Preliminary Design of the Cruise, Entry, Descent, and Landing Mechanical Subsystem for MSL

20th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

Steltzner

Witkowski

et al. 2009

Self Cite

In 2012, the Mars Science Laboratory Mission (MSL) will deploy NASA's largest extra-terrestrial parachute, a technology integral to the safe landing of its advanced robotic explorer on the surface. The supersonic parachute system is a mortar deployed 21.5 m disk-gap-band (DGB) parachute, identical in geometric scaling to the Viking era DGB parachutes of the 1970's. The MSL parachute deployment conditions are Mach 2.3 at a dynamic pressure of 750 Pa. The Viking Balloon Launched Decelerator Test (BLDT) successfully demonstrated a maximum of 700 Pa at Mach 2.2 for a 16.1 m DGB parachute in its AV4 flight. All previous Mars deployments have derived their supersonic qualification from the Viking BLDT test series, preventing the need for full scale high altitude supersonic testing. The qualification programs for Mars Pathfinder, Mars Exploration Rover, and Phoenix Scout Missions were all limited to subsonic structural qualification, with supersonic performance and survivability bounded by the BLDT qualification. The MSL parachute, at the edge of the supersonic heritage deployment space and 33% larger than the Viking parachute, accepts a certain degree of risk without addressing the supersonic environment in which it will deploy. In addition, MSL will spend up to 10 seconds above Mach 1.5, an aerodynamic regime that is associated with a known parachute instability characterized by significant canopy projected area fluctuation and dynamic drag variation. This aerodynamic instability, referred to as "area oscillations" by the parachute community has drag performance, inflation stability, and structural implications, introducing risk to mission success if not quantified for the MSL parachute system. To minimize this risk and as an alternative to a prohibitively expensive high altitude test program, a multi-phase qualification program using computation simulation validated by subscale test was developed and implemented for MSL. The first phase consisted of 2% of fullscale supersonic wind tunnel testing of a rigid DGB parachute with entry-vehicle to validate two high fidelity computational fluid dynamics (CFD) tools. The computer codes utilized Large Eddy Simulation and Detached Eddy Simulation numerical approaches to accurately capture the turbulent wake of the entry vehicle and its coupling to the parachute bow-shock. The second phase was the development of fluid structure interaction (FSI) computational tools to predict parachute response to the supersonic flow field. The FSI development included the integration of the CFD from the first phase with a finite element structural model of the parachute membrane and cable elements. In this phase, a 4% of full-scale supersonic flexible parachute test program was conducted to provide validation data to the FSI code and an empirical dataset of the MSL parachute in a flight-like environment. The final phase is FSI simulations of the full-scale MSL parachute in a Mars type deployment. Findings from this program will be presented in terms of code development and validation, empirica...

Section: Introductionmentioning

confidence: 99%

Findings from the Supersonic Qualification Program of the Mars Science Laboratory Parachute System

20th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

Steltzner

Witkowski

et al. 2009

Self Cite

“…The MSL EDL system leverages the technologies and architectures developed for Viking, MER and Phoenix missions and pushes the envelope of the existing heritage in terms of the induced aero-thermodynamic environment 2 . The MSL EDL system utilizes a lifting-body entry, active RCS control, 4.5-m entry-vehicle, 21.5-m meter supersonic parachute, and a retro-propulsive terminal descent system with a tethered touch-down 3 (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Supersonic Testing of 0.8 m Disk Gap Band Parachutes in the Wake of a 70 deg Sphere Cone Entry Vehicle

20th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar

Wernet

Roeder

et al. 2009

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Supersonic wind tunnel testing of Viking-type 0.8 m Disk-Gap-Band (DGB) parachutes was conducted in the NASA Glenn Research Center 10'x10' wind-tunnel. The tests were conducted in support of the Mars Science Laboratory Parachute Decelerator System development and qualification program. The aerodynamic coupling of the entry-vehicle wake to parachute flow-field is under investigation to determine the cause and functional dependence of a supersonic canopy breathing phenomenon referred to as area oscillations, characteristic of DGB's above Mach 1.5 operation. Four percent of full-scale parachutes (0.8 m) were constructed similar to the flight-article in material and construction techniques. The parachutes were attached to a 70-deg sphere-cone entry-vehicle to simulate the Mars flight configuration. The parachutes were tested in the wind-tunnel from Mach 2 to 2.5 in a Reynolds number range of 2x10 5 to 1x10 6 , representative of a Mars deployment. Three different test configurations were investigated. In the first two configurations, the parachutes were constrained horizontally through the vent region to measure canopy breathing and wake interaction for fixed trim angles of 0 and 10 degrees from the free-stream. In the third configuration the parachute was unconstrained, permitted to trim and cone, similar to free-flight (but capsule motion is constrained), varying its alignment relative to the entry-vehicle wake. Non-intrusive test diagnostics were chosen to quantify parachute performance and provide insight into the flow field structure. An in-line loadcell provided measurement of unsteady and mean drag. Shadowgraph of the upstream parachute flow field was used to capture bow-shock motion and wake coupling. Particle image velocimetry provided first and second order flow field statistics over a planar region of the flow field, just upstream of the parachute. A photogrammetric technique was used to quantify fabric motion using multiple high speed video cameras to record the location in time and space of reflective targets placed on the canopy interior. The experimental findings including an updated drag model and the physical basis of the area oscillation phenomenon will be discussed.

“…These sites have previously been inaccessible due to limitations in the precision and capability of the entry, descent, and landing (EDL) system/phase of the Mars Exploration Rover, Phoenix, and Pathfinder missions [2]. The EDL phase of MSL is uniquely equipped, however, to meet these landing site challenges with a lifting-body trajectory from hypersonic entry to parachute deploy, active reaction control system control throughout the EDL sequence, supersonic parachute, propulsive descent, and tethered touchdown maneuver [3], yielding an error ellipse of 10 km from the designated surface target [4,5].…”

mentioning

confidence: 99%

Supersonic Performance of Disk-Gap-Band Parachutes Constrained to a 0-Degree Trim Angle

Journal of Spacecraft and Rockets

Kelsch²,

Roeder³

et al. 2009

Self Cite

Supersonic wind-tunnel tests of 0.813 m disk-gap-band parachutes were conducted in a 10 10 ft cross section of a closed-loop wind tunnel. Four-percent-scale parachutes were attached to a 4%-scale Mars Science Laboratory (Viking-type) entry vehicle to simulate the free-flight configuration. The parachutes were tested from Mach 2 to 2.5 over a Reynolds number Re range of 2 10 5 to 1:3 10 6 , representative of the Mars flight deployment envelope. A constrained parachute configuration was investigated to quantify the effect of parachute trim angle with respect to alignment with the entry-vehicle wake. In the constrained configuration, the parachutes were supported at the vent, using a rod that restricted parachute translation along a single axis. This was investigated for fixed trim angles of 0 and 10 degrees from the velocity vector. In the unconstrained configuration, the parachute was permitted to translate as well as trim and cone, in a manner similar to free flight. Nonintrusive test diagnostics were selected. An in-line load cell provided measurement of unsteady and mean parachute normal force. High-speed shadowgraph video of the upstream parachute flowfield was used to capture bow-shock motion and standoff distance. Stereo particle image velocimetry of the flowfield upstream of the parachute provided spatially resolved measurements of all three velocity components. Multiple high-speed-video views were used to document the supersonic inflation, parachute trim angle, projected area, and frequency of area oscillations. In addition, reflective targets placed in the interior of the canopy enabled photogrammetric reconstruction of the canopy-fabric motion (in both time and space) from the high-speedvideo data. Nomenclatureor constructed diameter D p = projected diameter d = entry-vehicle diameter F D = axial drag force F D;RMS = axial rms drag M = Mach number m p = parachute mass q = freestream dynamic pressure Re = Reynolds number t = time t FI = time to full inflation t = nondimensional inflation time x=d = nondimensional trailing distance v = freestream velocity p = mass ratio ! AO = area oscillation frequency