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Pavlak, Thomas A.

Publications and source records attributed to Pavlak, Thomas A..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Initial Jupiter Orbit Insertion and Period Reduction Maneuver Plans for Juno

This paper describes the initial plans for the New Frontiers Juno mission at Jupiter. It includes the considerable contingency planning for mission recovery if the Jupiter Orbit Insertion (JOI) burn to place Juno into a large capture orbit were interrupted or terminated on a burn timer setting, and the options for the mission if the Period Reduction Maneuver (PRM) burn to achieve the final orbit period were terminated early. The analyses were based on the assumption that 14-day orbits were the desired operational orbit period.

Bordi, John J.↗
NASA NTRS2017

MColl: Monte Collocation Trajectory Design Tool

In this paper we describe a prototype low-thrust optimization software being developed at JPL. The software tool is based on a collocation algorithm where a trajectory discretization is fitted and adjusted until the underlying dynamics equations of motion are satisfied. The resulting large scale non-linear programming problem may either be optimized with IPOPT or KNITRO. The user specifies path constraints, boundary constraints, and objectives. We describe the collocation algorithm as well as various mesh refinement strategies, and apply the software tool to solve various example problems.

Grebow, Daniel J.↗
NASA NTRS2017

Juno Trajectory Redesign Following PRM Cancellation

In October 2016, the Juno spacecraft was operating in 53.5-day capture orbits and final preparations were underway for a Period Reduction Maneuver (PRM) to achieve the planned 14-day science orbits. However, one week before PRM execution, a main engine propulsion system anomaly prompted an indefinite PRM delay and immediate updates to the Juno reference trajectory. This paper outlines stopgap trajectory design activities immediately following PRM delay and longer-term trajectory redesign considerations including various possible PRM epochs, orbit period, longitude grid characteristics, and eclipse avoidance strategies that culminated in the decision to cancel PRM and adopt a new 53-day reference trajectory.

Bordi, John J.↗
NASA NTRS2017

Maneuver Operations During Juno’s Approach, Orbit Insertion, and Early Orbit Phase

The Juno spacecraft was launched on August 5, 2011 for a 1795-day journey to Jupiter, and arrived on July 5, 2016 with the successful Jupiter Orbit Insertion (JOI) maneuver. This paper will discuss the maneuver operations that took place starting from the Jupiter approach phase (specifically TCM11 on February 3, 2016) through JOI, and the first year of Juno orbital operations through OTM07.

Pavlak, Thomas A.↗
NASA NTRS2015

Quantifying Mapping Orbit Performance in the Vicinity of Primitive Bodies

Predicting and quantifying the capability of mapping orbits in the vicinity of primitive bodies is challenging given the complex orbit geometries that exist and the irregular shape of the bodies themselves. This paper employs various quantitative metrics to characterize the performance and relative effectiveness of various types of mapping orbits including terminator, quasi-terminator, hovering, pingpong, and conic-like trajectories. Metrics of interest include surface area coverage, lighting conditions, and the variety of viewing angles achieved. The metrics discussed in this investigation are intended to enable mission designers and project stakeholders to better characterize candidate mapping orbits during preliminary mission formulation activities.The goal of this investigation is to understand the trade space associated with carrying out remotesensing campaigns at small primitive bodies in the context of a robotic space mission. Specifically,this study seeks to understand the surface viewing geometries, ranges, etc. that are available fromseveral commonly proposed mapping orbits architectures.

Pavlak, Thomas A.↗
NASA NTRS2015

Quantifying Mapping Orbit Performance in the Vicinity of Primitive Bodies

Predicting and quantifying the capability of mapping orbits in the vicinity of primitive bodies is challenging given the complex orbit geometries that exist and the irregular shape of the bodies themselves. This paper employs various quantitative metrics to characterize the performance and relative effectiveness of various types of mapping orbits including terminator, quasi-terminator, hovering, ping pong, and conic-like trajectories. Metrics of interest include surface area coverage, lighting conditions, and the variety of viewing angles achieved. The metrics discussed in this investigation are intended to enable mission designers and project stakeholders to better characterize candidate mapping orbits during preliminary mission formulation activities. The goal of this investigation is to understand the trade space associated with carrying out remote sensing campaigns at small primitive bodies in the context of a robotic space mission. Specifically, this study seeks to understand the surface viewing geometries, ranges, etc. that are available from several commonly proposed mapping orbits architectures

Pavlak, Thomas A.↗
NASA NTRS2014

Maneuver Design for the Juno Mission: Inner Cruise

The Juno spacecraft launched in August 2011 and, following a successful Earth flyby in October 2013, is on course for a nominal orbit insertion at Jupiter in July 2016. This paper examines the design and execution of deterministic and statistical trajectory correction maneuvers during the first approximately 27 months of post-launch operations that defined the "Inner Cruise" phase of the Juno mission. Topics of emphasis include the two deep space maneuvers, Earth flyby altitude biasing strategy, and the sequence of trajectory correction maneuvers executed in the weeks prior to the successful Earth gravity assist.

Pavlak, Thomas A.↗
NASA NTRS2013

Preliminary Design Considerations for Access and Operations in Earth-Moon L1/L2 Orbits

Within the context of manned spaceflight activities, Earth-Moon libration point orbits could support lunar surface operations and serve as staging areas for future missions to near-Earth asteroids and Mars. This investigation examines preliminary design considerations including Earth-Moon L1/L2 libration point orbit selection, transfers, and stationkeeping costs associated with maintaining a spacecraft in the vicinity of L1 or L2 for a specified duration. Existing tools in multi-body trajectory design, dynamical systems theory, and orbit maintenance are leveraged in this analysis to explore end-to-end concepts for manned missions to Earth-Moon libration points.

Folta, David C.↗
NASA NTRS2013

Earth-Moon Libration Point Orbit Stationkeeping: Theory, Modeling and Operations

Collinear Earth-Moon libration points have emerged as locations with immediate applications. These libration point orbits are inherently unstable and must be maintained regularly which constrains operations and maneuver locations. Stationkeeping is challenging due to relatively short time scales for divergence effects of large orbital eccentricity of the secondary body, and third-body perturbations. Using the Acceleration Reconnection and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission orbit as a platform, the fundamental behavior of the trajectories is explored using Poincare maps in the circular restricted three-body problem. Operational stationkeeping results obtained using the Optimal Continuation Strategy are presented and compared to orbit stability information generated from mode analysis based in dynamical systems theory.

Folta, David C.↗