Engineering Papers⌕ Search

Engineering topics

Hitt, Darren

Publications and source records attributed to Hitt, Darren.

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Multi-Objective Optimization of Spacecraft Trajectories for Small-Body Coverage Missions

Visual coverage of surface elements of a small-body object requires multiple images to be taken that meet many requirements on their viewing angles, illumination angles, times of day, and combinations thereof. Designing trajectories capable of maximizing total possible coverage may not be useful since the image target sequence and the feasibility of said sequence given the rotation-rate limitations of the spacecraft are not taken into account. This work presents a means of optimizing, in a multi-objective manner, surface target sequences that account for such limitations.

Hinckley, David, Jr.↗
NASA NTRS2017

Multi-Objective Optimization of Spacecraft Trajectories for Small-Body Coverage Missions

Visual coverage of surface elements of a small-body object requires multiple images to be taken that meet many requirements on their viewing angles, illumination angles, times of day, and combinations thereof. Designing trajectories capable of maximizing total possible coverage may not be useful since the image target sequence and the feasibility of said sequence given the rotation-rate limitations of the spacecraft are not taken into account. This work presents a means of optimizing, in a multi-objective manner, surface target sequences that account for such limitations.

Hinckley, David, Jr.↗
NASA NTRS2016

Aeroacoustic Duster

The invention disclosed herein provides for high particle removal rate and/or heat transfer from surfaces. The device removes particulate matter from a surface using a bounded vortex generated over the surface, with suction in the vortex center and jets for blowing air along the periphery. The jets are tilted in the tangential direction to induce vortex motion within the suction region. The vortex is said to be bounded because streamlines originating in the downward jets are entrained back into the central vortex.

Marshall, Jeffrey S.↗
NASA NTRS2015

Global Optimization of Interplanetary Trajectories in the Presence of Realistic Mission Contraints

Interplanetary missions are often subject to difficult constraints, like solar phase angle upon arrival at the destination, velocity at arrival, and altitudes for flybys. Preliminary design of such missions is often conducted by solving the unconstrained problem and then filtering away solutions which do not naturally satisfy the constraints. However this can bias the search into non-advantageous regions of the solution space, so it can be better to conduct preliminary design with the full set of constraints imposed. In this work two stochastic global search methods are developed which are well suited to the constrained global interplanetary trajectory optimization problem.

Design↗
NASA NTRS2014

Aeroacoustic Duster

The aero-acoustic duster invention disclosed herein provides for high particle removal rate from surfaces with low energy expenditure relative to competing vacuum-based devices. The device removes particulate matter from a surface using a two-step process: 1. Acoustic radiation is used to break the adhesive bonds between dust and the surface, forcing particles into a mode where they continuously bounce up and down on the surface; and, 2. A bounded vortex is generated over the surface, with suction in the vortex center and jets for blowing air along the periphery. The jets are tilted in the tangential direction to induce vortex motion within the suction region. The vortex is said to be bounded because streamlines originating in the downward jets are entrained back into the central vortex.

Marshall, Jeffrey S.↗