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(meteorobs) Excerpts from "CCNet DIGEST, 22 June 1999"
Some fascinating reports in this issue, about some new professional
projects to DIRECTLY detect meteoroids and "small debris" in earth's
space-environment! Also some Leonid satellite-threat items... Enjoy!
Lew Gramer
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet DIGEST, 22 June 1999
Date: Tue, 22 Jun 1999 11:44:38 -0400 (EDT)
CCNet DIGEST, 22 June 1999
--------------------------
[...]
(9) SPACE DEBRIS MEASUREMENTS IN JAPAN
T. Takano et al., INST SPACE & ASTRONAUT SCI
(10) LIBRIS: DETECTING SMALL AND MEDIUM-SIZED SPACE DEBRIS
J.C. Worms et al., EUROPEAN SPACE SCI COMM
(11) DETECTING METEOROIDS AND SMALL-SIZED SPACE DEBRIS
N. McBride et al., UNIVERSITY OF KENT
(12) SECONDARY IMPACT GENERATED PARTICLES
J.C. Mandeville et al., OFF NATL ETUD & RECH AEROSP
(13) HYPERVELOCITY IMPACTS IN LOW EARTH ORIBIT: COSMIC DUST VS SPACE DEBRIS
G.A. Graham et al., OPEN UNIVERSITY
============================
(9) SPACE DEBRIS MEASUREMENTS IN JAPAN
T. Takano*), T. Tajima, T. Satoh, Y. Arimoto: Space debris measurements
in Japan. ADVANCES IN SPACE RESEARCH, 1999, Vol.23, No.1, pp.55-65
*) INST SPACE & ASTRONAUT SCI,3-1-1 YOSHINO DAI,SAGAMIHARA,KANAGAWA
229851,JAPAN
This paper describes the present status of space debris measurements in
Japan, focusing on the recent achievements of existing systems and the
design of new systems. Issues concerning the Leonids meteoroid storm in
November 1998/99 will be also discussed. (C) 1999 COSPAR. Published by
Elsevier Science Ltd.
=============
(10) LIBRIS: DETECTING SMALL AND MEDIUM-SIZED SPACE DEBRIS
J.C. Worms*), O. Girard, A. Hauchecorne, K. Muinonen: LIBRIS: An
orbital imaging lidar for the detection of small to medium-sized debris
in low-Earth orbit. ADVANCES IN SPACE RESEARCH, 1999, Vol.23, No.1,
pp.67-70
*) EUROPEAN SPACE SCI COMM,PARC INNOVAT,BLVD SEBASTIEN BRANDT,F-
67400 ILLKIRCH GRAFFENS,FRANCE
LIBRIS aims at detecting and locating orbital debris in the 0.1 mm - 1
cm size range, retrieving such parameters as distance at the time of
detection, trajectory parameters (incidence and velocity) and
estimated size. It makes use of backscattered lidar radiation and will
provide long-term information to improve cataloging of debris in
law-Earth orbit (LEO) and thus refine existing evolutionary debris
models. Knowledge about interplanetary dust particles (IDPs) will be
gained by discriminating between natural (micro-meteoroids) and
man-made debris in LEO by means of the retrieved orbital parameters.
(C) 1999 COSPAR. Published by Elsevier Science Ltd.
===============
(11) DETECTING METEOROIDS AND SMALL-SIZED SPACE DEBRIS
N. McBride*), S.F. Green, J.A.M. McDonnell: Meteoroids and small sized
debris in Low Earth Orbit and at 1 au: Results of recent modelling.
ADVANCES IN SPACE RESEARCH, 1999, Vol.23, No.1, pp.73-82
*) UNIVERSITY OF KENT,UNIT SPACE SCI & ASTROPHYS,SCH PHYS
SCI,CANTERBURY CT2 7NR,KENT,ENGLAND
We present consolidated flux data from the Long Duration Exposure
Facility (LDEF) and develop an isotropic meteoroid model applicable to
predicting damage to the LDEF surfaces. The model is shown to work
well, and is used to derive the resultant component of orbital debris
incident on the LDEF east (ram) and west (wake) faces. Overall, orbital
debris dominates the measured fluxes at small sizes (aluminium
penetration depth F-max < 30 mu m) whereas meteoroids dominate above
this size (see also McDonnell et al., 1997). The east and west face
comparison shows that at least 2 distinct populations of debris exist
with different size distributions. Analysis of data from the European
Retrievable Carrier (EuReCa) shows the interplanetary meteoroid flux to
he biased towards the Earth-apex direction (in the measured size
regime). An enhanced meteoroid model is derived which is consistent
with both EuReCa and LDEF data, and which does not affect the debris
fluxes derived from LDEF data. (C) 1999 COSPAR. Published by Elsevier
Science Ltd.
=============
(12) SECONDARY IMPACT GENERATED PARTICLES
J.C. Mandeville, M. Rival, F. Alby: Secondary impact generated
particles: Implications for the orbital debris population. ADVANCES IN
SPACE RESEARCH, 1999, Vol.23, No.1, pp.89-94
*) OFF NATL ETUD & RECH AEROSP,DESP,2 AV E BELIN,F-31400
TOULOUSE,FRANCE
Every time a debris or a meteoroid hits a part of a satellite in orbit,
a great amount of secondary particles is ejected in the neighborhood of
the impact site. This phenomenon is important for brittle materials,
such as used for solar generators. The secondary particles that do not
impact other parts of the spacecraft are added to the primary debris
population and increase the small debris flux. We present an ejecta
production model that gives the size and the velocity distribution of
ejected particles as a function of primary impact parameters. We derive
the parameters of all ejecta created during one orbital revolution of a
satellite. An orbital evolution program is used to extrapolate the
secondary debris position at later times. Preliminary results show that
spall fragments ejected at low velocities remain in the vicinity of the
parent satellite. The:, ejecta trajectories are similar and their
inclination is very close to those of the parent satellite. Their
orbital evolution depends mainly on the size of the debris and on the
altitude of the parent body: the smallest particles in low earth orbit
quickly reenter the earth atmosphere, while the largest spalls have a
very slow decay. The antagonistic action of debris production and
debris decay by drag leads to an equilibrium for particles within a
given size range. Quantitative results on densities and fluxes compared
to the primary debris population are presented for the peculiar case of
heliosynchronous orbits. (C) 1999 COSPAR. Published by Elsevier Science
Ltd.
=========
(13) HYPERVELOCITY IMPACTS IN LOW EARTH ORIBIT: COSMIC DUST VS SPACE DEBRIS
G.A. Graham*), A.T. Kearsley, M.M. Grady, I.P. Wright,
A.D. Griffiths, J.A.M. McDonnell: Hypervelocity impacts in low Earth
orbit: Cosmic dust versus space debris. ADVANCES IN SPACE RESEARCH,
1999, Vol.23, No.1, pp.95-100
*) OPEN UNIVERSITY,PSRI,MILTON KEYNES MK7 6AA,BUCKS,ENGLAND
The understanding of the micron-sized populations of natural
micrometeoroids and artificial space debris in low Earth orbit
has benefited considerably from the post-flight investigations of
retrieved surfaces from spacecraft, such as the Long Duration Exposure
Facility. The returned solar array from the Hubble Space Telescope has
added to this repository and has offered a further opportunity to
document these particles. 25 individual solar cells were specially
selected on the basis that they contained impact craters (diameter
100-1000 mu m) which had the most potential to retain impactor residue
chemistry. The solar cells were subject to a detailed investigation
using analytical scanning electron microscopy which identified 29
impact craters, the analysis of which identified 3 residues as
artificial in origin, 6 unclassified and 20 as natural in origin. The
limited number of unclassified residues identified indicates that the
methods of analysis employed in this investigation are a significant
step forward for such studies and, if employed on a greater number of
samples, will improve the calculations of the time-integrated flux
rates for micrometeoroids and space debris in the low Earth orbit
environment. Notwithstanding the small sample set examined, the
observed chemical classification of the impact residues in terms of
micrometeoroid to space debris (in the particle size range 8-80 mu m)
corresponds well to the flux model that predicts the dominance of
natural particles. (C) 1999 COSPAR. Published by Elsevier Science Ltd.
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