What this means of course is that Mercury is well situated for the
creation of an underground habitat with ample raw materials available
for sustaining life. Last week we had hard evidence that an
artificial rectangular pit had been built on the surface to depth and
likely to provide access to space transports and to protect them from
the external flux. Unless it is somehow faked, NASA's silence on it
is telling and compares to their silence on Phobos.
Been a clam is an effective strategy if you do not wish to encourage
public speculation.
In 2007, I did a quick calculation regarding the decline of Arctic
Sea Ice and came to the conclusion that it would reach crash and burn
by 2012, not the decades everyone was touting at the time. I spent
some money and put my prediction up on the wire services to see who
would salute. Lo and behold, shortly thereafter, NASA released a
statement say effectively the same thing. Someone did not want to
look like a donkey and my wire release obviously allowed his release
to go out. Needless to say the Arctic Sea Ice has done everything I
expected.
My point is that NASA manages the news very carefully.
We may have a monolith on Phobos begging explanation but we also now
have a Space Port on Mercury. Just when do we start admitting as
much or alternatively demonstrate that we have a reason for our
error?
Water and Organic
Material Discovered on Mercury
By Adam Mann
November 29, 201
Image: The north pole
of Mercury, featuring craters such as Prokofiev (the large one) that
have permanently shadowed regions and contain water ice and organic
material
For the first time,
scientists have confirmed that the planet Mercury holds at least 100
billion tons of water ice as well as organic material in permanently
shadowed craters at its north pole.
The findings come from
NASA’s MESSENGER spacecraft, which has been in orbit around
the solar system’s smallest and innermost planet since 2011.
Researchers have suspected that ice could exist in such craters since
1992, when Earth-based radar measurements found bright areas at
the planet’s polar regions. Craters in this area cast long shadows,
which prevent any sunlight from reaching their floors.
Though alternative
explanations had been put forward to account for the radar-bright
areas, MESSENGER has provided convincing evidence for water ice on
the planet closest to our sun, where surface temperatures can
sometimes reach 800 degrees Fahrenheit. The results appeared in three
studies Nov. 29 in Science.
MESSENGER was able to detect water ice because it carries
a neutron spectrometer that looks at energetic neutrons
bouncing off Mercury’s surface. Water gives off a characteristic
neutron signature.
The spacecraft
measured the area around Mercury’s north pole and found this
characteristic signature, suggesting that between 100 billion and 1
trillion tons of water ice was present somewhere in the area. But the
neutron spectrometer has fairly low resolution, on the order of
hundreds of miles, so it can’t definitively say if this water is
inside the craters. (If it were outside, daytime temperatures would
have boiled the water away.)
Because they contain
no light, MESSENGER’s cameras can’t see right inside the
permanently shadowed regions. But the spacecraft carries a useful
workaround tool. To map its height above the surface, the probe uses
an altimeter that shoots a 10-nanosecond infrared laser
pulse at the ground and intercepts the returning beam.
“We can measure the
energy that comes back from the laser,” said planetary
scientist Gregory Neumann of NASA’s Goddard Spaceflight
Center, and lead author on one of the Science studies.
Though the number of photons coming back is slight, “we could
expect to see glints of brightness from surface water ice.”
Early results from
MESSENGER presented a puzzle. Not only were there no bright spots in
the permanently shadowed craters where radar measurements suggested
ice, the surface was actually much darker than Mercury’s average
color. “We were really surprised by this,” said Neumann.
The spacecraft
continued to search, examining more and more craters. Finally, the
laser spotted some dazzling crater floors that were two to four times
brighter than the rest of Mercury’s surface. This was finally good
evidence for the long-sought water ice. By modeling the temperature
in and around different craters, scientists were able to determine
the northernmost craters stayed cold enough over millions of years to
hold onto water ice.
Image: The
topographic height of craters and surface features at Mercury’s
north pole (top) and a model of the maximum amount of
sunlight received in this area (bottom). Neumann et
al, Science, 10.1126/science.1229764
But what about the
strange dark craters? Radar measurements suggested ice, but MESSENGER
wasn’t confirming the result. The temperature models showed that
these craters corresponded exactly to regions that would sometimes
receive a small amount of scattered sunlight. This itsy bit of energy
would heat the frozen water’s surface enough to sublimate it away.
Dark organic compounds dissolved in the ice got left behind as
residue and would slowly form a black cover, about 8 to 11 inches
thick, which protected any remaining ice from getting vaporized by
random sunbeams.
The organic material
is likely made of hydrocarbons like methane and ethane, commonly
found in comets and asteroids. “At room temperature it would be
kind of gooey stuff, to use the technical term,” said planetary
scientist Sean Solomon of Columbia University, who leads
the MESSENGER team. Because the layer is relatively thin, it’s
invisible to radar.
The MESSENGER team now
thinks they have a good story to explain how these polar cold traps
work. Every once in a while, a comet or asteroid hits Mercury and
gets annihilated. The vaporized material either floats out into space
or gets blasted away by the sun but any that finds its way into a
permanently shadowed region will settle down. Molecule by molecule,
water and other compounds build up inside the craters. Those that
never see a ray of sunlight contain mostly clean water ice. But if
even a tiny amount of light intrudes, it may heat up the water and
cause it to recede below a layer of organic material.
“These look like
really good results, and I think they are very convincing,” said
planetary scientist Johannes Benkhoff from the Institute of
Planetary Research in Germany, who is the lead scientist on the
European Space Agency’s BepiColombo mission, which is expected
to orbit Mercury in 2022. MESSENGER will provide many follow-up
opportunities for this later mission, which will have its own neutron
spectrometer to map the water ice regions with greater resolution.
In addition to being
an astounding result, the finding can help scientists better
understand the history of Earth. Mercury is a terrestrial planet like
our own and the ice provides evidence for geologically recent
delivery of water and carbon-rich material to the inner solar system
from comets and asteroids. This process very likely happened billions
of years in the past, when the Earth first formed, creating our
planet’s oceans and possibly seeding them with the material to
produce life.
“There’s now this
record on Mercury, a place where we least expected to find it, of
this process,” said Solomon. “It gives us a window to
understanding this delivery system.”
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