The M.A.S.
Newsletter
Journal of the
Mauritius Astronomical Society
July 2000
The Next Meeting:
The next meeting will be due on
Sunday 16th of July at 17:00 on the beach at Belle Mare (East) for the
observation of the lunar eclipse. Note that the eclipse is observable from anywhere on the
island with a clear view towards the east. Food will be on a bring and share basis. The
meeting scheduled for the 28th of July has been cancelled.
The sky this month:
Maximum of the Alpha Capricornides
meteor shower on the 31st, very thin crescent moon visible in the morning. More
news to come about the coming lunar eclipse.
Mixed News:
Mars may have two to three times as much water today
than planetary scientists previously believed, one scientist has concluded in a new
research paper. In a report to be published in the July 15 issue of the journal
Geophysical Research Letters, Laurie Leshin of Arizona State University says that enriched
levels of a hydrogen isotope may have thrown off past estimates of the amount of water
Mars has lost. Scientists have estimated the amount of water Mars lost by measuring the
amount of hydrogen and deuterium, an isotope of hydrogen with one proton and one neutron
in its nucleus, versus the sole proton in the hydrogen atom. Like hydrogen,
deuterium can combine with oxygen to form water molecules, known in this case as
"heavy water". Spacecraft measurements of hydrogen isotopes in water vapour in
the Martian atmosphere show that the ratio of deuterium to hydrogen (D-to-H) in it is five
times higher than in terrestrial water. Since the lighter hydrogen is lost to space
more easily than deuterium, scientists had believed that Mars lost up to 90% of its
initial stocks of water to achieve the D-to-H ratio observed. This result is based on the
assumption that Mars had the same initial D-to-H ratio as the Earth when the atmospheric
loss began. This assumption has been challenged by new work by Leshin, who measured the
D-to-H ratio in a sample of the Martian meteorite QUE94201, found in Antarctica in 1994
three million years after being blasted off the surface. The meteorite contains
water-bearing crystals that come from the interior of the planet. Since water in
those crystals would not have been affected by atmospheric loss, it should provide a
measure of the planet's
initial D-to-H ratio. To the surprise of scientists, the meteorite data shows Mars had a
D-to-H ratio twice as high as the Earth's before atmospheric escape started. Since the
initial D-to-H ratio was already higher than Earth's, Mars needed to lose less water to
reach the modern ratio. Leshin estimates that the planet may have two to three times as
much water than previously thought, and that the water is likely located somewhere in the
Martian crust. That water may be in the form of groundwater reservoirs that create the
"seepage" landforms seen in over one hundred places on the Martian surface,
according to landmark findings from the Mars Global Surveyor mission released last
Thursday. However, Leshin cautioned that while the results tell us Mars has more
water than originally thought, it does not tell us exactly how much water still exists on
and within the planet. This result is the latest in a series of recent discoveries that
have bolstered beliefs that Mars not only had large amounts of water in the past, it has
retained a significant amount to the present day. In addition to the recent Mars
Global Surveyor results, other Arizona State University scientists studying Martian
meteorites concluded that the planet did once have salty oceans of liquid water, like the
Earth today.
A privately-funded prototype of a potential
future Mars habitat has been completed and is ready for tests in the Canadian Arctic, the
Mars Society reported late last month. The Flashline Mars Arctic Research Station
was completed last month in Colorado after a flurry of activity to get the facility
completed in time to be airlifted this week to Devon Island in the Canadian Arctic, home
to a research center in a region that closely resembles the terrain of Mars. The
habitat will be assembled over the next few weeks and inaugurated July 20 before beginning
a three-week shakedown test. The facility, designed to test technologies that could
be used in a future human Mars habitat, was paid for through corporate sponsorships,
grants, as well as donations by members of the Mars Society.
Astronomers have discovered what they believe to be
hydrogen that dates back nearly to the Big Bang, a discovery that may confirm current
theories about the composition of the universe. Astronomers detected deuterium, an
isotope of hydrogen, locked in molecules of hydrocyanic acid along with carbon and
nitrogen, in the Sagittarius A cloud just 30 ly from the center of the Milky Way and
25,000 ly from the Earth. The amount of deuterium in the cloud, and the proportion of
it to other elements, led them to conclude the deuterium dates back to just a few minutes
after the Big Bang. Using the deuterium abundance along with theoretical models,
astronomers believe that about 4% of the mass-energy of the universe is in the form of
ordinary matter. This closely matches other recent studies, which have put the
amount of ordinary matter at about 5% of the density of the universe.
Serge Florens,
Secretary
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