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Keldysh Institute of Applied Mathematics

G.K. Borovin, M.V. Zakhvatkin,

Yu.N. Ponomarev, V.A. Stepanyants

Pushino 2012

Orbit determination in "Radioastron" mission

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The main tasks of Radioastron navigation

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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

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Antennas of the service radio-system

RT-64, Bear Lakes RT-70, Ussuriysk

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Antenna RT-22, Pushino

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Telescopes of Scientific system of optical instruments for astrometric and photometric observation of space object

(NSOI APO)

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

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North CaucasusSpecial Laser Optical Locator

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• 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

The problems identified during the mission

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Laser range successful sessions

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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)

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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

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The time intervals where laser range measurements may be

perform by European stations

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Improvement of the dynamic model