Mars Pathfinder six-degree-of-freedom entry analysis

Braun, Robert D.; Powell, Richard W.; Engelund, Walter C.; Gnoffo, Peter A.; Weilmuenster, K. J.; Mitcheltree, Robert A.

doi:10.2514/3.26720

Cited by 91 publications

(34 citation statements)

References 6 publications

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“…The capsule was predicted to return to trim at α = 0 before the second instability region just below 4 km/s and near peak dynamic pressure. The first bounded instability was also predicted for Pathfinder 9 and MER 10 . Reference 7 shows that all instabilities occurred as predicted for the Phoenix entry.…”

Section: Static Pitch Stabilitymentioning

confidence: 96%

“…The Phoenix static aerodynamics database structure and methods builds upon those that were established for Mars Pathfinder 9 and extended for the MER 10 program. The database was arranged into flight regimes (Table 2 and Figure 5) and requires as input the attitude angles (α and β) and either Knudsen number, atmosphere-relative velocity, or Mach number, depending on the regime.…”

Section: Static Aerodynamicsmentioning

confidence: 99%

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Aerodynamics for Mars Phoenix Entry Capsule

Edquist

Desai

Schoenenberger

2011

Journal of Spacecraft and Rockets

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Pre-flight aerodynamics data for the Mars Phoenix entry capsule are presented. The aerodynamic coefficients were generated as a function of total angle-of-attack and either Knudsen number, velocity, or Mach number, depending on the flight regime. The database was constructed using continuum flowfield computations and data from the Mars Exploration Rover and Viking programs. Hypersonic and supersonic static coefficients were derived from Navier-Stokes solutions on a pre-flight design trajectory. High-altitude data (free-molecular and transitional regimes) and dynamic pitch damping characteristics were taken from Mars Exploration Rover analysis and testing. Transonic static coefficients from Viking wind tunnel tests were used for capsule aerodynamics under the parachute. Static instabilities were predicted at two points along the reference trajectory and were verified by reconstructed flight data. During the hypersonic instability, the capsule was predicted to trim at angles as high as 2.5 deg with an on-axis center-of-gravity. Trim angles were predicted for off-nominal pitching moment (4.2 deg peak) and a 5 mm off-axis center-ofgravity (4.8 deg peak). Finally, hypersonic static coefficient sensitivities to atmospheric density were predicted to be within uncertainty bounds.

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Section: Static Pitch Stabilitymentioning

confidence: 96%

Section: Static Aerodynamicsmentioning

confidence: 99%

Aerodynamics for Mars Phoenix Entry Capsule

Edquist

Desai

Schoenenberger

2011

Journal of Spacecraft and Rockets

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“…The Mars atmosphere version of the code 7 contains an 8-species C O 2 ,N 2 c hemical-kinetics model. This is the same computational code used to make aerodynamic and heating predictions for Mars Path nder 8,11 . Aerodynamic predictions from the code have agreed well with Viking ight data 11 and been shown to be in excellent agreement with Mars Path nder ight data 12 .…”

Section: Entry Trajectoriesmentioning

confidence: 99%

Aerothermal heating predictions for Mars Microprobe

Mitcheltree

DiFulvio

Horvath

et al. 1998

36th AIAA Aerospace Sciences Meeting and Exhibit

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A combination of computational predictions and experimental measurements of the aerothermal heating expected on the two Mars Microprobes during their entry to Mars are presented. The maximum, non-ablating, heating rate at the vehicle's stagnation point at = 0 0 is predicted for an undershoot trajectory to be 194 W=cm 2 with associated stagnation point pressure of 0.064 atm. Maximum stagnation point pressure occurs later during the undershoot trajectory and is 0.094 atm. From computations at seven overshoot-trajectory points, the maximum heat load expected at the stagnation point is near 8800 J=cm 2 . Heat rates and heat loads on the vehicle's afterbody are much lower than the forebody. At zero degree angle-of-attack, heating over much of the hemispherical afterbody is predicted to be less than 2 percent of the stagnation point v alue. Good qualitative agreement is demonstrated for forebody and afterbody heating between CFD calculations at Mars entry conditions and experimental thermographic phosphor measurements from the Langley 20-Inch Mach 6 Air Tunnel. A n o v el approach which incorporates six degree-of-freedom trajectory simulations to perform a statistical estimate of the e ect of angle-of-attack, and other o -nominal conditions, on heating is included. Nomenclature B = Ballistic coe cient, kg=m 2 C h = heat transfer coe cient M = Mach n umber P = pressure, atm q = heat rate, W=cm 2 R n = nose radius, m s = surface distance from geometric stagnation point, m t = independent v ariable time, s V = v elocity, m=s x; z = independent spatial dimensions, m = angle-of-attack, deg = side-slip angle, deg = density, kg=m 3 = standard deviation IntroductionWhen the Mars Surveyor 98 Lander is launched in January of 1999, it will transport not only its own lander to Mars, but two small soil penetrators. These Aerospace Engineer, Aerothermodynamics Branch, Aeroand Gas-Dynamics Division, NASA Langley Research Center, Senior member AIAA.y Aerospace Engineer, Aerothermodynamics Branch, Aeroand Gas-Dynamics Division, NASA Langley Research Center, Senior member AIAA.z Aerospace Engineer, Aerothermodynamics Branch, Aeroand Gas-Dynamics Division, NASA Langley Research Center, Senior member AIAA.x Aerospace Engineer, Vehicle Analysis Branch, Space Systems and Concepts Division, NASA Langley Research Center, Member AIAA.Copyright c 1998 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a r o y alty-free license to exercise all rights under the copyright claimed herein for governmental purposes. All other rights are reserved by the copyright o wner.two Mars Microprobes 1 are the second of the Deep Space missions from NASA's New Millennium Program O ce. Upon arrival at Mars, the penetrators will be released from the cruise stage and begin a free fall to the surface. This paper focuses on predicting the convective heating which the aeroshells will encounter during the hypersonic portion of that Mars entry. Knowledge of the...

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“…It has been used to describe the aerodynamics of several blunt bodies similar to the Stardust Sample Return Capsule including Mars Path nder. 11 Calculations were performed at the trajectory point corresponding to the lowest altitude given in Table 1 as well as several lower altitudes given in Ref. 4 for the continuum portion of the trajectory with no-slip boundary conditions imposed.…”

Section: Free-molecular and Dsmc Analysesmentioning

confidence: 99%

Low-Density Aerodynamics of the Stardust Sample Return Capsule

Richard

Robert

James

1999

Journal of Spacecraft and Rockets

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The aerodynamics of the Stardust Sample Return Capsule are analyzed in the lowdensity, transitional ow regime using free-molecular, Direct Simulation Monte Carlo, Navier-Stokes, and Newtonian methods to provide inputs for constructing a transitional ow bridging relation. The accuracy of this bridging relation in reconstructing the aerodynamic coe cients given by the more exact methods is presented for a range of ight conditions and vehicle attitudes. There is good agreement b e t w een the various prediction methods, and a simple sine-squared bridging relation is shown to provide a reasonably good description of the axial force, normal force, and pitching moment o v er a range of Knudsen numbers from 0.001 to 10. The predictions show a static instability of the Stardust capsule in the free-molecular regime that persists well into the transitional ow. The addition of a thin disk to the base of the capsule is shown to remove this static instability. H o w ever, the extremely high entry velocity of 12.6 km s for the proposed trajectory introduces di cult design issues for incorporating this disk caused by the high aerothermal loads that occur even under relatively rare ed conditions.

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Mars Pathfinder six-degree-of-freedom entry analysis

Cited by 91 publications

References 6 publications

Aerodynamics for Mars Phoenix Entry Capsule

Aerodynamics for Mars Phoenix Entry Capsule

Aerothermal heating predictions for Mars Microprobe

Low-Density Aerodynamics of the Stardust Sample Return Capsule

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