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Is there water on the Moon
The obvious answer seems to be No. because during a day
on the Moon, which lasts 2 earth weeks,
the temperature on the lunar surface
gets up to 123 degrees celsius,
which would be enough to boil away any water
if the Moon had an atmosphere like Earth,
which it doesn't.
And the reason that it doesn't
is because the Moon's gravity is weak,
just a sixth of Earth's gravity, which means
it can't hold onto light fast moving
molecules like water. Anything going
faster than 2.4 kilometers per second
the Moon's escape velocity is gone.
But that might sound pretty quick, but at any
given temperature there are always a
small number of molecules going
significantly faster than the average.
On the Moon
these molecules flap into space and then
other molecules take their place until
all the light fast moving molecules
are gone.
Plus, since the Moon has a very weak
magnetic field, there's little to protect
the lunar surface from the solar wind.
That's the stream of charged particles
coming from the Sun. These particles can
effectively blast molecules from the
surface of the Moon into space.
In fact that's how Mars lost most of its atmosphere.
So in short, if the Moon ever
had any water, it should be long gone by now.
And this appeared to be confirmed by
the Moon landings. Rock samples brought
back by Apollo astronauts
contained virtually no hydrated minerals.
Some water was detected but it was assumed
just to be terrestrial contamination
rather than actual Moon water, because
seals on some of the sample-return
containers were damaged by the gritty moondust.
But in 2009 a very different
picture emerged, when scientists
intentionally crashed part of a rocket
into the surface of the Moon.
It was going two point five kilometers per second
on impact, making a crater 25 meters wide
and 4 meters deep.
That injected 10,000 tons of material
with half of it making high enough to be lit
by the Sun. That allowed cameras on an
orbiting spacecraft, to look for the
emission lines of water in the dust.
And what did they find ?
The water emission lines were bright.
Scientists estimated that five
point six percent the mass of the
objective debris was water.
but how is this possible? Where did the
water come from and hadn't remain
on the Moon?
Well strangely enough, there are actually
three different sources of lunar water.
To understand the first source, you just
have to look at where they crashed that
rocket into theMmoon. Now it's a
misconception that the Moon has
a dark side.
Although the same side always faces earth,
all sides of the Moon do receive
sunlight.
However, at the poles there are some
craters which due to their location and depth,
are always in shade. They're called
but permanently shadowed regions.
Now since they never see the Sun,
these craters are some of the coldest places
in the whole solar system, colder than
the surface of Pluto. They can reach
negative 249 celcius. And it is here that
scientists decided to crash that piece
of rocket. Since the permanently shadowed
regions maintain such a consistently low
temperature, they act as cold traps
places where volatiles like water
remained frozen as ice.
But, where the water come from in the first place?
Well, from water containing comets
and asteroids that have struck the Moon over time.
Any water molecules that found
their way to the permanently shadowed regions
would be trapped there. Forever.
as ice but this is not the only source
of water on the Moon.
In a lunar samples from Apollo 15 and 17,
scientists found tiny glass beads. These beads were formed
back when the Moon was still
volcanically active. Fire fountains
launch droplets of lava into space, where
they cooled rapidly and then fell back
to the surface. In 2007 these beads were
sliced in half and tested for water.
The results showed significant amount of
water with concentrations highest in the
middle of the beads, and this indicates
that the water must have been trapped there
during the initial eruption, rather
than leaching in due to contamination
once those beads were back on earth.
Now, this water came from the interior of
the Moon. So the Moon must have contained
water to begin with, which kind of makes sense
considering the Moon is likely a
piece of Earth that broke off billions
of years ago in an impact with a mars-sized
body.
The third and final source of water
on the Moon is : Water created on the Moon
surface from the reaction of oxygen and hydrogen.
Now, the source of oxygen is easy.
Oxygen makes up
45 percent of the lunar surface
mostly bounded oxide mineral. But where
do you get the free hydrogen? The answer
is in the solar wind, which is constantly
bombarding the Moon surface with protons.
These can react with oxygen, to form
hydroxide, and ultimately water.
This water can then drift over the surface of
the Moon until either flys off into space,
or it lands in the cold traps and becomes ice.
So there is water on the Moon.
And this is important because
it means that future missions can take
advantage of this valuable resource.
Not only for Moon colonists to drink and
grow crops, but also for processing into
rocket fuel. If you can make your own
rocket fuel on the Moon, that
dramatically reduces the challenges and
cost of space travel. For a long time we
used to think the Moon was completely dry.
But now we know that hypothesis is all wet.
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