Development of high-precision thermal models for the simulation of thermally induced perturbation effects
Zusammenfassung der Projektergebnisse
Within this project a generic numerical method for the high precision analysis of thermal recoil pressure and solar radiation pressure on satellite surfaces has been developed. The accurate determination of the magnitude of these effects is of highest importance for a precise orbit determination and propagation as required by a growing number of scientific space missions. The method has been used for the detailed analysis of the influence of TRP and SRP on the trajectories of the NASA mission Pioneer 10 and the ESA spacecraft Rosetta. For Pioneer 10 the TRP analysis has shown that the Pioneer Anomaly, an at the time of the project application unresolved anomalous Doppler blue shift experienced for Pioneer 10 and 11, can fully be explained with thermal recoil. The analysis has employed the measured sensor and housekeeping data as well as the development of the most precise FE model of the Pioneer 10 spacecraft available. This includes the detailed interior and exterior configuration of the probe, detailed material models and the implementation of accurate models for the heat production of the individual components. The resolution of the origin of the PA has a major impact on fundamental physic science, since this conventional explanation of the anomaly (without the need for models of new physics) confirms the validity of general relativity within the scope of the solar system. By analysing existing FE solvers and comparing to our own tools and methods we found that the level of current measurement accuracy, in particular for the case of optical properties by far exceeds the modelling accuracies which can be achieved by current FE tools. We therefore proposed the development of numerical methods which enable a numerical precision at the 10−20 level. However, within the scope of this project this major task could only be formulated. The works performed for the LISA mission have shown, that at the current state of mission development, a sensible determination of thermal disturbances is not yet possible. However, we identified LISA pathfinder as a suitable mission, since high precision measurements, as planned for the post-mission at the Lagrangian points L1 or L2 demand a high precision knowledge of the perturbations acting on the spacecraft at all times. Due to fact that the proposal for these measurements is still in the design stage we decided to analyse the perturbations for an already launched mission, the ESA Rosetta mission, instead. For Rosetta the SRP and TRP analysis have shown that unexplained accelerations acting on the spacecraft, as observed by ESA/ESOC in the order of 10% of the magnitude of the SRP effect can be credited to an unmodeled TRP. As a consequence the next generation of ESOCs ODPs will also include a model for TRP which will be developed, in part, based on the results of this project. The analysis of TRP and SRP acting on the Rosetta spacecraft during the first Earth fly-by has enabled the exclusion of both effects as sources of the observed anomalous delta-v change (fly-by anomaly). Although by this the origin of the fly-by anomaly remains unknown the computation of TRP and SRP with high precision narrows the range of possible origins further and add a modification to the residuals thus adding to the level of data precision. The results of this project have caught the interest of the public media and led to several articles in newspapers (NZZ), journals (Spektrum der Wissenschaft, Bild der Wissenschaft, Physik in unserer Zeit) as well as radio reports (Deutschlandradio, 01.06.2011).
Projektbezogene Publikationen (Auswahl)
- New powerful thermal modelling for high-precision gravity missions with application to Pioneer 10/11, New J. Phys. 11, 113032 (24pp), 2009
B. Rievers, C. Lämmerzahl, M. List, S. Bremer, and H. Dittus
- Thermal dissipation force modeling with preliminary results for Pioneer 10/11, Acta Astronautica, Vol. 66, Issues 3-4, February-March 2010, Pages 467–476
B. Rievers, S. Bremer, M. List, C. Lämmerzahl, and H. Dittus
- High precision thermal modeling of complex systems with application to the flyby and Pioneer anomaly, Annalen der Physik 523, 6, pp. 439–449, 2011
B. Rievers and C. Lämmerzahl
- High precision modelling of thermal perturbations with application to Pioneer 10 and Rosetta, Dissertation, Universität Bremen, 2012
B. Rievers
