PLEASE NOTE:
*
CAMBRIDGE-CONFERENCE DIGEST, 31 March 1998
------------------------------------------
(1) HOW TO DO A BETTER JOB NEXT TIME
Richard Binzel <rpb@astron.mit.edu>
(2) GERVASE, FIVE GENTLEMEN FROM KENT & THE MOON
Peter Snow <psnow@esi.co.nz> wrote:
(3) THE NEAR SCIENCE DATA CENTER
K.J. Heeres et al., John Hopkins University
(4) NEAR MAGNETIC FIELD INVESTIGATION
D.A. Lohr et al., John Hopkins University
(5) THE NEAR LASER ALTIMETER
T.D. Cole et al., John Hopkins University
==========================
(1) HOW TO DO A BETTER JOB NEXT TIME
From: Richard Binzel <rpb@astron.mit.edu>
Dear Benny,
While there has been focus on "what went wrong" with
the public
announcement of 1997 XF11, it may be best to focus on how to do a
better job the next time. Below I present for discussion an axiom
for
public communication about new discoveries for which a collision
with
the Earth cannot be ruled out.
Sincerely,
Richard P. Binzel
Associate Professor of Planetary Science
M.I.T.
--------------------------------------------------------------------
"A public statement regarding an Earth approaching object
for which
a collision cannot be ruled out should not be issued without:
a) Giving a quantitative value for the
probability;
b) Having independent verification on
this probability;
c) Placing this probability into the
context of the
collision probability
with the background population
of similar-sized
objects."
============================
(2) GERVASE, FIVE GENTLEMEN FROM KENT & THE MOON
From: Peter Snow <psnow@esi.co.nz>
wrote:
Dear Brad,
I have an interest in Gervase's five Kentish gentlemens
observations and
Hartungs interpretation of them. In the Antipodes the Maori
traditions,
Rock Art, Poems and placenames would suggest they saw a similar
event
during the same time period albeit without the explosive
description.
This event was attributed to anihilating the Moa Hunter along
with the
Moa`s and Forests.
Why I reply is that I have communicated with Mark Bailey re the
positions of the moon in both places on that date. He kindly did
a
retrospective computor analysis which to me clearly shows that
the moon
in it's first day phase (Maori Whiro) was as Gervase described. I
wonder if you or Mark could comment on this apparent anomaly.
Peter Snow
============================
(3) THE NEAR SCIENCE DATA CENTER
K.J. Heeres, D.B. Holland, A.F. Cheng: The NEAR Science Data
Center,
SPACE SCIENCE REVIEWS, 1997, Vol.82, No.1-2, pp.283-308
JOHNS HOPKINS UNIVERSITY, APPLIED PHYSICS LAB, JOHNS HOPKINS
RD, LAUREL, MD, 20723
The NEAR (Near Earth Asteroid Rendezvous) Science Data Center
(SDC)
serves as the central site for common data processing activities
needed
by the NEAR science teams in particular and the scientific
community in
general. The SDC provides instrument and spacecraft data to the
science
teams from around the world and redistributes science products
produced
by those teams, all the science teams to focus on analysis. This
data
and the accompanying documentation are available at
'http://sd-www.jhuapl.edu/NEAR/'. In addition the SDC is
responsible
for archiving spacecraft, instrument, and science data to the
Planetary
Data System (PDS). Copyright 1998, Institute for Scientific
Information
Inc.
===================
(4) NEAR MAGNETIC FIELD INVESTIGATION
D.A. Lohr*), L.J. Zanetti, B.J. Anderson, T.A. Potemra, J.R.
Hayes,
R.E. Gold, R.M. Henshaw, F.F. Mobley, D.B. Holland: NEAR magnetic
field
investigation, instrumentation, spacecraft magnetics and data
access,
SPACE SCIENCE REVIEWS, 1997, Vol.82, No.1-2, pp.255-281
*) JOHNS HOPKINS UNIVERSITY,APPLIED PHYSICS LAB, JOHNS HOPKINS
RD,
LAUREL, MD, 20723
The primary objective of the investigation is the search for a
body-wide magnetic field of the near Earth asteroid Eros. The
Near
Earth Asteroid Rendezvous (NEAR) 3-axis fluxgate magnetometer
includes
a sensor mounted on the high-gain antenna feed structure. The
NEAR
Magnetic Facility Instrument (MFI) is a joint hardware effort
between
GSFC and APL. The design and magnetics approach achieved by the
NEAR
MFI effort entailed low-cost, up-front attention to engineering
solutions which did not impact the schedule. The goal of the
magnetometer is reliable magnetic field measurements within 5 nT,
which
necessitates the use of an extensive spacecraft magnetic
interference
model but is achievable with the full year's orbital data set.
Such a
goal has been shown viable with recent in-flight calibration data
and
comparisons to the WIND magnetometer data.. The NEAR MFI effort
has
succeeded in providing magnetic field measurements for the first
flight
in NASA's Discovery line. Copyright 1998, Institute for
Scientific
Information Inc.
===========================
(5) THE NEAR LASER ALTIMETER
T.D. Cole*), M.T. Boies, A.S. ElDinary, A. Cheng, M.T. Zuber,
D.E.
Smith: The Near-Earth Asteroid Rendezvous laser altimeter, SPACE
SCIENCE REVIEWS, 1997, Vol.82, No.1-2, pp.217-253
*) JOHNS HOPKINS UNIVERSITY, APPLIED PHYSICS LAB, DEPARTMENT OF
SPACE, JOHNS HOPKINS RD, LAUREL, MD, 20723
In 1999 after a 3-year transit, the Near-Earth Asteroid
Rendezvous
(NEAR) spacecraft will enter a low-altitude orbit around the
asteroid,
433 Eros. Onboard the spacecraft, five facility instruments will
operate continuously during the planned one-year orbit at Eros.
One of
these instruments, the NEAR Laser Rangefinder (NLR), will provide
sufficiently high resolution and accurate topographical profiles
that
when combined with gravity estimates will result with
quantitative
insight into the internal structure, rotational dynamics, and
evolution
of Eros. Developed at the Applied Physics Laboratory (APL), the
NLR
instrument is a direct-detection laser radar using a bistatic
arrangement. The transmitter is a gallium arsenide (GaAs)
diode-pumped
Cr:Nd:YAG (1.064-mu m) laser and the separate receiver uses an
extended
infrared performance avalanche-photodiode (APD) detector with
7.62-cm
clear aperture Dall-Kirkham telescope. The lithium-niobate
(LiNbO3)
Q-switched transmitter emits 15-ns pulses at 15.3 mJ pulse(-1),
permitting reliable NLR operation beyond the required 50-km
altitude.
With orbital velocity of 5 m s(-1) and a sampling rate of 1 Hz,
the NLR
spot size provides high spatial sampling of Eros along the
orbital
direction. Cross-track sampling, determined by the specific
orbital
geometry with Eros, defines the resolution of the global
topographic
model; this spacing is expected to be <500 m on the asteroid's
surface.
Combining the various sources of range errors results with an
overall
range accuracy of 6 m with respect to Eros' center-of-mass. The
NLR
instrument design, perfomance, and validation testing is
decribed. In
addition, data derived from the NLR are discussed. Using
altimetry data
from the NLR, we expect to estimate the volume of 433 Eros to
0.01% and
its mass to 0.0001% accuracies; significantly greater accuracies
than
ever possible before Copyright 1998, Institute for Scientific
Information Inc.
--------------------------------
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