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NASA NTRS2009

Design and Testing of Braided Composite Fan Case Materials and Components

Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.

Roberts, Gary D.↗

NASA NTRS2009

Pion Total Cross Section in Nucleon - Nucleon Collisions

Total cross section parameterizations for neutral and charged pion production in nucleon - nucleon collisions are compared to experimental data over the projectile momentum range from threshold to 300 GeV. Both proton - proton and proton - neutron reactions are considered. Overall excellent agreement between parameterizations and experiment is found, except for notable disagreements near threshold. In addition, the hypothesis that the neutral pion production cross section can be obtained from the average charged pion cross section is checked. The theoretical formulas presented in the paper obey this hypothesis for projectile momenta below 500 GeV. The results presented provide a test of engineering tools used to calculate the pion component of space radiation.

Norbury, John W.↗

NASA NTRS2009

Meteoroid and Orbital Debris Threats to NASA's Docking Seals: Initial Assessment and Methodology

The Crew Exploration Vehicle (CEV) will be exposed to the Micrometeoroid Orbital Debris (MMOD) environment in Low Earth Orbit (LEO) during missions to the International Space Station (ISS) and to the micrometeoroid environment during lunar missions. The CEV will be equipped with a docking system which enables it to connect to ISS and the lunar module known as Altair; this docking system includes a hatch that opens so crew and supplies can pass between the spacecrafts. This docking system is known as the Low Impact Docking System (LIDS) and uses a silicone rubber seal to seal in cabin air. The rubber seal on LIDS presses against a metal flange on ISS (or Altair). All of these mating surfaces are exposed to the space environment prior to docking. The effects of atomic oxygen, ultraviolet and ionizing radiation, and MMOD have been estimated using ground based facilities. This work presents an initial methodology to predict meteoroid and orbital debris threats to candidate docking seals being considered for LIDS. The methodology integrates the results of ground based hypervelocity impacts on silicone rubber seals and aluminum sheets, risk assessments of the MMOD environment for a variety of mission scenarios, and candidate failure criteria. The experimental effort that addressed the effects of projectile incidence angle, speed, mass, and density, relations between projectile size and resulting crater size, and relations between crater size and the leak rate of candidate seals has culminated in a definition of the seal/flange failure criteria. The risk assessment performed with the BUMPER code used the failure criteria to determine the probability of failure of the seal/flange system and compared the risk to the allotted risk dictated by NASA s program requirements.

deGroh, Henry C., III↗

NASA NTRS2009

Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

Melis, Matthew E.↗

NASA NTRS2009

Honeycomb vs. Foam: Evaluating a Potential Upgrade to ISS Module Shielding for Micrometeoroids and Orbital Debris

The presence of a honeycomb core in a multi-wall shielding configuration for protection against micrometeoroid and orbital debris (MMOD) particle impacts at hypervelocity is generally considered to be detrimental as the cell walls act to restrict fragment cloud expansion, creating a more concentrated load on the shield rear wall. However, mission requirements often prevent the inclusion of a dedicated MMOD shield, and as such, structural honeycomb sandwich panels are amongst the most prevalent shield types. Open cell metallic foams are a relatively new material with novel mechanical and thermal properties that have shown promising results in preliminary hypervelocity impact shielding evaluations. In this study, an ISS-representative MMOD shielding configuration has been modified to evaluate the potential performance enhancement gained through the substitution of honeycomb for open cell foam. The baseline shielding configuration consists of a double mesh outer layer, two honeycomb sandwich panels, and an aluminum rear wall. In the modified configuration the two honeycomb cores are replaced by open-cell foam. To compensate for the heavier core material, facesheets have been removed from the second sandwich panel in the modified configuration. A total of 19 tests on the double layer honeycomb and double layer foam configurations are reported. For comparable mechanical and thermal performance, the foam modifications were shown to provide a 15% improvement in critical projectile diameter at low velocities (i.e. 3 km/s) and a 3% increase at high velocities (i.e. 7 km/s) for normal impact. With increasing obliquity, the performance enhancement was predicted to increase, up to a 29% improvement at 60 (low velocity). Ballistic limit equations have been developed for the new configuration, and consider the mass of each individual shield component in order to maintain validity in the event of minor configuration modifications. Previously identified weaknesses of open cell foams for hypervelocity impact shielding such as large projectile diameters, low velocities, and high degrees of impact obliquity have all been investigated, and found to be negligible for the double-layer configuration.

Ryan, Shannon↗

NASA NTRS2011

Ballistic Performance of Porous-Ceramic, Thermal Protection Systems

Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on 8 lb/cu ft alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrous-insulation/ reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principals impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. Model extensions to look at the implications of greater than 10 GPa equation of state is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.

Miller, J. E.↗

NASA NTRS2009

Architectural Effects on Impact Resistance of Uncoated MI SiC/SiC Composites

Impact tests were conducted on uncoated 2D and 2.5D MI SiC/SiC composite specimens at room temperature and 1316 C in air. The specimens were analyzed before and after impact using optical microscopy, pulsed thermography (PT) and computed tomography (CT). Preliminary results indicate the following. Both 2-D and 2.5D composites show increase in surface and volumetric damages with increasing impact velocity. However, 2-D composites are prone to delamination cracks. In both 2D and 2.5D composites, the magnitude of impact damage at a fixed impact velocity is slightly greater at room temperature than at 1315 C. At a fixed projectile velocity and test temperature, the depth of penetration of the projectile into the substrate is significantly lower in 2.5D composites than in 2D composites. Fiber architecture plays a significant role controlling impact damage in MI SiC/SiC composites.

Bhatt, R. T.↗

NASA NTRS2010

Launch Pad Flame Trench Refractory Materials

The launch complexes at NASA's John F. Kennedy Space Center (KSC) are critical support facilities for the successful launch of space-based vehicles. These facilities include a flame trench that bisects the pad at ground level. This trench includes a flame deflector system that consists of an inverted, V-shaped steel structure covered with a high temperature concrete material five inches thick that extends across the center of the flame trench. One side of the "V11 receives and deflects the flames from the orbiter main engines; the opposite side deflects the flames from the solid rocket boosters. There are also two movable deflectors at the top of the trench to provide additional protection to shuttle hardware from the solid rocket booster flames. These facilities are over 40 years old and are experiencing constant deterioration from launch heat/blast effects and environmental exposure. The refractory material currently used in launch pad flame deflectors has become susceptible to failure, resulting in large sections of the material breaking away from the steel base structure and creating high-speed projectiles during launch. These projectiles jeopardize the safety of the launch complex, crew, and vehicle. Post launch inspections have revealed that the number and frequency of repairs, as well as the area and size of the damage, is increasing with the number of launches. The Space Shuttle Program has accepted the extensive ground processing costs for post launch repair of damaged areas and investigations of future launch related failures for the remainder of the program. There currently are no long term solutions available for Constellation Program ground operations to address the poor performance and subsequent failures of the refractory materials. Over the last three years, significant liberation of refractory material in the flame trench and fire bricks along the adjacent trench walls following Space Shuttle launches have resulted in extensive investigations of failure mechanisms, load response, ejected material impact evaluation, and repair design analysis (environmental and structural assessment, induced environment from solid rocket booster plume, loads summary, and repair integrity), assessment of risk posture for flame trench debris, and justification of flight readiness rationale. Although the configuration of the launch pad, water and exhaust direction, and location of the Mobile Launcher Platform between the flame trench and the flight hardware should protect the Space Vehicle from debris exposure, loss of material could cause damage to a major element of the ground facility (resulting in temporary usage loss); and damage to other facility elements is possible. These are all significant risks that will impact ground operations for Constellation and development of new refractory material systems is necessary to reduce the likelihood of the foreign object debris hazard during launch. KSC is developing an alternate refractory material for the launch pad flame trench protection system, including flame deflector and flame trench walls, that will withstand launch conditions without the need for repair after every launch, as is currently the case. This paper will present a summary of the results from industry surveys, trade studies, life cycle cost analysis, and preliminary testing that have been performed to support and validate the development, testing, and qualification of new refractory materials.

Calle, Luz M.↗

NASA NTRS2014

Data Processing and Experimental Design for Micrometeorite Impacts in Small Bodies

Comets and asteroids have been altered from their original "pristine" state by impacts occurring throughout their 4.5 billion year lives: [1]. Proof of shock deformation has been detected in the crystal structure of several Stardust samples from Comet Wild 2 [2, 3]. Analyses indicated that the planar dislocations in the crystal structure of the minerals had been imparted by impacts sustained during their lives, and not due to the aerogel capture process. Distortions to crystal structure also affect the ideal absorption spectra in the infrared, and [4], thus providing indirect evidence of its impact history and a means of remotely investigating the impact history of small bodies through comparing laboratory spectra with spectra observed by telescopes or spacecraft. -The effects of impacts propagating shock waves through minerals were investigated through laboratory impact experiments. Utilizing NASA Johnson Space Center's Experimental Impact Laboratory, projectiles were fired from the vertical gun at velocities ranging from 2.0 to 2.8 km/sec, projected impact velocities between Kuiper Belt Objects. Two types of projectiles were used, including spherical alumina ceramic, whose density mimics that of rock, and cylinders made from the same material that they impacted. The target materials chosen for testing included: OLIVINES forsterite (Mg2SiO4) and fayalite, Fe2SiO4); PYROXENES enstatite (Mg2Si2O6) and diopside (MgCaSi2O6); and CARBONATES magnesite (MgCO3) and siderite (FeCO3). Targets were impacted at either 25 C or cooled to -20 C to examine the effects of temperature, if any, on lattice distortions during the shock propagation. As comets and asteroids can undergo a wide range of temperatures in their orbital lifetimes, the effect of temperature on the equation of state of minerals being shocked needs to be examined for interpreting the results of these experiments. The porosity of the target mineral is varied by either grinding it into a powder/granular texture or as whole mineral rocks to investigate the differences in shock propagation when voids are present. By varying velocity, ambient temperature, and porosity, we can investigate different variables affecting impacts in the solar system. -Data indicates that there is a non-linear relationship between peak shock pressure and the variation in infrared spectral absorbances by the distorted crystal structure. The maximum variability occurs around 37 GPa in enstatite and forsterite. The particle size distribution of the impacted material similarly changes with velocity/peak shock pressure. -The experiments described above are designed to measure the near- to mid-IR effects from these changes to the mineral structure. See Lederer et al., this meeting for additional experimental results.

Jensen, E.↗

NASA NTRS2014

Multi-shock Shield Performance at 16.5 MJ for Catalogued Debris

While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, numerical simulations and an experiment using the multi‐shock shield system is described for a cylindrical projectile composed of Nylon, aluminum and void that is approximately 8 cm in diameter and 10 cm in length weighing 670 g impacting the multi‐shock shield normal to the surface with approximately 16.5 MJ of kinetic energy. The multi‐shock shield system has been optimized to facilitate the fragmentation, spread and deceleration of the projectile remnants using hydrodynamic simulations of the impact event. The characteristics and function of each of the layers of the multi‐shock system will be discussed along with considerations for deployment and improvement.

Miller, J. E.↗

NASA NTRS2015

Impact and Penetration of Thin Aluminum 2024 Flat Panels at Oblique Angles of Incidence

The U.S. Federal Aviation Administration (FAA) and the National Aeronautics and Space Administration (NASA) are actively involved in improving the predictive capabilities of transient finite element computational methods for application to safety issues involving unintended impacts on aircraft and aircraft engine structures. One aspect of this work involves the development of an improved deformation and failure model for metallic materials, known as the Tabulated Johnson-Cook model, or MAT224, which has been implemented in the LS-DYNA commercial transient finite element analysis code (LSTC Corp., Livermore, CA) (Ref. 1). In this model the yield stress is a function of strain, strain rate and temperature and the plastic failure strain is a function of the state of stress, temperature and strain rate. The failure criterion is based on the accumulation of plastic strain in an element. The model also incorporates a regularization scheme to account for the dependency of plastic failure strain on mesh size. For a given material the model requires a significant amount of testing to determine the yield stress and failure strain as a function of the three-dimensional state of stress, strain rate and temperature. In addition, experiments are required to validate the model. Currently the model has been developed for Aluminum 2024 and validated against a series of ballistic impact tests on flat plates of various thicknesses (Refs. 1 to 3). Full development of the model for Titanium 6Al-4V is being completed, and mechanical testing for Inconel 718 has begun. The validation testing for the models involves ballistic impact tests using cylindrical projectiles impacting flat plates at a normal incidence (Ref. 2). By varying the thickness of the plates, different stress states and resulting failure modes are induced, providing a range of conditions over which the model can be validated. The objective of the study reported here was to provide experimental data to evaluate the model under more extreme conditions, using a projectile with a more complex shape and sharp contacts, impacting flat panels at oblique angles of incidence.

Ruggeri, Charles R.↗

NASA NTRS2016

The Ames Vertical Gun Range

The Ames Vertical Gun Range (AVGR) is a national facility for conducting laboratory- scale investigations of high-speed impact processes. It provides a set of light-gas, powder, and compressed gas guns capable of accelerating projectiles to speeds up to 7 km s(exp -1). The AVGR has a unique capability to vary the angle between the projectile-launch and gravity vectors between 0 and 90 deg. The target resides in a large chamber (diameter approximately 2.5 m) that can be held at vacuum or filled with an experiment-specific atmosphere. The chamber provides a number of viewing ports and feed-throughs for data, power, and fluids. Impacts are observed via high-speed digital cameras along with investigation-specific instrumentation, such as spectrometers. Use of the range is available via grant proposals through any Planetary Science Research Program element of the NASA Research Opportunities in Space and Earth Sciences (ROSES) calls. Exploratory experiments (one to two days) are additionally possible in order to develop a new proposal.

The chamber provides a number of viewing ports and↗

NASA NTRS2016

Engineering Polymer Blends for Impact Damage Mitigation

Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

Gordon, Keith L.↗

NASA NTRS2016

Electromagnetic Dissociation Cross Sections for High LET Fragments

Nuclear interaction cross sections are used in space radiation transport codes to calculate the probability of fragment emission in high energy nucleus-nucleus collisions. Strong interactions usually dominate in these collisions, but electromagnetic (EM) interactions can also sometimes be important. Strong interactions typically occur when the projectile nucleus hits a target nucleus, with a small impact parameter. For impact parameters larger than the sum of the nuclear radii, EM reactions dominate and the process is called electromagnetic dissociation (EMD) if one of the nuclei undergo fragmentation. Previous models of EMD have been used to calculate single proton (p) production, single neutron (n) production or light ion production, where a light ion is defined as an isotope of hydrogen (H) or helium (He), such as a deuteron (2H), a triton (3H), a helion (3He) or an alpha particle (4He). A new model is described which can also account for multiple nucleon production, such as 2p, 2n, 1p1n, 2p1n, 2p2n, etc. in addition to light ion production. Such processes are important to include for the following reasons. Consider, for example, the EMD reaction 56Fe + Al --> 52Cr + X + Al, for a 56Fe projectile impacting Al, which produces the high linear energy transfer (LET) fragment 52Cr. In this reaction, the most probable particles representing X are either 2p2n or 4He. Therefore, production of the high LET fragment 52Cr, must include the multiple nucleon production of 2p2n in addition to the light ion production of 4He. Previous models, such as the NUCFRG3 model, could only account for the 4He production process in this reaction and could not account for 2p2n. The new EMD model presented in this work accounts for both the light ion and multiple nucleon processes, and is therefore able to correctly account for the production of high LET products such as 52Cr. The model will be described and calculations will be presented that show the importance of light ion and multiple nucleon production. The work will also show that EMD reactions contribute most to those fragments with the highest LET.

Norbury, John↗

NASA NTRS2016

Electromagnetic Dissociation and Spacecraft Electronics Damage

When protons or heavy ions from galactic cosmic rays (GCR) or solar particle events (SPE) interact with target nuclei in spacecraft, there can be two different types of interactions. The more familiar strong nuclear interaction often dominates and is responsible for nuclear fragmentation in either the GCR or SPE projectile nucleus or the spacecraft target nucleus. (Of course, the proton does not break up, except possibly to produce pions or other hadrons.) The less familiar, second type of interaction is due to the very strong electromagnetic fields that exist when two charged nuclei pass very close to each other. This process is called electromagnetic dissociation (EMD) and primarily results in the emission of neutrons, protons and light ions (isotopes of hydrogen and helium). The cross section for particle production is approximately defined as the number of particles produced in nucleus-nucleus collisions or other types of reactions. (There are various kinematic and other factors which multiply the particle number to arrive at the cross section.) Strong, nuclear interactions usually dominate the nuclear reactions of most interest that occur between GCR and target nuclei. However, for heavy nuclei (near Fe and beyond) at high energy the EMD cross section can be much larger than the strong nuclear interaction cross section. This paper poses a question: Are there projectile or target nuclei combinations in the interaction of GCR or SPE where the EMD reaction cross section plays a dominant role? If the answer is affirmative, then EMD mechanisms should be an integral part of codes that are used to predict damage to spacecraft electronics. The question can become more fine-tuned and one can ask about total reaction cross sections as compared to double differential cross sections. These issues will be addressed in the present paper.

Norbury, John W.↗

NASA NTRS2017

High Speed Thermal Imaging on Ballistic Impact of Triaxially Braided Composites

Ballistic impact experiments were performed on triaxially braided polymer matrix composites to study the heat generated in the material due to projectile velocity and penetration damage. Quantifying the heat generation phenomenon is crucial for attaining a better understanding of composite behavior and failure under impact loading. The knowledge gained can also be used to improve physics-based models which can numerically simulate impact of composites. Triaxially braided (0/+60/-60) composite panels were manufactured with T700S standard modulus carbon fiber and two epoxy resins. The PR520 (toughened) and 3502 (untoughened) resin systems were used to make different panels to study the effects of resin properties on temperature rise. Ballistic impact tests were conducted on these composite panels using a gas gun, and different projectile velocities were applied to study the effect on the temperature results. Temperature contours were obtained from the rear surface of the panel during the test through a high speed, infrared (IR) thermal imaging system. The contours show that high temperatures were locally generated and more pronounced along the axial tows for the T700S/PR520 composite specimens; whereas, tests performed on T700S/3502 composite panels using similar impact velocities demonstrated a widespread area of lower temperature rises. Nondestructive, ultrasonic C-scan analyses were performed to observe and verify the failure patterns in the impacted panels. Overall, the impact experimentation showed temperatures exceeding 525 K (485degF) in both composites which is well above the respective glass transition temperatures for the polymer constituents. This expresses the need for further high strain rate testing and measurement of the temperature and deformation fields to fully understand the complex behavior and failure of the material in order to improve the confidence in designing aerospace components with these materials.

thermal imaging↗

NASA NTRS2018

Low Risk Technique for Sample Acquisition from Remote and Hazardous Sites on a Comet

This paper describes a mission comet sampling strategy, known as CORSAIR (COmet Rendezvous, Sample Acquisition, Investigation, and Return), which was proposed for NASA New Frontiers 2017. The proposal was led by Applied Physics Lab (APL) with partners Goddard Space Flight Center (GSFC) and Deutsches Zentrum für Luft- und Raumfahrt (DLR). The mission concept is to launch a projectile from a satellite that is capable of gathering a 300 cc sample. The projectile is tethered and is reeled back to the spacecraft after gathering the sample. Once back at the spacecraft, a robotic manipulator extracts the sample cartridge and places the cartridge into an earth return vehicle (ERV). This method has the following favorable characteristics: 1. Places the mission at minimal risk by isolating the spacecraft from the comet 2. Allows access to remote and otherwise inaccessible locations 3. Permits deep penetration into the surface

Comet Sample↗

NASA NTRSDate not supplied

Using Controlled Impact Experiments to Understand the Effects of Cohesive Blocks on the Cratering Process

When considering large-scale impact events that occur in the gravity-regime, smallscale target heterogeneities (on order of the projectile diameter) are anticipated to have a minimal effect on the cratering process and are therefore not considered in scaling relations [1-3]. Such heterogeneities and other details of the target's strength and structure, however, become increasingly influential as the magnitude of the impact decreases [4]. At the scale of craters forming mostly in regolith on the Moon (< a few meters), for example, target properties such as cohesive strength, density, porosity, and friction have more leverage than gravity to influence the resultant crater dimensions [5]. Further complications beyond just target properties can manifest in many forms, such as subsurface layers [6]; the presence of random, competent blocks [7]; buried lenses of impact melt; and/or pockets of regolith compacted or indurated to varying degrees by previous impacts. Summing the total effect of target properties and any additional heterogeneities for integration into scaling relations is not straightforward, as each individual parameter will have unequal, and so far, unquantified, effects on the final crater. Even when craters are produced under a best-case scenario of controlled laboratory conditions, understanding the entire relevant parameter space can be a formidable task, and deconvolution of all the contributing factors can be a complex undertaking. To begin the process of quantifying such effects, we are conducting an extensive series of impact experiments to build a framework for the interpretation of craters observed on the characteristically complex surfaces throughout the solar system. Here we present the first, and simplest, configuration to be examined in this multi-year experimental campaign: one in which solitary, cohesive blocks are placed in the path of the projectile’s trajectory at different burial depths in granular, sand targets. Among the variables to be investigated in this configuration are the influence of block size, compressive strength, and burial depth.

impact crater↗