| Optical SETI Map | Conferences Map | Illustrations Map | Photo Galleries Map | Observations Map | Constructing Map |
|
Life on Mars?
Date: Wed, 7 Aug 1996 12:51:43 -0400
From: NASA HQ Public Affairs Office <NASANews@luna.osf.hq.nasa.gov>
To: press-release-com@venus.hq.nasa.gov
Subject: Meteorite Yields Evidence of Primitive Life on Early Mars
Donald L. Savage
Headquarters, Washington, DC August 7, 1996
(Phone: 202/358-1727)
James Hartsfield
Johnson Space Center, Houston, TX
(Phone: 713/483-5111)
David Salisbury
Stanford University, Palo Alto, CA
(Phone: 415/723-2558)
RELEASE: 96-160
METEORITE YIELDS EVIDENCE OF PRIMITIVE LIFE ON EARLY MARS
A NASA research team of scientists at the Johnson Space
Center (JSC), Houston, TX, and at Stanford University, Palo
Alto, CA, has found evidence that strongly suggests primitive
life may have existed on Mars more than 3.6 billion years ago.
The NASA-funded team found the first organic molecules
thought to be of Martian origin; several mineral features
characteristic of biological activity; and possible
microscopic fossils of primitive, bacteria-like organisms
inside of an ancient Martian rock that fell to Earth as a
meteorite. This array of indirect evidence of past life will
be reported in the August 16 issue of the journal Science,
presenting the investigation to the scientific community at
large for further study.
The two-year investigation was co-led by JSC planetary scientists
Dr. David McKay, Dr. Everett Gibson and Kathie Thomas-Keprta
of Lockheed-Martin, with the major collaboration of a Stanford
team headed by Professor of Chemistry Dr. Richard Zare, as
well as six other NASA and university research partners.
"There is not any one finding that leads us to believe
that this is evidence of past life on Mars. Rather, it is a
combination of many things that we have found," McKay said.
"They include Stanford's detection of an apparently unique
pattern of organic molecules, carbon compounds that are the
basis of life. We also found several unusual mineral phases
that are known products of primitive microscopic organisms on
Earth. Structures that could be microsopic fossils seem to
support all of this. The relationship of all of these things
in terms of location - within a few hundred thousandths of an
inch of one another - is the most compelling evidence."
"It is very difficult to prove life existed 3.6 billion
years ago on Earth, let alone on Mars," Zare said. "The
existing standard of proof, which we think we have met,
includes having an accurately dated sample that contains
native microfossils, mineralogical features characteristic of
life, and evidence of complex organic chemistry."
"For two years, we have applied state-of-the-art
technology to perform these analyses, and we believe we have
found quite reasonable evidence of past life on Mars," Gibson
added. "We don't claim that we have conclusively proven it.
We are putting this evidence out to the scientific community
for other investigators to verify, enhance, attack -- disprove
if they can -- as part of the scientific process. Then,
within a year or two, we hope to resolve the question one way
or the other."
"What we have found to be the most reasonable
interpretation is of such radical nature that it will only be
accepted or rejected after other groups either confirm our
findings or overturn them," McKay added.
The igneous rock in the 4.2-pound, potato-sized
meteorite has been age-dated to about 4.5 billion years, the
period when the planet Mars formed. The rock is believed to
have originated underneath the Martian surface and to have
been extensively fractured by impacts as meteorites bombarded
the planets in the early inner solar system. Between 3.6
billion and 4 billion years ago, a time when it is generally
thought that the planet was warmer and wetter, water is
believed to have penetrated fractures in the subsurface rock,
possibly forming an underground water system.
Since the water was saturated with carbon dioxide from
the Martian atmosphere, carbonate minerals were deposited in
the fractures. The team's findings indicate living organisms
also may have assisted in the formation of the carbonate, and
some remains of the microscopic organisms may have become
fossilized, in a fashion similar to the formation of fossils
in limestone on Earth. Then, 16 million years ago, a huge
comet or asteroid struck Mars, ejecting a piece of the rock
from its subsurface location with enough force to escape the
planet. For millions of years, the chunk of rock floated
through space. It encountered Earth's atmosphere 13,000 years
ago and fell in Antarctica as a meteorite.
It is in the tiny globs of carbonate that the
researchers found a number of features that can be interpreted
as suggesting past life. Stanford researchers found easily
detectable amounts of organic molecules called polycyclic
aromatic hydrocarbons (PAHs) concentrated in the vicinity of
the carbonate. Researchers at JSC found mineral compounds
commonly associated with microscopic organisms and the
possible microscopic fossil structures.
The largest of the possible fossils are less than 1/100
the diameter of a human hair, and most are about 1/1000 the
diameter of a human hair - small enough that it would take
about a thousand laid end-to-end to span the dot at the end of
this sentence. Some are egg-shaped while others are tubular.
In appearance and size, the structures are strikingly similar
to microscopic fossils of the tiniest bacteria found on Earth.
The meteorite, called ALH84001, was found in 1984 in
Allan Hills ice field, Antarctica, by an annual expedition of
the National Science Foundation's Antarctic Meteorite Program.
It was preserved for study in JSC's Meteorite Processing
Laboratory and its possible Martian origin was not recognized
until 1993. It is one of only 12 meteorites identified so far
that match the unique Martian chemistry measured by the Viking
spacecraft that landed on Mars in 1976. ALH84001 is by far
the oldest of the 12 Martian meteorites, more than three times
as old as any other.
Many of the team's findings were made possible only
because of very recent technological advances in high-
resolution scanning electron microscopy and laser mass
spectrometry. Only a few years ago, many of the features that
they report were undetectable. Although past studies of this
meteorite and others of Martian origin failed to detect
evidence of past life, they were generally performed using
lower levels of magnification, without the benefit of the
technology used in this research. The recent discovery of
extremely small bacteria on Earth, called nanobacteria,
prompted the team to perform this work at a much finer scale
than past efforts.
The nine authors of the Science report include McKay,
Gibson and Thomas-Keprta of JSC; Christopher Romanek, formerly
a National Research Council post-doctoral fellow at JSC who is
now a staff scientist at the Savannah River Ecology Laboratory
at the University of Georgia; Hojatollah Vali, a National
Research Council post-doctoral fellow at JSC and a staff
scientist at McGill University, Montreal, Quebec, Canada; and
Zare, graduate students Simon J. Clemett and Claude R. Maechling
and post-doctoral student Xavier Chillier of the Stanford
University Department of Chemistry.
The team of researchers includes a wide variety of
expertise, including microbiology, mineralogy, analytical
techniques, geochemistry and organic chemistry, and the
analysis crossed all of these disciplines. Further details on
the findings presented in the Science article include:
* Researchers at Stanford University used a dual laser mass
spectrometer -- the most sensitive instrument of its type in
the world -- to look for the presence of the common family of
organic molecules called PAHs. When microorganisms die, the
complex organic molecules that they contain frequently degrade
into PAHs. PAHs are often associated with ancient sedimentary
rocks, coals and petroleum on Earth and can be common air
pollutants. Not only did the scientists find PAHs in easily
detectable amounts in ALH84001, but they found that these molecules were
concentrated in the vicinity of the carbonate globules. This
finding appears consistent with the proposition that they are
a result of the fossilization process. In addition, the
unique composition of the meteorite's PAHs is consistent with
what the scientists expect from the fossilization of very
primitive microorganisms. On Earth, PAHs virtually always
occur in thousands of forms, but, in the meteorite, they are
dominated by only about a half-dozen different compounds. The
simplicity of this mixture, combined with the lack of light-
weight PAHs like napthalene, also differs substantially from
that of PAHs previously measured in non-Martian meteorites.
* The team found unusual compounds -- iron sulfides and
magnetite -- that can be produced by anaerobic bacteria and
other microscopic organisms on Earth. The compounds were
found in locations directly associated with the fossil-like
structures and carbonate globules in the meteorite. Extreme
conditions -- conditions very unlikely to have been
encountered by the meteorite -- would have been required to
produce these compounds in close proximity to one another if
life were not involved. The carbonate also contained tiny
grains of magnetite that are almost identical to magnetic
fossil remnants often left by certain bacteria found on Earth.
Other minerals commonly associated with biological activity on
Earth were found in the carbonate as well.
* The formation of the carbonate or fossils by living
organisms while the meteorite was in the Antarctic was deemed
unlikely for several reasons. The carbonate was age dated
using a parent-daughter isotope method and found to be 3.6
billion years old, and the organic molecules were first
detected well within the ancient carbonate. In addition, the
team analyzed representative samples of other meteorites from
Antarctica and found no evidence of fossil-like structures,
organic molecules or possible biologically produced compounds
and minerals similar to those in the ALH84001 meteorite. The
composition and location of PAHs organic molecules found in
the meteorite also appeared to confirm that the possible
evidence of life was extraterrestrial. No PAHs were found in
the meteorite's exterior crust, but the concentration of PAHs
increased in the meteorite's interior to levels higher than
ever found in Antarctica. Higher concentrations of PAHs would
have likely been found on the exterior of the meteorite,
decreasing toward the interior, if the organic molecules are
the result of contamination of the meteorite on Earth.
Additional information may be obtained at 1 p.m. EDT via
the Internet at
http://www.jsc.nasa.gov/pao/flash/
Date: Thu, 8 Aug 1996 17:20:29 -0700
From: Rick E. Borchelt <rborchelt@OSTP.EOP.GOV>
To: Multiple recipients of list NEWS <NEWS@OSTP.EOP.GOV>
Subject: Clinton statement on Mars meteorite discovery
THE WHITE HOUSE
Office of the Press Secretary
_____________________________________________
For Immediate Release
August 7, 1996
REMARKS BY THE PRESIDENT
UPON DEPARTURE
The South Lawn
1:15 P.M. EDT
THE PRESIDENT: Good afternoon.
I'm glad to be joined by my science and
technology adviser, Dr. Jack Gibbons, to make
a few comments about today's announcement by
NASA.
This is the product of years of
exploration and months of intensive study by
some of the world's most distinguished
scientists. Like all discoveries, this one
will and should continue to be reviewed,
examined and scrutinized. It must be
confirmed by other scientists. But clearly,
the fact that something of this magnitude is
being explored is another vindication of
America's space program and our continuing
support for it, even in these tough financial
times. I am determined that the American
space program will put it's full intellectual
power and technological prowess behind the
search for further evidence of life on Mars.
First, I have asked Administrator
Goldin to ensure that this finding is subject
to a methodical process of further peer
review and validation. Second, I have asked
the Vice President to convene at the White
House before the end of the year a bipartisan
space summit on the future of America's space
program. A significant purpose of this
summit will be to discuss how America should
pursue answers to the scientific questions
raised by this finding. Third, we are
committed to the aggressive plan we have put
in place for robotic exploration of Mars.
America's next unmanned mission to Mars is
scheduled to lift off from the Kennedy Space
Center in November. It will be followed by a
second mission in December. I should tell
you that the first mission is scheduled to
land on Mars on July the 4th, 1997 --
Independence Day.
It is well worth contemplating how
we reached this moment of discovery. More
than 4 billion years ago this piece of rock
was formed as a part of the original crust of
Mars. After billions of years it broke from
the surface and began a 16 million year
journey through space that would end here on
Earth. It arrived in a meteor shower 13,000
years ago. And in 1984 an American scientist
on an annual U.S. government mission to
search for meteors on Antarctica picked it up
and took it to be studied. Appropriately, it
was the first rock to be picked up that year
-- rock number 84001.
Today, rock 84001 speaks to us
across all those billions of years and
millions of miles. It speaks of the
possibility of life. If this discovery is
confirmed, it will surely be one of the most
stunning insights into our universe that
science has ever uncovered. Its implications
are as far-reaching and awe-inspiring as can
be imagined. Even as it promises answers to
some of our oldest questions, it poses still
others even more fundamental.
We will continue to listen closely
to what it has to say as we continue the
search for answers and for knowledge that is
as old as humanity itself but essential to
our people's future.
Thank you.
Date: Fri, 9 Aug 1996 00:27:57 GMT
From: (Sender of message unknown)
Subject: SpaceViews Special Edition: Was There Once Life on Mars?
S P A C E V I E W S
SPECIAL EDITION: Was There Once Life on Mars?
http://www.seds.org/spaceviews/hotnews.html
Contents:
Editorial
Scientists Announce Evidence of Life on Ancient Mars
Clinton Announces "Space Summit"
Goldin Chooses Logic Over Emotion
Space Advocacy Groups Divided Over Future Mars Plans
NRC Report Criticizes NASA's Mars Mission Plans
Future Missions to Mars
How Do We Know It Came From Mars?
Editorial
The events of the last couple days have been very exiciting, at the
risk of understatement. Whether we're seeing one of the "biggest
discoveries in the history of science," as one people put it, or simply one
of biggest scientific controversies or false alarms in recent years, the
news has gotten our attention and forced us to think about its
implications. If life can start on two planets in a modest little solar
system, does it mean the universe is rich in life? Or, are we special in
some incomprehensible way?
This special edition of SpaceViews is designed to provide updated
information on the recent discovery, along with some other information that
might not be easily found in the mass media. More information on the
discovery, as well as other space news, will be printed in a condensed
version of the usual mid-month SpaceViews Update, which will be published
this month on the 20th.
In the meantime, you can get the latest Mars information, including
images and links to other Web sites, on the Web at
http://www.seds.org/spaceviews/hotnews.html
Regards,
Jeff Foust
jeff@astron.mit.edu
Editor, SpaceViews
Scientists Announce Evidence of Life on Ancient Mars
"Today, rock 84001 speaks to us across all those billions of years
and millions of miles. It speaks of the possibility of life."
-- President Bill Clinton
NASA and Stanford University scientists announced Wednesday they
had compelling, but not conclusive, evidence that primitive microscopic
life may have existed several billion years ago on the planet Mars.
At a press conference in Washington Wednesday afternoon, a team of
scientists led by Dr. David McKay of NASA's Johnson Space Center
presented several key pieces of evidence which, put together, "strongly
suggests" that life once existed on the Red Planet.
"There is not any one finding that leads us to believe that this
is evidence of past life on Mars. Rather, it is a combination of many
things that we have found," McKay said.
The Evidence
The team presented four lines of evidence obtained from the
analysis of a meteorite ejected from Mars millions of years ago and
landed on the Antarctic continent over 10,000 years ago.
The first was the confirmation that the meteorite came from Mars,
based on compositional analysis of the rock, and the discovery of
globules of calcium carbonate. These globules formed in cracks in the
rock as the carbonates settled out of solution on the early Mars.
The second line of evidence was the correlation of these globules
with biological activity. Such globules are formed on Earth by
microorganisms, and the size of the globules (250 millionths of a meter,
or five times the thickness of a human hair) is consistent with
terrestrial globules created by living creatures.
A third line of evidence came from the microscopic examination of
the globules. Scientists noticed the globules have alternating white-
and-black rims ("Oreo cookie rims," as one scientist called them)
composed of the minerals magnetite, phyrrhotite and greigite.
Using a transmission electron microscope (TEM), scientist Kathie
Thomas-Keprta was able to study the distinctive shapes and chemical
composition of crystals of these minerals as well as the environment in
which they formed. The characteristics of the crystals closely match
those found on Earth created by microorganisms.
"They may be created by complicated inorganic explanations, but
the simplest explanation is an organic origin," Thomas-Keprta said.
The final, and most controversial, line of evidence was scanning
electron microscope images of the surfaces of the globules. The surfaces
showed a large number of elongated forms which can be explained by
microfossils formed by bacteria or other microorganisms.
The surfaces can also be explained by weathering and other
inorganic processes, but McKay said they favor an organic origin for the
structures seen.
"Skeptical Optimism"
Not everyone was optimistic or enthusiastic as the NASA
scientists. Dr. William Schopf of UCLA, a scientist not part of the
discovery, expressed a "note of caution" about the findings.
Quoting famed astronomer Carl Sagan, Schopf said, "Extraordinary
claims require extraordinary evidence." He applied seven critical tests
of his own on the data, based on the both the meteorite and the organic
samples found within.
While acknowledging that the age and origin of the rock, as well
as the existence of indigenous organic material, was well known, he was
less supportive of the claims of microfossils and biologic origins for
the organic materials.
He noted that the fractures in the meteorite, in which the
globules of organic materials were found, may have been formed when the
meteorite was ejected from Mars by an asteroid impact. If that was the
case, and if the meteorite was subject to high temperatures during that
time, it is unlikely that any organic material found in the meteorite
could have been created biologically on Mars.
He was also less than convinced that the organic materials found
in the meteorite came from living creatures, stating that organic
materials have been found on other meteorites with no biological
formation claimed.
The microfossils claimed by the researchers are also 100 times
smaller than similar microfossils found in terrestrial rocks, according
to Schopf.
Two Viking landers carried experiments designed to look for
microscopic life forms in the Martian soil. After puzzling early
results, scientists concluded no such life forms currently exist on
Mars, at least near the surface.
He concluded that more science was needed to move a biological
explanation for the data "up the probability scale."
Reaction from Goldin, Clinton
Schopf's conclusion was readily agreed by NASA Administrator Dan
Goldin. "This is the most important thing that must be done," he said.
Goldin also appealed for a logical, scientific approach to future
work, rather than making any appeals to emotion. "We will be governed by
scientific thought and principles and not emotion," Goldin said.
President Clinton also expressed his support for further research
on the possibility of ancient Martian life. Speaking shortly before
traveling to California on a campaign trip, he said, "Like all
discoveries, this one will and should continue to be reviewed, examined
and scrutinized. It must be confirmed by other scientists."
"The fact that something of this magnitude is being explored is
another vindication of America's space program and our continuing
support for it, even in these tough financial times," Clinton said. "I
am determined that the American space program will put its full
intellectual power and technological prowess behind the search for
further evidence of life on Mars."
Clinton used the opportunity to announce the creation of a bi-
partisan "space summit" led by Vice President Al Gore, which will meet
later this year. "A significant purpose of this summit will be to
discuss how America should pursue answers to the scientific questions
gotoraised by this finding," Clinton said.
Implications
Although the results announced today were not conclusive,
scientists were clearly very optimistic about the implications of the
data.
"If it [life] originated in this solar system, and on more than
one planet in the solar system," said NASA official Wesley Huntress,
"why wouldn't it originate in other solar systems?"
Acknowledging the highly unlikely but not impossible hypothesis of
cross-pollenation of primitive lifeforms between the two young worlds,
Stanford chemist Dr. Richard Zare said, "Who is to say we are not all
Martians?"
Clinton Announces "Space Summit"
Making a rare public statement about space, President Bill Clinton
praised NASA for its efforts to help discover evidence of long-ago life
on Mars and used the occasion to announce a "space summit" later this
year.
"The fact that something of this magnitude is being explored is
another vindication of America's space program and our continuing
support for it, even in these tough financial times," Clinton said in a
brief statement.
Clinton was speaking on the South Lawn of the White House before
departing on a campaign trip to California. He was accompanied by
science and technology advisor Dr. Jack Gibbons.
Clinton used the statement to outline a three-item plan for
continued investigation of the possibility that Mars once harbored
primitive life.
The first part of Clinton's plan is to confirm the initial
findings of the NASA team that made Wednesday's announcement. "I have
asked Administrator Goldin to ensure that this finding is subject to a
methodical process of further peer review and validation," Clinton said.
Like all discoveries, this one will and should continue to be
reviewed, examined and scrutinized," Clinton said. "It must be confirmed
by other scientists." The second part of Clinton's plan is his
announcement of a "space summit" later this year to discuss the future
of the space program. The bipartisan summit will be organized by Vice
President Al Gore and will be held at the White House.
"A significant purpose of this summit will be to discuss how
America should pursue answers to the scientific questions raised by this
finding," Clinton said.
The third part of Clinton's plan is to continue with NASA's series
of robotic Mars missions, including two scheduled for later this year:
Mars Pathfinder, a small lander with rover; and Mars Global Surveyor, an
orbiter designed to be a partial replacement of the failed Mars Observer
spacecraft.
Clinton took time for several questions after his statement, but
none of them were space-related. Two dealt with the abortion issue and
the Republican party, and one reporter asked him about his tie.
Clinton even made a joke about the discovery and future NASA
mission plans. Refering to the Mars Pathfinder mission, and making an
implicit reference to a blockbuster movie about an alien invasion of
Earth, he said, "I should tell you that the first mission is scheduled
to land on Mars on July the 4th, 1997 -- Independence Day."
Clinton did take a moment to look at the implications of the
possible discovery of ancient Martian life. "If this discovery is
confirmed, it will surely be one of the most stunning insights into our
universe that science has ever uncovered," he said. "Its implications
are as far-reaching and awe-inspiring as can be imagined."
"Today, rock 84001 speaks to us across all those billions of years
and millions of miles. It speaks of the possibility of life."
Goldin Chooses Logic Over Emotion
In a theme repeated throughout Wednesday's press conference, NASA
Administrator Dan Goldin emphasized that the emotional impact of the
possible discovery of ancient life on Mars will not impact future plans
for the space agency.
"We will be governed by scientific throught and principles and not
emotion," Goldin said during the press conference. "We will not do
anything irresponsible."
Goldin did admit, though, that the scientific outcome of current
and followup work may cause NASA to revise its schedule of planned
robotic missions to Mars by moving a planned sample return mission up
several years.
"We may have to accelerate our scientific activities," Goldin
said, and mentioned that a sample return mission, planned for 2005, may
be moved up to 2001.
Throughout the press conference, Goldin emphasized that despite
the historic significance of the discovery, if confirmed, the ten-year
plan of robotic missions to Mars would be unaltered unless scientists
believe that a different set of priorities should be adopted. "We will
be driven by a scientific process and not a rush to go to Mars," he
said.
Goldin addressed the possibility of cross-contamination between
Earth-based and any Martian lifeforms by noting that there are strict
procedures for sterilization of Mars-bound spacecraft and contamination
prevention procedures on Earth. "We would rather not have a mission go
until we are sure there is no front or back contamination," he said.
"That is non-negotiable."
Goldin rejected suggestions that this discovery might allow NASA
to increase its shrinking budget. "Let's not think in the old-think that
money is the magic ingredient," he said.
While maintaining a logical course for the space agency's Mars
program, he did not contain his personal enthusiasm for the event. "What
a time to be alive!" he announced. "In the last year we've discovered
planets around nearby stars, we've probed to the depths of the universe
to see the formation and birth of galaxies. And today, we are on the
threshold of establishing that life is not unique to planet earth."
"As a small boy," Goldin said, "my father took me to the Hayden
Planetarium in New York City. And I'll never forget that first view of
the heavens that was interpreted to me. And last night, I called my
father in Florida, who isn't feeling too well lately. And when I told
him what was about to happen today, I could hear the vibrancy in his
voice."
"And if this meeting did anything, it helped my father feel
better."
Space Advocacy Groups Divided Over Future Mars Plans
Wednesday's announcement about the possible discovery of life on
ancient Mars has resulted in sharply different responses from two space
advocacy groups.
The National Space Society has announced its support of efforts to
"get aggressive" and expand NASA's program of Martian exploration, while
the Space Frontier Foundation announced its opposition to any expanded
government-supported Mars exploration program, preferring to see private
organizations take up the slack.
"Our future in space has become more clear," NSS president Charlie
Walker said. "What has long been science fiction has changed overnight.
We now have compelling evidence for life beyond our shores and now we
have to set sail."
"We hope that what we learn... will mobilize our nation and its
political leaders, as well as galvanize NASA and the science community,
to accept the challenge that has been before us since our Apollo
journeys to the Moon: to initiate a program to send human explorers to
the Red Planet," said aerospace engineer Robert Zubrin, chairman of
NSS's executive committee.
NSS officials hope that the discovery wil result in "expressions
of intent by the political parties and their candidates before the end
of the campaign season as to what they intend to do in the near term to
plan the nation's long-term commitment to a systematic study of the
Martian planet," in the words of Apollo 11 astronaut Buzz Aldrin, who
serves as chairman of the NSS's board of directors.
The NSS released Wednesday a four-part call for action in response
to the discovery. The plan calls for the organization to:
* ask NASA to re-evaluate its Mars mission strategy, with a
special emphasis on moving up the date of a Mars sample return mission;
* support President Clinton's call for a bi-partisan "space
summit" later this year;
* focus on Mars exploration with a logical, well-thought-out
series of missions; and
* recommend Martian landing sites where drilling of up to 30
meters (100 feet) or more is possible, in an effort to look for existing
life on the planet hidden deep under the surface
"Like all discoveries, this one will and should continue to be
reviewed, examined and scrutinized," Clinton said. "It must be confirmed
by other scientists."
While the NSS pushed for an expanded, vigorous government-led
program of Mars exploration, the Space Frontier Foundation issued a call
again any "massive international program to explore Mars."
Citing the high costs of proposed robotic and human Mars missions,
the organization believes empowering private organizations to operate
Mars missions is the best policy.
"NASA's traditional plans to return a sample of Mars soil would
cost around $8 billion," said Rick Tumlinson, president of the SFF. "A
far better way would be for the space agency to procure soil samples
from private firms, which are better equipped to mount low cost missions
than the government."
"We believe this would cost the taxpayers a tenth of the
traditional government-does-it-all approach."
The SFF proposes that the U.S. offer to buy Martian soil samples
fom American firms. The government would only pay money for delivered
soil samples, thus avoiding the possibility of spending billions of
dollars on a spacecraft and launch vehicle and not have it operate
properly.
"We can spend tens of billions of dollars today on a series of
huge international projects that might someday in the future repeat the
old Apollo flags and footsteps stunt in the red sands of Mars,"
Tumlinson said, "or we can toss out the old way of doing things, save
billions, get there faster and create a new and vital space industry
that can provide the infrastructure we need to permanently open the
space frontier to our children."
The Space Frontier Foundation is a grassroots organization based
in New York City. It is "dedicated to opening space to economic
development and human settlement as soon as possible."
The National Space Society is also a grassroots organization,
based in Washington, D.C. and claiming a membership worldwide of over
27,000 people.
NRC Report Criticizes NASA's Mars Mission Plans
In a report released this week, the National Research Council
criticized some aspects of upcoming NASA robotic missions to Mars, claiming
that the missions were not sophisticated enough to do the thing that is now
of the greatest interest among researchers: look for signs of past life on
the red planet.
"Cost and payload limitations imposed on Mars Surveyor's small
landers might prevent the flight of advanced rovers capable of adequate
sampling of the rock record," the Committee on Planetary and Lunar
Exploration (COMPLEX), part of the NRC, concluded in its report.
"Because evidence for past climate changes and ancient life, if
any, is most likely embedded in the rocks, this is a major shortcoming,"
they added.
The problem, according to the report, is that the planned series of
Mars Surveyor missions, scheduled for approximately every two years between
this November and 2005, are strongly constrained by the need to keep costs
down. This requires cheaper, less powerful boosters, and hence a smaller
spacecraft.
This problem could be remedied by developing lightweight but
powerful scientific instruments for the spacecraft, but funding for
instrument development is not a priority. "Because funding within the
Surveyor program is too limited to foster significant development of
so-called microinstruments, the scientific objectives of the program could
be seriously undermined unless instrument development is externally
supported," the committee reported.
The small size of the rovers, such as the microrover "Sojourner"
that is part of this fall's Mars Pathfinder mission, will make exploration
of the surface and the search for clues of past life difficult. "A...
concern is that as the program progresses it may become increasingly
difficult to make major discoveries with the small landers currently
envisaged."
"In any transition to more ambitious missions, including sample
return, long-range rovers equipped with significant instrumentation may be
necessary for the definitive resolution of questions concerning past
climates and history."
The committee made a number of recommendations that would enhance
the scientific goals of the missions and make it more feasible to discover
evidence of life on the planet. Those recommendations included developing
larger, more advanced rovers; starting an "aggressive" program for
developing small instruments; keeping the plans for upcoming missions
flexible; and to seek out international cooperation wherever possible.
Despite the committee's criticism of certain aspects of the Mars
Surveyor missions, they were generally pleased with the possible scientific
results themissions will provide. "The Mars Surveyor program... provides a
major opportunity to broaden and deepen our understanding of Mars -- its
atmosphere and climate, its geochemistry and geophysics, and, to a somewhat
lesser extent, its present and past potential for harboring life."
The committee also praised the general plan of the program, where
missions are spread out over a ten-year period. This strategy, as opposed
to launching a few large spacecraft, allows mission planners to take bolder
risks.
Future Missions to Mars
Within six months of the announcement of the discovery of possible
life on ancient Mars, three spacecraft will be on their way to the Red
Planet. However, these spacecraft will not be a response to the discovery,
but rather the first wave in a ten-year plan for robotic exploration of
Mars.
While a plan is already in place, NASA Administrator Dan Goldin
acknowledged Wednesday that the discovery may force a revision in those
plans, including moving up the date of a Mars sample return mission, if it
can be scientifically justified.
The armada begins this November, with the launch of Mars Global
Surveyor from Cape Canaveral atop a Delta II rocket. The 665-kg (1,460-lb.)
spacecraft is a partial replacement for the Mars Observer spacecraft, which
failed shorly before arriving at Mars in August 1993.
Mars Global Surveyor will cruise for 10 months before entering into
polar orbit around Mars. after it achieves its final orbit around the
planet in earl 1998, it will start a systematic study of the planet using
its six on-board instruments, which include a high-resolution camera,
magnetometer, laser altimeter, thermal emission spectrometer, and
ultra-stable oscillator for radio science experiments.
The following month, NASA will launch the Mars Pathfinder mission.
One of the original Discovery-class low-cost missions, the small spacecraft
will race ahead of Mars Global Surveyor and arrive at Mars on July 4, 1997.
The spacecraft will then land on the planet, using a combination of
parachutes and airbags to slow its descent and cushion its landing on the
planet. The spacecraft carries three instruments -- a camera, an alpha
proton x-ray spectrometer, and a meteorology package -- to study the
planet.
In addition to the instruments, Mars Pathfinder carries a
microrover named Sojourner. The 16-kg (35-lb.) rover, named after
abolitionlist Sojourner Truth in a student contest last year, will use the
spacecrafts spectrometer to sample rocks and determine their chemical
composition.
Because Mars is too far away from Earth to allow for real-time
navigation of the rover, Sojourner has its own autonomous navigation system
that allows it to move around rocks and other obstacles and avoid any
dangerous regions.
While the Americans launch two spacecraft, Russia restarts its Mars
exploration program with the Mars 96 mission. An all-purpose mission, the
spacecraft includes an orbiter, two landers, and two surface penetrators.
As part of the growing international cooperation among the world's
space agencies, American and Russian scientists will be working on the Mars
96 project, and the Mars Global Surveyor spacecraft will help relay data
from the Mars 96 surface spacecraft back to Earth using a dedicated relay
mounted on the spacecraft.
The next wave of Mars spacecraft will launch in 1998. They include
Mars Surveyor '98 Orbiter, a follow-up mission to Mars Global Surveyor;
Mars Surveyor '98 Lander; which is planned to be the first spacecraft to
land on Mars's polar caps; and Planet B, the first Japanese mission to
Mars.
Future American missions are planned for the launch opportunities
in 2001, 2003, and 2005, cumulating in 2005 with the launch of a sample
return mission.
Wednesday's announcement of possible life on ancient Mars may move
the launch date of a sample return mission up by several years, however.
NASA Administrator Goldin acknowledged that the sample return mission may
be moved up if there is a scientific justification for it.
"We may have to accelerate some activities," he said, saying a
sample return mission could be moved up to as early as 2001.
Goldin also supported international cooperation in future robotic
missions to Mars. "I believe it [a sample return mission] will be a
worldwide mission," he said.
How Do We Know It Came From Mars?
A common question asked by the public after Wednesday's
announcement of evidence of life on ancient Mars based on the analysis
of a Martian meteorite was simply, "How do we know the meteorite came
from Mars?"
The answer comes from a Sherlock Holmes-like detective story,
where scientists eliminated all impossible sources for a class of
meteorites leaving Mars, as improbable as seemed, as the source.
There are about a dozen meteorites that fall under a
classification known as "SNC", pronounced "snick." SNC is an acronym for
Shergottite, Nakhlite, and Chassigny, three similar classes of
meteorites that are quite different from all other known classes of
meteorites.
In the mid-1970s, studies of the nakhlite class of meteorites
showed they were much younger than typical meteorites, with an average
age of only about 1.3 billion years, billions of years younger than
other small meteorites. The chemical composition of these objects was
also unusual, with abundances of rare-earth and other elements more
typical of the Earth than of other meteorites.
The first proposals that the SNC meteorites were from Mars came in
the late 1970s. These proposals were formed by process of elimination:
all other parent bodies for these meteorites were rejected to their
chemical composition or orbital dynamics.
New experimental techniques in the mid-1980s provided the first
solid proof that the SNC meteorites came from Mars. Scientists were able
to study tiny pockets of Martian air trapped inside of these meteorites.
The ratios of isotopes of argon and xenon, two noble gases, found in the
meteorites were very similar to ratios measured by the Viking spacecraft
on Mars.
More substantial proof came soon after, when researchers found an
enrichment of the isotope nitrogen-15. This enrichment was very similar
to what is found in Mars's atmosphere, and is not found anywhere else in
the solar system.
Although Mars was pinned down as the source of the SNC's, the
mechanism for removing the rocks from the Martian surface and bringing
them to Earth was still unknown. By the late 1980s, Ann Vickery and Jay
Melosh at the University of Arizona found that ejection by a large
impact was the most likely method for removing the rocks from Mars.
Vickery and Melosh proposed that a single impact event around 200
million years ago ejected all the known SNC meteorites, which traveled
through space for millions of years before reaching the Earth.
-------------
End of SpaceViews Special Edition
| ||||||