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Дата: 24 июля 1998 (1998-07-24)
От: Alexander Bondugin
Тема: Researcher Presents Case For Liquid Water On Mars
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Reseacher presents case for liquid water on Mars
A Biospherics news release
July 21, 1998
Dr. Gilbert V. Levin, Mars Viking Experimenter, reported on
his study that water exists on the Red Planet's surface in
sufficient amounts to sustain microbial life. His findings
were presented to the Annual Meeting of the Society of
Photo-Optical Instrumentation Engineers (SPIE) in San Diego
on Monday. Dr. Levin, President of Biospherics in Beltsville,
Maryland, shared authorship with his son, Dr. Ron Levin,
physicist at the MIT Lincoln Laboratory in Boston. The
importance of the study, Dr. Gilbert Levin said, is that it
clinches the case that his Viking LR experiment found life on
Mars in 1976, a conclusion that he announced in 1997.
In recent years, all arguments against the LR experiment had
been eliminated except the claim that there was no
life-requiring liquid water on the surface of the Red Planet.
Last February, in discussing Mars against the background of
startling new findings of life in hostile Earth environments,
Dr. Wesley Huntress, NASA's Associate Administrator for Space
Science, said: "We used to think that life was fragile, but
wherever liquid water and chemical energy are found, there is
life. There is no exception. Life may be a cosmic
imperative."
Dr. Levin described a dynamic daily cycle on Mars in which
the extreme cold of the Martian atmosphere greatly restricts
its ability to hold water vapor. Thus, the scant water vapor
on Mars is forced down to the surface, where it is deposited
in frozen form. As the sun rises, the ice melts, but its
evaporation is restricted by the low vapor capacity of the
overlying cold atmosphere. Levin cited Pathfinder's results
to show that the atmosphere immediately above the surface
warms considerably, equaling a spring day on Earth, but, just
a couple of feet above the surface, temperatures are
sub-freezing. The warmed surface layer of air absorbs water
vapor until saturated. No more water can then evaporate from
the surface, and the ice remaining there melts into liquid
water. As the sun mounts, the temperature of the atmosphere
above the surface warms sufficiently to permit any remaining
water and ice to evaporate. However, during this daily cycle,
the soil has been moistened with enough water to sustain
microorganisms.
Dr. Levin explained: "Based on Viking and Pathfinder data,
and consistent with the principles of thermodynamics of the
triple point of water, a model has been created for a diurnal
water cycle on Mars. The model predicts the presence of
several tenths of a percent to one percent water moisture in
the topmost layer of the surface material over large regions
of Mars. Images taken by the Viking Lander cameras show
nightly deposits of surface water frost, even snow, verifying
the prediction of the model. Terrestrial experiments in
natural environments, including the Death Valley sand dunes
of California, demonstrated that the amount of soil water
moisture predicted by the model is sufficient to sustain
survival and growth of common soil microorganisms." Levin
states: "This model removes the final constraint preventing
acceptance of the biological interpretation of the Viking LR
Mars data as having detected living microorganisms in the
soil of Mars. It comes at a time when a growing body of
evidence from the Earth and space are supporting the presence
of life not only on Mars, but on many celestial bodies." As a
result, Levin pressed for early Mars biology missions, none
of which is currently planned by NASA, to verify and study
life forms, and for caution in current plans for returning a
Mars sample to Earth.
Under its motto, "Technologies for Information and Health,"
Biospherics' mission is to provide guidance and products to
improve the quality of life. In addition to its BioTechnology
unit, the Company offers telecommunications and database
management information, and proprietary environmental, food
and medical innovations.
For more information, visit the Biospherics Web site
http://www.biospherics.com/mars/spie2/spie98.htm
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Дата: 24 июля 1998 (1998-07-24)
От: Alexander Bondugin
Тема: Mars Global Surveyor Update - July 17, 1998
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Mars Global Surveyor
Flight Status Report
Friday, 17 July 1998
As of today, the Mars Global Surveyor spacecraft has completed
nearly seven weeks of science collection operations since the end of
solar conjunction in late May. During that month, the flight team
suspended science operations because Mars passed behind the Sun as viewed
from the Earth. This geometry physically blocked radio communications
with the spacecraft.
Since the end of conjunction, Surveyor has completed over 100
revolutions around the red planet and has transmitted almost two
gigabytes of scientific information back to Earth. Some of the latest
images released from this summer's science observations include pictures
of a crater that may have contained a lake long ago in Martian history.
Other highlights include laser topography measurements of the North Pole,
and analysis of radio signals sent from the spacecraft to aid the
understanding of the gravity field in the northern hemisphere.
Over the remainder of this summer's science operations,
investigators on Earth will receive their data in less time after
transmission as the Earth to Mars distance decreases from its June 22nd
maximum of 234 million miles (377 million kilometers). At that distance,
2.5 times greater than Earth's distance to the Sun, radio signals from
the spacecraft took 21 minutes to reach Earth. This time delay will
gradually decrease to just under five minutes by next May.
Currently, members of the flight team are preparing for upcoming
activities in the late summer and fall months. In late August and early
September, Surveyor will pass within a thousand miles of the Martian moon
Phobos. This satellite orbits the red planet once every 7.7 hours and is
a potato-shaped rock about the size of Manhattan. During the close
approaches, several of the science instruments are scheduled to make
observations of the moon.
During August, the flight team will also begin training for the
next phase of aerobraking. This phase will begin in mid-September and
last until February 1999. Over the course of those four months, Surveyor
will repeatedly fly through the upper Martian atmosphere and use air
resistance to gradually shrink the size of the orbit. The goal is to
reduce the period from its current value of 11.6 hours to just under two
hours. Global mapping operations from this two-hour orbit will begin in
March or April of next year.
After a mission elapsed time of 617 days from launch, Surveyor is
232.68 million miles (374.46 million kilometers) from the Earth and in an
orbit around Mars with a high point of 11,111 miles (17,881km), a low
point of 109.6 miles (176.4 km), and a period of 11.6 hours. The
spacecraft is currently executing the P430 command sequence, and all
systems continue to perform as expected. The next status report will be
released sometime in August.
Status report prepared by:
Office of the Flight Operations Manager
Mars Surveyor Operations Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
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Дата: 24 июля 1998 (1998-07-24)
От: Alexander Bondugin
Тема: New Mars Global Surveyor Image Of Valles Marineris
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NEW MARS GLOBAL SURVEYOR IMAGE OF VALLES MARINERIS
A new image taken by the Mars Global Surveyor spacecraft of Valles Marineris
is now available on the MGS website:
http://mars.jpl.nasa.gov/mgs/msss/camera/images/7_20_98_marineris_rel/index.ht
ml
More than 4,000 km in length, Valles Marineris is the largest canyon system
in the solar system. Image caption is appended below.
Ron Baalke
Mars Global Surveyor
Mars Orbiter Camera
Mars Orbiter Camera (MOC) High Resolution Images
Western Candor Chasma, Valles Marineris
Mars Global Surveyor Mars Orbiter Camera Release: MOC2-59a, -59b,
-59c, -59d, -59e
Mars Global Surveyor Mars Orbiter Camera Image ID: 568534375.8403
P084-03 (C, below);
576779012.23304
P233-04 (D, below);
577575955.25205
P252-05 (E, below).
(A) [Image]
270 KByte GIF image
(A) The Valles Marineris trough system is more than 4,000 kilometers (2500
miles) in length. Each "Chasma" that makes up the trough system is labeled
above (e.g., Ophir is "Ophir Chasma"). White box indicates the location of
the context image shown below in (B). Three MOC images within this box are
presented in (C), (D), and (E). Picture is a mosaic of Viking Orbiter images
from the U.S. Geological Survey. North is up.
(B) [Image]
113 KByte GIF image
(B) Western Candor Chasma. Small white boxes indicate the approximate
locations of each of the MOC images shown below. Each box is labeled with an
image number--8403 is the third image from Mars Global Surveyor orbit 84
(shown in (C), below); 23304 is the fourth image from orbit 233 (D, below);
and 25205 is the fifth image from orbit 252 (E, below). Picture is a mosaic
of Viking Orbiter images from the U.S. Geological Survey. North is up.
(C) [Image]
136 KByte GIF image
(C) Layers in western Candor Chasma northern wall. MOC image 8403 subframe
shown at full resolution of 4.6 meters (15 feet) per pixel. The image shows
an area approximately 2.4 by 2.5 kilometers (1.5 x 1.6 miles). North is up,
illumination is from the left. Image 8403 was obtained during Mars Global
Surveyor's 84th orbit at 10:12 p.m. (PST) on January 6, 1998.
(D) [Image]
291 KByte GIF image
(D) Layers exposed near the middle of western Candor Chasma. MOC image 23304
subframe shown at 10.7 meters (35 feet) per pixel. Two layered buttes (upper
right and lower right) and a layered or stepped mesa (center right) are
shown. The image covers an area approximately 5.5 by 5.5 kilometers (3.4 x
3.4 miles). North is approximately up, illumination is from the lower right.
Image 23304 was obtained during Mars Global Surveyor's 233rd orbit at 9:23
a.m. (PDT) on April 11, 1998.
(E) [Image]
273 KByte GIF image
(E) Massive (non-layered) material exposed in central Candor Chasma. MOC
image 25205 subframe shown at 11.7 meters (38.4 feet) per pixel resolution.
Image shows the southern tip of a massive "interior deposit" that points
like a giant tongue from Ophir Chasma (to the north) down into the center of
Candor Chasma. The ridged and grooved bright unit is the "interior deposit".
South of this ridged unit is a low elevation surface mantled by dark dunes
and sand. Image covers an area approximately 5.7 by 5.7 kilometers (3.5 x
3.5 miles). North is approximately up, illumination is from the lower right.
Image 25205 was obtained during Mars Global Surveyor's 252nd orbit at 2:45
p.m. (PDT) on April 20, 1998.
You may need to adjust the images for the gamma of your monitor to insure
proper viewing.
Note: This MOC image is made available in order to share with the public
the excitement of new discoveries being made via the Mars Global Surveyor
spacecraft. The image may be reproduced only if the image is credited to
"Malin Space Science Systems/NASA". Release of this image does not
constitute a release of scientific data. The image and its caption should
not be referenced in the scientific literature. Full data releases to the
scientific community are scheduled by the Mars Global Surveyor Project
and NASA Planetary Data System. Typically, data will be released after a
6 month calibration and validation period.
Click Here for more information on MGS data release and archiving plans.
CAPTION
One of the most striking discoveries of the Mars Global Surveyor mission has
been the identification of thousands of meters/feet of layers within the
wall rock of the enormous martian canyon system, Valles Marineris.
Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft,
from which the troughs get their name: Valles--valleys, Marineris--Mariner.
Some hints of layering in both the canyon walls and within some deposits on
the canyon floors were seen in Mariner 9 and Viking orbiter images from the
1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been
examining these layers at much higher resolution than was available
previously.
MOC images led to the realization that there are layers in the walls that go
down to great depths. An example of the wall rock layers can be seen in MOC
image 8403, shown above (C).
MOC images also reveal amazing layered outcrops on the floors of some of the
Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D,
above), which shows extensive, horizontally-bedded layers exposed in buttes
and mesas on the floor of western Candor Chasma. These layered rocks might
be the same material as is exposed in the chasm walls (as in 8403--C,
above), or they might be rocks that formed by deposition (from water, wind,
and/or volcanism) long after Candor Chasma opened up.
In addition to layered materials in the walls and on the floors of the
Valles Marineris system, MOC images are helping to refine our classification
of geologic features that occur within the canyons. For example, MOC image
25205 (E, above), shows the southern tip of a massive, tongue-shaped massif
(a mountainous ridge) that was previously identified as a layered deposit.
However, this MOC image does not show layering. The material has been
sculpted by wind and mass-wasting--downslope movement of debris--but no
obvious layers were exposed by these processes.
Valles Marineris is a fascinating region on Mars that holds much potential
to reveal information about the early history and evolution of the red
planet. The MOC Science Team is continuing to examine the wealth of new data
and planning for new Valles Marineris targets once the Mapping Phase of the
Mars Global Surveyor mission commences in March 1999.
------------------------------------------------------------------------
Malin Space Science Systems and the California Institute of Technology built
the MOC using spare hardware from the Mars Observer mission. MSSS operates
the camera from its facilities in San Diego, CA. The Jet Propulsion
Laboratory's Mars Surveyor Operations Project operates the Mars Global
Surveyor spacecraft with its industrial partner, Lockheed Martin
Astronautics, from facilities in Pasadena, CA and Denver, CO.
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Дата: 24 июля 1998 (1998-07-24)
От: Alexander Bondugin
Тема: New Marathon!
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Every amateur astronomer has heard of the Messier Marathon, the one
night event around the night of March 21. Now there's a new marathon
that anyone (in the northern hemisphere) with a pair of binoculars can
participate in.
To find out how this came about and what objects are on the list (no
Messier objects at all) then visit the ALL NEW eFOCUS at:
http://www.geocities.com/CapeCanaveral/Lab/1000/eFOCUS.html
This would be a great observing session for any astronomy club.
Good Stargazing,
Richard Bell
http://www.geocities.com/CapeCanaveral/Lab/1000/stargazer.html
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Дата: 24 июля 1998 (1998-07-24)
От: Alexander Bondugin
Тема: Galileo Update - July 21, 1998
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MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
GALILEO EUROPA MISSION STATUS
July 21, 1998
The Galileo spacecraft experienced an anomaly during its latest flyby of
<b style="color:black;background-color:#ffff66">Jupiter</b>'s moon Europa. Neither the spacecraft nor its instruments are in
immediate danger. During this encounter, a problem was detected by one of
the spacecraft's two command and data subsystems, which receive commands
from Earth and send back telemetry, or data from the spacecraft. Because
of this, a built-in, fault-protection routine was activated, which put the
spacecraft in a "safe" mode. That means the anomalous command and data
subsystem was shut down, and control was turned over to the identical,
second command and data subsystem. The second subsystem also detected a
problem, but it is programmed to remain active as long as the first
subsystem is not functioning normally.
At 11:14 a.m. Pacific time on Monday, July 20, the problem was reported to
ground controllers, and telemetry was initially lost. By 11:35 p.m.
Pacific time, engineering telemetry from the spacecraft had been restored
and communications are continuing.
Engineers have activated a recovery process designed to tell them why the
problem occurred; it is expected to restore full functioning to both
command and data subsystems. Because of the anomaly, nearly all the data
from yesterday's Europa flyby were lost and no science data will be
gathered until the anomaly is corrected.
Galileo successfully completed its two-year primary mission in December
1997, and is currently in the midst of its two-year extended mission. This
current flyby was the fifth of the extended mission. Three more Europa
flybys are scheduled, with the next one on Sept. 26. A wealth of data and
pictures of Europa have already been gathered during flybys of both the
primary and extended missions.
The Galileo Europa Mission is managed by JPL for NASA's Office of Space
Science, Washington, D.C.
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