# Improvement of a radiation model for Cryosat-2

**CoAuthors**

**Event: **2014 IDS Workshop

**Session: **Precise orbit modeling and Precise Orbit Determination

**Presentation type: **Type Oral

In this paper we discuss the precision orbit modeling of Cryosat-2 launched on 8-April-2010 to map the cryosphere with an advanced radar altimeter system. The satellite is tracked with laser and DORIS for which we find residuals of 1.58 cm and 0.4 mm/sec respectively. The radial difference of our solutions relative to precision orbits provided by CNES is at the level of 1.6 cm one sigma. Since the launch of Cryosat-2 we have seen that the rms of fit of laser and Doppler residuals gradually changes over time; the same effect is seen in empirical parameters that we estimate during precision orbit determination, which are part of an empirical model to describe remnant accelerations that are not caught by reference models. The level of the estimated empirical accelerations is approximately 5 nanometer per second squared, and their evolution in time shows a dependency relative to the beta angle that describes the geometry of the orbit plane relative to the Sun. Therefore it is suggested that the reference radiation pressure model for Cryosat-2 can be improved. This paper discusses results obtained by tuning of the thermal radiation constants in an attempt to improve the corresponding satellite model.