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The article presents a study aimed at formulating a solution procedure, exploring the robustness of the solution procedure and assessing various entry mission scenarios in Mars using the new methodology. It discusses the challenges of landing on Mars due to the aerodynamic combination of atmospheric density and gravity, the bank angle modulation and dynamics of entry module. It demonstrates the problem of parachute deployment and the derivation of bank control law using Pontryagin's principle.

The article presents a study which examines the characteristics of the five kinds of orbits around Mars. In order to analyze the orbits, researchers used analytical formulations and numerical simulation methods. The five orbits include sun-synchronous orbits, orbits at the critical inclination, frozen orbits, repeating ground track orbits and areostationary orbits. Researchers found that the restrictive definition of the orbits cannot be drawn in the 80 x 80 Mars gravity field.

This paper aims at reducing the sensitivity of the minimum-fuel powered descent trajectory on Mars in the presence of uncertainties and perturbations, using the desensitized optimal control methodology. The lander is modeled as a point mass in a uniform gravitational field, and the engine throttle is considered the control variable, which is bounded between two nonzero settings. Unlike the conventional practice of designing separately the nominal trajectory and a feedback tracking controller, desensitized optimal control strategy incorporates the two designs in synergy, delivering a superior performance. Sensitivities of the final position and velocity with respect to perturbed states at all times are derived and augmented onto the minimum-fuel performance index through penalty factors. The linear quadratic regulator technique is used to design the feedback control gains. To reduce the likelihood of the closed-loop throttle exceeding the prescribed bounds, a multiplicative factor is applied to the feedback gains. This reshapes the nominal trajectory from the well-known maximum-minimum-maximum structure in that the nominal throttle is encouraged to stay away from the prescribed bounds, leaving room for the feedback control. Monte Carlo simulations show that the occurrence of out-of-bound closed-loop throttles is significantly reduced, leading to improved landing precision. [ABSTRACT FROM AUTHOR]