PLEASE NOTE:
*
Date sent: Wed, 18 Jun 1997 10:15:10 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: ORBIT ALTERATION OF NEOs
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
ALTERNATIVE SYSTEMS FOR ORBIT ALTERNATIONS OF
NEAR-EARTH ASTEROIDS AND COMETS
Many members of this network who are engaged in NEO research and
in
developing detection/deflection programmes will be interested in
the research of Dr Christian Gritzner, a new member of the
CC-net.
Dr Gritzner's special interest is the field of NEO collisons with
Earth and how to prevent them. He is an engineer of space
technology
at the German Aerospace Research Establishment DLR - Institute of
Planetary Exploration in Berlin and has written his Thesis on
"Analysis of alternative systems for orbit alteration of
near-Earth
asteroids and comets." This analysis will soon be available
in an
English translation. For further details, please contact Dr
Gritzner <Christian.Gritzner@dlr.de> directly.
Benny J Peiser
-----------------------------------------------------------------------
Christian Gritzner
Thesis at Technische Universitaet Berlin, Germany, August 12th
1996: "Analysis of alternative systems for orbit alteration
of
near-Earth asteroids and comets" original written in German,
translated by ESA, will be soon available as ESA technical
translation: ESA-TT-1349)
Abstract:
The present study examines various systems for altering the orbit
of near-Earth asteroids and comets (ECOs - Earth crossing
objects).
The aim of such orbit alteration is to prevent a collision
between
these bodies and the Earth, since, depending on the size of the
ECO, this can have catastrophic consequences for the entire
terrestrial biosphere. Whereas small ECOs can be deflected at
relatively low cost given a sufficiently long time, ECOs with
diameters of several kilometres present a serious problem. This
also holds in particular for long-period comets. In addition to a
description of possible deflection systems in conjunction with
the
creation of mass models, the systems are analysed as to their
effectiveness and compared with one another. The upper limit of
the
deflection possibilities is determined by the maximum available
payload of the launch systems. A simple system design of a
typical
mission is also drawn up for four deflection systems regarded as
suitable (of which two are non-nuclear).
*
Date sent: Wed, 18 Jun 1997 09:54:20 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: MAMMOTH EXTINCTION AROUND 2000 BC?
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
EXTINCTION OF THE MAMMOTH AROUND 2000 BC?
It is generally believed that the sudden extinction of the
Mammoth
(and some 40 other species) coincided with a major climate
catastrophe at the Pleistocene/Holocene boundary (also called the
Younger Dryas boundary) at around 10,000 BP. Russian scholars,
however, claim to have discovered evidence for a "mammoth
refugium"
during the Holocene up until ~2000 BC. If these findings are
fairly
correct, the final blow to the mammoth might have come from the
abrupt climate change at the start of the Subboreal boundary
around
2300 BC.
Benny J Peiser
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S.L. Vartanyan, K.A. Arslanov, T.V. Tertychnaya, S.B. Chernov:
RADIOCARBON DATING EVIDENCE FOR MAMMOTHS ON WRANGEL ISLAND,
ARCTIC-OCEAN, UNTIL 2000-BC. In: RADIOCARBON, 1995, Vol.37, No.1,
pp.1-6
Radiocarbon dating results of mammoth tusks, teeth and bones
collected on Wrangel Island between 1989 and 1991 reveal a unique
mammoth refugium during the Holocene. We used an improved
chemical
procedure to obtain and purify collagen from bone. Benzene
synthesized from the samples was measured using a liquid
scintillation counter. The validity of our data has been
confirmed by the results of our measurements on two
international control sample series (IAEA and TIRI) and by
parallel measurements of Wrangel Island mammoth remains at
other laboratories.