A dynamic simulation method for evaluating atomic oxygen effect based on spatial geometric transformation

Abstract

Atomic oxygen is one of the most abundant enviromental element which impacts spacecraft reliability in LEO(Leo earth orbit) space enviroment. Orbiting in LEO, the surface material of spacecraft may be eroded away through the reaction of the atomic oxygen, which seriously reduces the spcaecraft’s orbit life. Therefore, effectively testing the atomic oxygen adapation of the spacecraft, before the spacecraft launching, is the key to ensure the spacecraft can compelete the orbiting task. However, most ground simulation experiments or digital simulation technologies using to evaluate atomic oxygen adapation recently, are desighed on condition that the specimen is static in the atomic oxygen enviroment. These methods are diffcult to evaluate atomic oxygen erosion while the spacecraft’s attitude have transformed, because atomic oxygen impact is related to the orientation of specimen’s surface. Aim to this problem, this paper proposes a dynamic simulation method to evaluate atomic oxygen erosion, based on spatial geometric transformation. First, using point group to describe specimen’s surface in Cartesian coordinates. Secondly, breaking down the specimen’s attitude transformation into several static moments by interpolation calculation of equal time interval, and calculating the coordinates of point group in each moment by rotation equation. Thirdly, calculating the atomic oxygen density of the point group in every moment, accroding to the atomic oxygen density equation. Finally, from every static moment atomic oxygen density, using numerical integration to calculate accumulated flux and erosion of atomic oxygen. Using the proposed method, this paper simulates the process that several ideal geometries(including cube, sphere, cylinder and regular octahedron) rotate in the atomic oxygen particle filed. All geometries contain two kinds of materials. As a result, the simulation ouputs the 3D distribution diagram of accumulated flux and erosion which can be used to evaluate the specimen’s atomic oxygen adapation during the rotation. Compared to normal simulation experiments outputing mean erosion, the proposed method can output the 3D distribution diagram of the atomic oxygen erosion, which is more comprehensive and intutive. The proposed method can be used on the situation that the specimen is consisted of different kinds of materials and has rotated in the atomic oxygen envirment. Therefore, the proposed method can be used in more cases.