1. 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

2. 2 On-Earth control structure of Phobos-Grunt mission

3. 3 The schedule of LEO operations OperationTime, MskNote Launch to base orbit00:16:03.1 - 00:18:28.7Separation of spacecraft from 2nd stage of the rocket Base orbit00:18:28.7 - 02:55:47.9Hp=207 km Ha=347 km 1st maneuver02:55:47.9 - 03:05:18.2  V=815.7 m/s Separation of external tank Intermediate orbit03:05:18.2 - 05:02:48.8Hp=244 km Ha=4162 km 2nd maneuver05:02:48.8 - 05:20:09.9  V=2851.9 m/s

4. 4 The trace of Phobos-Grunt in low Earth orbits

5. 5 Relative movement of PG and 37947 (SGP4 model)

6. 6 Relative movement of PG and 37947 (SGP4 model, compensation of time error is applied)

7. 7 The evolution of A/m ratio (Nov 9 – Dec 10)

8. 8 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. These parameters 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)

9. 9 Evolution of the orbit parameters Nov 9-22 passive movement, A/m=0.0016 m 2 /kg (nominal)

10. 10 Evolution of the orbit parameters Nov 9-Dec 6 passive movement, A/m=0.0016 m 2 /kg (nominal)

11. 11 Evolution of the orbit parameters Nov 9-22 passive movement, A/m=0.00093 m 2 /kg (58% nominal)

12. 12 Evolution of the orbit parameters Nov 9-22 nominal A/m, acceleration along velocity: 2.83∙10 -6 m/sec 2

13. 13 Evolution of the orbit parameters Nov 9-22 accelerations: along velocity: 2.49∙10 -6 m/sec 2, s/c-Sun direction 1.16∙10 -5 m/sec 2

14. 14 Conclusions 1.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. 2.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. 3.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.