Lunar Reconnaissance Orbiter SPK files, University of Bonn ************************************************************************************** Author: Anno Löcher Institute of Geodesy and Geoinformation Nussallee 17 D-53115 Bonn Date of this file: 21 August 2017 Revision: 5 September 2017 (reference to PHASES.txt) 14 February 2018 (solutions added: 10.5 days radio and 2.5 days radio + laser) Content and usage -------------------------------------------------------------------------------------- This directory contains orbit data for the Lunar Reconnaissance Orbiter (LRO) for use with the Spice software system (https://naif.jpl.nasa.gov/naif/). The Spice ID for LRO is -85. The orbits should be used together with the lunar ephemeris from DE421. The orbits are provided in different flavours characterized by the arc length and the observation types used in the determination of the orbit. Each solution is stored in a separate subdirectory. Currently, the following solutions are provided: ================================================================================== Subdirectory | Arc length | Observation types | Mean overlap | | | error ================================================================================== LRO_IGG_2.5d_DT_210817 | 2.5 days | Doppler ranges + | 2.81 m | | two-way ranges | ----------------------------|---------------|------------------------------------- LRO_IGG_4.5d_DT_210817 | 4.5 days | Doppler ranges + | 2.21 m | | two-way ranges | ----------------------------|---------------|------------------------------------- LRO_IGG_6.5d_DT_210817 | 6.5 days | Doppler ranges + | 2.15 m | | two-way ranges | ----------------------------|---------------|------------------------------------- LRO_IGG_8.5d_DT_210817 | 8.5 days | Doppler ranges + | 1.99 m | | two-way ranges | ----------------------------|---------------|------------------------------------- LRO_IGG_10.5d_DT_130218 | 10.5 days | Doppler ranges + | 2.13 m | | two-way ranges | ----------------------------|---------------|------------------------------------- LRO_IGG_2.5d_DTL_130218 | 2.5 days | Doppler ranges + | 2.74 m | | two-way ranges + | | | laser ranges | ----------------------------|---------------|------------------------------------- Each subdirectory contains 64 SPK kernels covering in total the period from 23 June 2009 to 9 September 2014 corresponding to the mission phases Commissioning Orbit (CO), Nominal Orbit (NO), Science Mission (SM) and the first two years of the Extended Science Mission (ES). The periods covered by the single kernels correspond to the mission subphases as defined and used by NASA. The mission subphase is indicated in the file name after the leading "LRO_IGG". For the start and end times of mission subphases see the file PHASES.txt. Short description -------------------------------------------------------------------------------------- The orbits in this directory were produced from tracking data from the LRO ground network retrieved from the Planetary Data System (http://pds-geosciences.wustl.edu/). The orbit determination was performed using an independent software which applies the variational equations approach. The dynamical modelling is based on the GRAIL gravity field model GL0900D truncated at degree 400. The solar radiation pressure was modelled using a spacecraft 3-D model accounting for the effects of self-shadowing and a model for the lunar albedo force. The parameter set estimated for each arc included a scale factor for solar radiation and a piecewise linear acceleration in along-track direction. For the details of data processing see the publication in the "Reference" section. For the orbit computation, the data were processed in overlapping arcs. The orbits in the SPK kernels were assembled from several such arcs with linear transitions in the overlap periods. The state vectors from the orbit integration were converted to the SPK data type 9 (Lagrange interpolation, unequal time steps, polynomial degree 9). Reference -------------------------------------------------------------------------------------- When using these orbits please cite: A Löcher, J Kusche (2017): Precise orbits of the Lunar Reconnaissance Orbiter from radiometric tracking data. Submitted to Journal of Geodesy Acknowledgement -------------------------------------------------------------------------------------- The orbits in this directory were computed at the University of Bonn in the framework of the research unit FOR 1503 "Space-Time Reference Systems for Monitoring Global Change and for Precise Navigation in Space" funded by the German Research Foundation (DFG). Contact -------------------------------------------------------------------------------------- If you have any questions regarding these orbits please contact: Anno Löcher Institute of Geodesy and Geoinformation Nussallee 17 D-53115 Bonn loecher@geod.uni-bonn.de