Spacecraft Thermal And Optical Modeling Impacts on Estimation Of The GRAIL Lunar Gravity Field Eugene G. Fahnestock, Ryan S. Park, Dah-Ning Yuan, and Alex S. Konopliv Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91101, USA We summarize work performed involving thermo-optical modeling of the two Gravity Recovery And Interior Laboratory (GRAIL) spacecraft. We derived several reconciled spacecraft thermo-optical models having varying detail. We used the simplest in calculating SRP acceleration, and used the most detailed to calculate acceleration due to thermal re-radiation. For the latter, we used both the output of pre-launch finite-element-based thermal simulations and downlinked temperature sensor telemetry. The estimation process to recover the lunar gravity field utilizes both a nominal thermal re-radiation accleration history and an apriori error model derived from that plus an off-nominal history, which bounds parameter uncertainties as informed by sensitivity studies. Fahnestock, E.G., R.S. Park, D. Yuan, and A.S. Konopliv, Spacecraft Thermal And Optical Modeling Impacts on Estimation Of The GRAIL Lunar Gravity Field, AIAA/AAS Astrodynamics Specialist Conference, Minneapolis, Minnesota, 13-16 August 2012, DOI: 10.2514/6.2012-4428. The full paper can be found on the web: http://arc.aiaa.org/doi/pdf/10.2514/6.2012-4428 A subscription is required unless accessed via JPL.