1. InJanuary2007, NASAassembledateamthroughouttheagencytoundertaketheMarsDesignReference Mission5.0ArchitectureAnalysis,astudytodevelopacurrentassessmentofobjectives,systemrequirements, andprerequisitesforhumanexplorationofMars. Onekeychallengeunderexaminationaspartofthisstudyis thatofhowtoconductentry,descent,andlandingforhuman-classpayloads. Couplingthesemassivepayloads with launch-vehicle-limited aeroshell diameters typically results in very high vehicle ballistic coefficients which, for Mars, results in high supersonic terminal velocities. It is generally impossible to decelerate these vehicles to velocities much lower than Mach 1.5 or Mach 2 without the assistance of propulsion, large parachutes, or other large inflatable aerodynamic decelerators, all of which are yet unproven for the Martian environment.1
2. To define best-case entry scenarios for the evaluation of potential descent and landing system designs, a study that optimizes entry flight path angles and bank angle profiles for a variety of entry velocities, vehicle ballistic coefficients, and lift-to-drag ratios, was carried out at the Flight Mechanics and Trajectory Design Branch of the Johnson Space Center in August 2007.2Final altitude maximization was chosen in that study as an appropriate objective function because it is generally a fair surrogate for time-to-ground maximization, which is typically a concern and a limitation to the use of parachutes or other deployables.
3. The predicted range-to-go (Rp) is calculated as a function of drag (D) and altitude rate () errors with respect to the nominal reference trajectory profile and the associated influence coefficients. See equation 1
4. Rp =Rref +@R@ D(DDref) @R@(ref)