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We investigated 634 crater clusters on Mars detected between 2007 and 2021, which represent more than half of all impacts discovered in this period. Crater clusters form when meteoroids in the 10 kg–10 ton mass range break up in Mars' atmosphere to produce a few to a few hundred fragments that hit the ground. The properties of the clusters can inform our understanding of meteoroid properties and the processes that govern their fragmentation. We mapped individual craters >1 m within each cluster and defined a range of cluster properties based on the spatial and size distributions of the craters. The large data set, with over eight times more cluster observations than previous work, provides a more robust statistical investigation of crater cluster parameters and their correlations. Trends in size, dispersion, and large crater fraction with elevation support weak atmospheric filtering of material. The diversity in the number of individual craters within a cluster, and their size‐frequency distributions, may reflect either a diversity in fragmentation style, fragility, or internal particle sizes. Plain Language Summary: Between 2007 and 2021, over a thousand newly formed impact craters have been detected on the surface of Mars. Over half are from bodies that have broken up in the atmosphere, forming clusters of craters. We have mapped all the individual craters in each of these clustered impact sites. By investigating the properties of these sites, such as how many individual craters are there, their dispersion and their size, we can improve our understanding of the impacting bodies and how they break up. We find a wide diversity of cluster patterns, with some elevation dependence. This suggests that, although the atmosphere plays a role in meteoroid break up, there is great variety in the impactor bodies themselves. Key Points: Crater cluster properties inform our understanding of meteoroid fragmentationAtmospheric influence reflected in crater cluster properties varies with elevationSize‐frequency crater distribution in clusters suggests larger impactors are weaker in bulk strength [ABSTRACT FROM AUTHOR]

Seismic activity generated by impacts depends on impact conditions and properties of the impact site. Here, we combined mapping of the regolith thickness with numerical impact simulations to better estimate the seismic efficiency and seismic moment generated in small impact events in the uppermost crust on Mars. We used mapping of crater morphology to determine the regolith thickness that craters formed in. We found that local regolith thickness in the late Amazonian units is between 4 and 9 m. Combined with previous estimates for the NASA InSight landing site, we composed a more realistic uppermost crust analog and implemented it in numerical impact simulations. We estimated the seismic efficiency and seismic moment for small craters on Mars impacting a non‐porous or fractured bedrock overlaid by 5, 10, or 15 m thick regolith. Seismic energy showed more dependence on target properties. Three orders of magnitude more energy were produced in stronger targets. The seismic moment does not depend on target properties, and we confirm that seismic moment is almost proportional to impact momentum. The resulting seismic moment is in agreement up to a factor of 4 between different target types. We improved the scaling relationships developed from numerical simulations used in seismic moment approximations by constraining its dependence on more realistic target properties. Plain Language Summary: Small impacts form in the top few meters of the crust of Mars. From the NASA InSight mission data, we learned that the uppermost crust of Mars is layered. Here, we mapped and used rocky ejecta craters as a proxy to estimate the thickness of this top layer. We demonstrated that a younger, late Amazonian geological unit, has a thinner top regolith layer (4–9 m) compared to an older, Hesperian unit (3–17 m). We modeled several target scenarios, constrained by mapping results, and performed a suite of numerical simulations of small impacts. From these simulations, we determined a relationship between impact‐generated seismic energy and the seismic moment for different types of Martian upper‐crust analogs. Our models show that impact‐generated seismic energy strongly depends on target properties (three orders of difference among different analogs investigated here). On the contrary, seismic moment shows agreement up to a factor of 4 in different targets. We discussed our modeling results to the newly detected impacts on Mars, and confirmed that our models are reliable for predicting seismic moments of small impacts. Our results contribute to the understanding of the size and energy of impact‐generated seismic sources in different target analogs. Key Points: Using rocky ejecta craters, we mapped regolith thickness on Mars and found that in the late Amazonian volcanic unit, it is 4–9 mSeismic efficiency shows larger sensitivity on target properties (up to three orders of magnitude) than the seismic moment (factor of four)A comparison of numerical simulations with the new seismic detections of craters on Mars showed agreement with our models [ABSTRACT FROM AUTHOR]

The third stage of the Saturn IV rocket used in the five Apollo missions made craters on the Moon ∼30 m in diameter. Their initial impact conditions were known, so they can be considered controlled impacts. Here, we used the iSALE‐2D shock physics code to numerically simulate the formation of these craters, and to calculate the vertical component of seismic moment (∼4 × 1010 Nm) and seismic efficiency (∼10−6) associated with these impacts. The irregular booster shape likely caused the irregular crater morphology observed. To investigate this, we modeled six projectile geometries, with footprint area between 3 and 105 m2, keeping the mass and velocity of the impactor constant. We showed that the crater depth and diameter decreased as the footprint area increased. The central mound observed in lunar impact sites could be a result of layering of the target and/or low density of the projectile. Understanding seismic signatures from impact events is important for planetary seismology. Calculating seismic parameters and validating them against controlled experiments in a planetary setting will help us understand the seismic data received, not only from the Moon, but also from the InSight Mission on Mars and future seismic missions. Plain Language Summary: Observations of meteoroid strikes on the Moon, including artificial impacts made by the Saturn boosters from the Apollo missions, present valuable information for connecting impact conditions with seismic properties of the lunar and planetary crusts. These artificial impacts on the Moon were made by irregularly shaped spacecraft with low density. We numerically simulated these artificial impacts, using several different projectile geometries in order to represent the spacecraft's low density and shape. We found that the projectile representation affected the crater size. We calculated the amount of energy transferred into seismic waves and seismic moment created in these impacts to be consistent with previous studies. These parameters did not change with different projectile representations, but were affected by the material properties of the impact site. The aim is to use the results from the controlled lunar impacts to help understand the seismic signatures of impacts on Mars. Key Points: Numerical impact simulations of the Apollo rocket stage drop on the MoonProjectile geometry affects cratering process, cratering efficiency, and momentum transferEstimates of the seismic moment and seismic efficiency in these impacts [ABSTRACT FROM AUTHOR]

Impact basins on the Moon can serve as a benchmark for timing and intensity of the impact flux in the inner solar system. The basin morphology and morphometry depend on impactor size, mass, and velocity as well as the thermal state of the lunar lithosphere which is a function of the cooling history. Erosion by superimposed impact bombardment has altered the surface expression of basin structures over time, making it difficult to determine the size unequivocally solely based on topographic expression. The gravity signature of basins is thought to be a less altered measure of the size of impact structures. By a systematic study of basin formation using the iSALE‐2D shock‐physics code, we investigate the influence of the lunar thermal state and different impactor properties on the transient crater and final basin size and on the resulting gravity anomaly. As constraints we use gravity data of 16 farside basins and their assumed formation ages to estimate the subsurface temperature related to the cooling history of the Moon. Our modeling results confirm that the thermal state affects the basin formation process and the basin sizes significantly. We provide quantitative relationships between the observed gravity signal, the different basin sizes, and the impactor diameter considering the thermal state of the Moon upon impact, which correlates with the formation ages or periods in the literature. Our study allows for estimating the impactor size from the observed gravity field if the formation age and, thus, the thermal state of the lithosphere is approximately known. Plain Language Summary: Large basin structures testify to the lunar bombardment history by bodies several tens to hundreds of kilometers in diameter. To reconstruct how often the Moon, and thus also Earth, was hit by large cosmic bodies of a given size, it is essential to relate the size of basin structures with impactor size. However, since the surface expression of most known basins on the Moon is not pristine, the definition of the actual basin size is often ambiguous. As an alternative, we use the observed pronounced positive gravity excursion across lunar basins as a measure of basin size. In addition, we consider the thermal evolution of the Moon which is thought to affect the characteristics of the gravity signature of basins. Therefore, the timing when a given basin was formed in the cooling history of the Moon plays an important role. We use the gravity signature and the lunar thermal state as constraints for modeling the formation of the lunar basins as a function of impactor size. Our results allow for estimating the impactor size and thermal state of the Moon for 16 lunar farside basins. The predicted thermal states are in line with proposed absolute ages of the basins. Key Points: We provide relationships between impactor size, gravity signal, and farside basin size as a function of cooling history and formation timeGravity anomalies serve as a measure of basin size as impacts altered morphology and crustal thickness models simplify subsurface structureOur basin formation models agree with the assumed formation time based on crater chronology and the estimated cooling history of the Moon [ABSTRACT FROM AUTHOR]

The first seismometer operating on the surface of another planet was deployed by the NASA InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission to Mars. It gives us an opportunity to investigate the seismicity of Mars, including any seismic activity caused by small meteorite bombardment. Detectability of impact generated seismic signals is closely related to the seismic efficiency, defined as the fraction of the impactor's kinetic energy transferred into the seismic energy in a target medium. This work investigated the seismic efficiency of the Martian near surface associated with small meteorite impacts on Mars. We used the iSALE‐2D (Impact‐Simplified Arbitrary Lagrangian Eulerian) shock physics code to simulate the formation of the meter‐size impact craters, and we used a recently formed 1.5 m diameter crater as a case study. The Martian crust was simulated as unfractured nonporous bedrock, fractured bedrock with 25% porosity, and highly porous regolith with 44% and 65% porosity. We used appropriate strength and porosity models defined in previous works, and we identified that the seismic efficiency is very sensitive to the speed of sound and elastic threshold in the target medium. We constrained the value of the impact‐related seismic efficiency to be between the order of ∼10‐7 to 10‐6 for the regolith and ∼10‐4 to 10‐3 for the bedrock. For new impacts occurring on Mars, this work can help understand the near‐surface properties of the Martian crust, and it contributes to the understanding of impact detectability via seismic signals as a function of the target media. Plain Language Summary: Impact cratering is a common geological process on solid planetary bodies. When impact occurs, it releases shock waves into the target medium. The impactor's kinetic energy is spent on internal energy change (heating), plastic (irreversible) and elastic (reversible) deformation in the target. Seismic efficiency describes how much of the impact's kinetic energy is transferred into seismic energy. Having estimates for the values of the seismic efficiency in such events can help in further describing the properties of the Martian surface, particularly if impact conditions are known. In this work, we are using the iSALE‐2D (Impact‐Simplified Arbitrary Lagrangian Eulerian) shock physics code to simulate meter‐size crater formation on Mars. Our results show that the pressure wave behaves differently in different target properties. The numerical simulation results showed that the seismic efficiency spans 2 orders of magnitude, for the investigated crater size range and target analog for the Martian bedrock and regolith. Key Points: Seismic efficiency decreases with the increase of porositySeismic efficiency is ∼8 × 10‐4 in bedrock and ∼4 × 10‐7 to ∼4 × 10‐6 in highly porous regolith, for Martian simulantsPressure propagation is significantly dependent on the target's crushing strength, elastic threshold and speed sound, and resolution [ABSTRACT FROM AUTHOR]

Since landing in late 2018, the InSight lander has been recording seismic signals on the surface of Mars. Despite nominal prelanding estimates of one to three meteorite impacts detected per Earth year, none have yet been identified seismically. To inform revised detectability estimates, we simulated numerically a suite of small impacts onto Martian regolith and characterized their seismic source properties. For the impactor size and velocity range most relevant for InSight, crater diameters are 1–30 m. We found that in this range scalar seismic moment is 106–1010 Nm and increases almost linearly with impact momentum. The ratio of horizontal to vertical seismic moment tensor components is ∼1, implying an almost isotropic P wave source, for vertical impacts. Seismic efficiencies are ∼10−6, dependent on the target crushing strength and impact velocity. Our predictions of relatively low seismic efficiency and seismic moment suggest that meteorite impact detectability on Mars is lower than previously assumed. Detection chances are best for impacts forming craters of diameter >10 m. Plain Language Summary: NASA's InSight lander has been recording signals, including ground vibrations, on the surface of Mars since early 2019. On Earth, seismologists routinely study earthquakes, but equivalent disturbances on Mars, marsquakes, are not expected to be as large in magnitude. Meteorite impacts were therefore expected to provide another valuable source of seismic energy on Mars, but none have been detected so far. Our understanding of how efficiently meteorites of a given size generate seismic energy therefore requires revision. Using a suite of numerical simulations replicating small impacts on Mars, we conclude that both the magnitude of seismic vibrations and the proportion of the meteorite's kinetic energy that is transferred into distant ground motions are below previous estimates. Small meteorite impacts thus produce smaller and less energetic disturbances than previously predicted, which partially explains lack of detected impacts by InSight. Our results show that the best opportunity of detection is offered by impacts forming craters larger than 10 m in diameter. Key Points: Numerical simulations of small impacts on Mars show that scalar seismic moment is proportional to impact momentumSeismic efficiency is ∼10−6, comparable with that measured for artificial impacts on the MoonInSight's impact detection chances are best for impacts forming craters of diameter >10 m [ABSTRACT FROM AUTHOR]

This paper gives a detailed state-of-the art in the research area o f the important function o f Intelligent Manufacturing Systems (IMS) - integrated process planning and scheduling o f manufacturing systems in dynamic environment (DIPPS). Referring to this, description o f the DIPPS problem is given, the criteria on the basis o f which the optimal rescheduling plan are formulated and considered, the adopted assumptions are defined and the mathematical model o f this problem is presented. Furthermore, the disturbances that occur in manufacturing systems are considered in detail: (i) machine breakdown, (ii) arrival of a new job and (iii) job cancellation. Approaches for solving DIPPS problems based on multiagent systems as well as approaches based on algorithms are analyzed. When it comes to approaches based on algorithms, the focus of this paper is on biologically inspired optimization algorithms: evolutionary algorithms, swarm intelligence based algorithms as well as hybrid approaches. The critical analysis within this research area is shown in order to conclude that biologically inspired artificial intelligence techniques have great potential in optimizing the considered IMS function.

Introduction: More than ~1000 newly formed impact features have been detected in images taken by orbiting spacecraft around Mars [1]. In recent months, several of these impacts were also detected seismically by the InSight seismometer [2]. Detailed characterization of the observed impact features [3, 4] has been used to calibrate a model of atmospheric disruption of meteoroids on Mars [5]. This paves the way for relating observed impact features to the properties of the impacting meteoroids. Here we use a Markov-Chain Monte Carlo (MCMC) approach to determine the statistical distribution of impactor parameters that are most likely to have formed recent impact craters and crater clusters observed on Mars that were also detected seismically. Our results inform interpretation of seismic wave signals generated by these impacts [2]. Methods: We simulate the formation of specific craters and clusters on Mars using an implementation of the Separate Fragments Model [SFM; 6, 7], calibrated by comparison with observed craters and clusters on Mars [5]. Crater sizes are predicted from fragment properties at the ground using p-group crater scaling relationships [8]. A MCMC approach is used to generate a statistical distribution of impact scenarios consistent with the observed feature. Given an observed crater or cluster of craters, we determine its characteristics B (e.g., size and number of craters). Using the SFM, together with knowledge about the variability of cluster characteristics, we compute the likelihood p(B|A) that an impact with parameters A (mass, velocity, etc.), produces a crater or cluster with the same characteristics B as the observed one. p(A) expresses our prior knowledge of impactor parameter probability. Then, with Bayes' theorem p(A|B) ? p(A)p(B|A), we can infer the likelihood of impact parameters A given the observations B. We employed the Metropolis-Hastings MCMC algorithm with Metropolis sampling, which assumes that there is no correlation between impactor parameters. Prior distributions of impactor mass [9], angle [10], velocity [11] and strength [5] were based on previous work. Impactor density and ablation parameter were held constant at representative values for stoney meteorites. We defined the likelihood p(B|A) to be the product of likelihoods for four cluster characteristics: effective diameter, number of craters, median separation distance between craters and the aspect ratio of the best-fit ellipse encompassing the craters. We assumed that all characteristics are log-normally distributed with the standard deviations based on observed cluster characteristics [4]. Because MCMC algorithms reach the desired distribution asymptotically, the first n samples were discarded. The distribution of remaining accepted samples defines the impactor parameters of maximum likelihood. Results: Impactor parameter likelihood distributions were determined for four impacts (two single craters and two clusters). One cluster-forming impact provides a particularly useful test of the approach as its highly elongated distribution of craters implies a shallow trajectory angle. The inferred trajectory is consistent with the interpreted ray paths of acoustic phases in the seismogram of the associated seismic event that were generated by the meteoroid's flight through the atmosphere [2]. The most likely pre-entry impactor mass informs comparison of the impact flux rate at the top of the atmosphere on Earth and Mars [5, 9]. The most likely impactor momentum at the ground provides a test of empirical relationships between seismic moment and impactor momentum [e.g., 12]. Acknowledgments: GSC and NW were funded by UK Space Agency grants ST/T002026/1 and ST/S001514/1. IJD was funded by NASA award 80NSSC20K0789. TN, KM and EKS were funded by the Australian Research Council (DE180100584, DP180100661 and DP200102073). [ABSTRACT FROM AUTHOR]

Introduction: The geological record of the formation and differentiation of our planet has been destroyed by its subsequent evolution, but extremely rare clues may be obtained from other terrestrial planets. Mars provides a unique and accessible example of an early evolutionary path corresponding to that, inaccessible, of our own world. We can investigate it with spacecraft, and samples are available for in-depth analysis on Earth in the form of martian meteorites. So far, the only available martian samples that appear to have recorded the early conditions and the evolution of the planet until the present time are Northwest Africa (NWA) 7034 and its paired stones, nicknamed "Black Beauty". This regolith breccia has been ejected a few million years ago by the formation of a large impact crater, and contains the oldest martian igneous material ever dated: ~4.5 Ga old [1-4]. However, its source and geological context have so far remained unknown. and with it, a region where the earliest geological records of the planet [1-4] are exposed on the surface. Knowing this source region would provide insights into early Mars geological history and crustal extraction [1-4]. This source region may therefore become a high-priority target for detailed orbital analyses and in-situ exploration [5]. Constraints on the meteorite launch site: Following a hypervelocity impact, ejecta materials moving faster than the escape velocity (5 km/s) may get through the martian atmosphere and continue their course into interplanetary space to become martian meteorites [6]. Slower debris fall back on the surface in a radial pattern or ray around the primary crater, forming secondary craters. The presence of 100 meter-size secondaries attests to the freshness of their associated primary craters [7]. Using the size and spatial distribution of more than 90 million impact craters >50 m (both primaries and secondaries) detected using a Crater Detection Algorithm (CDA) [7-8] on the whole surface of Mars from the global Context Camera (CTX) mosaic [9], a previous work [7] identified ray systems of secondary craters <150 m associated with 19 large primary craters, potential source of the ejection of martian meteorites. Here we compare the abundance of K and Th [10-11] as well as the magnetic field intensity and the magnetization of the surface of Mars derived from orbital measurements [12] at the immediate vicinity of each crater candidate with those of the breccia. We also compare the geological context of each of the crater candidates with the chronology and the lithology of the meteorite [e.g. 1-3, 13-14]. The ejection site for Black Beauty: Among the 19 crater candidates investigated, we found that only one match with the characteristics of the meteorite: a 10 km crater located in the north-east of the Terra Cimeria - Sirenum (TCTS) region, between Hesperia Planum and the Tharsis bulge. Our work suggests that clasts contained in the regolith breccia are representative of the TCTS province, making this region a relic of the early crustal processes on Mars [e.g. 15], and thus, a region of high interest for future missions. Details on the identification of the crater source of this unique meteorite, as well a its geological context and broader implications for early crustal processes on Mars will be presented at the conference. [ABSTRACT FROM AUTHOR]

Abstract: Using the light gas gun at the Open University’s Hypervelocity Impact facility, a series of impact experiments exploring impacts into water ice and gypsum have been performed. Fragmentation of solid ejecta was recorded using two different methods, analysed and compared with the total ejecta. Preliminary results show that the size distribution of the ejecta fragments from water ice is very similar to those from gypsum. These results also represent a step towards a better understanding of ejecta fragmentation in geological materials, including icy surfaces in the Solar System. [Copyright &y& Elsevier]