Table 5 - uploaded by Benjamin A. Stahl
Content may be subject to copyright.
Source publication
In the past decade, the scientific community has become more interested in Near Earth Objects (NEOs) and the threat they pose to existence of life on this planet. The recent trend in NEO deflection technique research has been toward "slow push" techniques in order to absolve the need for sending nuclear weapons into space. A software tool was devel...
Similar publications
Seeing that the prosperity of people and society is possible with the aid of sustained and inclusive economic growth of all countries and regions, the sustainable development of our world has gained the particular attention of a wide range of decisional factors; civil society, the business sector, and the scientific community. Education has a decis...
Several studies in Bioinformatics, Computational Biology and Systems Biology rely on the definition of physico-chemical or mathematical models of biological systems at different scales and levels of complexity, ranging from the interaction of atoms in single molecules up to genome-wide interaction networks. Traditional computational methods and sof...
Full three-dimensional (3D) unstructured grids offer a great degree of flexibility to perform accurate reservoir numerical simulations. However, when the space discretization is done using the Integral Finite Difference Method (IFDM), the requested orthogonality between the segment connecting the nodes and the blocks interface area complicates the...
A detailed new upgrade of the FEAST eigensolver targeting non-Hermitian
eigenvalue problems is presented and thoroughly discussed. It aims at
broadening the class of eigenproblems that can be addressed within the
framework of the FEAST algorithm. The algorithm is ideally suited for computing
selected interior eigenvalues and their associated right/...
Citations
... Missions to asteroids using electric propulsion have been studied for various destinations and thruster options [1][2][3][4][5][6][7]. Asteroid impact missions, such as the Double Asteroid Redirection Test (DART) [8], employ a kinetic impactor to change the orbit of an asteroid. ...
... These individual Fourier coefficients used to calculate γ(t), τ(t), and ψ(t) are a part of the "chromosome" in Equation (1). To optimize propellant use, the thruster was turned on/off in the following fashion. ...
A streamlined genetic algorithm was developed and implemented on a GPU to evaluate low-thrust trajectories of spacecraft propelled by an ion thruster. It was then applied to examine the utility of a specific thruster for an asteroid impact mission. This method was validated by comparing impact speeds of non-thruster results with the DART mission, which does not significantly use the equipped ion thruster. Then, by utilizing the ion thruster for prolonged periods, this model demonstrated the possibility of significant increases in the impact speed and significant decreases in the trip times. This specific test case was used to examine the utility of the model and, by methodically varying relevant variables, this article shows the influence of the genetic algorithm on the results. By examining a range of electrical power levels, the results presented here provide hints as to the possible effects of spacecraft design trade-offs on impact speed. The analysis of the effects of the algorithm on the results and the evaluation of thruster operating parameters indicate the applicability of this model to a variety of spaceflight missions.
We examine the effectiveness of a near-optimal steering strategy for a gravity tractor mission to deflect asteroid Apophis from the possible passage through a key hole in 2029. Direct optimization of the tug vector is compared against along track tugging using patched conics analysis. The objective is to maximize Apophis' perigee distance. Results suggest that a steering strategy may more effective than along-track tugging to maximize perigee distance when a deflection mission is implemented with short lead times prior to close en counter. For long lead times tugging along the velocity vector showed to be more effective to maximize fly by distance.
The electricity for an electric propulsion spacecraft is provided by the solar arrays, so the working conditions of the electric thruster are constrained by the radius of the spacecraft from the sun in deep space exploration missions. The trajectory design of a solar electric propulsion spacecraft constrained by the solar power is studied here. The power constraint is formed as a constraint on the thrust. An indirect method is then used to solve the two-point boundary-value problem (TPBVP) derived from the fuel optimal control problem. The heliocentric distance is used in solving the solar electric propulsion problem. Effective techniques, such as the homotopic approach and switch detection, are used to find the designed trajectory satisfying the power constraint. A case study shows that this algorithm is effective and may be widely used in engineering problems.
An indirect method, which exploits the theory of optimal control, is applied to optimize a kinetic impactor mission for the deflection of an Earth-crossing asteroid. The trajectory of the deflecting spacecraft from Earth escape to asteroid deviation is determined to maximize the miss distance at the asteroid's closest approach to the Earth. A procedure to find mission opportunities is developed and applied to both ballistic and electric propulsion trajectories. The optimization method proves to be robust and efficient.Alarge number of deflection opportunities are found with limited computational effort. The comparison of results shows the benefit that the use of electric propulsion can provide with respect to ballistic trajectories; high-performance trajectories, which move far from the sun and become retrograde, are enabled. Counterintuitive effects related to asteroid inclination are also highlighted.
