PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2012-10-30 NOTE = "This file describes the files in the extras/orbnum directory of this volume." END_OBJECT = TEXT END Orbit Number Files for the GRAIL Mission to the Moon ==================================================== This directory contains the orbit number files generated by NAIF's ORBNUM utility program using the archived spacecraft trajectory SPK files for the orbital phases of the mission starting with the Science phase. The orbit number files are plain ASCII text files that have lines terminated with a line feed character, LF (ASCII 10). The orbit number files with the ``.nrb'' extension contain data that follow the ``node-to-node'' orbit numbering scheme -- with the orbit number changing at the ascending node. GRAIL Orbit Number Kernels Provided in This Data Set ==================================================== The following GRAIL orbit number files are provided in this data set (only name portion of the file name is shown; the extension of all file names is ``.nrb''): grail_v01 orbit number file providing the orbit numbers and other time and geometric values for the GRAIL-B spacecraft for the orbital phases from Science to Hiatus, generated using the PCK file ``moon_pa_de421_1900_2050.bpc'', with the subsolar and subspacecraft longitudes and latitudes in the ``MOON_ME'' reference frame. The information contained in the orbit number files includes the following, in which the ``Column Title'' entries are along the top of the orbit number file and ``Meaning'' describes what the column represents. Column Title Meaning --------------------- ----------------------------------- No. orbit number Event UTC A-NODE GRAIL-B ascending node UTC time Event SCLK A-NODE GRAIL-B ascending node SCLK time OP-Event UTC D-NODE GRAIL-B descending node UTC time SolLon & SolLat planetocentric subsolar longitude and latitude in the ``MOON_ME'' frame defined by the Moon rotation provided in the PCK file used to generate the orbit number file SC Lon, SC Lat, & Alt GRAIL-B planetocentric subspacecraft longitude, latitude, and altitude relative to the reference ellipsoid in the ``MOON_ME'' frame defined by the Moon shape and rotation models provided in the PCK files used to generate the orbit number file Sol Dist Distance between Sun and Moon For the GRAIL mission, the orbit number is changing at the ascending node crossings by the GRAIL-B spacecraft with the first science orbit numbered ``0'' starting at the first crossing after 2012 FEB 29 13:00 UTC. From that point the orbits are numbered continuously till the end of the mission without resets at the orbit phase boundaries. Contact Information =================== Regarding GRAIL project-specific information provided in this data set and for general information about the SPICE system: Boris Semenov (818)-354-8136 Boris.Semenov@jpl.nasa.gov address: Navigation and Ancillary Information Facility (NAIF) Jet Propulsion Laboratory MS 301-125L 4800 Oak Grove Drive Pasadena CA 91109 USA