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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Optimal orbital rendezvous using high and low thrust

Optimal control theory is used to examine a specific class of spacecraft trajectory problems where high- and low-thrust propulsion systems are utilized. These problems assume a spacecraft is in an established orbit about a planet. It is desired to execute an intercept of a pre-determined position in space in a specified amount of time using an optimal high-thrust program. The spacecraft then returns to the original orbit station using the low-thrust propulsion system in an optimal fashion. A minimum fuel solution is sought using the linearized equations of motion, known as the CW equations, which simplify the necessary computations. Solutions are obtained for problems with a fixed final time. However, for the time-open case, the optimal solution is for the final time to be infinite. With a weighted function of the final time in the performance index, a limited range of optimal single impulse solutions for the time -open case can also be found.

Prussing, John E.↗
NASA NTRS1991

Low thrust viscous nozzle flow field predictions

The low thrust viscous nozzle flows have been studied numerically by using the steady-state Reynolds-averaged Navier-Stokes equations in conservative form. A new Lower-Upper factorization scheme in the axisymmetric coordinate system has been developed and is analyzed in this paper. This new Navier-Stokes solver has shown that the numerical analog is accurate and stable for the convergent and divergent nozzle flowfield calculation. The range of the chamber pressure is (1.85-29.4)psi with the chamber temperature equal to 600 F. The results are compared with the data collected in the NASA/MSFC vacuum chamber, and they are in very reasonable agreement.

Chou, L. C.↗
NASA NTRS2018

Parallel Monotonic Basin Hopping for Low Thrust Trajectory Optimization

Monotonic Basin Hopping has been shown to be an effective method of solving low thrust trajectory optimization problems. This paper outlines an extension to the common serial implementation by parallelizing it over any number of available compute cores. The Parallel Monotonic Basin Hopping algorithm described herein is shown to be an effective way to more quickly locate feasible solutions, and improve locally optimal solutions in an automated way without requiring a feasible initial guess. The increased speed achieved through parallelization enables the algorithm to be applied to more complex problems that would otherwise be impractical for a serial implementation. Low thrust cislunar transfers and a hybrid Mars example case demonstrate the effectiveness of the algorithm. Finally, a preliminary scaling study quantifies the expected decrease in solve time compared to a serial implementation.,

McCarty, Steven L.↗
NASA NTRS2018

Parallel Monotonic Basin Hopping for Low Thrust Trajectory Optimization

Monotonic Basin Hopping has been shown to be an effective method of solving low thrust trajectory optimization problems. This paper outlines an extension to the common serial implementation by parallelizing it over any number of available compute cores. The Parallel Monotonic Basin Hopping algorithm described herein is shown to be an effective way to more quickly locate feasible solutions, and improve locally optimal solutions in an automated way without requiring a feasible initial guess. The increased speed achieved through parallelization enables the algorithm to be applied to more complex problems that would otherwise be impractical for a serial implementation. Low thrust cislunar transfers and a hybrid Mars example case demonstrate the effectiveness of the algorithm. Finally, a preliminary scaling study quantifies the expected decrease in solve time compared to a serial implementation.

McCarty, Steven L.↗
NASA NTRSDate not supplied

Low-Thrust Transfer to Interplanetary Trajectories from Lunar Trajectories with Rideshare

Accessing interplanetary space is challenging when using low thrust systems. Injecting spacecraft onto interplanetary trajectories is difficult with small launch vehicles, but it is possible to instead transfer to an interplanetary trajectory from a lunar flyby. Such cases are useful, for example, in rideshares between lunar and interplanetary missions. This work examines the problem of rideshare for small satellites onto lunar flyby trajectories, with transfers to an interplanetary trajectory. Low thrust interplanetary trajectories are examined starting from a rideshare mission on a lunar trajectory using delivery systems based on a modified Rocket Lab USA Electron vehicle and Photon stage.

Darcey R Graham↗
NASA NTRS1990

A trajectory generation and system characterization model for cislunar low-thrust spacecraft. Volume 2: Technical manual

The documentation of the Trajectory Generation and System Characterization Model for the Cislunar Low-Thrust Spacecraft is presented in Technical and User's Manuals. The system characteristics and trajectories of low thrust nuclear electric propulsion spacecraft can be generated through the use of multiple system technology models coupled with a high fidelity trajectory generation routine. The Earth to Moon trajectories utilize near Earth orbital plane alignment, midcourse control dependent upon the spacecraft's Jacobian constant, and capture to target orbit utilizing velocity matching algorithms. The trajectory generation is performed in a perturbed two-body equinoctial formulation and the restricted three-body formulation. A single control is determined by the user for the interactive midcourse portion of the trajectory. The full spacecraft system characteristics and trajectory are provided as output.

Korsmeyer, David J.↗
NASA NTRS1980

Low-thrust vehicle concept studies

Part of NASA's orbit transfer vehicle propulsion program is devoted to the development of analytical tools to define propulsion system performance, weight, size, and other parameters, and to develop packing concepts for LSS mission propulsion and payload systems. Packing studies discussed relate to shuttle cargo bay constraints; low thrust engine profile and performance; large space frame concept and weight; low thrust vehicles stowed in shuttle, LSS payload capability, and weight distribution. Further study is needed to determine interactions among propulsion system, payload structures, and shuttle. Low thrust-to-weight ratios are desirable to maximize payload weights and deployed areas.

Smolak, G. R.↗
NASA NTRS1984

Optimal low-thrust, three-burn orbit transfers with large plane changes

Optimal low-thrust, three-burn solutions have been obtained for orbit transfers between a 28.5-degree inclined low earth orbit and a series of 63.4-degree inclined circular orbits as well as a series of 63.4-degree inclined elliptical orbits with twelve hour periods. Solutions have also been obtained for orbit transfers between 97-degree inclined orbits and a 57-degree inclined low earth orbit. Thrust to weight ratios as low as 0.02 were considered. A hybrid nonlinear programming method was used to obtain the solutions. Analysis of the optimal steering during various burns reveals a natural division of the steering strategies into two categories based on whether a burn results in a change predominantly in semi-major axis or orbit plane. The similarity of these optimal steering strategies to previously obtained simple near-optimal steering strategies is discussed.

Zondervan, K. P.↗