Re: Mars-Klimawechsel verblüfft Astronomen

Geschrieben von IT Oma am 22. August 2002 03:15:01:

Als Antwort auf: Re: Pluto-Atmosphäre verblüfft Astronomen geschrieben von Joachim am 21. August 2002 19:56:28:

>Danke Oma. Habe letztes Jahr, weiß nicht mehr wo,
>gelesen, daß sich auch die Marsathmosphäre aufheizt. Es war
>jedenfalls ein NASA-Artikel.
>
>MfG
>Joachim

Hallo Joachim,
ist zwar nur ABC, aber trotzdem interessant zur Klimaänderung auf dem Mars:

"ABC-News 07.12.2001

Red Planet Warming
Images Show Mars' Ice Caps Are Melting Fast

By Amanda Onion

Dec. 7 - It might seem like the weather's getting
warmer here on Earth, but Mars appears to have an even
bigger global warming problem.

High-resolution images snapped by NASA's Mars Global
Surveyor show that levels of frozen water and carbon
dioxide at the Red Planet's poles have dwindled
dramatically - by more than 10 feet - over a single
Martian year (equivalent to 687 days or about two
Earth years).
Touring Mars in a Parka?

Michael Caplinger of San Diego's Malin Space Science
Systems points out that if the warming were to
continue at the same rate (that's a big "if"), Mars
could become a nearly inhabitable place for people
within 5,000 years or so.

"Rather than wearing a spacesuit, you could get away
with wearing just an oxygen mask and a thick parka,"
said Caplinger, who co-authored a study about the
observations in this week's issue of Science. "It
would be like standing on top of Everest."

The change in climate could also support the presence
of more liquid water on Mars.

The evidence came by monitoring icy pits, ridges and
mounds at Mars' south pole at the start and end of a
Martian year. By comparing images in 1998 and 2001,
the team noticed a dramatic widening of pits in the
frozen mass and a shrinking of the mounds and ridges.
The images were captured and relayed by NASA's robotic
orbiter, the Surveyer, which was launched in 1996 and
began orbiting Mars in 1997.

"We weren't expecting to see something nearly this
large," said Caplinger.

Driving Warm and Wet Cycles

Caplinger and lead author Michael Malin, also of Malin
Space Science Systems, suggest that the dwindling
layers of frozen carbon dioxide could be sublimating
(changing from solid to gas the same way ice cubes
shrink over time in a freezer) and contributing carbon
dioxide gas to the Martian atmosphere.

More carbon dioxide gas in the air would create a
denser atmosphere. And a denser atmosphere insulates
the planet and leads to warmer temperatures and higher
evaporation points for carbon dioxide and water.

As Caplinger explains, the dramatic change observed at
Mars' south pole could help scientists understand why
images taken of the Red Planet's surface show signs of
former lakes and rivers.

These markings suggest the planet was once much warmer
and wetter, with a thicker atmosphere. Scientists are
not sure what caused that to change, but this evidence
indicates such changes could happen rapidly on Mars.

"We know that the pits we see at the surface today are
not very old, and that they will not last very long,"
said Malin. "These layers of carbon dioxide are very
ephemeral on a geological timescale."

CO2 Snow: It's Not Fluffy

Mars might not only change dramatically from year to
year, it also appears to host very extreme seasons.

In a separate study published this week in Science,
researchers analyzed the surface of Mars using a laser
instrument on the Mars Surveyor and found the planet
loses up to a third of its ice caps - tons of ice -
every summer.

The six-month-long Martian winter, meanwhile, hosts
chilling carbon dioxide snowfalls. By combining
Surveyor's laser data, the team learned carbon dioxide
snowfalls don't produce the same kind of powder that
skiers crave.

"It's not fluffy snow," said Maria Zuber of the NASA
Goddard Space Flight Center and the Massachusetts
Institute of Technology. "It's almost like when snow
melts and then gets very icy at the end of the winter.
So the density is about that of water ice, but
denser."

And, much like the weather here on Earth, Zuber and
her colleague Gregory Neumann learned that weather on
Mars is unpredictable and influenced by many factors.

For example, the team observed a sudden dust storm
over Mars' south pole led to a spike in temperatures
at the other side of the planet from about -188
degrees Fahrenheit to (a not much warmer) -135
degrees.

"It shows that most of our models of Martian weather
are probably too simple," said Zuber. "Whenever you go
in and look at things more closely, you find out
they're a lot more complicated than you thought."

Gruß
ITOma

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