Keldysh Institute of Applied Mathematics Orbit determination in "Radioastron" mission G.K. Borovin, M.V. Zakhvatkin, Yu.N. Ponomarev, V.A. Stepanyants Pushino 2012

The main tasks of Radioastron navigation

Perturbations from the jet engines during the flywheels unload Two engines D1 and D2 are not a pair. They provide SC turn round the Z exes and create the center of masses acceleration Two pairs of engines rotate SC round X axes, not disturbing the center of masses motion

Antennas of the service radio-system RT-64, Bear Lakes RT-70, Ussuriysk

Antenna RT-22, Pushino

Telescopes of Scientific system of optical instruments for astrometric and photometric observation of space object (NSOI APO)

International Laser Ranging Service (ILRS) Observatoire de la Cote d'Azur

North Caucasus Special Laser Optical Locator

The problems identified during the mission Measurement of service systems in Ussuriysk and Bear Lakes contain systematic errors Many of laser range station still have not been able to perform the measurements, despite the efforts Actual disturbance from jet engines of the stabilisation systen differ significantly from those of telemetry data

Laser range successful sessions

The SC motion model the SC Noncentral gravitational field of the Earth model EGM-96 (degree 75x75) Gravity of the Moon, Sun and planets (coordinates are taken from the DE 403) Solid Earth tides (Model of Rezos and Stolz, 1985) Solar radiation pressure, taking into account the Midel area changes due to SC orientation Earth atmosphere up to a height of 1500 km (dynamic model)

Prospects for improving the accuracy of the orbital parameters We are going to continue to calibrate the measurement system performance and achieve accuracy range of 20 m and the radial velocity of 1 mm / c Currently under revision of the software and hardware at the laser range station in the North Caucasus. There are plans to attract the laser ranging station in Simeiz (Ukraine). Currently there work carried out for equipments modification. Efforts to begin the work at the Australia laser ranging station

The time intervals where laser range measurements may be perform by European stations

Improvement of the dynamic model