# Influence of Flow Field on the Imaging Quality of Star Sensors for Hypersonic Vehicles in near Space

## TL;DR

This paper studies how the flow field affects star sensor imaging quality in hypersonic vehicles flying in near space.

## Contribution

The study introduces a comparative analysis of ray tracing methods and evaluates how altitude, velocity, and angle of attack influence imaging quality.

## Key findings

- Higher altitudes reduce the impact of the flow field on imaging quality.
- The relationship between velocity and offset is nonlinear when the optical window is at the tail.
- Runge–Kutta and Adams–Bashforth–Moulton methods each have strengths and limitations in ray tracing.

## Abstract

When hypersonic vehicles fly in near space, the flow field near the optical window leads to light displacement, jitter, blurring, and energy attenuation of the star sensor. This ultimately affects the imaging quality and navigation accuracy. In order to investigate the impact of aerodynamic optical effects on imaging, the fourth-order Runge–Kutta and the fourth-order Adams–Bashforth–Moulton (ABM) predictor-corrector methods are used for ray tracing on the density data. A comparative analysis of the imaging quality results from the two methods reveals their respective strengths and limitations. The influence of the optical system is included in the image quality calculations to make the results more representative of real data. The effects of altitude, velocity, and angle of attack on the imaging quality are explored when the optical window is located at the tail of the vehicle. The results show that altitude significantly affects imaging results, and higher altitudes reduce the impact of the flow field on imaging quality. When the optical window is located at the tail of the vehicle, the relationship between velocity and offset is no longer simply linear. This research provides theoretical support for analyzing the imaging quality and navigation accuracy of a star sensor when a vehicle is flying at hypersonic speeds in near space.