Astrophysics

From: [email protected]
To: [email protected]
Date: 28. August 1997 18:29
Subject: New Publications

Wave of New Publications Indicates Scientific Revolution is Under Way

You can be certain to be in the midst of a scientific revolution once you realize that it is no longer possible to keep up with the stream of new publications on the new paradigm - or when rash scholars start to dream about a "unified model". This exactly is now the case with the theory of cosmic catastrophism and the problem of assessing the according impact hazard.

Four of the earliest contributors to this major intellectual revolution and the main representatives of the British School of Neo-Catastrophism, who usually advance in tandems, have now joined forces and have published the main findings of more than 20 years of astronomical and neo-catastrophist research as a quartet. Whilst this intellectual transformation is currently sweeping through research centers in Britain and the USA, it is no longer restricted to the British or American academic world. What is more, even historical catastrophism seems to have become part of the standard paradigm, as can be seen by Dr Izokh's research on the catastrophe at the Pleistocene-Holocene boundary. The attached papers, many of which come from the current issue of the Annals of the New York Academy of Sciences (Vol.822, 1997), document a wide variety of research topics and will certainly cater for the diverse interest of list members.

Benny J Peiser

P.S. Fred Hoyle and Chandra Wickramasinghe have also published a new book: Life on Mars? (London, 1997).

S.V.M. Clube, F. Hoyle, W.M. Napier & N.C.Wickramasinghe: Giant Comets, Evolution and Civilization. In: Astrophysics and Space Science, 1996, Vol.245, No.1, pp.43-60

Giant comets thrown into short-period, Earth-crossing orbits are a major source of mass flux into the inner planetary system. Their disintegration products may give rise to climatic cycles, ice epochs, periodic mass extinctions and other global disturbances. Comets greater than or similar to 100 kilometers in diameter, in chaotic orbits beyond Jupiter, probably constitute a more substantial current hazard than stray asteroids.

E.P Izokh: Australo-Asian tektites and a global disaster of about 10,000 years BP, caused by collision of the Earth with a comet (in Russian). In: Geologiya I Geofizika, 1997, Vol.38, No.3, pp.628-660

About 10,000 years ago, at the Pleistocene-Holocene border, some important events occurred: the glaciation stopped abruptly; the sea level elevated, and quick (for 20-50 years) climatic and ecological changes took place, leading to the extinction of the so-called mammoth fauna and exerting a direct effect on the mankind's evolution and appearance of civilizations. These and other disastrous events providing a distinct boundary between the Pleistocene and the Holocene received no relevant explanation in the Quaternary geology until now.

It is shown in the paper that the disaster under study was caused by the collision of the Earth with an eruptive comet, brought various volcanic tektite glasses from a remote planetary body. This extra-terrestrial source of tektites is proven by the well-known but not adopted paradox of tektite age, i.e. a difference in hundreds of thousands and millions of years between the radiogenic age of tektites (time of formation) and time of their fall onto the Earth. The volcanic nature of tektites is supported (by analogy with volcanic bombs, lavas, tufflavas, and extrusive formations taking into account extraterrestrial conditions) by their long and many-stage formation, by ordered trends of composition variability inherent only in magmatic differentiation, etc. Relying on a diversity of forms, structure, and composition of tektites, we made an attempt to reconstruct various types of volcanic eruptions. Most likely, the place of volcanic activity was a small or light planetary body of the type of Io, Callisto, Triton, etc. with ice crust, acid upper and relatively basic lower mantle, with small gravitation, without atmosphere, etc., situated somewhere on the periphery of the Solar System.

It is supposed that a very powerful explosion ejected into space some part of a stone-ice volcanic construction, i.e. eruptive comet, according to S. K. Ysekhsvyatsky. The comet hypothesis permits explanation of main features of distribution of tektites over the Earth's surface, various forms of their connection with impact craters as well as many other features of tektites. The common Earth impact hypothesis for tektite origin is not able to explain all these facts; it is deeply perplexed and is severely criticized in this paper. The 'mammoth' disaster is comparable with the so-called 'dinosaur' catastrophe at the Cretaceous-Paleogene border, which also was accompanied with impact craters and fall of tektites. An analogy is traced with the collision of the Shoemaker-Levi comet with the Jupiter. Thus, a special class of eruptive comets, cosmic bodies the most dangerous for the Earth, which are beyond attention of investigators, is discussed for the first time.

D. K. Yeomans: Comet and Asteroid Ephemerides for Spacecraft Encounters. In: Celestial Mechanics & Dynamical Astronomy, 1997, Vol.66, No.1, pp.1-12

To a significant degree, the success of spacecraft missions to comets and asteroids depends upon the accuracy of the target body ephemerides. In turn, accurate ephemerides depend upon the quality of the astrometric data set used in determining the object's orbit and the accuracy with which the target body's motion can be modelled. Using error analyses studies of the target bodies for the NEAR, Muses-C, Clementine 2, Stardust, and Rosetta missions, conclusions are drawn as to how to minimize target body position uncertainties at the times of encounter. In general, these uncertainties will be minimized when the object has a good number of optical observations spread over several orbital periods. If a target body lacks a lengthy data interval, its ephemeris uncertainties can be dramatically reduced with the use of radar Doppler and delay data taken when the body is relatively close to the Earth. The combination of radar and optical angle data taken at close Earth distances just before a spacecraft encounter can result in surprisingly small target body ephemeris uncertainties.