Programmer's manual for the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)

The Mission Analysis Evaluation and Space Trajectory Operations program known as MAESTRO is described. MAESTRO is an all FORTRAN, block style, computer program designed to perform various mission control tasks. This manual is a guide to MAESTRO, providing individuals the capability of modifying the program to suit their needs. Descriptions are presented of each of the subroutines descriptions consist of input/output description, theory, subroutine description, and a flow chart where applicable. The programmer's manual also contains a detailed description of the common blocks, a subroutine cross reference map, and a general description of the program structure

Survey of highly non-Keplerian orbits with low-thrust propulsion

Celestial mechanics has traditionally been concerned with orbital motion under the action of a conservative gravitational potential. In particular, the inverse square gravitational force due to the potential of a uniform, spherical mass leads to a family of conic section orbits, as determined by Isaac Newton, who showed that Kepler‟s laws were derivable from his theory of gravitation. While orbital motion under the action of a conservative gravitational potential leads to an array of problems with often complex and interesting solutions, the addition of non-conservative forces offers new avenues of investigation. In particular, non-conservative forces lead to a rich diversity of problems associated with the existence, stability and control of families of highly non-Keplerian orbits generated by a gravitational potential and a non-conservative force. Highly non-Keplerian orbits can potentially have a broad range of practical applications across a number of different disciplines. This review aims to summarize the combined wealth of literature concerned with the dynamics, stability and control of highly non-Keplerian orbits for various low thrust propulsion devices, and to demonstrate some of these potential applications

COLD-SAT dynamic model

This report discusses the development and underlying mathematics of a rigid-body computer model of a proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer spacecraft (COLD-SAT). This model, referred to in this report as the COLD-SAT dynamic model, consists of both a trajectory model and an attitudinal model. All disturbance forces and torques expected to be significant for the actual COLD-SAT spacecraft are modeled to the required degree of accuracy. Control and experimental thrusters are modeled, as well as fluid slosh. The model also computes microgravity disturbance accelerations at any specified point in the spacecraft. The model was developed by using the Boeing EASY5 dynamic analysis package and will run on Apollo, Cray, and other computing platforms

High fidelity thrust model for solar photon sailing

Taking into consideration the importance of a detailed model in the trajectory propagation, three space missions using solar photon sailing has been studied with a different thrust model. Then, an equipment has been designed and built to measure the deformation of a real sample of solar sail on several work conditions. An analysis of the deformations and they distributions has been taken in account to extrapolate a more accurate model for thrust. A comparison between models in function of the sail parameters has been presented to compare the optimal time of travel to reach a circular-to-circular orbital change

Controls Algorithm For A Satellite Using Earth\u27s Magnetic Field: Orbit Maneuvers And Attitude Positioning

This document describes the design, analysis of Orbit Maneuvers and Attitude Control for NanoSat class satellites, which uses an electro-magnetic force controller which was proposed by the Florida Space Institute (FSI). Orbit Maneuvering and the Attitude Control System (ACS) play a very important role for the success of this mission, as that can allow making the satellite go to the desired orbit as well do the sun pointing of the solar arrays with su¢ cient accuracy to achieve desired power levels. The primary mission would be to attain attitude stabilization using the torque from the coils. This is also used for pointing at the direction of the sun, for achieving desired power levels. The secondary mission would be to use the force of the magnetic field and utilize that for orbit maneuvering, and attain the desired trajectory. This thesis gives a presentation of this detailed analysis with a simulation using Matlab/Simulink. Mathematical model of the actuators and sensors used for this satellite are designed, so that the simulation gives us results very near to the actual ones.Health Monitoring is also one of the main issues addressed in this work. This simulation helps us in understanding the mission as well as the requirements very well, and helps us know all the shortcomings. The FUNSAT satellite is modeled as an example in Simulink together with a Kalman filter for attitude estimation based on all sensor measurements. The theory behind this, and extending the Kalman filter, is also presented

Analysis of Electric Sail Heliocentric Motion under Radial Thrust

The contribution of this Note is to analyze the heliocentric trajectory of an E-sail with an outward radial thrust by reducing the problem, by means of a suitable change of variables, to the dynamics of a known equivalent nonlinear oscillator with a single degree of freedom. An analytical, albeit approximate, expression of the spacecraft heliocentric trajectory is also given in polar form when the motion is periodic. This result is shown to be sufficiently accurate for a preliminary mission analysis and is obtained with a reduced computational time, considerably smaller than what is necessary for a numerical integration of the spacecraft equations of motion

The Prospect of Responsive Spacecraft Using Aeroassisted, Trans-Atmospheric Maneuvers

Comprised of exo- and trans-atmospheric trajectory segments, atmospheric re-entry represents a complex dynamical event which traditionally signals the mission end-of-life for low-Earth orbit spacecraft. Transcending this paradigm, atmospheric re-entry can be employed as a means of operational maneuver whereby aerodynamic forces can be exploited to create an aeroassisted maneuver. Utilizing a notional trans-atmospheric, lifting re-entry vehicle with L/D =6, the first phase of research demonstrates the terrestrial reachability potential for skip entry aeroassisted maneuvers. By overflying a geographically diverse set of ground targets, comparative analysis indicates a significant savings in delta V expenditure for skip entry compared with exo-atmospheric maneuvers. In the second phase, the Design of Experiments method of orthogonal arrays provides optimal vehicle and skip entry trajectory designs by employing main effects and Pareto front analysis. Depending on re-circularization altitude, the coupled optimal design can achieve an inclination change of 19.91° with 50-85% less delta V than a simple plane change. Finally, the third phase introduces the descent-boost aeroassisted maneuver as an alternative to combined Hohmann and bi-elliptic transfers in order to perform LEO injection. Compared with bi-elliptic transfers, simulations demonstrate that a lifting re-entry vehicle performing a descent-boost maneuver requires 6-12% less for injection into orbits lower than 650 km. In addition, the third phase also introduces the Maneuver Performance Number as a dimensionless means of comparative maneuver effectiveness analysis

Astronautics

Many people have had and still have misconceptions about the basic principle of rocket propulsion. Here is a comment of an unknown editorial writer of the renowned New York Times from January 13, 1920, about the pioneer of US astronautics, Robert Goddard, who at that time was carrying out the ?rst experiments with liquid propulsion engines: Professor Goddard … does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react – to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools

Optimal aeroassisted orbital transfer with plane change using collocation and nonlinear programming

The fuel optimal control problem arising in the non-planar orbital transfer employing aeroassisted technology is addressed. The mission involves the transfer from high energy orbit (HEO) to low energy orbit (LEO) with orbital plane change. The basic strategy here is to employ a combination of propulsive maneuvers in space and aerodynamic maneuvers in the atmosphere. The basic sequence of events for the aeroassisted HEO to LEO transfer consists of three phases. In the first phase, the orbital transfer begins with a deorbit impulse at HEO which injects the vehicle into an elliptic transfer orbit with perigee inside the atmosphere. In the second phase, the vehicle is optimally controlled by lift and bank angle modulations to perform the desired orbital plane change and to satisfy heating constraints. Because of the energy loss during the turn, an impulse is required to initiate the third phase to boost the vehicle back to the desired LEO orbital altitude. The third impulse is then used to circularize the orbit at LEO. The problem is solved by a direct optimization technique which uses piecewise polynomial representation for the state and control variables and collocation to satisfy the differential equations. This technique converts the optimal control problem into a nonlinear programming problem which is solved numerically. Solutions were obtained for cases with and without heat constraints and for cases of different orbital inclination changes. The method appears to be more powerful and robust than other optimization methods. In addition, the method can handle complex dynamical constraints

On the Advantages of Using a Strict Hierarchy to Model Astrodynamical Problems

In this paper an algorithm is developed that combines the capabilities and advantages of several different astrodynamical models of increasing complexity. Splitting these models in a strict hierarchical order yields a clearer grasp on what is available. With the effort of developing a comprehensive model overhead, the equations for the spacecraft motion in simpler models can be readily obtained as particular cases. The proposed algorithm embeds the circular and elliptic restricted three-body problems, the four-body bicircular and concentric models, an averaged n-body model, and, at the top hierarchic ladder, the full ephemeris spice-based restricted n-body problem. The equations of motion are reduced to the assignment of 13 time-varying coefficients, which multiply the states and the gravitational potential to reproduce the proper vector field. This approach is powerful because it allows, for instance, an efficient and quick way to check solutions for different dynamics and parameters. It is shown how a gradual increase of the dynamics complexity greatly improves accuracy, the chances of success and the convergence rate of a continuation algorithm, applied to low-energy transfers