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Papers by Mario Di Martino

Meteoritics & Planetary Science, 2021

The Cavezzo meteorite, which fell on January 1, 2020, is the first meteorite detected and recover... more The Cavezzo meteorite, which fell on January 1, 2020, is the first meteorite detected and recovered by the Italian PRISMA Fireball Network. Two specimens, weighing 3.12 g (specimen 1) and 52.19 g (specimen 2), were collected 3 days after the bolide was observed, thanks to an effective media campaign that encouraged the involvement of local people. The two specimens of this meteorite have not only completely different lithological characteristics but also a different geochemistry and oxygen isotopic composition as well. Specimen 1 is anomalous both for the textural–structural features, varying seamlessly from chondritic to “achondritic,” and a very unusual modal mineralogy—such as the relatively high amount of olivine (63.1 vol%), plagioclase (18.2 vol%), high‐Ca pyroxene (10.3 vol%), and chlorapatite (2.1 vol%); and the unusually low content of low‐Ca pyroxene (5.8 vol%), metal (0.1 vol%), and troilite (much lesser than 0.1 vol%)—although the compositional values for olivine (Fa 24....

Encyclopedic Atlas of Terrestrial Impact Craters, 2019

Near-Earth asteroid 1998 WT24 will have a very close approach to Earth at a distance of 0.012 AU ... more Near-Earth asteroid 1998 WT24 will have a very close approach to Earth at a distance of 0.012 AU on 16 December 2001. We are planning the radar observation of this asteroid at 6 cm wavelength using a bistatic system: Evpatoria, Crimea, 70-m dish and power transmitter → Medicina, near Bologna, Italy, 32-m dish and two-channel receiver. The essence of this proposal is to use the two antennas also to carry out the first attempt of centimetric space debris (SD) radar detection in geostationary ring, on October-November 2001, the scheduled period for the Evpatoria → Medicina system testing. 1. GEO SCAN EXPERIMENT Unlike the LEO space debris, the GEO region cannot be scanned to take advantage of the Earth’s rotation. Moreover, the GEO region represents a relatively narrow layer with more definite coordinates, where the dominant orbital period of GEO objects is near 24 hour, so in beam park case the event frequency will be very small. Therefore, in order to detect by radar any uncatalogued...

Astronomy and Astrophysics

Nowadays radars provide a powerful source of information, often complementary to that obtained by... more Nowadays radars provide a powerful source of information, often complementary to that obtained by other observational techniques, about physical and dynamical properties of asteroids and space debris. A number of large Italian antennas, as radiotelescopes and telecommunication facilities, could be used as elements of a radar network for the study of Near Earth Objects (NEOs) and space debris orbital environment.

Proceedings of the International Astronomical Union, 2006

Near-Earth objects (NEOs) are objects of a special interest from the point of view not only of co... more Near-Earth objects (NEOs) are objects of a special interest from the point of view not only of cosmogonic problems of the Solar system, but of the applied problems as well (the problem of asteroid hazard, NEOs as the potential sources of raw materials, etc.). They are much smaller in sizes than main-belt asteroids (MBAs), very irregular in shape and covered with a great number of craters of different sizes. Most of NEOs are covered by regolith of low thermal inertia and different thickness. Objects with complex non-principal axis rotation (tumbling bodies) and with super-fast rotational periods have been detected among them. The new data, based on photometric and radar observations, evidence that about 15-20 %; of NEOs could be binary systems. Most of the classified NEOs fragments of differentiated assemblages of S-and Q-types. Analysis of physical properties of NEOs clearly indicates that the asteroid main-belt is the principal source of their origin and only about 10 % of NEOs hav...

ABSTRACT Impact craters up to a few hundreds of meters in diameter are common structures of solid... more ABSTRACT Impact craters up to a few hundreds of meters in diameter are common structures of solid surfaces of planetary bodies in the solar system. Statistics predict that impacts producing small craters on Earth occur on decadal to secular time scales (1, 2). However, small craters are rare on Earth because they are rapidly eroded, and the few identified so far [15 &lt;300 m in diameter out of 176 craters up to 300 km in diameter (3)] have lost most of their primary features. We report the detection in southern Egypt of a rayed impact crater 45min diameter (Fig. 1A) on a Cretaceous sandstone target. The ejecta rays highlight the exceptional freshness of the structure. The crater was identified by V. De Michele during a Google Earth survey and named Kamil Crater after nearby Gebel Kamil. A geophysical expedition undertaken [supporting online material (SOM)] in February 2010 revealed that the crater is bowl shaped and has an upraised rim (~3 m above preimpact surface) (figs. S1 and S2) typical of simple craters (4). The true crater floor depth is 16 m and is overlain by ~6-m-thick crater-fill material (fig. S2). Morphometric parameters agree with those predicted by models (5) for a transient crater generated by an iron meteorite 1.3 min diameter (equivalent to 9.1 × 103 kg) impacting at a velocity of 3.5 kms−1, assuming an average meteoroid entry velocity and entry angle of 18 kms−1 and 45°, respectively. Centimeterscale masses of scoriaceous impact melt glass (fig. S3) occur in and close to the crater and indicate local shock pressures &gt;60 GPa (4). We identified 5178 iron meteorite specimens totaling ~1.71 tons in the crater and surrounding area during systematic searches (SOM). They consist of &lt;34-kg shrapnel produced by the explosion of the impactor upon hypervelocity collision with the target (Fig. 1B), except one individual fragment of 83 kg (fig. S4). This evidence indicates that the Kamil Crater was generated by an impactor that landed nearly intact without substantial fragmentation in the atmosphere. The meteorite is classified as an ungrouped Ni-rich ataxite [Ni = 19.8 weight % (wt %), Co = 0.75 wt %, Ga = 49.5 mg g−1, Ge = 121 mg g−1, Ir = 0.39 mg g−1; data following (6); fig. S5]. Magnetic anomaly data show no evidence of buried meteorites larger than some tens of centimeters (fig. S1). On the basis of systematic meteorite searches, the estimated total mass of the impactor is of the order of 5 ×103 to 10 × 103 kg, corresponding to a preatmospheric mass of ~20 ×103 to 40 × 103 kg (2). According to geophysical models (2, 7), iron masses &lt;3 × 106 kg normally fragment upon impact with Earth’s atmosphere, thereby reducing the energy of the impact at Earth’s surface. However, the present statistics, which include the recently discovered Whitecourt Crater (8) and the Kamil Crater, suggest that ~35% of the iron meteorites in the above mass range are not disrupted in the atmosphere.

Astronomy & Astrophysics - ASTRON ASTROPHYS, 1997

Rotationally resolved visible spectroscopy (6000~9500Å) of (7) Iris is presented. Within a few pe... more Rotationally resolved visible spectroscopy (6000~9500Å) of (7) Iris is presented. Within a few percents, no variation in Iris' visible spectrum over a rotational period has been found. These data suggest that the mineralogic properties of Iris' surface are globally homogeneous, although we cannot exclude the presence of some texture and/or albedo variegation as suggested by previous photometric and polarimetric studies available in the literature. From a dynamical point of view, we estimate the ejection velocity required for collisional fragments from this asteroid to be injected into the surrounding chaotic regions. The resulting velocity values are fairly high, but not incompatible with the values suggested by the present knowledge of catastrophic break-up phenomena and by the observational constraints put by asteroid families. Taking into account the close similarity between Iris' spectrum and that of (6) Hebe, a typical S(IV)-type object according with the most mo...

The Astronomical Journal, 2011

Science, 2010

An unusually well-preserved 45-meter-diameter crater provides ground truth for small-scale meteor... more An unusually well-preserved 45-meter-diameter crater provides ground truth for small-scale meteorite impacts on Earth.

ESA …, 2003

The terrestrial cratering record is unique in providing a detailed picture of the history of our ... more The terrestrial cratering record is unique in providing a detailed picture of the history of our Solar System over the last few billion years, as well as its celestial environment. The search for the scars of ancient cosmic impacts is therefore of fundamental importance from ...