Precision Landing at Mars Using Discrete-Event Drag Modulation

Abstract

An entry, descent, and landing architecture capable of achieving Mars Science Laboratory-class landed accuracy (within 10 km of target) while delivering a Mars Exploration Rover-class payload to the surface of Mars is presented. The architecture consists of a Mars Exploration Rover-class aeroshell with a rigid, annular drag skirt. Maximum vehicle diameter, including drag skirt, is limited to be compatible with current launch-vehicle fairings. A single dragskirt jettison event is used to control range during entry. Three-degree-of-freedom trajectory simulation is used in conjunction with Monte Carlo techniques to assess the flight performance of the proposed architecture. Results indicate that landed accuracy is competitive with preflight Mars Science Laboratory estimates, and peak heat rate and integrated heat load are significantly reduced relative to the Mars Exploration Rover entry system. Modeling parachute descent within the onboard guidance algorithm is found to remove range error bias present at touchdown; the addition of a range-based parachute deploy trigger is found to significantly improve landed accuracy. Nomenclature a = acceleration vector, m∕s 2 a axial = axial acceleration magnitude, m∕s 2 a sens = sensed acceleration magnitude, m∕s 2 C A = axial force coefficient= mass, kg P = covariance matrix r = position vector, m S ref = aerodynamic reference area, m 2 t = time, s v = inertial velocity vector, m∕s v rel = planet-relative velocity magnitude, m∕s v wind = wind-relative velocity magnitude, m∕s x = random vector x = random variable β = ballistic coefficient, kg∕m 2 η = Markov process noise ρ = atmospheric density, kg∕m 3 σ = standard deviation τ = time constant, s Δ = change in parameter

Investigation of Drag-Modulated Supersonic Inflatable Aerodynamic Decelerators for Sounding Rocket Payloads

“…In this study, discrete-event drag modulation (SIAD deployment) is used to control vehicle downrange and the subsequent deployment conditions of the parafoil. For a more detailed discussion on drag modulation, refer to [8]. Both a fixed deployment altitude trigger and a predictor-corrector trigger were implemented in this study for range control evaluation.…”

“…For example, NASA is currently investigating this technology further through the low-density supersonic decelerator program to land larger payload masses on the surface of Mars [4]. Another use of a SIAD is to provide discrete (or continuous) drag modulation as a means of landing site control [5][6][7][8]. In this case, SIAD deployment reduces the ballistic coefficient β, providing a means to directly control downrange.…”

Supersonic Inflatable Aerodynamic Decelerators for use on Sounding Rocket Payloads

“…As discussed in previous work, 12,13 drag modulation is a guidance technique used to control downrange travel by adjustment of a vehicle's drag area. The vehicle drag area for this investigation is modified by the inflation of a decelerator device.…”

Precision Guidance for Mars Entry with a Supersonic Inflatable Aerodynamic Decelerator

“…Therefore, a numerical predictor-corrector approach, see [15][16][17] for example, that does not rely on a reference trajectory is a better choice for Mars entry with a SIAD. A predictor-corrector approach for Mars entry is investigated by Putnam and Braun [18] to control the drag-skirt jettison time which is also a discrete-event. In contrast to the SIAD, the drag-skirt is jettisoned during the entry to reduce the reference area.…”

“…The lateral guidance is accomplished using previously developed bank reversal logic [24]. A range trigger, which has been found to be effective for the landing accuracy improvement [14,18,[25][26][27], is employed for the parachute deployment. The performance of the Mars entry guidance algorithm is assessed for various cases by numerical simulations.…”