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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 1,099 records · Page 61

All sources NASA NTRS DOE OSTI

NASA NTRSDate not supplied

6-DoF Uranus Aerocapture Trajectory Analysis

The Uranus Orbiter and Probe mission has been identified as the highest priority flagship mission for this decade. Delays in launch opportunities may make existing fully-propulsive orbit insertion mission types unfeasible. Aerocapture can potentially alleviate these challenges while providing a solution flexible to different launch opportunities. While the space technology that aerocapture leverages have been flight-proven, aerocapture as-a-whole has not been formally demonstrated. This paper presents a novel 6-DoF aerocapture trajectory analysis applied to Uranus. The paper presents the 6-DoF simulation framework, inspired from Mars Science Laboratory. Trajectory comparisons, including Monte Carlo simulations, to existing 3-DoF solutions are presented to understand the information learned from increasing the modeling level-of-fidelity.

Aerocapture↗

NASA NTRSDate not supplied

Blade and Takeoff Trajectory Optimization of a Propeller-Driven Electric Aircraft with Acoustic Constraints

In this work, a multi-disciplinary toolchain is described and used to optimize the takeoff trajectory of a electrified general aviation aircraft, subjected to acoustic constraints. The Dymos multi-disciplinary optimal control library is used to optimize the trajectory, with propeller aerodynamic and acoustic models provided by blade element momentum theory (CCBlade.jl) and acoustic analogy (AcousticAnalogies.jl) codes, respectively. Each model is implemented in the OpenMDAO framework, with all derivatives calculated either analytically or via automatic differentiation tools. The toolchain is applied to a hypothetical electrified form of the Cirrus SR20 and compared to the conventional piston-driven form.

gradient-based optimization↗

NASA NTRSDate not supplied

Q-Law for Rapid Assessment of Low Thrust Cislunar Trajectories Via Automatic Differentiation

Q-Law is a Lyapunov-based control law used to determine optimal controls for a low thrust trajectory. One major issue with its use is the difficult derivatives re-quired for calculating optimal controls at a given time. In this paper, an implementation of Q-Law with automatic differentiation via a Python package called JAX is applied. With automatic differentiation, the difficult derivatives for Q-Law’s optimal controls are calculated with ease, and derivatives of final states with respect to Q-Law’s weights are found enabling gradient-based optimization of Q-Law for the first time. Different search and optimization methods for finding optimal weights are then compared using the LEO to GEO problem, and it was found that gradient-free methods like design of experiments and genetic algorithm produced the best results, but they took the longest time to get a solution, while the gradient-based method found a locally optimal result in a much faster time. Overall, the run time for a single propagation is manageable and well-suited for a mission designer to use as an initial guess generator for trajectory optimization, or for simple orbit transfer analysis.

Nathan Steffen↗

NASA NTRS1962

A Summary of the Characteristics of Ballistic Interplanetary Trajectories, 1962-1977

Characteristics of ballistic interplanetary trajectories, 1962-1977

SPACE PROBE↗

NASA NTRS1963

AN ANALYSIS OF FREE-FLIGHT CIRCUMLUNAR TRAJECTORIES

Determination of free-flight circumlunar trajectories, from orbital launch to reentry into the earths atmosphere

CIRCUMLUNAR TRAJECTORY↗

NASA NTRS1963

THE ENGINEERING DESIGN OF INTERPLANETARY BALLISTIC TRAJECTORIES

Heliocentric transfer orbit and launch hyperbolic excess velocity analyses are included in a study of interplanetary ballistic trajectories

ORBITAL MECHANICS↗

NASA NTRS1964

An analysis of free return circumlunar trajectories.

Determination of free flight circumlunar trajectories from orbital launch to reentry into earth atmosphere

SPACE FLIGHT↗

NASA NTRS2018

Integrated Demand Management Findings from March 2018 Simulation: Demonstrating Benefits of Submitting Multiple Trajectory Options

This presentation provides a summary of August 2017 Newark airport simulation, with focus on impact of varying Trajectory Options Set (TOS) "participation levels" (i.e., the percentage of flights that submit TOSs), as well as the results from March 2018 LaGuardia simulation with Flow Evaluation Team, which focused on benefits to individual carriers of participation. During the study, we demonstrated that both the participating and non-participating airlines benefited when TOSs but that the participating airlines benefited most and the improvement seen by participants was greatest when overall participation was lower.

New York↗

NASA NTRS1963

A Variational Method for the Optimization of Interplanetary Round-Trip Trajectories

The indirect method of the calculus of variations is used to optimize interplanetary round-trip trajectories for the case of a single, central, attracting body. The method of solution makes use of certain partial derivative properties of the Lagrangian multipliers associated with the Mayer formulation of the variational problem. This property of the multipliers allows the construction of mathematical expressions for certain other partial derivatives that must vanish when an optimum round trip has been found. These expressions are developed for the cases of propulsion systems using (1) fixed thrust and specific impulse or (2) variable thrust and constant exhaust jet power. Two numerical examples demonstrate how the analytical results may be applied to the solution of round-trip problems including (1) actual three-dimensional planetary positions and (2) planetocentric maneuvers.

VARIATIONAL CALCULUS↗

NASA NTRS1963