Entry Dispersion Analysis for the Genesis Sample Return Capsule

Genesis will be the first mission to return samples from beyond the Earth-moon system. The spacecraft will be inserted into a halo orbit about the sun-Earth collinear libration point L sub(1) located between the sun and Earth, where it will remain for 2 years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. Analysis of the entry, descent, and landing scenario of the returning sample capsule is described. In particular, the use of gyroscopic stiffness to suppress aerodynamic instabilities is presented. The robustness of the overall entry sequence is assessed through a Monte Carlo dispersion analysis, where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3- sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.