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Tumbling Stone

Number 3: 24-04-2001
A scientific publication by SGF and NEODyS.

Risk perception:
NEOs vs Mir

by David Morrison *
Recent "the sky is falling" news stories have dealt with the fall from orbit of the Mir Space Station rather than NEO impacts. The press and public are clearly interested in the risk of falling objects, but sometimes risks are perceived in ways that are quite different from the hazard as calculated numerically. The following is a very rough estimate of risks, in "order of magnitude" terms only. It is intended to be illustrative, but certainly not precise. By risk I mean the chance or probability that any individual will be killed as a result of either a spacecraft atmospheric entry or the impact of a NEO.
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David Morrison * - NASA AMES Research Center

Small objects discovery and recovery
Is the next Tunguska predictable?

by Andrea Milani*
Let me first state clearly that I fully agree with the goal of the Spaceguard Survey, namely discovering the potential impactors with diameter 1 kilometer or larger. The smaller objects are a minor fraction of the impact risk, since each one of them would only be capable of local damage, if any. Indeed the objects smaller than about 50 meters in diameter may not reach the ground...
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Andrea Milani *- Director of NEODyS

The Monthly Monitor...
What is heading our
this month?

Tumbling Laughs

by Ettore Perozzi (full version)

Focus on comets: Lexell (part 2)
Le Verrier's computations and the concept of chaos by Giovanni Valsecchi
Reading an orbit: the orbital elements
by Livia Giacomini

Asteroids' shapes
Two more binary asteroids: Sylvia and TNO 1998 WW_31
by Germano D'Abramo and Andrea Boattini
A result of collisions
by Germano D'Abramo

People looking for NEOs...
The Spacewatch Project by Robert McMillan


Surveys: Rendez vous, announcements... Images of the day: asteroid Toutatis, comet LINEAR,crater Clearwater...
Dictionary of this number: words you have to know to understand the topics of this number Links of this number: web resources you can visit to learn more about the topics of this number


TS general dictionary TS general links Index of past Issues of TS Past Tumbling Laughs   Italian Version


The Spaceguard Foundation (SGF) is a private, non profit scientific organization aimed at supporting and co-ordinating NEO researches in the world
The NEO Dynamic Site (NEODyS) is a service offered by the University of Pisa (Italy). It provides catalogues, computation of orbits, and projection of the behavior of NEOs in the future, in order to identify possible impacts in advance.

Images of this page: courtesy of NASA

Editor: Nanni Riccobono
Assistant Editor: Livia Giacomini
Web design: Livia Giacomini
Collaborators of this issue: Andrea Boattini - Germano D'Abramo - Robert McMillan - Andrea Milani - David Morrison - Ettore Perozzi - Giovanni Valsecchi