A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite's state, even when it is impossible to apply the classical single-point solutions (S...

The ICESat-2 Precision Orbit Determination (POD) system computes the precise position of laser altimeter instrument in inertial space, a measurement necessary for accurate geolocation individual photon surface returns. POD solutions are generated by reduction Global Positioning System (GPS) double-difference carrier phase observable residuals with NASA Goddard Space Flight Center's GEODYN softw...

Acknowledgements Abstract I ACKNOWLEDGEMENTS

Abstract Orbit-determination programs find the orbit solution that best fits a set of observations by minimizing root mean square residuals fit. For near-Earth asteroids, uncertainty may be compatible with trajectories impact Earth. This paper shows how incorporating condition as an observation in orbit-determination process results robust technique for finding so-called virtual impactors, i.e....