PLEASE NOTE:
*
ROYAL ASTRONOMICAL SOCIETY
PRESS INFORMATION NOTE
Date: 8 December 1998
Ref. PN 98/28
Issued by:
Peter Bond,
RAS Space Science Advisor.
10 Harrier Close,
Cranleigh,
Surrey, GU6 7BS,
United Kingdom.
Phone: +44 (0)1483-268672
Fax: +44 (0)1483-274047
E-mail: 100604.1111@compuserve.com
DEFINING THE EFFECTS OF SUB-CRITICAL COSMIC IMPACTS ON THE EARTH.
DISCUSSION MEETING AT GEOLOGICAL SOCIETY, BURLINGTON HOUSE,
PICCADILLY,
LONDON W1.
"Sub-Critical Scale Impactors" i.e. near-Earth
asteroids and small
comets, will be the subject of a one-day discussion meeting in
London
on Friday December 11th as part of the Royal Astronomical
Society's
regular monthly programme. Media representatives are cordially
invited
to attend as observers.
The symposium brings together leading UK and French scientists to
discuss the probability of such impacts, the different
environmental
and biological effects they create, and the known impact record
on
Earth.
Impacts have defined the evolution of life throughout the Earth’s
history. At least one significant impact-related event has
occurred in
recent history, the explosion of a comet or asteroid over
Tunguska in
Siberia in 1908. There is no reason why a similar event could not
eventually happen, through an accident of geometry and
time, over
London, Paris or New York.
Whilst a large impact could result in global devastation, the
likelihood of Earth being struck by objects 10 km (6 miles)
across is
extremely remote - perhaps once every 50 million to 100 million
years.
On the other hand, much smaller, Tunguska-like events are
expected to
occur, on average, once every 50-100 years. Although these
sub-critical
impacts do not threaten large-scale extinctions, they are still
likely
to have significant effects on the surrounding environment.
For
example, it is now realised that the environmental effects of a
SCI
vary greatly depending on where the impactor lands.
The speakers at the symposium will discuss the hazard presented
by
these sub-critical impacts (SCIs) and the likely consequences for
Earth’s climate and biosphere. In recent years this subject
has
developed into an important scientific discipline. The
significance of
comets and asteroids in the formation of the Earth, as well as
the
origin and evolution of life, has been increasingly recognised.
According to one theory, most of Earth’s water was delivered
by comets
and flavoured with the building blocks of life brought by
both
asteroids and comets. However, only in the past few years has the
reality and magnitude of the hazard presented by these objects
been
appreciated as evidence has been accumulated supporting the
theory that
a major impact 65 million years ago ended the rule of the
dinosaurs and
paved the away for the emergence of the mammals.
The meeting has been organised by Richard Taylor, David Hughes,
and
Julian Hiscox, under the auspices of the Royal Astronomical
Society and
the British Interplanetary Society (BIS).
An outline of the programme, and contact details for the
organisers is
given below. For further information on individual contributions,
please contact the meeting organisers.
###
RAS/BIS/GS Joint Discussion meeting at the
GEOLOGICAL SOCIETY LECTURE THEATRE
BURLINGTON HOUSE, PICCADILLY, LONDON W1
FRIDAY 11th DECEMBER 1998
Organisers:
Dr. David Hughes, Dept. of Physics, University of Sheffield,
Sheffield
S3 7RH. Tel: +44 (0)114-222-4288. Fax: +44 (0)114-272-8079
E-mail: d.hughes@sheffield.ac.uk
Dr. Julian Hiscox, IAH Compton Laboratory, Compton, Berkshire
RG20 7NN.
Tel: +44 (0)1635-577274. Fax: +44 (0)1635-577263
E-mail: julian.hiscox@bbsrc.ac.uk
Richard Taylor, Probability Research Group, 4 Abingdon Road,
Norbury,
London SW16 5QP. Tel: +44 (0)181-764-2774.
E-mail: richard.taylor3@virgin.net
PROGRAMME AND SPEAKERS.
FIRST SESSION - The Nature and Frequency of Small Impactors.
Chairman: Dr. Julian Hiscox.
10:30 Dr. Matthew Genge (Natural History Museum)
The implications of meteorites and micrometeorites for the nature
of
sub-critical impactors.
10:45 Mr. Jonathan Tate (Spaceguard UK)
The frequency of SCI impactors with diameters in the 0.1 to 1km
range
11:00 Dr. David Hughes (University of Sheffield)
The cratering rate of planet Earth.
SECOND SESSION - Geological and Climatic Evidence.
Chairman: Dr. David Hughes.
11:15 Professor Ian Smalley & Mr. Ian Jefferson
(Nottingham Trent
University)
Sedimentological consequences of sub-critical impacts in sandy
deserts
or loess regions.
11:30 Professor Nicholas Fedoroff - (Institut
National Agronomique,
France)
Registration of abrupt events in loess: around 67000 yrs BP
(before
present)transition reveals unusual attributes.
11:50 Professor Claudio Vita-Finzi (University
College, London)
Seasonal enhancement and seismic triggering by impacts
12:05 Professor Chandra Wickramasinghe, M.K. Wallis
and D.H. Wallis
(University of Wales, College of Cardiff)
Climatic Switches Induced by Stratospheric Dust Loading.
12:20 Discussion.
12:35 LUNCH
THIRD SESSION - Evidence for Evolutionary and Recent
Environmental
Effects. Chairman: Professor Ian Smalley.
1:35 Dr. Norman MacLeod (Natural History
Museum, London)
Identifying instances of past environmental change and their
causal
mechanisms.
1:55 Dr. Julian Hiscox (IAH Compton Laboratory)
Possible biochemical/bioevolutionary consequences of SCI events.
2:10 Dr. Marie-Agnes Courty (National Centre
for Scientific
Research,
France)
Recognition of instantaneous soil collapse at 3950 BP (before
present)
throughout the Middle East in response to a blast wave, wild
fires and
heavy rains caused by an extra-terrestrial event.
2:30 Dr. Benny Peiser (Liverpool John Moores
University)
Current research on Holocene impact events and its implications
for
impact rate calculations.
2:50 Dr. Victor Clube (Oxford University and
Armagh Observatory)
Sub-cometary and sub-asteroidal impacts: historical
considerations.
FOURTH SESSION - Wider Implications of Impacts.
Chairman: Professor Claudio Vita-Finzi.
3:10 Professor Neville Price (formerly
University College, London)
Evidence for impact as a significant and periodic geological
process.
3:25 Close.