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TRACKING OF PHOBOS-GRUNT MISSION IN LOW EARTH ORBIT. Alexander S. Samotokhin, Andrey G. Tuchin M.V. Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, Moscow, Russia Sergey A. Sukhanov, Zakhary N. Khutorovsky, Andrey V. Rykin
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TRACKING OF PHOBOS-GRUNT MISSION IN LOW EARTH ORBIT Alexander S. Samotokhin, Andrey G. Tuchin M.V. Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, Moscow, Russia Sergey A. Sukhanov, Zakhary N. Khutorovsky, Andrey V. Rykin Interstate Joint-Stock Corporation “Vympel”, Moscow, Russia
Relative movement of PG and 37947 (SGP4 model, compensation of time error is applied)
Analyzed orbital parameters The draconic period (the time that elapses between two passages of the object through its ascending node) The height of perigee The latitude of under-satellite point in perigee Considered parameters are not osculated elements. Theseparameters were calculated during one revolution with use of the corresponding propagator. The designations used in subsequent figures The propagated evolution Actual Russian SSS data Actual American SSS public data (TLE)
Evolution of the orbit parameters Nov 9-22passive movement, A/m=0.0016 m2/kg (nominal)
Evolution of the orbit parameters Nov 9-Dec 6passive movement, A/m=0.0016 m2/kg (nominal)
Evolution of the orbit parameters Nov 9-22passive movement, A/m=0.00093 m2/kg (58% nominal)
Evolution of the orbit parameters Nov 9-22nominal A/m, acceleration along velocity: 2.83∙10-6m/sec2
Evolution of the orbit parameters Nov 9-22accelerations: along velocity: 2.49∙10-6m/sec2, s/c-Sun direction 1.16∙10-5m/sec2
Conclusions • Really space surveillance systems were the only source of information about behavior of Phobos-Grunt onboard systems in low Earth orbit. It is a very unusual situation. • The data both Russian and American SSS proves that the movement of Phobos-Grunt were not passive during the first 12-13 days after the launch. These data allowed to obtain a estimation of actual perturbations. • The interaction between on-Earth control structure of the mission and Space surveillance system was unsatisfactory. It is necessary to provide real time data exchange between these systems in the future.