Precise Modeling of Solar Radiation and Thermal Accelerations on Rosetta

Paper number

IAC-10.C1.6.2

Author

Mr. Takahiro Kato, Kyushu University, Japan

Coauthor

Prof. Jozef C. van der Ha, Kyushu University, Japan

Year

2010

Abstract

The navigation of a deep-space spacecraft requires precise models of all forces affecting the orbital motion. The relevant gravitational forces are well known and can be modeled and incorporated adequately. This is not the case for the so-called “small forces” that may be induced by Solar Radiation Pressure and Thermal Radiation Forces. In many missions, these forces can be calibrated with the help of the observed residuals resulting from the orbit determination process.
  An issue that must be kept in mind is the enormous ranges in solar distances that deep-space missions must be able to cope with. For instance, ESA’s Rosetta spacecraft has a trajectory that ranges from 0.886 AU to 5.292 AU. The consequence of this wide range of solar distance is that the Solar Radiation and Thermal Radiation Forces vary significantly over the mission. 
  Apart from the Solar Radiation Pressure, there is an effect from the Thermal Radiation Force, which has not been incorporated in the present models. However, an interplanetary spacecraft which has large surface areas exposed to the sunlight will receive a large amount of heat flux from the Sun. The varying distance from the Sun affects the magnitudes of the Solar Radiation Pressure and Thermal Radiation Forces. Also, the temperatures of the solar arrays and body surfaces change significantly and this affects the surface thermo-optical properties, in particular the emissivity. 
  For the establishment of a high-fidelity acceleration model, we implement the Solar Radiation Pressure model including temperature dependent thermal radiation effects. The variations of temperature dependent parameters, such as surface emissivity, are implemented using the thermal analysis of the spacecraft. Furthermore, contributions of a high gain antenna and sun-exposed surface of the body surfaces are also included in the model. 
  In addition to the effect of the high gain antenna itself, we include the shadowing effect of the antenna dish. Then, the established model will include all relevant effects acting on a spacecraft. Therefore, we have established a realistic acceleration model for the Rosetta spacecraft over its mission. This also includes its actual attitude and high gain antenna pointing histories.
  Finally, the acceleration model will be validated by the comparison with the actual orbit determination data of the Rosetta.

Abstract document

IAC-10.C1.6.2.brief.pdf

Manuscript document

IAC-10.C1.6.2.pdf (🔒 authorized access only).

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