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Trajectory Control During an Aeroassisted Maneuver Between Coplanar Circular Orbits Willer Gomes Dos Santos1, Evandro Marconi Rocco1, Valdemir Carrara1

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Trajectory Control During an Aeroassisted Maneuver Between Coplanar Circular Orbits Willer Gomes Dos Santos1, Evandro Marconi Rocco1, Valdemir Carrara1 doi: 10.5018/jatm.v6i2.351 Trajectory Control During an Aeroassisted Maneuver Between Coplanar Circular Orbits Willer Gomes dos Santos1, Evandro Marconi Rocco1, Valdemir Carrara1 ABSTRACT: This paper presents the simulation results of an aeroassisted maneuver around the Earth, between coplanar INTRODUCTION circular orbits, from a geostationary orbit to a low orbit. The simulator developed considers a reference trajectory and a An orbital maneuver is the transfer of a satellite from one trajectory perturbed by external disturbances combined with non-idealities of sensors and actuators. It is able to operate orbit to another by means of a change in velocity. To perform in closed loop, controlling the trajectory (drag-free control) at this change, the spacecraft has to engage the thrusters or use the each instant of time using a Proportional-Integral-Derivative natural forces of the environment. The Hohmann transfer and (PID) controller and propulsive jets. We adopted a spacecraft the bi-elliptic transfer are some alternatives to perform an with a cubic body composed of two rectangular plates arranged perpendicular to the velocity vector of the vehicle. orbital maneuver by propulsive means. In 1961, Howard London Propulsive jets are applied at the apogee of the transfer orbit presented the approach of using aerodynamic forces to change in order to keep the perigee altitude and control the rate the trajectory and velocity of a spacecraft, this new technique of heat transfer suffered by the vehicle during atmospheric passage. A PID controller is used to correct the deviation became known as aeroassisted maneuvers (Walberg, 1985). This in the state vector and in the keplerian elements. The U.S. type of orbital transfer can be accomplished in several layers Standard Atmosphere is adopted as the atmospheric model. of the atmosphere. The altitude reached by vehicle is linked The results have shown that the aeroassisted transfer to the mission’s purpose and to the maximum thermal load presents a smaller fuel consumption when compared to a Hohmann transfer or a bi-elliptic transfer. supported by the vehicle structure. The main advantage of this type of maneuver is the fuel economy. According to Walberg KEYWORDS: Aeroassisted maneuvers, Orbital dynamic, (1985), many papers on aeroassisted orbital transfer have been Trajectory control. made in recent decades and it has been shown that a significant reduction in fuel can be achieved using aeroassisted maneuvers instead of Hohmann transfer. Consequently, the reduction of fuel provides an increase in the payload capacity of the vehicle. Orbit transfer between two circular and coplanar orbits is very common. The technique of using atmospheric drag to reduce the semi-major axis is known as aerobraking and it was first used on March 19th, 1991, by spacecraft Hiten. The launch was conducted by the Institute of Space and Astronautical Science of Japan (ISAS). The spacecraft passed through Earth’s atmosphere at an altitude of 125.5 km over the Pacific Ocean at a speed of 11 km/s. The experience resulted in a decrease in apogee altitude of 8,665 km. In May 1993, an aerobraking maneuver was used on a mission to Venus by Magellan spacecraft, whose goal was to circularize the orbit of the spacecraft. In 1997, the probe U.S. Mars Global Surveyor (MGS) 1.Instituto Nacional de Pesquisas Espaciais – São José dos Campos/SP – Brazil Author for correspondence: Willer Gomes dos Santos | Instituto Nacional de Pesquisas Espaciais | Avenida dos Astronautas 1758, São José dos Campos/SP | CEP: 12227-010 – Brazil | Email: [email protected] Received: 12/01/2013 | Accepted: 03/25/2014 J. Aerosp. Technol. Manag., São José dos Campos, Vol.6, No 2, pp.159-168, Apr.-Jun., 2014 Gomes dos Santos, W., Rocco, E.M. and Carrara, V. 160 used its solar panels as “wings” to control its passage through the placed in opposite sides of the vehicle’s body. The inclination tenuous upper atmosphere of Mars and lower its apoapsis. angle of the plates, regarding its molecular flow (attack angle), There are several missions requirements that become feasible was fixed at 90 degrees, in order to maximize the projected with the use of aeroassisted vehicles, as for example, to reconfigure area and the drag force. The spacecraft will be transferred from orbital systems that are unable to perform an orbital maneuvering the GEO to a low orbit. The orbits are considered circular and (such as replacing a malfunctioning satellite by a spare), to transfer coplanar. A multipass aeroabraking strategy is used to perform space debris to a new orbit, to operate Space Transportation the transfer. Systems (STS), to use the atmospheric drag as a brake force to First, the spacecraft applies an impulse to take the vehicle provide orbit capturing of the vehicle, to assist the International out of the GEO and put it into an elliptical orbit with perigee Space Station with the transfer of cargo between geostationary within the limits of the atmosphere. After each passage at orbit (GEO) and low earth orbit (LEO), among others. atmospheric region, a reduction of the apogee transfer orbit Within the context of this paper, we can cite the scientific occurs. When the spacecraft reaches its final apogee altitude, micro-satellite Franco-Brazilian (FBM) project, in partnership then, a new impulse is applied to the vehicle to remove between the Brazilian and French space agencies (INPE and it from the transfer orbit and insert it into the final orbit. CNES), which would be released as piggy-back on an Ariane 5, In order to control the rate of heat transfer suffered by the and then would perform aerobraking maneuvers to transfer vehicle during the passage through atmosphere, propulsive the satellite to the orbit service (Furlan, 1998). The Ariane 5 jets are applied at the apogee, correcting the decay of perigee. rocket has the capacity to carry up to eight microsatellites with This transfer strategy is shown in Fig. 1. a maximum individual weight of 120 kg through the Ariane Structure for Auxiliary Payload (ASAP). However, the rocket was designed to place satellites in geostationary transfer orbits. The propellant required to transfer the FBM to a low orbit (between 800 and 1,300 km) by means of chemical propellants, would deorbit (OTV) exceed the allowed amount of mass. This question has led space agencies to study the concept of aerobraking as a workaround. Atmosphere Limit However, CNES, in 2003, left the program which was subsequently discontinued (Brezun et al., 2000). In another interesting study with the same context, Schulz (2001) developed an optimal control law that minimizes the fuel consumption during an aeroassisted Target Orbit (LEO FOR OTV) maneuver, as well as analyzed orbital changes. Apoapsis trim Final circularization maneuvers to GEO and periapsis This paper will present the simulation of an aerobraking adjust periapsis raise maneuver maneuver between GEO and low orbit. The study aims at examinining the effects that this kind of maneuver can cause in Figure 1. Multipass aerobraking (Walberg, 1985). the orbital elements. It will also demonstrate the difference in fuel costs and the elapsed transfer time between an aeroassisted maneuver and a fully propulsive maneuver. The results show In this work, it was used the Aeroassisted Spacecraft Maneuver that the aeroassisted transfer has a propellant consumption Simulator (SAMS) based on the Spacecraft Trajectory Simulator lower than a Hohmann or a bi-elliptic transfer. (STRS), which uses a drag-free control architecture to control the spacecraft trajectory (Rocco, 2006, 2008, 2009, 2010). Usually, a ground based open loop control is used for maneuver correction and orbit transfer. However, in some drag-free PROBLEM DEFINITION missions (Gravity Probe B, Hipparcos, GOCE, etc) the feedback control is mandatory. The STRS and SAMS consider a reference In this paper, a spacecraft with a cubic body composed of trajectory and a trajectory perturbed by external disturbances, two rectangular plates was adopted, called aerodynamic plates, including the aerodynamic effects, combined with non-idealities J. Aerosp. Technol. Manag., São José dos Campos, Vol.6, No 2, pp.159-168, Apr.-Jun., 2014 Trajectory Control During an Aeroassisted Maneuver Between Coplanar Circular Orbits 161 of sensors and actuators. The simulator works in closed loop According to Theil and Silas-Guilherme (2005), drag-free controlling the trajectory at each instant of time, which is one of technology is essential for scientific missions which need a very the input parameters, using a Proportional-Integral-Derivative low disturbance environment. Several missions have used this (PID) controller and propulsive jets. Santos (2011) used the technology, such as Gravity Probe B (GP-B) to test the relativistic SAMS to study how the orbital elements can be changed by an effects on a gyroscope; STEP and MICROSCOPE had the objective aeroassisted maneuver and how much fuel is saved comparing of testing the weak principle of equivalence; Laser Interferometer with a propulsive maneuver. Figure 2 shows a basic diagram Space Antenna (LISA) for the detection of gravitational waves; of the running logic of the aeroassisted maneuver simulator. and Gravity Field and Steady State Ocean Circulation Explorer In this work, noises and non-idealities in the actuator and in (GOCE), launched in March 2009, to determine the gravity-field the sensor were not considered. anomalies with high accuracy; among others. AEROASSISTED MANEUVER The main forces acting on a spacecraft in LEO are gravitational Disturbance force (mg), thrusters force (Ts) and aerodynamic forces (F), + caused by the interaction of the satellite with the atmosphere. Reference + PID Propulsive + Orbital Disturbed state State - Controller System Dynamic The spacecraft position in space determines the magnitude of aerodynamic forces suffered by the spacecraft. The higher the Sensor planetary atmospheric density is, the stronger the aerodynamic forces are. The aerodynamic force can be divided into two: the drag force (FD), whose direction is opposite to the velocity Figure 2.
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