(Georgia Institute of Technology, 2007-09)
Alemany, Kristina; Braun, Robert D.
In 2006, the 2nd Global Trajectory Optimization Competition (GTOC2) posed a
“Grand Asteroid Tour” trajectory optimization problem, where participants were
required to find the best possible low-thrust trajectory that would rendezvous
with one asteroid from each of four defined groups. As a first step, most teams
employed some form of design space pruning, in order to reduce the overall
number of possible asteroid combinations. Because of the large size of the
problem, teams were not able to determine if their pruning technique had
successfully eliminated only bad solutions from the design space. Therefore, a
small subset of the GTOC2 problem was analyzed, and several design space
pruning techniques were applied to determine their effectiveness. The results
indicate that the pruning techniques chosen by the participants likely eliminated
good solutions from the design space, because they either did not accurately
represent the low-thrust problem or could not be considered independently
without the effect of other factors.
(Georgia Institute of Technology, 2006-08)
Alemany, Kristina; Wells, Grant William; Theisinger, John; Clark, Ian G.; Braun, Robert D.
Entry, descent, and landing (EDL) is a multidimensional, complex problem, which is
difficult to visualize in simple plots. The purpose of this work is to develop a systematic
visualization scheme that could capture Mars EDL trades as a function of a limited number
of variables, such that programmatic design decisions could be effectively made with insight
of the design space. Using the Mars Science Laboratory (MSL) as a basis, contour plots have
been generated for key EDL figures of merit, such as maximum landed elevation and landed
mass as a function of four input parameters: entry mass, entry velocity, entry flight path
angle, and vehicle L/D. Additionally, sensitivity plots have been generated in an attempt to
capture the effects of varying the fixed input parameters. This set of EDL visualization data
has been compiled into a Mars EDL handbook to aid in pre-phase A design space
exploration and decision making.