PLEASE NOTE:
*
CCNet DIGEST, 11 January 1999
------------------------------------------------
(1) NEWS REPORT ON ALASKAN FIREBALL
Steven Excell <excell@cris.com>
(2) METEORITE IMPACT IN PORTUGAL
J al Silva <joaolealsilva@mail.sonet.pt>
(3) STARDUST MISSION SET TO BRING BACK A PIECE OF A COMET
Ron Ballke <BAALKE@kelvin.jpl.nasa.gov>
wrote:
(4) IS LIFE A FLUKE?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) HOW NEAR WAS SAVED
Andrew Yee <ayee@nova.astro.utoronto.ca>
(6) NASA - NAMN COOPERATION ANNOUNCED
Mark Davis <MeteorObs@charleston.net>
(7) NEAR PEEP SHOW OF EROS AVAILABLE
Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
wrote:
=============================
(1) NEWS REPORT ON ALASKAN METEORITE IMPACT
From Steven Excell <excell@cris.com>
Anchorage Daily News, Sunday, January 10, 1998:
"Great ball of fire - Flash in sky likely exploding
meteor"
By ELIZABETH MANNING
Daily News reporter
A brilliant flash and earthshaking boom noticed by thousands of
Alaskans late
Friday were likely a meteor exploding in Earth's atmosphere,
scientists said
Saturday.
Donald Martins, an astronomy professor at the University of
Alaska Anchorage,
wasn't lucky enough to see the object that streaked blue, green
and red across
the Southcentral Alaska sky. But based on witness accounts,
Martins and other
scientists believe the flash came from a meteor or comet fragment
- probably
the size of a pumpkin - that exploded about 50 miles above
Earth's surface.
"That's almost certainly what it was," Martins said.
"They aren't uncommon.
But it is very rare to have one explode and hear it."
Dozens of people phoned authorities late Friday to report the
event, which
happened about 10:25 p.m. Most eyewitnesses described a brilliant
and colorful
flash, followed several minutes later by a boom. The boom was so
loud it shook
houses in Palmer and Wasilla and was heard from South Anchorage
to Sutton and
beyond.
"I wish I could describe it," said Gina Gilmore, who
watched the fireball from
a hot tub near Palmer. "It was an eerie blue and green color
and lit up the
whole area. Then we heard an explosion, and it stilled our
conversations."
Gilmore said she thought at first that the object was a shooting
star or
meteor, but its intensity made the group in the hot tub wonder:
Could it have
been a missile, an electrical explosion or something from the
"X-Files"?
"It was greenish, and it was loud," said Rachael
Wagner, 16, another observer
from Wasilla. She was inside her home and noticed the flash
through the
window.
Assuming the object was a meteor, Martins said, it's possible
that the
fireball was part of the Quandrantid meteor shower, which was
expected to be
active from Dec. 28 through Thursday. On Tuesday, Anchorage
residents reported
an object streaking low in the sky across the backdrop of the
Chugach
Mountains.
The Quandrantids are one of the year's most intense meteor
showers but are
among the least observed because of their location high in the
Northern sky.
The meteors appear to emanate from the obsolete constellation
Quadrans
Muralis, hence the name Quandrantids.
Though the origin of the Quandrantids is unknown, most meteor
showers are
caused by fragments of comets - dust and ice debris - that boils
away from a
comet's nucleus when it passes close to the sun. A meteor shower
results when
Earth passes through a comet's debris stream.
Martins said most meteors burn up from friction as they enter
Earth's
atmosphere. When the chunks are large enough, they sometimes
explode
because the core of the object is much cooler than the outside.
"Imagine a cold rock coming in and getting very hot,"
said Greg Durocher, a
scientist with the U.S. Geological Survey. "It's under
tremendous stress."
Durocher and other observers of the fireball said they heard the
boom about
three or four minutes after they saw the flash. Based on that
information,
Martins estimated that the object was about 50 miles away at the
time of the
explosion.
The noise people reported may have been a sonic boom. However, a
single noise
heard at the same time by everyone would indicate an explosion,
he said.
Martins said he once heard of a fireball so loud it almost
deafened several
fishermen in the South Pacific.
Although the object may have been fairly large for a meteor,
Martins said, it
is unlikely that anyone will find a meteorite, which is a
fragment of a meteor
that falls to Earth.
There were rumors Friday of objects striking the Parks Highway at
Mile 141 and
reports by pilots of debris falling, but meteorites are extremely
hard to
find, Martins said.
"Unless you can actually determine where the impact
occurred, you're worse off
than finding a needle in a haystack," he said.
And if the object was part of a comet, Martins said, most of the
fireball was
probably composed of ice, which would have melted before hitting
the ground.
Martins said the colors people described suggest that the
fragment was part of
a comet.
"It had a good tail on it," Gilmore said. "And it
was amazing to watch it
going across the sky. I probably won't ever see that again."
* Reporter Elizabeth Manning can be reached at emanning@adn.com
Copyright 1999, Anchorage Daily News
==================
(2) METEORITE IMPACT IN PORTUGAL
From <joaolealsilva@mail.sonet.pt>
[as posted on the metorite-list]
Hi.
Last December, around new year's eve, a meteorite impacted the
south of
Portugal.
It made a small crater and it had around 30kg. Most off the
pieces are gone
and the leftovers are already away to our natural history museum
in Lisbon.
Anyway there is a work we would like to make, which is trying to
determinate the exact trajectory off this meteorite.
If by any chance some one saw in this days around 1 am the meteor
we
would appreciate the information.
Thanks
JLS
Member off APAA ( Portuguese Amateur Astronomers Association )
==================
(3) STARDUST MISSION SET TO BRING BACK A PIECE OF A COMET
From Ron Ballke <BAALKE@kelvin.jpl.nasa.gov>
wrote:
NASA's Stardust mission, scheduled for launch February 6, 1999
from Cape
Canaveral, FL, will send a spacecraft flying through the cloud of
dust that
surrounds the nucleus of a comet - and, for the first time ever,
bring
cometary material back to Earth.
Comets, which periodically grace our sky like celestial bottle
rockets, are
thought to hold many of the original ingredients of the recipe
that created
the planets and brought plentiful water to Earth. They are also
rich in
organic material, which provided our planet with many of the
ready-to-mix
molecules that could give rise to life. They may be the oldest,
most
primitive bodies in the solar system, a preserved record of the
original
nebula that formed the Sun and the planets.
"Scientists have long sought a sample directly from a known
comet because of
the unique chemical and physical information these bodies contain
about the
earliest history of the solar system," said Dr. Edward
Weiler, NASA's
associate administrator for space science. "Locked within
comet molecules
and atoms could be the record of the formation of the planets and
the
materials from which they were made."
Stardust is the first U.S. mission dedicated solely to a comet
and will be
the first to return extraterrestrial material from outside the
orbit of the
Moon. Stardust's main objective is to capture a sample from a
well-preserved
comet called Wild-2 (pronounced "Vilt-2").
The spacecraft will also collect interstellar dust from a
recently
discovered flow of particles that passes through our solar system
from
interstellar space. As in the proverbial "from dust to
dust," this
interstellar dust represents the ultimate in recycled material;
it is the
stuff from which all solid objects in the universe are made, and
the state
to which everything eventually returns. Scientists want to
discover the
composition of this "stardust" to determine the
history, chemistry, physics
and mineralogy of nature's most fundamental building blocks.
Because it would be virtually impossible to equip a spacecraft
with the most
sophisticated lab instrumentation needed to analyze such material
in space,
the Stardust spacecraft is more of a robotic lab assistant whose
job it is
pick up and deliver a sample to scientists back on Earth. The
spacecraft
will, however, radio some on-the-spot analytical observations of
the comet
and interstellar dust.
"The samples we will collect are extremely small, less than
a micron, or
1/25,000th of an inch, in size, and can only be adequately
studied in
laboratories with sophisticated analytical instruments,"
said Dr. Donald C.
Brownlee of the University of Washington, principal investigator
for the
Stardust mission.
"Even if a ton of sample were returned, the main information
in the solids
would still be recorded at the micron level, and the analyses
would still be
done a single grain at a time." Stardust will meet up with
Comet Wild-2 on
January 2, 2004. A gravity assist flyby of Earth will put
Stardust on a
trajectory that will allow it to capture cometary dust intact at
a low
relative speed of 6.1 kilometers per second (about 13,600 miles
per hour).
An onboard camera will aid in navigating the spacecraft as close
as about
150 kilometers (100 miles) from the comet's nucleus, permitting
the capture
of the freshest samples from the heart of the comet.
Dressed for survival behind armored shields, Stardust will
document its
10-hour passage through the hailstorm of comet debris with
scientific
instruments and the navigation camera. On approach to the dust
cloud, or
"coma," the spacecraft will flip open a
tennis-racket-shaped particle
catcher filled with a smoke-colored glass foam called aerogel to
capture the
comet particles. Aerogel, the lowest-density material in the
world, has
enough "give" in it to slow and stop particles without
altering them too
much. After the sample has been collected, the aerogel capturing
device will
fold down into a return capsule, which closes like a clamshell to
enclose
the sample for its safe delivery to Earth.
In addition, a particle impact mass spectrometer will obtain
in-flight data
on the composition of both cometary and interstellar dust,
especially very
fine particles. The optical navigation camera should provide
excellent
images of the dark mass of the comet's nucleus. Other equipment
will reveal
the distribution in both time and space of coma dust, and could
give an
estimate of the comet's mass.
On January 15, 2006, a parachute will set the capsule gently onto
the salt
flats of the Utah desert for retrieval. The scientifically
precious samples
can be studied for decades into the future with ever-improving
techniques
and analysis technologies, limited only by the number of atoms
and molecules
of the sample material available. Many types of analyses now
performed on
lunar samples, for example, were not even conceived at the time
of the
Apollo missions to the Moon.
Comets are small, irregularly shaped bodies composed of a mixture
of grains
of rock, organic molecules and frozen gases. Most comets are
about 50
percent water ice. Typically ranging in size up to about 10
kilometers (6
miles) in diameter, comets have highly elliptical orbits that
bring them
close to the Sun and then swing them back out into deep space.
They spend
most of their existences in a deep freeze beyond the orbit of
Pluto - far
beyond the Sun's dwindling influence, which is why so much of
their original
material is well-preserved.
When a comet approaches within about 700 million kilometers (half
billion
miles) of the Sun, the surface of the nucleus begins to warm, and
material
on the comet's nucleus heats and begins to vaporize. This
process, along
with the loss of rocky debris or other particles that fly off the
surface,
creates the cloud around the nucleus called the coma. It is the
glowing,
fuzzy coma that appears as the head of a comet when one is
observed from
Earth. A tail of luminous debris and another, less apparent, tail
of gases
flow millions of miles beyond the head in the direction away from
the Sun.
Comet Wild-2 is considered an ideal target for study because,
until
recently, it was a long-period comet that rarely ventured close
to the Sun.
A fateful pass near Jupiter and its enormous gravity field in
1974 pulled
Comet Wild-2 off-course, diverting it onto a tighter orbit that
brings it
past the Sun more frequently and also closer to Earth's
neighborhood.
Because Wild-2 has only recently changed its orbit, it has lost
little of
its original material when compared with other short-period
comets, so it
offers some of the best-preserved comet samples that can be
obtained.
Stardust was competitively selected in the fall of 1995 under
NASA's
Discovery Program of low-cost, highly focused science missions.
As a
Discovery mission, Stardust has met a fast development schedule,
uses a
small Delta launch vehicle, is cost-capped at less than $200
million, and is
the product of a partnership involving NASA, academia and
industry.
Principal investigator Brownlee is well-known for his discovery
of cosmic
particles in Earth's stratosphere known as Brownlee particles.
Dr. Peter
Tsou of NASA's Jet Propulsion Laboratory, Pasadena, CA, an
innovator in
aerogel technology and maker of aerogel, serves as deputy
investigator. JPL,
a division of the California Institute of Technology, manages the
Stardust
mission for NASA's Office of Space Science, Washington, DC. Dr.
Kenneth L.
Atkins of JPL is project manager. The spacecraft is designed,
built and
operated by Lockheed Martin Astronautics, Denver, CO. JPL
provided the
spacecraft's optical navigation camera, and the Max Planck
Institute of
Germany provided the real-time dust composition analyzer.
Extensive information on the Stardust mission is available on the
Stardust home page:
http://stardust.jpl.nasa.gov
======================
(4) IS LIFE A FLUKE?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Services
University of Arizona
Contact(s):
Neville J. Woolf, 520-621-3234, nwoolf@as.arizona.edu
J. Roger Angel, 520-621-6541, rangel@as.arizona.edu
James H. Burge, 520-626-7356, jburge@as.arizona.edu
January 9, 1999
Life a fluke? Telescopes will tell
AUSTIN, TX -- A planned telescope called the Terrestrial Planet
Finder and
its successors will search planetary atmospheres for tell-tale
signatures of
life -- and biologists and astronomers should collaborate in the
hunt, an
astronomer from The University of Arizona in Tucson said today
(Jan. 9).
"If all Earth-like planets eventually develop life, we may
expect that about
half of them will show an ozone signature, because buildup of an
oxygen
atmosphere is slow -- at least it was on Earth," said UA
astronomy Professor
Neville J. Woolf . "If life development is difficult, then
we will find many
Earth-like planets, but none of them will show an ozone
signature," he added.
"One proviso is that a hotter planet like Venus did develop
an ozone signature
in the past that likely existed for one two-hundredth of Venus'
lifetime.
Fortunately, we can distinguish Venus-like planets because they
are closer to
their stars than Earth is to our sun."
Woolf is presenting a poster paper titled "The Observational
Problem of
Whether Life on Earth is a Fluke" on Saturday morning, Jan.
9, at the
American Astronomical Society meeting in Austin, Texas. His is
giving the
presentation in conjunction with related sessions he organized or
helped
present at the meeting earlier in the week. These were a program
titled "An
Evening with the Terrestrial Planet Finder Project" and
sessions titled "The
Astronomy Biology Connection."
Woolf is part of the Terrestrial Planet Finder project for the
NASA Origins
program. In association with other UA astronomers, including
Regents'
Professor of astronomy Roger Angel and James Burge of the Steward
Observatory, Woolf has proposed the construction of a linear
nulling
interferometer for the detection of extra-solar Earth-like
planets whose
planetary atmospheres bear gases indicative of life. It would be
based in
space one astronomical unit from Earth.
The linear nulling interferometer is essentially a four-mirror
device that
determines planetary position, atmospheric emission spectrum and
surface
temperature. Four mirrors are spread evenly along a straight line
for the
detection of radiation. The mirrors, because of their
arrangement, block out,
or "null" the light from a star so astronomers can
observe the surrounding
space for Earth-like planets. The design defeats one of the major
difficulties
in detecting such planets -- the fact that the planets like ours
are ten
million times dimmer than their suns.
The Terrestrial Planet Finder will separate the bands of the
spectrum and map
the sky in each band, as well as measure surface temperature. In
particular,
the linear nulling interferometer will search for the presence of
carbon
dioxide, ozone and water in planetary atmospheres. The
substantial presence
of all three gases would show that microorganisms live on the
planet, Woolf
said.
He noted that the technology needed for this project is similar
to the
technology for the Next Generation Space Telescope (NGST), so the
proposed
date for construction of the Terrestrial Planet Finder project in
2007 is
feasible. Speedy development depends on advances in both nulling
and mirror
technology, he added. Astronomers at the UA Steward Observatory
have
successfully produced small-scale model mirrors, and they
currently work on
a 2-meter NGST mirror prototype for smaller, thinner
space-telescope mirrors
that cost only a fraction of the cost of the Hubble Space
Telescope mirror.
The Terrestrial Planet Finder project is important for biologists
as well as
astronomers, Woolf emphasized. "Biologists would be keenly
interested in the
discovery of life on an extra-solar planet. And if that life
operates with
very different chemistry than most life at Earth's surface, that
would be
extremely interesting."
"The discovery of life on another planet may arguably be the
crowning
achievement in the exploration of space," Woolf and Angel
wrote in an article
"Searching for Life on Other Planets," published in the
April 1996 Scientific
American.
"Finding life elsewhere, NASA administrator Daniel S. Goldin
has said, (and
they quoted in the article) 'would change everything -- no human
endeavor or
thought would be unchanged by that discovery.' "
LINKS:
http://athene.as.arizona.edu:8000/caao/
http://www.as.arizona.edu/
==========================
(5) HOW NEAR WAS SAVED
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Service
Cornell University
Contact: Blaine P. Friedlander, Jr.
Office: (607) 255-3290
E-Mail: bpf2@cornell.edu
FOR RELEASE: Jan. 8, 1999
How a down-to-the-wire computer fix at Cornell enabled a troubled
spacecraft
to take images of an asteroid
ITHACA, N.Y. -- Some 240 million miles from Earth, a spacecraft
hurtled
through the black void of space, off its intended course. But
thanks to the
creation of a last-minute fix by Cornell University mission
engineers during
a tense 24 hours just before Christmas, the $150 million mission
now has
hundreds of new images of a distant asteroid.
The Near Earth Asteroid Rendezvous (NEAR) had almost been given
up for dead
after a signal failure Dec. 20, but after contact was renewed
scientists
quickly had to formulate a new mission plan. Thanks to the
considerable
ingenuity of researchers at Cornell, NASA's Jet Propulsion
Laboratory (JPL)
in Pasadena, Calif., and Johns Hopkins University's Applied
Physics
Laboratory (APL) in Baltimore, signals were sent enabling the
spacecraft to
capture images as it approached the asteroid 433 Eros. But it was
touch-and-go.
Cornell astronomy professor Joseph Veverka leads the mission's
science team
in charge of the visual light camera and near-infrared
spectrometer, two of
the five science instruments carried by NEAR. His operations team
here
designs the spacecraft command sequences that point and operate
the
instruments. NEAR's primary mission is to remain in orbit around
Eros for
one year collecting high-resolution images and other science
data.
The drama began Sunday, Dec. 20, when a signal was sent from APL
to
implement a main engine burn to reduce the spacecraft's speed
from 2,180 to
700 miles per hour on its approach to Eros. This was to be
followed by three
additional burns to further reduce the speed to 11 miles per hour
relative
to Eros and enable the spacecraft to go into orbit around the
asteroid Jan.
10. But the first engine burn went awry.
When the first main engine burn began, the spacecraft's built-in
safety
devices detected a problem and shut down the burn after one
second. The
spacecraft began to tumble violently, and onboard communications
systems
also were shut down. Contact between scientists and NEAR was lost
for 36
hours. Instead of closing in on Eros at a relatively slow pace,
the
spacecraft continued to speed along at more than 2,000 miles an
hour.
"Afterward, it was Black Monday. We thought we had lost the
spacecraft. We
thought that we had lost everything we had worked toward for the
past four
years," says Ann P. Harch, a research support specialist in
Cornell's
astronomy department, who designs command sequences to acquire
camera and
spectrometer data.
The failure of the burn meant the postponement of NEAR's orbit of
Eros until
next year. But mission scientists calculated that within about 60
hours NEAR
would pass Eros, about two weeks ahead of schedule.
Cornell engineers and astronomers with help from colleagues at
APL cobbled
together a plan to salvage at least something from the flyby by
commanding
NEAR to take photographs and infrared spectrographic images of
Eros. But no
computer programs were available to send such commands.
"It was nerve-racking. We really weren't sure about the
spacecraft. We
didn't know if this was perhaps our last and only chance to see
Eros," says
Harch. "We really weren't sure if the main engine would burn
or not."
For the impromptu Eros flyby, beginning at about 10:30 a.m.
Eastern time
Dec. 23, Harch, Maureen Bell, also a member of Veverka's Cornell
team, and
Scott Murchie of APL were asked at noon Dec. 22 to write a new,
error-free,
computer command sequence for the spacecraft. The sequence would
have to
slue the spacecraft to keep the instruments pointed continuously
in the
vicinity of Eros throughout the flyby, while simultaneously
keeping the
spacecraft's photovoltaic cells pointed toward the sun. Since
Eros' location
was not known precisely, it would require taking a mosaic of four
images to
guarantee capture of each view of Eros.
Harch had written the command programs for NEAR's flyby of
asteroid Mathilde
in June 1997, a task that took her six months. But the new
sequence would
have to be written in just 12 hours in order to reach the
spacecraft in time
to make the complex onboard revisions.
Using electronic mail and constant phone conferencing, Harch and
Bell at
Cornell kept in contact with Murchie in Baltimore, and with true
grit, and
much sweat, the trio wrote the sequence. It was sent
electronically to APL
in Baltimore close to midnight.
From midnight and into the morning hours, sleep-deprived APL
scientists
tested the sequence for errors that could permanently
incapacitate NEAR.
Then, the sequence was sent by microwave transmission to the
craft during
the early morning hours Dec. 23. The "enable command"
for the sequence was
sent at about 10 a.m. Eastern time and received by the craft at
about 10:22
a.m., eight minutes before the first scheduled event in the
imaging
sequence. Had the enabling command arrived eight minutes later,
the
information would have been too late.
Then, more nail-biting. Scientists at Cornell, APL and JPL waited
anxiously
to see if the program worked. If it didn't, the scientists would
have to
wait until the rescheduled February 2000 rendezvous with Eros..
Hours later, Harch received an e-mail from Mark Robinson of
Northwestern
University, a member of imaging science team: "We have an
asteroid! ...
Here's a cut-out (partial frame) of M0089838063-F0-s showing
'Christmas
Dinner!'"
Editors: A composite photo of several views of Eros from the NEAR
spacecraft
is available in the online version of this release at
http://www.news.cornell.edu/releases/Jan99/NEAR.pix.bpf.html
Related World Wide Web sites: The following sites provide
additional
information on this news release. Some might not be part of the
Cornell
University community, and Cornell has no control over their
content or
availability.
Johns Hopkins Applied Physics Laboratory, http://www.jhuapl.edu/
Jet Propulsion Laboratory, http://www.jpl.nasa.gov/
Official NEAR Mission site, http://near.jhuapl.edu/
===================
(6) NASA - NAMN COOPERATION ANNOUNCED
From Mark Davis <MeteorObs@charleston.net>
NASA - NAMN Cooperation Announced
I am pleased to announce that the groundwork for a cooperative
effort
between NASA's Space Sciences Laboratory and the North American
Meteor
Network has been laid. Located at the Marshall Space Flight
Center, the
mission of the Space Sciences Laboratory is to "plan,
coordinate, direct,
and conduct original and supporting theoretical, experimental,
and
observational research in a number of research areas, including
astrophysics, microgravity science, and Earth science." The
North American
Meteor Network, an affiliate of the American Meteor Society, will
be
assisting the Space Sciences Lab by providing visual meteor data.
Dr. Tony Phillips (NASA) and I have discussed projects in which
our extensive network of our observers, and their data, can be of
the most
benefit. At present these include providing data for attempts at
orbital
refinement on select meteor streams and the monitoring of the
sporadic
background component. Other projects may be added in the future.
Additional information and updates will be provided as soon as
they are
available. For information on how to become involved in meteor
observing, or
how to hone your observing skills for these new projects, please
contact me
at the address below.
Clear skies!
Mark Davis, MeteorObs@charleston.net
Mt. Pleasant, South Carolina, USA
Visual Program Coordinator
North American Meteor Network & American Meteor Society
NAMN: http://medicine.wustl.edu/~kronkg/namn.html
AMS: http://www.serve.com/meteors
=======================================================
(7) NEAR PEEP SHOW OF EROS AVAILABLE
From Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
wrote:
NEAR image of the day for 1999 Jan 08
http://near.jhuapl.edu/iod/000/index.html
Two Views of Eros
This pair of images of the asteroid Eros was acquired by the Near
Earth
Asteroid Rendezvous (NEAR) spacecraft on December 23, 1998, as
the spacecraft
flew by the night side of the asteroid at a distance of 2300
miles (3800
kilometers) at 1:43 PM EST. These views, taken at 1:44 PM and
2:05 PM EST as
the spacecraft range increased from 2300 miles to 2500 miles
(4100
kilometers), show only a tiny portion of the day side of Eros
(phase angle
~119°). The smallest resolved detail is approximately 1300 feet
(400 meters)
across.
A firing of the main engine at 5 PM EST December 20, designed to
slow the
spacecraft for insertion into orbit around the asteroid, was
aborted by the
spacecraft. Contact with ground controllers was temporarily lost,
but was
regained at 8 PM EST December 21 when autonomous spacecraft
safety protocols
took over and transmitted a signal to the ground. All spacecraft
systems were
determined to be healthy and operational. Within hours, a flyby
observation
sequence was developed and uploaded to the spacecraft. 1026
images were
acquired by the multispectral imager, to determine the size,
shape,
morphology, rotational state, and color properties of Eros, and
to search for
small moons. The infrared spectrometer measured spectral
properties of the
asteroid to determine what minerals are present, and the
magnetometer searched
for a natural magnetic field. Analysis of the spacecraft radio
signal will
yield bounds on the asteroid's mass and density.
The main engine was fired successfully on January 3, 1999,
placing NEAR
on-course for a February 2000 rendezvous. Eros is NEAR's second
asteroid
encountered. On June 27, 1997, NEAR flew by the main-belt
asteroid Mathilde at
a range of 1212 kilometers (750 miles).
--------------------------------------------------------
Built and managed by The Johns Hopkins University Applied Physics
Laboratory,
Laurel, Maryland, NEAR was the first spacecraft launched in
NASA's Discovery
Program of low-cost, small-scale planetary missions. See the NEAR
web page at
http://near.jhuapl.edu for
more details.
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*
THE PROBLEM OF BACK CONTAMINATION FROM AN OPERATIONAL
PERSPECTIVE
From E.P. Grondine <epgrondine@hotmail.com>
Benny -
Some recent posts to the
Conference have put forward several
hypothesis of the rather tentative sort on the nature of life in
our
solar system as resembling hard facts. First of these
hypothesis was
that either life or its precursors originated on asteroids or
comets,
and that these had then seeded both the Earth and Mars.
Next came the
hypothesis that impacts on the Earth and Mars had transported
pieces of
rock carrying life forms from one planet to the other, and that
these
life forms had survived the voyage. While not explicitly
stated, a
further hypothesis building on these, that these transfers had
taken
place so recently that these life forms had not diverged, was
implicit
in the statement that these transfers had "inoculated"
the Earth
against back contamination by potentially hazardous life forms
from
Mars.
While not directly on the topic of
castastrophism, the
contamination of the Earth's biosphere by an organism from Mars
might
have truly catastrophic consequences, so perhaps some Conference
members
may be interested in the following information on back
contamination
problem from an operational perspective. Here goes -
In 1992 I attended the Eighth Congress
of the Association of Space
Explorers in Washington, D.C. Dr. Carl Sagan was the
luncheon speaker,
and he shared with the assembled astronauts and cosmonauts his
current
views on the evolution of Mars. In Dr. Sagan's view, Mars
would be an
ideal place to study the evolution of life, as he thought that
life most
likely had evolved there, but then had been completely
exterminated by
the evolution of Mar's atmosphere into a rain of hydrogen
peroxide. In
Dr. Sagan's view the astronauts would thus be able to look for
fossils
without encountering the danger of being exposed to any living
organism.
At this time, while the Soviet Union had
collapsed, the
Commonwealth of Independent States was still in the process of
formation, and serious economic collapse had not yet set
in. Russia had
at least 2 long range Marsokhod rovers set to go, with additional
follow-up rovers likely; Dr. Sagan and the attendees expected
that the
question of life on Mars would receive a definite answer in the
immediate future.
At the Congress, I had a chance to talk for
nearly an hour with
Cosmonaut Konstantin Feoktistov, one of the lead engineers for
the
Soviet manned Mars program, with Cosmonaut Georgi Grechko serving
as
translator. The Soviet manned Mars program was not merely a
paper
program, but had started in 1961 as part of the distribution of
tasks
between the N1 launcher team under Korolev at OKB-1 and the UR
700
launcher team under Chelomei and Glushko at Krunichev.
Since 1961
several nuclear thermal engines had been developed and had
undergone
long duration test firings; a completely closed environmental
system had
been constructed and had undergone 2 long duration tests; 3
different
manned Mars craft for launch by the N-1 rocket had been
completely
designed; these designs had then been adapted for launch by the
Energia
heavy lift launcher; models of Mars entry craft had
undergone
aerodynamic tests; cosmonauts had been put through extended
periods of
weightlessness identical to those that would be encountered on a
manned
Mars flight. This was no paper program, but one on which a
sizable
amount of money had been spent.
As the program had developed a
serious problem had emerged: The
possibility that the cosmonauts might be exposed and contaminated
by a
Martian life form. The solution that had been developed was
as follows:
The first flight of the manned Mars ship would merely be to Mars
orbit,
with manned landings on the Martian moons of Phobos and
Deimos. The
cosmonauts would operate from Mars orbit a long range rover on
the
surface, which would collect possible life bearing samples and
deliver
them to a vehicle which would carry them up to the manned Mars
ship.
There the samples would be exposed to a chemical wash and
radiation,
following which they would be studied to see if the remains of
life
forms existed. As you can see, the problem was taken most
seriously. If
any life had survived and the crew were then exposed to it, both
it and
they would be contained on board the ship, and the possibility of
bringing the surviving organisms back to Earth was set at zero.
The Soviet Space Research
Institutes' Phobos and Deimos probes and
their long range Marsokhod rovers may be viewed as unmanned
precursor
missions to this manned mission. Indeed, the Space Research
Institute
had also looked at a sample return mission, but as one of the
participants in this put it to me, the problem of sample handling
had
proved to be a real nightmare. The containment mechanism
itself stood
to be contaminated when storing the samples; finally, a device
something
like a "Chinese Box" had been proposed, with each
containment being
cleaner than the proceeding, down to an acceptable level of risk.
This brings us to today, and the
current NASA manned Mars effort.
As I previously reported in my coverage of Dan Goldin's interview
with
John McLaughlin, NASA Administrator Goldin has stated that he
thinks
that manned flight to Mars may be possible by 2010. While
surprising to
some, this comes as little surprise to those familiar with
Goldin's
start in the space program back in the 1960's as an engineer for
a
proposed manned Mars craft to be launched by the Saturn 5
rocket..
In recent testimony before the
House Space Sub-Committee Goldin
re-iterated that his second priority after crew safety is to
lower US
launch costs. The X-33 project currently under development
is a
technological test-bed for a Reusable Launch Vehicle (RLV), which
it is
hoped will be made operational by about 2005. It is hoped
that this RLV
will be capable both of putting into orbit both large
communication
satellites, and of servicing the International Space Station with
both
manned and un-manned payloads. As a back-up to the RLV, two
Enhanced
Expendable Launch Vehicles (EELVs) are under development, as well
as a
manned Crew Return Vehicle (CRV) for use with the EELVs for the
International Space Station.
For the small satellites low end of the
market (those used to put
into low Earth orbit the small satellites used for relay
communication
systems like Iridium) NASA is supporting the development of small
launchers by private firms. This leads to the
question, "What becomes
of the Shuttle?" The Shuttle isn't effective for the
small payloads;
manned flight will be done with the RLV or EELVs, as well as
large
communication satellites and reconnaissance satellites.
It is now becoming clear that Goldin is
hoping to convert the
Shuttle into a heavy lift vehicle, sometime after 2005. By
removing the
main engines from the shuttle and mounting them on a return
shell, you
no longer have to put the mass of the shuttle's airframe into
orbit for
each launch. This variant, called Shuttle C, has already
been not only
studied, but a return shell for the 2 engine variant has already
been
designed and tested by Boeing. Furthermore, with a lift of 150
tons,
such a heavy lift vehicle is capable of putting into orbit a
manned Mars
craft; and indeed, NASA has already developed a reference manned
Mars
mission using 2 launches of this vehicle.
Additionally, Goldin has set out the
cost limits for the manned
Mars mission. In a talk at the American Astronautical Society
conference
held at Houston in November, NASA's John Lewis set them out as
follows:
Before Goldin will endorse it, the overall per-mission price has
to be
$2 billion dollars, with foreign (either European, Japanese, or
Russian)
interests picking up at least 25% of this, or $500 million
dollars.
Since the launch costs with the Shuttle C are significantly lower
than
for the shuttle, around $120 million a piece or 2 for $240
million,
these numbers can be met, if the foreign partners join in.
Development
costs for the Shuttle C have been estimated at around $3 billion,
and
spread out over a number of years could fit inside of the NASA
budget.
In sum, it is clear that Goldin wants to
move NASA and the US
launch industry into a position such that a US President,
speaking in
the year 2000, will be able to realistically propose the goal of
placing
a man on Mars and returning him safely to the Earth before the
end of
the decade (2010). Goldin is relying upon political support
for this
goal coming from the home states of the shuttle contractors in
Florida,
California, Alabama, Texas, Mississippi, Washington, and other
states.
As this dream moves from paper to the
drawing boards, NASA now
finds that it is hitting the same problem the Soviet scientists
hit back
in 1970 or so: Is there any life on Mars, and how do you protect
the
Earth from any danger it might present? So far, a sample
return mission
in cooperation with France, returning samples gathered by both US
and
French craft is under development, and this will present the
first test
case.
At the ALH 84001 press conference
I asked Dan Goldin about this
and he explicitly stated that he will allow NASA to do nothing
that
might expose the Earth's biosphere to a potentially hazardous
organism.
Despite his assurances, the National Research Council has
proposed that
the biological safety group be moved from out of NASA control and
placed
in an independent oversight capacity. Given that the National
Review
Council's panel had members from other US government agencies,
you may
expect them to take stands on this matter shortly. Indeed,
since by
statute either the Centers for Disease Control, the National
Institute
of Health, the Surgeon General, or the Army Biological and
Chemical
Warfare Command could by themselves stop NASA in its tracks if
they felt
that the situation warranted it, you may expect NASA to take very
careful measures in order to assure that they don't become
involved.
My understanding is that under the
current scheme John Rummel,
former planetary biology officer for NASA, and now of the
Woods Hole
Oceanographic Institute, will be the planetary quarantine officer
for
Mars, though I am sure that Dr. Morrison will be able to give us
more
information on this. Given the problems that have been
caused by
organisms from East Europe, Asia, and South America which have
been
introduced into US waters through the discharge of waters from
freighters from these areas, I expect the utmost care to be taken
with
all Mars missions.
Best wishes -
EP