A constant bank angle-based two-stage predictor-corrector method for Mars atmospheric entry

The Mars atmospheric entry is the first phase in the entry, descent, and landing (EDL) process for Mars exploration. There is a high demand for the proper guidance law for atmospheric entry under the effects of uncertainties in the entry state condition and model parameters. This paper presents a two-stage numerical predictor-corrector method based on the constant bank angle to achieve precise guidance of Mars atmospheric entry with less trajectory segmentation and a more concise guidance concept. According to the flight characteristics of the Mars vehicle during the entry phase, the entry trajectory is segmented into two stages for numerical predictor-corrector guidance. In the first stage, only one guidance cycle is involved, which can reduce energy consumption. In the second stage, more guidance cycles are exploited to reduce trajectory error. The Monte Carlo simulation experiment results show that the proposed guidance algorithm has relatively steady performance under uncertainties such as entry state, lift-to-drag ratio, ballistic coefficient, and atmospheric density.