PLEASE NOTE:
*
Date sent: Thu, 15 Jan
1998 11:11:07 -0500 (EST)
From:
Benny J Peiser B.J.PEISER@livjm.ac.uk
Subject:
CC-DIGEST, 15/01/98
To:
cambridge-conference@livjm.ac.uk
Priority: NORMAL
CAMBRIDGE-CONFERENCE DIGEST, 15 Juanary 1998
--------------------------------------------
(1) NEAR-EARTH ASTEROID 1995 HM: A HIGHLY-ELONGATED MONOLITH
ROTATING UNDER TENSION?
(2) DETECTION OF A DUST TRAIL IN THE ORBIT OF AN
EARTH-THREATENING
LONG-PERIOD COMET
(3) POLITICAL CORRECTNESS GOES OTT: NASA SORRY ASHES WILL
DEFILE MOON
========================================================================
(1)
NEAR-EARTH ASTEROID 1995 HM: A HIGHLY-ELONGATED MONOLITH
ROTATING UNDER TENSION?
From: Duncan Steel dis@a011.aone.net.au
Dear Benny,
WRT: 'SEARCHING FOR THE PHYSICAL NATURE OF IMPACTING BODIES'
...another aspect of significance is whether NEAs are rubble
piles held
together by self-gravity, or monoliths. Until now no asteroid had
been
observed to be spinning so fast that it could not be held
together by
self-gravity, whereas our observations of 1995 HM indicate that
it is very
elongated and spinning under tension, and is thus a monolith. See
the
abstract etc. appended.
Cheers,
Duncan
===================================================================
D.I. Steel, R.H. McNaught, G.J. Garradd, D.J. Asher and A.D.
Taylor
Near-Earth asteroid 1995 HM:
A highly-elongated monolith rotating under tension?
Planetary & Space Science, 45, 1091-1098 (1997).
Abstract. We report photometry of near-Earth asteroid 1995 HM
obtained in
1995 June. This object has dimensions of at most a few hundred
metres. The
85 observations result in a lightcurve with an amplitude of at
least two
magnitudes, indicating a highly elongated shape. The full drop in
brightness
occurred within 15 minutes, and the cyclicity of the lightcurve
indicates
that the rotation period of 1995 HM is only about 97 minutes, the
briefest
ever determined for an asteroid. If 1995 HM is indeed spinning
this quickly
then it must be a monolithic body rotating under tension, because
the
density required for an object with zero tensile strength to
maintain
integrity through self-gravitation at such a rotation rate is
unreasonably
high (~4 gm cm-3 for a spherical profile, and above 8 gm cm-3 for
the
elongation indicated by the observed lightcurve amplitude). The
search for
an asteroid with such a spin rate has been a long-term quest
(A.W. Harris,
Lunar Planet. Sci., XXVII, 493-494, 1996). Some difficulties in
fitting a
single lightcurve over the full 15 day time-span of the
observations may be
indicative of this asteroid being in a tumbling state, rather
than
undergoing simple principal axis rotation.
======================================================================
(2) DETECTION OF A DUST TRAIL IN THE ORBIT OF AN
EARTH-THREATENING
LONG-PERIOD COMET
P. Jenniskens*), H. Betlem, M. deLignie, M. Langbroek: The
detection of a
dust trail in the orbit of an Earth-threatening long-period
comet.
ASTROPHYSICAL JOURNAL, 1997, Vol.479, No.1 Pt1, pp.441-447
DUTCH METEOR SOC, NL-2318 NB LEIDEN, NETHERLANDS
IRAS has detected dust trails in the orbit of short-period
comets but
has been unable to detect such trails in the orbit of long-period
comets. We now present observations from the study of a meteor
outburst that
identify the event as being due to just that. Ten orbits of
meteoroids were
measured during a brief but intense outburst of the alpha
Monocerotid shower
that confirm the theory that a trail of dust is brought
occasionally in
collision with the Earth by planetary perturbations. Observations
of this
event by multiple meteor observing techniques provide the first
direct
measurement of the size distribution of dust in a comet dust
trail, the dust
density in the trail of a long-period comet, and a cross section
of such a
trail in the path of Earth. The implication for detecting
potential
Earth-threatening long-period comets by their meteoric signature
is
discussed.
========================================================================
(3)
POLITICAL CORRECTNESS GOES OTT: NASA SORRY ASHES WILL DEFILE MOON
From: The Arizona Daily Star, 13 January 1998
NASA SORRY ASHES WILL DEFILE MOON
Promises Navajos more sensitivity
By Enric Volante
NASA will consult with American Indians before it rockets any
more
human ashes to the moon, a spokeswoman for the space agency
pledged
yesterday.
The National Aeronautics and Space Administration quickly
apologized
after the president of the Navajo Nation complained of
insensitivity
to traditional Navajo religious beliefs. NASA's Lunar Prospector
spacecraft blasted off Tuesday and started orbiting the moon
Sunday.
Inside the 650-pound craft is a 2-inch-long capsule containing an
ounce of the cremated remains of renowned planetary scientist
Gene
Shoemaker of Flagstaff.
In a tribute to Shoemaker, his remains are to be the first
ever laid
to rest on another celestial body.
Navajo President Albert Hale learned of the plan over the
weekend
as he emerged from the customary four days of seclusion that
follows
a Blessing Way ceremony.
"I read this, and I was appalled and upset," he said
in an interview
yesterday. "The moon is revered and it regulates life
cycles,
according to Navajo traditions and stories. To send something
like
that over there is sacrilege."
Traditional Navajos avoid the dead to the point of not
mentioning the
names of deceased relatives. Some still observe the old custom of
abandoning a home in which someone has died.
"It is one thing to prove, to study, to examine and even
for men to
walk upon the moon," Hale said in a statement issued Sunday.
"But it
is sacrilege, a gross insensitivity to the beliefs of many Native
Americans, to place human remains on the moon."
NASA meant no disrespect, said Peggy Wilhide, the agency's
director
of public affairs.
"None of the scientists on the program were aware that
this would be
insensitive," she said last night in apologizing on behalf
of NASA.
"I give my commitment that if we ever discuss doing
something like
this again, we will consult more widely and we will consult with
Native Americans."
She would not rule out another launch of cremated remains, but
said
none is planned.
Hale said he appreciated the agency's apology. But he said
even
scientists unfamiliar with Navajo beliefs should have known
better
than to scatter the dead on "something as sacred as the
moon," he
said.
He noted that President Clinton, early in his first term,
ordered
federal agencies to consult with Indian nations before taking
actions
that affect tribes.
The criticism from the leader of the country's largest Indian
tribe comes as Clinton's commission on race relations is to meet
in
Phoenix today and tomorrow.
University of Arizona planetary scientist Carolyn C. Porco
conceived the tribute to Shoemaker when she read his obituary and
learned he would be cremated. Shoemaker died in a July car wreck.
His widow and longtime research companion, Carolyn, watched
the
launch in Florida last Tuesday.
Reached at her Flagstaff home last night, she said she was
"completely astonished" to hear the space mission
disturbed Navajos.
"One reason it would never have entered my mind that they
or
anyone else would be offended is just knowing Gene's feelings
about
going into space, and particularly about going to the moon. It's
almost a religious thing with him," she said.
The Shoemakers are best known as part of the team that
discovered
Comet Shoemaker-Levy 9, the vast ball of ice that crashed into
Jupiter four years ago. But Gene Shoemaker, an astronomer and
geologist, also conducted important studies decades earlier of
Northern Arizona's Meteor Crater.
"He always said that every crater was a sacred site to
him," Carolyn
Shoemaker recalled yesterday. "I think he felt that same way
about
the moon because he had studied it so much and had yearned to be
there so much. It was just an important part in his life, and he
would never have thought about desecrating it."
Her husband's ashes will hit the lunar surface a year from now
as
the spacecraft's fuel runs out.
The ashes of the dead are not a new issue for the Navajo. Last
summer, medicine men warned tribe members to stay away from the
San
Francisco Peaks north of Flagstaff after they learned the sacred
mountains had been defiled by people scattering cremated remains.
Navajo holy men arranged purification ceremonies last year to
restore
the sanctity of the mountains.
U.S. Forest Service officials later confirmed that people
scatter
ashes in the peaks even though depositing human remains on
federal
lands is illegal. They said there was no way to prevent the
practice.
Those illegal acts not only offend Navajos, but force them to
pay
for costly ceremonies, Hale said.
Explore American Indian culture at NativeWeb's Resource
Center.
Also, learn more about the Navajo Nation at its Web site.