Adam Steltzner

Mars Science Laboratory Entry, Descent, and Landing System Overview

In 2010, the Mars science laboratory (MSL) mission will pioneer the next generation of robotic entry, descent, and landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. The MSL EDL sequence is a result of a more stringent requirement set than any of its predecessors. Notable among these requirements is landing a 900 kg rover in a landing ellipse much smaller than that of any previous Mars lander. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars viking, Mars pathfinder, and Mars exploration rover missions. Thus, there are many design challenges that must be solved for the mission to be successful. Several pieces of the EDL design are technological firsts, such as guided entry and precision landing on another planet, as well as the entire sky crane maneuver. This paper discusses the MSL EDL architecture and discusses some of the challenges faced in delivering an unprecedented rover payload to the surface of Mars.

Mars Science Laboratory entry, descent, and landing system

In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic entry, descent, and landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. By providing an EDL system capable of landing at altitudes as high as 2 km above the reference areoid, as defined by the Mars Orbiting Laser Altimeter (MOLA) program, MSL will demonstrate sufficient performance to land on a large fraction of the Martian surface. By contrast, the highest altitude landing to date on Mars has been the Mars Exploration Rover (MER) MER-B at 1.44 km below the areoid. The coupling of this improved altitude performance with latitude limits as large as 60 degrees off of the equator and a precise delivery to within 10 km of a surface target will allow the science community to select the MSL landing site from thousands of scientifically interesting possibilities. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars Viking, Mars Pathfinder, and MER missions. This paper discusses the MSL EDL architecture, system, and subsystem design and discusses some of the challenges faced in delivering such an unprecedented rover payload to the surface of Mars

Results from the Mars Science Laboratory Parachute Decelerator System Supersonic Qualification Program

In 2010 the Mars Science Laboratory (MSL) Mission will deliver the most massive and scientifically capable rover to the surface of Mars. To deliver this payload, an aerodynamic decelerator is required to decelerate the entry vehicle from supersonic to subsonic speeds, in advance of propulsive descent and touchdown on Mars. The aerodynamic deceleration will be accomplished by a mortar-deployed 21.5-m Viking-type disk-gap-band parachute (DGB), and will be the largest extra-terrestrial decelerator in the history of space exploration [1]. The parachute will deploy at up to Mach 2.2 and 750 Pa, resulting in the highest load and speed experienced by a parachute on Mars. The MSL parachute extends the envelope of the existing heritage deployment space in terms of load, size and Mach number. This has created the challenge of leveraging the existing heritage supersonic- high-altitude database, implementing a ground-based qualification program, and quantifying known aerodynamic instabilities associated with supersonic operation in the Mach regime of the MSL deployment. To address these challenges MSL has embarked upon a physics-based modeling and validation program to explore the fundamental physics associated with DGB-parachute operation in supersonic flow. The functional dependence of parachute performance and stability on Mach number, Reynolds number, parachute size, entry-vehicle size and parachute to entry vehicle proximity, is under investigation. The quantitative understanding garnered from this analytical effort will be used to leverage the existing heritage database of the Viking Lander, Viking Balloon Launched Decelerator Test (BLDT), Mars Pathfinder (MPF) and Mars Exploration Rover (MER) programs for the larger scale, deployment conditions, and modern construction techniques of the MSL parachute system. The physics-based modeling and validation effort includes the development of a coupled fluid and structural solver, i.e. fluid-structure-interaction code, and supersonic wind-tunnel experiments with subscale representations of the flight configuration.

Asymptotic parachute performance sensitivity

In 2010, the Mars Science Laboratory mission will pioneer the next generation of robotic Entry, Descent, and Landing systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than any other mission to Mars, Mars Science Laboratory will also provide scientists with unprecedented access to regions of Mars that have been previously unreachable. By providing an Entry, Descent, and Landing system capable of landing at altitudes as high as 2 km above the reference gravitational equipotential surface, or areoid, as defined by the Mars Orbiting Laser Altimeter program, Mars Science Laboratory will demonstrate sufficient performance to land on 83% of the planets surface. By contrast, the highest altitude landing to date on Mars has been the Mars Exploration Rover at 1.3 km below the areoid. The coupling of this improved altitude performance with latitude limits as large as 60 degrees off of the equator and a precise delivery to within 10 km of a surface target, will allow the science community to select the Mars Science Laboratory landing site from thousands of scientifically interesting possibilities. In meeting these requirements, Mars Science Laboratory is extending the limits of the Entry, Descent, and Landing technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions. Specifically, the drag deceleration provided by a Viking-heritage 16.15 m supersonic Disk-Gap-Band parachute in the thin atmosphere of Mars is insufficient, at the altitudes and ballistic coefficients under consideration by the Mars Science Laboratory project, to maintain necessary altitude performance and timeline margin. This paper defines and discusses the asymptotic parachute performance observed in Monte Carlo simulation and performance analysis and its effect on the Mars Science Laboratory entry, descent, and landing architecture

Anchoring technology for in situ exploration of small bodies

Comets, asteroids and other small bodies found in the solar system do not possess enough gravity to ensure spacecraft contact forces sufficient to allow many types of in situ science, such as core or surface sampling. Some method of providing sufficient contact force must be used for successful in situ exploration. A range of possible anchoring technologies for use with small bodies is discussed and a specific technology developed in greater detail. This anchoring technology is based on a high energy, gas driven telescoping spike that has demonstrated success in anchoring into targets with a wide range of material properties. It is expected to be successful in anchoring to bodies with surface properties that may range in unconfined compressive strengths from 10 kPa to 10 MPa. The physics of the device and the penetration mechanics of the anchoring are discussed. The development of the hardware for NASAs now cancelled ST4/Champollion mission is detailed and finally, results from the test and verification program for the ST4/Champollion spacecraft anchoring mechanism are discussed.

Supersonic delta qualification by analysis program for the mars science laboratory parachute decelerator system

The Mars Science Laboratory Mission (MSL) plans to deploy NASA’s largest, highest Mach number, and highest payload extra-terrestrial aerodynamic decelerator to the surface of Mars in 2010. The 21.5-m Viking-scaled Disk-Gap-Band (DGB) parachute will deploy at up to Mach 2.2 and 750 Pa, the upper deployment condition range demonstrated by the Viking Balloon Launched Decelerator Test (BLDT) program. All previous Mars parachute systems have derived their supersonic qualification from Viking heritage. MSL differs from the previous Mars programs in that it is 33% larger than the Viking parachute and will spend up to seven seconds above Mach 1.5, a flight regime known to induce the canopy area oscillations, characterized by variations in drag and collapses in the band region of the parachute. To reduce risk to the mission, MSL has embarked on a multi-phase delta qualification by analysis and subscale supersonic wind tunnel test program to address the fundamental physics of the supersonic operation of DGB parachutes. The program explores the cause of the area oscillation phenomena and the performance of the parachute system as a function of Mach number, Re number, parachute to capsule size and proximity. With a physical understanding of the parachute flow field and parachute response to it, the existing Viking BLDT heritage qualification data can be leveraged to the larger scale of MSL, enabling a heritage-based supersonic qualification. To achieve this, MSL will determine by fluid dynamics simulation validated by subscale supersonic wind tunnel tests, that the supersonic flight characteristics of the Viking scale/material DGB and MSL scale/material DGB are aerodynamically similar. The first phase is computational fluid dynamics of a 2% scale rigid parachute canopy and capsule validated by a 2% scale wind tunnel test of the rigid configuration in the NASA AMES 9x7 ft unitary tunnel. Results from this program indicate excellent qualitative and quantitative validation of the capsule wake velocity predictions and fundamental physics of the aerodynamic drivers of the supersonic instability. Phase two is fluid structure interaction analysis of a flexible canopy with capsule validated by 4% scale wind tunnel tests in the GRC 10x10 ft unitary tunnel. The final phase is the application of the validated FSI tools to the prediction of the full scale parachute performance in Mars type deployment conditions, providing predictions of supersonic drag performance, stability and canopy loading. The methodology and results of the analysis and test program as well as validation results to date will be presented.

Mars Science Laboratory Parachute Inversion Phenomenon and Flight Risk Assessment

During full-scale wind tunnel testing of the parachute for the Mars Science Laboratory two of the test parachutes experienced an inversion. These were unexpected occurrences and required an analysis of the phenomenon as observed in test and an assessment of what risks it may imply for flight on Mars. The test conditions and the inversion morphology are discussed as they relate to the wind tunnel tests and the impacts on the test effort. The timeline for the formation of the inversions is described and compared to the timeline expected in flight. Differences between the physics and behavior in test and flight are discussed as they relate to the threat of inversion. Mitigating actions are described as well as arguments used in determining the final configuration for use in flight. Nomenclature Do = parachute reference diameter DGB = disk-gap-band parachute M = Mach number MD = mortar deployment SD = sleeve deployment I. Introduction HE Mars Science Laboratory (MSL) mission will use a 21.5 m reference diameter (Do) Viking scaled disk-gapband (DGB) parachute as a critical component of its entry, descent, and landing system. Structural testing of the MSL parachute was performed in the 80’x120’ test section of the National Full-Scale Aerodynamics Complex (NFAC) operated by the Arnold Engineering Development Center (AEDC) at NASA’s Ames Research Center, Moffett Field, California. These developmental tests were conducted in five different tunnel entries over a ten month period from October of 2007 through July of 2008, while the final flight lot qualification tests were conducted in April of 2009. During the second tunnel entry in December, 2007, the parachute that was used in the second of three planned mortar deployment (MD) tests inverted below the band of the canopy. This was the first time that a DGB parachute had ever inverted in any nominally executed test which includes all wind tunnel, low altitude, high altitude, subsonic, supersonic, and Mars flight condition deployments. Following the MD2 inversion a Risk Assessment Workshop (RAW) was convened in January, 2008, at Pioneer Aerospace in South Windsor, Connecticut, to discuss possible mitigations to the inversion phenomenon both for NFAC testing as well as for flight. The historical flight and test experience was reviewed and a number of options were considered before a down selection exercise reduced the design space to two modifications which were implemented for the third NFAC entry in March, 2008. The two modifications were shown to have no ill effects on the mortar deployment of two 21.5 m and two 23 m parachutes and all four of the openings were observed to be within expectations. Observations made during the second and third tunnel entries showed that the weakest point in the design was at the suspension line to band joint and this junction could fail under certain conditions during test. In order to build some added strength margin into the parachute the suspension line material was changed from Kevlar-29 to Technora-T221 which necessitated a fourth tunnel entry to verify the new material margins. In addition, the testing

Organic and inorganic contamination control approaches for return sample investigation on Mars 2020

The Mars 2020 Rover mission will have the capability to collect and cache samples for potential Mars sample return. Specifically, the sample caching system (SCS) is designed for coring Mars samples and acquiring regolith samples as well as handling, sealing and caching on Mars. As the potential first Martian samples that could be returned to Earth, assuring low levels of terrestrial contamination is of the utmost concern. In developing the SCS, the project prioritizes limiting sample contamination in organic, inorganic and biological areas. The focus of this paper is on the strategies being implemented to limit terrestrial organic and inorganic contamination in the samples.