Real-Time Satellite Tracking and Orbit Prediction with GPREDICT Alexandru Csete (Rovsing A/S) alc@rovsing.dk 3. International Workshop on Astrodynamics Tools and Techniques ESTEC, October 2-5, 2006 September 23, 2006 1
Gpredict Real-time satellite tracking Where is the satellite now? Future pass predictions Where will the satellite be tomorrow? Fast and accurate algorithms (SGP4/SDP4) Position, velocity, bearing, visibility, signal properties One or more ground stations Presents data in tabular or graphical form Modular design, portable ANSI C code Free/open-source software (GNU GPL) Unix/Linux/BSD, Mac, and Windows September 23, 2006 2
Satellite Tracking Keplerian Elements Size and shape of orbit Orientation of the orbit in space Satellite position on the orbit path Time when the satellite was there Current Date and Time Solve Kepler s Equation + Corrections Position of Satellite Vector Calculations Azimuth and elevation from ground station to satellite Latitude and longitude of ground station September 23, 2006 3
SGPx/SDPx Algorithms Gravitational models of Earth (1959-1980) Solve Kepler s equation for orbital motion SGPx: Near-Earth objects (period < 255 min) SDPx: SGPx + deep space perturbations, e.g. Sun and Moon SGP, SGP4/SDP4, and SGP8/SDP8 Input: Orbital elements at t 0 generated and published on the web by NORAD Orbital elements must be updated periodically September 23, 2006 4
Initial Orbital Elements Also known as Keplerian Elements or TLE Size, shape, and orientation of the orbit Satellite position on the orbit at t 0 Average atmospheric drag ISS (ZARYA) 1 25544U 98067A 06252.44258404.00014635 00000-0 96907-4 0 6335 2 25544 51.6331 113.4131 0011142 320.8285 104.5775 15.75745231446454 September 23, 2006 5
Gpredict Design Satellite Data at time t 0 Ground Station Data (Lat,Lon) Time Input Data SGP4/SDP4 Engine Driver Future Pass Predictions Backend User Interface September 23, 2006 6
Map View Which satellite is where at any given time Shows footprints and covered areas September 23, 2006 7
List View Details about many satellites Automatically sorts itself User can show/hide each column individually September 23, 2006 8
Polar View Also known as Radar View Shows satellites within range Sky track (path) Radio Amateurs love this September 23, 2006 9
Single-Satellite View Shows details about one satellite at a time Good to show many details Better performance than the list view User can show/hide each data field September 23, 2006 10
Modules: Combination of Views Group satellites and ground stations into separate workspaces Include up to 3 views (map, list, ) Individual configuration Many modules at the same time Module States: Docked, window or full-screen September 23, 2006 11
Modules: Combination of Views Map + List September 23, 2006 12
Modules: Combination of Views List + Polar + Single-Sat September 23, 2006 13
Modules: Combination of Views Map + Polar + List September 23, 2006 14
Modules: Combination of Views List + 2! Single-Sat September 23, 2006 15
Live Demo September 23, 2006 16
Future Plans Automatic update of orbital elements Automatic control of communication equipment More prediction gadgets Mobile ground stations Formalise plug-in infrastructure More algorithms and user interface modules External hooks Simulated real-time Embedded devices PDA, car navigation computers, Fix bugs September 23, 2006 17
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows September 23, 2006 18
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows Use it September 23, 2006 19
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows Use it Enjoy it September 23, 2006 20
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows Use it Enjoy it Explore it September 23, 2006 21
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows Use it Enjoy it Explore it Learn from it September 23, 2006 22
Summary Real-time satellite tracking Future pass predictions Runs out of the box High quality anti-aliased graphics Many customisation options Nice playground to test algorithms Modular Design Clean, portable ANSI C code Free/open-source (GNU GPL) Unix/Linux/BSD, Mac, and Windows Use it Enjoy it Explore it Learn from it Enjoy freedom September 23, 2006 23
Availability http://groundstation.sf.net/gpredict Questions? September 23, 2006 24