A Guidance Method for Solid Propulsion Ascent Phase Considering the Martian Atmosphere

To fulfill the precise guidance requirements during the ascent phase of the Mars sample return mission，considering the characteristics of the Martian atmospheric model，a guidance law tailored for the solid-propellant ascent segment is devised. This guidance law actively pursues the target orbital altitude while dynamically rectifying positional and route deviations through coordinated constraints on longitudinal and lateral motions，thus more accurately aligning with the orbital insertion parameters. In terms of longitudinal guidance，an innovative improved nominal trajectory guidance algorithm is introduced，which precisely calculates the terminal value of the costate variable through state transition mechanisms. Additionally，a method for solving guidance parameters applicable to models incorporating atmospheric drag is developed，significantly enhancing the guidance accuracy for achieving the desired orbital radius. For lateral motion，a route-following guidance algorithm is designed，which integrates corrections for right ascension and declination based on track declination tracking，enabling simultaneous optimization of track direction and positional errors to ensure the orbital plane accuracy of the ascent vehicle during insertion. Through ascent simulations and Monte Carlo analyses，the guidance law’s capabilities in error correction，orbital insertion precision，and its performance under diverse deviation and random error scenarios are comprehensively validated.