Engineering topics

Mark J. Cintala

Publications and source records attributed to Mark J. Cintala.

3 records

NASA NTRS2024

Toward Prebiotic Chemistry on Titan: Impact Experiments on Organic Haze Particles

Impacts are critical to producing the aqueous environments necessary to stimulate prebiotic chemistry on Titan's surface. Furthermore, organic hazes resting on the surface are a likely feedstock of biomolecules. In this work, we conduct impact experiments on laboratory-produced organic haze particles and haze/sand mixtures and analyze these samples for life's building blocks. Samples of unshocked haze and sand particles are also analyzed to determine the change in biomolecule concentrations and distributions from shocking. Across all samples, we detect seven nucleobases, nine proteinogenic amino acids, and five other biomolecules (e.g., urea) using a blank subtraction procedure to eliminate signals due to contamination. We find that shock pressures of 13 GPa variably degrade nucleobases, amino acids, and a few other organics in haze particles and haze/sand mixtures; however, certain individual biomolecules become enriched or are even produced from these events. Xanthine, threonine, and aspartic acid are enriched or produced in impact experiments containing sand, suggesting these minerals may catalyze the production of these biomolecules. On the other hand, thymine and isoleucine/norleucine are enriched or produced in haze samples containing no sand, suggesting catalytic grains are not necessary for all impact shock syntheses. Uracil, glycine, proline, cysteine, and tyrosine are the most unstable to impact-related processing. These experiments suggest that impacts alter biomolecule distributions on Titan's surface, and that organic hazes co-occurring with fine-grained material on the surface may provide an initial source for further prebiotic chemistry on Titan.

impact experiments↗

NASA NTRSDate not supplied

Impact Experiments into Granular Targets Containing Solitary Blocks of Varying Strength and Size

Crater scaling relationships provide a means to correlate dimensions of laboratory-scale impact experiments to naturally formed craters at planetary scales. For relatively larger impact events, where gravity is the dominant arresting force against crater growth, these scaling relations are comparatively simple. For smaller craters, however, the target properties have increasing influence over the cratering process. Further complexities are easily envisaged when considering realistic surfaces that contain small-scale heterogeneities in cohesive strength, density, porosity, friction, as these properties will each have unequal effects on the resultant crater morphometry. Even when produced under controlled laboratory conditions, understanding (and controlling) the entire relevant parameter space is daunting, and deconvolution of the relevant contributors can be complicated even in the best-case scenario. To this end, we have begun an extensive series of impact experiments that will provide a nascent framework that will aid in the interpretation of craters observed on complex natural surfaces throughout the solar system. To start with the simplest configuration, experiments were performed with cylindrical PVC buckets that were filled with quartz sand and contained a single cubic block of synthetic sandstone. The blocks varied in size (14-33 mm) and unconfined compressive strength (0.5-7.4 MPa) and were placed in/on the sand along the trajectory of the incoming impactor and buried to different depths. All experiments were conducted using the vertical gun located in the Experimental Impact Lab at NASA Johnson Space Center with alumina projectiles that were accelerated to ~1.53 km s^-1 under a vacuum of 1 torr. After the impact, target containers were removed from the chamber are morphometric data were extracted by using a Peel 2 3D-scanner in combination with the open-source software, CloudCompare. Initial results show that block strength is a secondary effect on crater diameter and depth, but when at least one edge of the block is exposed and the surface (partial burial) the strength will dictate the number of surviving block fragments around the crater, as well as how much disrupted block material is retained within the crater walls.

Christopher J. Cline II↗

NASA NTRSDate not supplied

Effects of Limiting Container Diameter on Crater Morphometry in Laboratory Impact Experiments.

Laboratory impact experiments provide a mechanism to test and understand impact events that affect every planetary object in our Solar System. Impact experiments have been conducted on a wide variety of mediums (e.g., sand, ice, solid rock, regolith simulant [1–4]) in a variety of container sizes, depending on the laboratory. While the specific parameters of each impact experiment vary greatly from impacting medium, projectile type and size, speed, etc., there has not been any in depth analysis of the effects that limiting container dimensions might have on the resulting subsurface flow field and ultimately the crater structure. Here we asses the effects of container diameter by conducting a series of cratering experiments on five different container sizes. The results of this study will be informative to the impact community such that closer consideration will be taken regarding the selection of container size to insure the most high quality results with less interference from the boundary conditions.

Megan D. Mouser↗