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(Drops of) Water on Mars!



 
 
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  #1  
Old March 27th 09, 06:58 PM posted to sci.astro
Bluuuue Rajah
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Posts: 299
Default (Drops of) Water on Mars!


(Drops of) Water on Mars!

http://www.skyandtelescope.com/commu.../41728642.html

When English poet Samuel Taylor Coleridge penned "Water, water
everywhere, and not a drop to drink" more than 200 years ago, he could
not possibly have foreseen how aptly this now-famous line might describe
the polar plain where NASA's Phoenix spacecraft touched down last year.

The Robotic Arm Camera on NASA's Phoenix Mars Lander captured this image
underneath the lander, showing smooth surfaces cleared from overlying
soil by the rocket exhaust during landing. The two level, overexposed
surfaces in the center, plus the shadowed one at lower left, were
scoured clean by rocket exhaust and are almost certainly exposures of
water ice.

NASA / JPL / Univ. of Arizona / Max-Planck Inst.

The robotic prospector went looking for Martian ice and found it in
abundance. A camera on the craft's robotic arm glimpsed slabs of ice
directly beneath the main chassis. Apparently the lander's descent
rocket had scoured away a few inches of loose grit to expose the icy
bedrock. However, repeated attempts to deposit a sample of ice into any
of several instrumental hoppers failed. The rock-hard slab proved
difficult to scrape, and the clumpy soil above it clung tenaciously to
the sampling scoop or clogged the instruments' inlets with unyielding
clods.

Yet the Phoenix scientists caught an unexpected break. The superheated
exhaust also splashed small bits of mud onto the craft's landing struts
— little beads of material that grew, merged, and even dripped over the
next few weeks. Those dynamic blobs must have been drops of concentrated
sal****er, concludes a large scientific team led by Nilton Renno, a
Phoenix investigator at the University of Michigan.

Renno presented his case today at a meeting of planetary scientists near
Houston, Texas. Liquid water would hardly be expected at the north-polar
landing site, where the temperature never climbed above -5°F (-20°C)
during five months of operation. For example, images showed that
whenever the lander's mechanical scoop unearthed fresh exposures of ice,
it quickly sublimated (vaporized) directly into the atmosphere.

Droplets on a leg of the Phoenix lander enlarge and coalesce in this
image sequence taken on sols (Martian days) 8, 31, and 44 following the
craft's arrival in the north polar region of Mars last year.
NASA / JPL / Univ. of Michigan / Max Planck Inst.The key to keeping
water from freezing, Renno explained, was the discovery that the silty,
clumpy soil in the landing zone contains abundant chlorine-rich salts
called perchlorates. Through a process called deliquescence, the salty
spatter on the landing strut absorbed enough water vapor directly from
the thin Martian air to liquefy. These droplets of concentrated brine
freeze at temperatures some 125°F (70°C) lower than that for water
alone.

According to Renno, the droplets grew in size at just the right rate to
match theoretical predictions. This growth diluted the salt content and
made them more susceptible to nighttime freezing. After some six weeks,
the beads' enlargement stopped, suggesting that they'd reached balance
with the relative humidity of the surrounding air. Toward the mission's
end, they shrank somewhat, a sign that the droplets were slowly
desiccating.

Supersonic exhaust from the Phoenix lander's braking rockets had a
temperature of more than 1,800°F (1,000°C).

NASA / JPL / Univ. of Arizona

Although scientists are now convinced that liquid water must have once
existed on the Red Planet, it's a surprise to find it in one of the
planet's coldest environments. Emboldened by this discovery, Renno now
believes that supersalty brines might be common on Mars.

Does this mean present-day has suddenly blossomed into an abode for
life? Not exactly, though in a follow-up presentation astrobiologist
Carol Stoker (NASA-Ames Research Center) rated the Phoenix site as far
more bio-friendly than any other Martian landing site to date.

Read more about the case for liquid Martian sal****er in this University
of Michigan press release.
  #2  
Old March 27th 09, 09:44 PM posted to sci.astro
BradGuth
external usenet poster
 
Posts: 21,544
Default (Drops of) Water on Mars!

On Mar 27, 9:58*am, Bluuuue Rajah Bluuuuue@Rajah. wrote:
(Drops of) Water on Mars!

http://www.skyandtelescope.com/commu.../41728642.html

When English poet Samuel Taylor Coleridge penned "Water, water
everywhere, and not a drop to drink" more than 200 years ago, he could
not possibly have foreseen how aptly this now-famous line might describe
the polar plain where NASA's Phoenix spacecraft touched down last year.

The Robotic Arm Camera on NASA's Phoenix Mars Lander captured this image
underneath the lander, showing smooth surfaces cleared from overlying
soil by the rocket exhaust during landing. The two level, overexposed
surfaces in the center, plus the shadowed one at lower left, were
scoured clean by rocket exhaust and are almost certainly exposures of
water ice.

NASA / JPL / Univ. of Arizona / Max-Planck Inst.

The robotic prospector went looking for Martian ice and found it in
abundance. A camera on the craft's robotic arm glimpsed slabs of ice
directly beneath the main chassis. Apparently the lander's descent
rocket had scoured away a few inches of loose grit to expose the icy
bedrock. However, repeated attempts to deposit a sample of ice into any
of several instrumental hoppers failed. The rock-hard slab proved
difficult to scrape, and the clumpy soil above it clung tenaciously to
the sampling scoop or clogged the instruments' inlets with unyielding
clods.

Yet the Phoenix scientists caught an unexpected break. The superheated
exhaust also splashed small bits of mud onto the craft's landing struts
— little beads of material that grew, merged, and even dripped over the
next few weeks. Those dynamic blobs must have been drops of concentrated
sal****er, concludes a large scientific team led by Nilton Renno, a
Phoenix investigator at the University of Michigan.

Renno presented his case today at a meeting of planetary scientists near
Houston, Texas. Liquid water would hardly be expected at the north-polar
landing site, where the temperature never climbed above -5°F (-20°C)
during five months of operation. For example, images showed that
whenever the lander's mechanical scoop unearthed fresh exposures of ice,
it quickly sublimated (vaporized) directly into the atmosphere.

*Droplets on a leg of the Phoenix lander enlarge and coalesce in this
image sequence taken on sols (Martian days) 8, 31, and 44 following the
craft's arrival in the north polar region of Mars last year.
NASA / JPL / Univ. of Michigan / Max Planck Inst.The key to keeping
water from freezing, Renno explained, was the discovery that the silty,
clumpy soil in the landing zone contains abundant chlorine-rich salts
called perchlorates. Through a process called deliquescence, the salty
spatter on the landing strut absorbed enough water vapor directly from
the thin Martian air to liquefy. These droplets of concentrated brine
freeze at temperatures some 125°F (70°C) lower than that for water
alone.

According to Renno, the droplets grew in size at just the right rate to
match theoretical predictions. This growth diluted the salt content and
made them more susceptible to nighttime freezing. After some six weeks,
the beads' enlargement stopped, suggesting that they'd reached balance
with the relative humidity of the surrounding air. Toward the mission's
end, they shrank somewhat, a sign that the droplets were slowly
desiccating.

Supersonic exhaust from the Phoenix lander's braking rockets had a
temperature of more than 1,800°F (1,000°C).

NASA / JPL / Univ. of Arizona

Although scientists are now convinced that liquid water must have once
existed on the Red Planet, it's a surprise to find it in one of the
planet's coldest environments. Emboldened by this discovery, Renno now
believes that supersalty brines might be common on Mars.

Does this mean present-day has suddenly blossomed into an abode for
life? Not exactly, though in a follow-up presentation astrobiologist
Carol Stoker (NASA-Ames Research Center) rated the Phoenix site as far
more bio-friendly than any other Martian landing site to date.

Read more about the case for liquid Martian sal****er in this University
of Michigan press release.


No Mars surface water, no Mars brines of h2o2. Thus far Mars hasn't
exposed 0.1% the salt that we have to work with, perhaps because of
the lack of nitrogen.

Give us something else to fathom.

~ BG
 




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