Aero-gravity assist maneuvers: controlled dynamics modeling and optimization

Abstract

The aero-gravity assist maneuver is here proposed as a tool to improve the efficiency of the gravity assist as, thanks to the interaction with the planetary atmospheres, the angular deviation of the velocity vector can be definitely increased. Even though the drag reduces the spacecraft velocity, the overall υ gain could be remarkable whenever a high lift-to-drag vehicle is supposed to fly. Earlier studies offer simplified approaches according to both the dynamics modeling and the atmospheric trajectory constraints. In this paper a 3D dynamical model is adopted and a more realistic L/D performance for the hypersonic vehicle is assumed. Some relevant aspects related to the multidisciplinary design have been considered such as heating rates and structural loads bounding. Comparisons between in and out of plane maneuvering have been performed by assuming, as control variables, either the angle of attack or the bank angle, respectively. The optimal control problem has been solved by selecting a direct method approach. The dynamics has been transcribed into a set of non-linear constraints and the arising non-linear programming problem has been solved with a sequential quadratic programming solver. To gain the global optimum convergence the initial guess has been supplied by solving the same problem by a direct shooting technique and a genetic optimizer.

Effects of Bank Angle During Powered Aerogravity-Assist Maneuver

“…A traditional model to quantify the effects of the GAM in the spacecraft VOE giving by the passage is the CRTBP, widely explained in multiple studies, showing excellent results and validation of the mathematical model [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. The CRTBP describes an orbital system formed by a set of three bodies, in this case the massive body M 1 (the sun), the second body M 2 (target planet), both of them moving in Keplerian orbits around their common center of mass, and a third body of infinitesimal mass M 3 (waverider spacecraft).…”

“…The possible uses of this powered maneuver have been analyzed for planets and moons of the solar system [17][18][19][20][21][22][23][24]. When the maneuver is made close to planets that have significant atmosphere and using a spacecraft with wing-body shape (waverider), the AGAM could also be controlled by the direction and/or magnitude of the aerodynamic forces generated during atmospheric flight [2][3][4][25][26][27][28][29][30][31][32]. Since 2015, the combination of the GA with the application of an impulse and a passage by the atmosphere was studied.…”

“…In that sense, the present paper has the goal of studying a new version of this maneuver, where the bank angle is assumed to be variable and constituting in a new form to control the AGAM and PAGAM, which was not used before. The mathematical model selected to analyze the applications of the maneuvers and the resulting trajectories around the center of mass of the orbital system is the circular restricted three-body problem (CRTBP) [36], which is highly accepted in this kind of problems [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. The choice of this model is based on our solar system, where the massive body is the sun, the secondary body is a planet with atmosphere used for the maneuver, and the third body is the spacecraft, represented as a massless waverider.…”

Binary collisions and the slingshot effect

“…The nature of the interaction is irrelevant, as long as it is central and conservative. Evidently we are not considering for the moment variations of the manoeuvre such as aero-gravity assisted slingshots (Armellin et al 2006) where at perigee the forces involved are neither conservative nor central. The particular value of θ that corresponds to the theoretical maximum slingshot case is when θ equals half the angle ψ o between v o − u o and V cm , which means that u 1 and v 1 would both come out collinear to the CM velocity V cm .…”

Optimal Mars transfers for small payload transportation

“…Miele et al (2005a,b) gave an accurate description of the effect of the constraints on the thrust direction. Eventually, the effects of an aero-braking capture have been described (Sengupta et al 2008;Armellin et al 2006). Several trajectories have been designed, each of them fitting a given task: cyclers or half-cyclers, and free return in case of damage of the spacecraft (Landau and Longusky 2006a,b).…”