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Ames Flight Dynamics


Dynamics of Orbits near 4:1 Lunar Resonance

Abstract: Periodic orbits near 4:1 lunar resonance provide long-term stability for missions requiring high apogee altitudes. The planar family of 4:1 resonant orbits is stable with two quasi-periodic modes: a slow out-of-plane mode with a period approaching 25 years and a fast in-plane mode with a period approaching 1 year. We analyze these orbits in the circular restricted three-body problem and compare the results with long-term propagations in a high fidelity ephemeris model. We also investigate the behavior of quasi-periodic spatial orbits near the planar periodic orbit

Spin Orbit Resonance and Stability in Eccentric, Low Altitude Mars Orbits

Abstract: Low orbit perturbations derive from mass concentrations and show high sensitivity to certain initial orbit parameters and spin-orbit resonance conditions. Evaluation of spin-orbit resonance and gravity perturbation effects are important in mission design applications. Here we examine low altitude and polar orbits of Mars. The method uses analytical derivations to identify regimes of interest and computational modeling and graphical design aids for detailed investigation.


HelioSwarm: Swarm Mission Design in High Altitude Orbit for Heliophysics

Abstract: Resolving the complex three-dimensional turbulent structures that characterize the solar wind requires contemporaneous spatially and temporally distributed measurements. HelioSwarm is a mission concept that will deploy multiple, coorbiting satellites to use the solar wind as a natural laboratory for understanding the fundamental, universal process of plasma turbulence. The HelioSwarm transfer trajectory and science orbit use a lunar gravity assist to deliver the ESPA-class nodes attached to a large data transfer hub to a P/2 lunar resonant orbit. Once deployed in the science orbit, the free-flying, propulsive nodes use simple Cartesian relative motion patterns to establish baseline separations both along and across the solar wind flow direction.

Stability and Spin-Orbit Resonance Analysis of Low Altitude Martian Orbits

Abstract: Orbit stability has been thoughtfully studied in various celestial bodies. In particular the focus has been placed on the Moon, due to the unstable natural perturbations of its gravity field. The increasing interest in Mars orbiters brings the question of the likelihood of natural decay in low altitude regimes. This paper studies the change in shape of low altitude Mars orbits by carrying out large sets of numerical high fidelity simulations. Results showed that various configurations of the orbital elements gave perturbations that resulted in unstable orbits. The paper also studies the potential causes of the observed unstable regions. First by taking a close look at zonal and tesseral harmonics to find the implications of Mars mass concentrations of the used gravity fields, and second by computing theoretical spin-orbit resonances to study their implications in the stability at low altitudes.


Arcus Mission Design: Stable Lunar-resonant High Earth Orbit for X-ray Astronomy

Abstract: The Arcus mission, proposed for NASA’s 2016 Astrophysics Medium Explorer (MIDEX) announcement of opportunity, will use X-ray spectroscopy to detect previously unaccounted quantities of normal matter in the Universe. The Arcus mission design uses 4:1 lunar resonance to provide a stable orbit for visibility of widely-dispersed targets, in a low background radiation environment, above the Van Allen belts for the minimum two-year science mission. Additional advantages of 4:1 resonance are long term stability without maintenance maneuvers, eclipses under 4.5 hrs, perigee radius approx. 12 Re for data download, and streamlined operational cadence with approx. 1 week orbit period.


DARE Mission Design: Low RFI Observations from a Low-altitude, Frozen Lunar Orbit

Abstract: The Dark Ages Radio Experiment (DARE) seeks to study the cosmic Dark Ages approximately 80 to 420 million years after the Big Bang. Observations require truly quiet radio conditions, shielded from Sun and Earth electromagnetic (EM) emissions, on the far side of the Moon. DARE’s science orbit is a frozen orbit with respect to lunar gravitational perturbations. The altitude and orientation of the orbit remain nearly fixed indefinitely, maximizing science time without the need for maintenance. DARE’s observation targets avoid the galactic center and enable investigation of the universe’s first stars and galaxies.

Trajectory and Navigation Design for an Impactor Mission Concept

Abstract: This paper introduces a trajectory design for a secondary spacecraft concept to augment the science return in interplanetary missions. The concept consists of a single-string probe with a kinetic impactor on board that generates an artificial plume to perform in-situ sampling. A Monte Carlo simulation was used to validate the nominal trajectory design for a particular case study that samples ejecta particles from the Jupiter’s moon Europa. Details regarding the navigation, targeting, and disposal challenges related to this concept are presented herein. 


AAS 15-396 Trade Studies in LADEE Trajectory Design

Abstract: The Lunar Atmosphere and Dust Environment Explorer (LADEE) mission design challenge was a “design to capabilities” approach in a tightly constrained trade space. Several trade studies defined feasible trajectory designs and launch opportunities. One trade study selected the insertion orbit and identified usable combinations of transfer orbit plane and arrival nodes per launch block. The next trade study assessed each monthly launch period by day with three-sigma launch energy dispersions against several parameters including delta-v budget, lunar orbit beta angle, and maximum shadow duration. In the final trade study, detailed technical and operational considerations dictated the daily launch windows.

LADEE Flight Dynamics: Overview of Mission Design and Operations

Abstract: The Lunar Atmosphere and Dust Environment Explorer (LADEE) mission set out on September 7, 2013 to observe the lunar exosphere at low altitudes. This mission overview from a flight dynamics perspective addresses solid rocket dispersions in the first use of the Minotaur V, science orbit maintenance for over 5 months, high precision past and predicted orbit estimation, the automated approach to calculating over 40,000 attitude waypoints, and strong teamwork at an intense operational pace. The unique flight dynamics solutions for the near-circular , near-equatorial orbit in non-uniform lunar gravity resulted in a successful mission from both engineering and scientific standpoints.