Recurrent nature of Lagrange multipliers for optimal low-thrust earth-Jupiter transfers.
Recurrent Lagrange multipliers for optimal low thrust earth-Jupiter transfers, using three dimensional solar system model
Fowler, W. T.↗
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Low-thrust solar electric propulsion navigation simulation program
An interplanetary low-thrust, solar electric propulsion mission simulation program suitable for navigation studies is presented. The mathematical models for trajectory simulation, error compensation, and tracking motion are described. The languages, input-output procedures, and subroutines are included.
Hagar, H. J.↗
Asymptotic solution to the tangential low thrust energy increase trajectory
A approximate analytic solution to the low thrust constant acceleration energy increase trajectory using a tangential steering program is presented. The solution is based on a two-variable asymptotic expansion of the equations of motion formulated in regularized variables. The high accuracy of the second order solution derived is demonstrated by comparing it with numerically integrated trajectories.
Schwenzfeger, K. J.↗
A guidance and navigation system for continuous low thrust vehicles
A midcourse guidance and navigation system for continuous low thrust vehicles is described. A set of orbit elements, known as the equinoctial elements, are selected as the state variables. The uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time nominal trajectory is defined and the equation of motion and the measurement equation are linearized about this nominal trajectory. An exponential cost criterion is constructed and a linear feedback guidance law is derived to control the thrusting direction of the engine. Using this guidance law, the vehicle will fly in a trajectory neighboring the nominal trajectory. The extended Kalman filter is used for state estimation. Finally a short mission using this system is simulated. The results indicate that this system is very efficient for short missions.
Tse, C. J. C.↗
A guidance and navigation system for continuous low-thrust vehicles
A midcourse guidance and navigation system for continuous low thrust vehicles was developed. The equinoctial elements are the state variables. Uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time trajectory is defined; equations of motion and measurements are linearized about this trajectory. An exponential cost criterion is constructed and a linear feedback quidance law is derived. An extended Kalman filter is used for state estimation. A short mission using this system is simulated. It is indicated that this system is efficient for short missions, but longer missions require accurate trajectory and ground based measurements.
Jack-Chingtse, C.↗
Minimum fuel lunar trajectories for a low-thrust power-limited spacecraft
Minimum fuel trajectories from a low Earth parking orbit to a low Moon orbit are obtained for a low-thrust power-limited spacecraft with thrust acceleration levels of the order of 10(exp -3) G. The trajectories are found by matching an Earth spiral to a Moon spirit at some intermediate distance. Results are given for the planar case and for the three dimensional case where the Moon orbit is polar.
Golan, Oded M.↗
Application of a novel optimal control algorithm to low-thrust trajectory optimization
An application of the new optimization algorithm Static/Dynamic Control (SDC) to the design of low-thrust interplanetary trajectories is presented. The interplanetary trajectory is integrated with a multi-body force model and may include gravity assists.
optimization↗
Application of the SDC optimal control algorithm to low-thrust escape and capture trajectory optimization
An application of the new optimization alorithm called Static/Dynamic Control (SDC) to design low-thrust escape and capture trajectories is presented.
low-thrust↗
Proof-of-Concept Trajectory Designs for a Multi-Spacecraft, Low-Thrust Heliocentric Solar Weather Buoy Mission
A new solar weather mission has been proposed, involving a dozen or more small spacecraft spaced at regular, constant intervals in a mutual heliocentric circular orbit between the orbits of Earth and Venus. These solar weather buoys (SWBs) would carry instrumentation to detect and measure the material in solar flares, solar energetic particle events, and coronal mass ejections as they flowed past the buoys, serving both as science probes and as a radiation early warning system for the Earth and interplanetary travelers to Mars. The baseline concept involves placing a mothercraft carrying the SWBs into a staging orbit at the Sun-Earth L1 libration point. The mothercraft departs the L1 orbit at the proper time to execute a trailing-edge lunar flyby near New Moon, injecting it into a heliocentric orbit with its perihelion interior to Earth s orbit. An alternative approach would involve the use of a Double Lunar Swingby (DLS) orbit, rather than the L1 orbit, for staging prior to this flyby. After injection into heliocentric orbit, the mothercraft releases the SWBs-all equipped with low-thrust pulsed plasma thrusters (PPTs)-whereupon each SWB executes a multi-day low-thrust finite bum around perihelion, lowering aphelion such that each achieves an elliptical phasing orbit of different orbital period from its companions. The resulting differences in angular rates of motion cause the spacecraft to separate. While the lead SWB achieves the mission orbit following an insertion burn at its second perihelion passage, the remaining SWBs must complete several revolutions in their respective phasing orbits to establish them in the mission orbit with the desired longitudinal spacing. The complete configuration for a 14 SWB scenario using a single mothercraft is achieved in about 8 years, and the spacing remains stable for at least a further 6 years. Flight operations can be simplified, and mission risk reduced, by employing two mothercraft instead of one. In this scenario: the second mothercraft stays in a libration-point or DLS staging orbit until the first mothercraft has achieved nearly 180 separation from the Earth. The timing of the second mothercraft's subsequent lunar flyby is planned such that this spacecraft will be located 180 from the first mothercraft upon completion of its heliocentric circularization maneuvers. Both groups of satellites then only have to spread out over 180 to obtain full 360 coverage around the Sun.
Muller, Ronald↗
Low-thrust trajectory and payload analysis for solar system exploration utilizing the accessible regions method
Accessible regions method for delineating generalized low thrust trajectory energy requirements and payload capabilities of vehicle systems for exploration of solar system
PLANETARY EXPLORATION↗
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↗
Application of the SDC optimal control algorithm to low-thrust escape and capture including fourth body effects
An application of the new optimization algorithm called Static/Dynamic Control (SDC) to design low-thrust escape and capture trajectories is presented.
low-thrust optimization escape capture↗
Modeling of thruster and solar array characteristics in the JPL low-thrust trajectory analysis
Recent advances in thruster and solar array technology have resulted in the possibility of performing many high energy space missions previously considered infeasible. This capability was demonstrated by an extensive study last year of a comet Halley rendezvous mission. In order to perform this extremely high energy mission, several advanced concepts in electric propulsion technology were investigated; notably the use of very high power, lightweight solar arrays which directly powered the beam supply of the electric propulsion thrusters, and the use of solar concentrators on the arrays together with conventional thrusters and power processors. These technology advances have directly impacted the modeling of the solar arrays and thrusters in the programs used in generating low-thrust trajectories. The intent of this paper is to discuss the modeling of the solar arrays and thrusters as employed in the trajectory programs presently being used in low-thrust mission studies at JPL.
Sauer, C. G., Jr.↗
Low-thrust chemical propulsion system pump technology
Candidate pump and driver systems for low thrust cargo orbit transfer vehicle engines which deliver large space structures to geosynchronous equatorial orbit and beyond are evaluated. The pumps operate to 68 atmospheres (1000 psi) discharge pressure and flowrates suited to cryogenic engines using either LOX/methane or LOX/hydrogen propellants in thrust ranges from 445 to 8900 N (100 to 2000 lb F). Analysis of the various pumps and drivers indicate that the low specific speed requirement will make high fluid efficiencies difficult to achieve. As such, multiple stages are required. In addition, all pumps require inducer stages. The most attractive main pumps are the multistage centrifugal pumps.
Sabiers, R. L.↗
Combined high-low thrust propulsion for the close solar probe mission
Combined high-low thrust propulsion for close solar probe mission
SOLAR PROBE↗
Precision flow measurement techniques for low-thrust auxiliary-propulsion liquid rockets
Precision flow measurement techniques for low thrust auxiliary propulsion liquid rockets
Grant, D. J.↗
Low-thrust trajectories using the two-variable asymptotic expansion method
Heliocentric low thrust spacecraft trajectory analysis using two-variable asymptotic expansion method
Stavro, W.↗
Minimum fuel lunar trajectories for a low-thrust power-limited spacecraft
Minimum-fuel trajectories from a low earth parking orbit to a low moon orbit are obtained for a low-thrust power-limited spacecraft with thrust acceleration levels of the order of 0.001 G. The trajectories are found by matching an earth spiral to a moon spiral at some intermediate distance. Results are given for the planar case and for the three-dimensional case where the moon orbit is polar.
Breakwell, John V.↗