPLANE NORMAL #----------------------- ------- ------- ------- 1988-01-05T15:59:03.815 -0.501 -0.208 0.092 1988-01-12T15:59:03.815 1.203 0.484 -0.203 1988-01-19T15:59:03.815 0.994 0.391 -0.141 1988-01-25T15:59:03.815 -0.461 -0.183 0.048 1988-02-04T15:59:03.815 -0.232 -0.083 0.015 1988-02-11T15:59:03.814 -0.169 -0.061 -0.008 1988-02-18T15:59:03.814 0.086 0.035 0.015 1988-02-25T15:59:03.814 0.047 0.023 0.008 1988-03-03T15:59:03.814 0.025 0.006 -0.109 1988-03-16T15:59:03.814 -0.029 -0.007 0.009 1988-03-23T15:59:03.814 0.208 0.074 -0.083 1988-03-30T15:59:03.814 0.205 0.071 -0.078 1988-04-06T15:59:03.814 -0.853 -0.285 0.257 1988-04-13T15:59:03.814 0.474 0.150 -0.124 1988-04-20T15:59:03.814 0.529 0.172 -0.142 1988-04-27T15:59:03.814 -0.109 -0.033 0.027 1988-05-04T15:59:03.814 -0.487 -0.151 0.118 1988-05-20T21:59:03.814 0.278 0.319 -0.163 Appendix 3: Summary of Arcs in the SSD1999 PVO Trajectory Set =========================================================================== Each line not starting with '#' pair provides the arc's start and stop time. Lines starting with '#' are notes. xxxxxx 19-NOV-1988 02:55:00 TO 25-DEC-1987 00:00:00 # Maneuver 30-NOV-1987 22:00 xxxxxx 25-DEC-1987 00:30:00 TO 30-DEC-1987 00:00:00 # Maneuver 28-DEC-1987 18:57 ARC006 29-DEC-1987 16:00:00 TO 05-JAN-1988 16:00:00 ARC008 05-JAN-1988 16:00:00 TO 12-JAN-1988 16:00:00 ARC010 12-JAN-1988 16:00:00 TO 19-JAN-1988 16:00:00 ARC012 19-JAN-1988 16:00:00 TO 25-JAN-1988 16:00:00 ARC013 25-JAN-1988 16:00:00 TO 28-JAN-1988 16:00:00 # Maneuver 28-JAN-1988 16:44 ARC014 28-JAN-1988 18:00:00 TO 04-FEB-1988 16:00:00 ARC016 04-FEB-1988 16:00:00 TO 11-FEB-1988 16:00:00 ARC018 11-FEB-1988 16:00:00 TO 18-FEB-1988 16:00:00 ARC020 18-FEB-1988 16:00:00 TO 25-FEB-1988 16:00:00 ARC022 25-FEB-1988 16:00:00 TO 03-MAR-1988 16:00:00 ARC024 03-MAR-1988 16:00:00 TO 09-MAR-1988 16:00:00 # Maneuver 09-MAR-1988 16:38 ARC026 09-MAR-1988 18:00:00 TO 16-MAR-1988 16:00:00 ARC028 16-MAR-1988 16:00:00 TO 23-MAR-1988 16:00:00 ARC030 23-MAR-1988 16:00:00 TO 30-MAR-1988 16:00:00 ARC032 30-MAR-1988 16:00:00 TO 06-APR-1988 16:00:00 # There appears to be something near the end of the # 06-APR arc - maneuver?? ARC034 06-APR-1988 16:00:00 TO 13-APR-1988 16:00:00 ARC036 13-APR-1988 16:00:00 TO 20-APR-1988 16:00:00 ARC038 20-APR-1988 16:00:00 TO 27-APR-1988 16:00:00 ARC040 27-APR-1988 16:00:00 TO 04-MAY-1988 16:00:00 ARC042 04-MAY-1988 16:00:00 TO 11-MAY-1988 16:00:00 # Maneuver 11-MAY-1988 19:55 ARC044 11-MAY-1988 20:30:00 TO 20-MAY-1988 21:00:00 # Maneuver 20-MAY-1988 21:27 ARC046 20-MAY-1988 22:00:00 TO 01-JUN-1988 01:00:00 # Maneuver 01-JUN-1988 16:18 # Maneuver 16-JUN-1988 17:10 xxxxxx 01-JUN-1988 01:00:00 TO 25-SEP-1990 01:00:00 End of comment