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A general perturbation solution to a restricted low-thrust Lambert rendezvous problem, considering circular-to-circular in-plane maneuvers using tangential thrust and including a coast arc, is developed. This provides a fully analytical solution to the satellite reconnaissance problem. The solution requires no iteration. Its speed and simplicity allow problems involving numerous spacecraft and maneuvers to be studied; this is demonstrated through two case studies. In the first, a range of maneuvers providing a rapid flyover of Los Angeles is generated, giving an insight to the trade space and allowing the maneuver that best fulfills the mission to be selected. A reduction in flyover time from 13.8 to 1.6 days is possible using a less than 17 m/s velocity change. A comparison with a numerical propagator including atmospheric friction and an 18th-order tesseral model shows 4 s of difference in the time of flyover. A second study considers a constellation of 24 satellites that can maneuver into repeating ground track orbits to provide persistent coverage of a region. A set of maneuvers for all satellites is generated for four sequential targets, allowing the most suitable maneuver strategy to be selected. Improvements in coverage of greater than 10 times are possible as compared to a static constellation using 35% of the propellant available across the constellation.

Onboard, fuel-optimal, constrained powered-descent guidance based on the theory of lossless convexification has been implemented as the Guidance for Fuel-Optimal Large Diverts (G-FOLD) algorithm. Here, “guidance” means generating feedforward reference trajectories for control systems. This paper presents terrestrial flight-test demonstrations of large diverts planned by G-FOLD onboard a vertical-takeoff/vertical-landing rocket. The G-FOLD parser, which transforms the guidance problem into a second-order cone program and so encodes the divert constraints, is described at an engineering level, including new and modified constraints incorporated for these flight tests. Several practical issues, such as discretization effects, are addressed, and the flight-test architecture is presented. A total of eight flight tests were performed. In the first three, the rocket executed diverts of increasing size preplanned by G-FOLD on the ground. Then G-FOLD was demonstrated running onboard five times. Three qualitatively...

Aerocapture is the maneuver by an interplanetary spacecraft to fly through the atmosphere of a planet with the aim of attaining a specified orbit around the planet. By appropriately controlling the...

A direct multiple shooting method has been applied to the optimization of an aeroassisted orbital transfer. The objective has been to provide optimal trajectories for a vehicle with a high lift-over-drag ratio that minimizes the energy loss during the atmospheric part of an aeroglide maneuver subject to limits on heating rate. In addition, thrusting segments have been inserted within the atmospheric part of the trajectory, and both aeroglide and aerocruise trajectories have been evaluated. Here, the objective has been to maximize the achievable inclination change subject to limits on heating rate, total heat load, and lift coefe cient. The respective parameter optimization procedures have been set up as multiphase optimization problems. All guidance-related parameters along the trajectory, together with the deorbiting, boost, and circularizing impulses, have been optimized.

An optimal terminal maneuver is presently defined for the cooperative impulsive rendezvous of two spacecraft, in which each vehicle is capable of furnishing all or a part of the velocity change required for the rendezvous. In this maneuver, the final masses of the two vehicles are maximized in a fashion that is equivalent to minimum total propellant consumption. If neither propellant mass fraction constraint is active, one vehicle will supply all of the required velocity change.