Duchek M.E.,Analytical Mechanics Inc.
Advances in the Astronautical Sciences | Year: 2015
Active debris removal (ADR) mission concepts that utilize a solar electric propulsion (SEP) spacecraft bus to rendezvous with and deorbit multiple objects have been proposed in various forms. These concepts have used low-thrust delta-V approximations to estimate the amount of fuel needed for the mission profile. These approximations, based on separate maneuvers for altitude raising, plane changing, etc. are useful for initial sizing, but are conservative and do not account for many of the trade-offs in trajectory design, including real target ephemeris, target order, loiter at low or high altitudes, right ascension of the ascending node (RAAN) drift, etc. This paper analyzes trajectory options with a low-thrust propagator for a group of representative ADR targets. A more complete picture of the trajectory required for an ADR mission is presented that provides insight into the techniques that can be used to make a multi-target mission more efficient. Results related to target selection for an efficient trajectory are discussed. Referencing previous research by the authors, the effects of the trajectory analysis on sizing of a demonstration mission concept are examined. Copyright © 2015 California Institute of Technology.
Dutta S.,Georgia Institute of Technology |
Braun R.D.,Georgia Institute of Technology |
Karlgaard C.D.,Analytical Mechanics Inc.
Journal of Spacecraft and Rockets | Year: 2014
Mars entry, descent, and landing trajectories are highly dependent on the vehicle's aerodynamics and the planet's atmospheric properties during the day of flight. A majority of previous Mars entry trajectory and atmosphere reconstruction analyses do not simultaneously estimate the flight trajectory and the uncertainties in the atmospheric and aerodynamics models. Adaptive filtering techniques, when combined with traditional trajectory estimation methods, can improve the knowledge of the aerodynamic coefficients and atmospheric properties, while also estimating the confidence interval for these parameters. Simulated data sets with known truth data are used in this study to show the improvement in state and uncertainty estimation by using adaptive filtering techniques. Such a methodology can then be implemented on existing and future Mars entry data sets to determine the aerodynamic and atmospheric uncertainties and improve engineering design tools. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Schubert M.,Analytical Mechanics Inc. |
Applied Optics | Year: 2016
Electron cascades from electrical discharge produce secondary emissions from atmospheric plasma in the ultraviolet band. For a single point of discharge, these emissions exhibit a stereotypical discharge morphology, with latent information about the discharge location. Morphological processing can uncover the location and therefore have diagnostic utility. © 2016 Optical Society of America.
Jesick M.,Analytical Mechanics Inc.
Advances in the Astronautical Sciences | Year: 2013
Abort trajectories are optimized for human halo orbit missions about the translunar libration point (L2), with an emphasis on the use of free return trajectories. Optimal transfers from outbound free returns to L2 halo orbits are numerically optimized in the four-body ephemeris model. Circumlunar free returns are used for direct transfers, and cislunar free returns are used in combination with lunar gravity assists to reduce propulsive requirements. Trends in orbit insertion cost and flight time are documented across the southern L2 halo family as a function of halo orbit position and free return flight time. It is determined that the maximum amplitude southern halo incurs the lowest orbit insertion cost for direct transfers but the maximum cost for lunar gravity assist transfers. The minimum amplitude halo is the most expensive destination for direct transfers but the least expensive for lunar gravity assist transfers. The on-orbit abort costs for three halos are computed as a function of abort time and return time. Finally, an architecture analysis is performed to determine launch and on-orbit vehicle requirements for halo orbit missions. © 2013 2013 California Institute of Technology.
Way D.W.,Langley Research Center |
Davis J.L.,Langley Research Center |
Shidner J.D.,Analytical Mechanics Inc.
Advances in the Astronautical Sciences | Year: 2013
On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle. © 2013 2013 California Institute of Technology.