Venus and Mars gravity-assist trajectories to Jupiter using nuclear electric propulsion
Optimal low-thrust gravity-assist trajectories to Jupiter using nuclear electric propulsion are presented.
Sims, Jon A.↗
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Control of node crossings in Saturnian gravity-assist tours
In the Saturnian system, the control of the node-crossing point is important to avoid debris in Saturn's ring plane and to target flybys of moons other than Titan. This paper describes how to use gravity assists to control a spacecrft's node crossings.
Titan↗
Rapid Design of Gravity Assist Trajectories
Several International Solar Terrestrial Physics (ISTP) missions require the design of complex gravity assisted trajectories in order to investigate the interaction of the solar wind with the Earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. The philosophy and methodology that enable an analyst to design and analyse such trajectories are discussed. The so called 'floating end point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques, is described. The combination of floating end point targeting with analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions, is demonstrated. A multiconic orbit integration scheme allows fast and accurate orbit propagation. A prototype software tool, Swingby, built for trajectory design and launch window analysis, is described.
Carrico, J.↗
Control of node crossing points in Saturnian gravity-assist tours
In the Saturnian system, the control of the node crossing point is important to avoid debris in Saturn's ring plane and to target flybys of moons other than Titan. This paper describes how to use Titan gravity assists to control the spacecraft's node crossing point.
Saturn node crossing point flyby Titan gravity ass↗
The accessible regions presentation of gravity-assisted trajectories using Jupiter
Accessibility of solar system regions to earth launched spacecraft using Jupiter gravity- assisted trajectories
JUPITER /PLANET/↗
Solar electric earth gravity assist /SEEGA/ missions to the outer planets
The optimization of solar electric propulsion earth-gravity-assist trajectories to the outer planets is presented. Included in the optimization is both earth swingby velocity and swingby date. Mission modes with and without optimal post swingby thrust are compared. Performance suitable for preliminary mission studies is presented for the four major outer planets using circular-coplanar planetary orbits and additional performance is presented for a Saturn Orbiter-Dual Probe mission.
Sauer, C. G.↗
Rapid design of gravity assist trajectories
Several International Solar-Terrestrial Physics (ISTP) missions require the design of complex gravity-assisted trajectories in order to investigate the interaction of the solar wind with the earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. This paper discusses the philosophy and methodology that enable an analyst to design and analyze such trajectories. The authors describe what is called 'floating end-point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques. This paper demonstrates how floating end-point targeting combines analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions. A Multiconic orbit integration scheme allows fast and accurate orbit propagation. This paper also describes a prototype software tool, Swingby, which has been built for trajectory design and launch window analysis.
Carrico, J.↗
Gravity-assist trajectories to Jupiter using nuclear electric propulsion
This paper examines optimal low-thrust gravity-assist trajectories to Jupiter using nuclear electric propulsion.
nuclear electric↗
Fuel-Optimal Trajectories in a Planet-Moon Environment Using Multiple Gravity Assists
For low energy spacecraft trajectories such as multi-moon orbiters for the Jupiter system, multiple gravity assists by moons could be used in conjunction with ballistic capture to drastically decrease fuel usage. In this paper, we outline a procedure to obtain a family of zero-fuel multi-moon orbiter trajectories, using a family of Keplerian maps derived by the first author previously. The maps capture well the dynamics of the full equations of motion; the phase space contains a connected chaotic zone where intersections between unstable resonant orbit manifolds provide the template for lanes of fast migration between orbits of different semimajor axes. Patched three body approach is used and the four body problem is broken down into two three-body problems, and the search space is considerably reduced by the use of properties of the Keplerian maps. We also introduce the notion of Switching Region where the perturbations due to the two perturbing moons are of comparable strength, and which separates the domains of applicability of the corresponding two Keplerian maps.
Ross, Shane D.↗
OSIRIS-REx Conjunction Screenings: Earth Gravity Assist and Earth Return Analysis and Results
The NASA OSIRIS-REx asteroid sample return mission performed an Earth gravity assist on September 22, 2017, and returned to Earth to drop off the sample on September 24, 2023. In each case, the NASA Conjunction Assessment Risk Analysis (CARA) team screened the OSIRIS-REx trajectories against the satellite catalog in search of high-risk close approaches. This paper describes the preparation for collision avoidance and screening results, along with lessons learned, providing a baseline for support of future missions in this category, particularly as space traffic around the Earth and in cis-lunar space continues to rapidly expand.
Dolan E. Highsmith↗
OSIRIS-REx Conjunction Screenings: Earth Gravity Assist and Earth Return Analysis and Results
The NASA OSIRIS-REx asteroid sample return mission performed an Earth gravity assist on September 22, 2017, and returned to Earth to drop off the sample on September 24, 2023. In each case, the NASA Conjunction Assessment Risk Analysis (CARA) team screened the OSIRIS-REx trajectories against the satellite catalog in search of high-risk close approaches. This paper describes the preparation for collision avoidance and screening results, along with lessons learned, providing a baseline for support of future missions in this category, particularly as space traffic around the Earth and in cis-lunar space continues to rapidly expand.
Dolan Highsmith↗
A Tool For Identifying Key Gravity-Assist Trajectories From Broad Search Results
A tool is presented that identifies desirable trajectory candidates from among tens of thousands of gravity-assist trajectories. A broad trajectory search technique creates an exhaustive set of possible trajectories to a given planet. From this dataset, our tool reveals candidate trajectories with user-defined characteristics. Typical discriminating characteristics are launch V-infinity, time-of-flight, and delivered mass. Mission planners evaluate and plot interesting trajectories from within the tool. Our tool generates catalogs of selected trajectories for further evaluation with higher-fidelity trajectory solvers. This paper outlines the key features of the tool and gives examples of typical analyses.
uranus, interplanetary↗
A shape-based algorithm for the automated design of low-thrust, gravity-assist trajectories
We describe the computational implementation of an analytic, shape-based method for the design of low-thrust, gravity-assist trajectories. We also augment the method by allowing coast arcs to be patched with thrust arcs on the transfers between bodies.
low-thrust↗
An interactive tool for design and support of lunar, gravity assist, and libration point trajectories
The 'Swingby' interactive tool for design, analysis, and support of maneuver planning for missions that involve transfers to the moon, the lunar orbits, multiple-gravity assists, and the libration-point orbits, runs on a PC and uses pull-down and pop-up menus to allow users to change physical constants and select perturbations for inclusion. Swingby can also target by ascertain parameters, or allow the computer to generate goals on the basis of mission requirements. Rapid mission analyses, operational maneuvers, and contingency plans are thereby obtainable.
Carrico, J.↗
Thermal re-design of the Galileo spacecraft for a Venus-earth-earth-gravity assist (VEEGA) trajectory
The cancellation of the Centaur upper stage program in the aftermath of the Challenger tragedy forced a redesign of the flight trajectory of the Galileo spacecraft to Jupiter, i.e., from a direct trajectory to the Venus-earth-earth-gravity-assist (VEEGA) trajectory on the lower energy two-stage inertial upper stage (IUS), with the result that the spacecraft would be exposed to more than twofold increase in peak solar irradiance. This paper describes the general system-level thermal redesign effort for the Galileo spacecraft, from the start of feasibility studies to its final implementation. Results indicate that the addition of sunshades and the generous utilization of second-surface aluminized Kapton surface material for reflecting high percentages of incident solar irradiation would 'harden' the spacecraft's existing thermal protection system adequately, provided that sun-pointing at the relatively higher solar irradiance levels could be maintained. The final miximum flight temperature predictions for the spacecraft's subsystem thermal designs are given.
Reeve, R.↗
The Second Year of Dawn Mission Operations: Mars Gravity Assist and Onward to Vesta
Dawn launched in September 2007 on a mission to orbit main belt asteroids (4) Vesta in 2011 - 2012 and (1) Ceres in 2015. The mission is enabled by an ion propulsion system, which will be operated for the majority of the interplanetary cruise. Following 10.5 months of thrusting that concluded in October 2008, the spacecraft began a period of optimal coast that ended in June 2009. A Mars gravity assist in February 2009 provided an effective deltav of 2.6 km/s. The mission flexibility afforded by the use of ion propulsion provided relatively simple targeting at Mars. Additional engineering activities were conducted during the coast period after Mars, including loading new software into the spacecraft's central computer. This paper describe the progress of the mission, including the approach to Mars, the encounter itself, special activities conducted prior to the resumption of ion thrusting, and the continuation toward Vesta.
Rayman, Marc D.↗
Low launch-energy trajectories to the outer solar system via Venus and earth gravity-assist flybys
Recent cancellation of the program to develop a Centaur upper stage for use in the Space Transportation System (STS) has motivated considerable interest in trajectory modes with low launch-energy requirements to the outer solar system. Flyby encounters of the inner planets, especially Venus and earth, may be used to enable missions to Jupiter, Saturn, and a restricted class of comets. An examination of mission opportunities to these targets is presented through the end of this century using gravity-assist trajectories.
Diehl, Roger↗
Automated design of multiple encounter gravity-assist trajectories
Given a range of initial launch dates and a set of target planets, a new approach to planetary mission design is developed, using an automated method for finding all conic solutions. Each point on the diagrams reproduced represents a single ballistic trajectory and is computed by modeling the trajectory as a conic section and solving the corresponding Lambert problem for each set of launch and arrival dates. An example which prescribes a launch period of 1975-2050 and target planets Uranus, Saturn, Jupiter, Neptune and Pluto is described whereby, all possible grand tour missions of this class are found, including the Voyager II trajectory. It is determined that this automated design tool may be applied to a variety of multiple encounter gravity-assist trajectories that are being considered for future missions.
Longuski, James M.↗