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Akos Baszo: The role of the Moon for impacts on the Earth

Mag. Akos Bazso

The role of the Moon for impacts on the Earth

This project considers the role of Earth's Moon as a crucial factor for the probability and frequency of impacts of hazardous asteroids on the Earth. As the so called Near Earth Asteroids (NEAs) might have frequent close encounters with Earth, it is evidently important to know their impact probabilities. We have to also include the gravitational attraction of the Moon when dealing with asteroid orbits, since it can considerably influence these highly chaotic trajectories. Our goal is to investigate if the Moon rather deflects incoming NEAs, and thus helps to "protect" the Earth, or on the contrary it focuses them posing additional danger on the Earth.

As a first step we consider a simple four body model Sun-Earth-Moon-asteroid to determine the most important parameters, like encounter velocity, inclination of orbit, minimum orbital distance, etc. In a next step we plan to investigate a number of real NEAs as well as main belt asteroids. A fundamental shortcoming of all models is the very high value of the so called Lyapunov characteristic exponent, a sort of chaos indicator, meaning that we can only describe the asteroid's orbits statistically, but not individually for longer times. After a close encounter the asteroid's trajectory can change substantially, in such a way that we have to deal with a large number of test bodies to get reliable statistics.

Mattia Galiazzo MSc

Dynamics of asteroids

I am working on dynamics of asteroids, my aim is to see dynamically the origin of the asteroids (and the Hazards) which may hit the Earth or had hit it. To do this I perform numerical integrations with particular programs, i.e. the Lie-program, which computes the orbits of these objects with the help of the Lie-Series, a mathematical method to fit the real orbit of these kind of objects and also other bigger objects such as the planets with the Sun.

Working on this I will try to improve this program to fit better the reality, this program considers only gravitational interactions. In particular I consider objects of the Main Belt and something farer over the Centaurs, KBOs and maybe till the Oort Cloud. I could introduce some photometry in these studies, considering some peculiar interactions which I am going to illustrate after finishing some works during these three years. Some other options are going on, but they will come with the development of the studies, so wait for updatings...as it is usual to say WORK IN PROGRESS :)

Matthew Huber MSc

Ejecta from large impacts

The largest two impacts in the history of the Earth with remnants of their structure preserved, the Vredefort structure and the Sudbury structure, have been extensively studied for their economic usefulness.  However, the nature of the impacts themselves has not been well established.  There are a number of open questions, from the type and size of impactor to the nature of the effects of the impact.  The key to finding the answers to these questions is to study ejecta from the impacts.  Until recently, the location of such ejecta from these impacts was not known.  These newly discovered sites (Chadwick et al, 2001; Addison et al, 2005) have not yet been thoroughly examined for their geochemical potential to solve these mysteries.

This project will geochemically analyze distal ejecta deposits from the 2.020 Ga. Vredefort impact, located in southern Greenland, and intermediate-distal ejecta deposits from the 1.850 Ga. Sudbury impact, located in Michigan, Minnesota, and Ontario.  The samples from each of these impacts will be examined petrographically and geochemically by methods of scanning electron microscope, electron microprobe, cathodoluminescence, X-ray diffraction, neutron activation analysis, mass spectrometry for isotopic analysis, and laser ablation mass spectrometry.

Anna Losiak MSc

Surface material component in the suevitic breccia from Bosumtwi crater

According to the conventional understanding of the on-land impact process, almost entire surface material is removed from the crater in form of ejecta (mostly distal) or vaporized/melted (e.g. Melosh, 1989). If the conditions of the impact are appropriate (e.g. high velocity of bolid – above 20 km/s, impact angle between 30 and 50 degrees and impactor larger than ~1km in diameter (Artemieva, 2000)), it is know that the outermost layer of targets rocks is transformed into tektites.  The formation of tektites out of surfacial layer of sediments, has been well established using the 10Be content (e.g. Pal et al. 1982, Ma et al. 2004, Serefiddin et al. 2007) as well as using chemical comparison to the possible source-surface material (e.g. Engelhardt et al. 2005, Son and Koeberl, 2005). However, singular data (e.g. Reimold et al. 1992) suggest that part of the surface material can be also incorporated in the in-crater suevite.

The aim of this research is to reveal if part of the surface material became incorporated in the suevitic breccia located within the Bosumtwi crater. Bosumtwi crater is 1.07 Ma old, 10.5 km in diameter and located inGhana. It is a source crater for the Ivory Coast tektite field.

The surfacial component within the in-crater suevite breccia will be revealed using 10Be measurements. 10Be is a cosmogenic radionuclide produced by spallation reactions from O, N and to lesser extend Mg, Al, Si and Ca (e.g. Dunai, 2010, Mchargue and Damon. 1991). The concentration of this isotope is the highest at the Earth surface and decreases quickly with depth. Isotope analysis will be accompanied by a ISale hydrocode model of Bosumtwi crater (Collins et al. 2010).

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