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Vacuum space, temperature and pressure
close to zero, solar irradiation and thermal
conductivity between all the components
including the electronic circuits. All of that,
without the chance to dissipate heat
because there is no conductivity and no
attrition. And after a 10-year trip in total
hibernation in which the probe traveled
adrift in the most obscure and deepest
parts of the solar systems, with most of the
personnel changing with the years. Before
the launch, of course, some "qualification"
tests were held. Violent vibrations to
simulate the launch itself, tests in the
hyperbaric and cryogenic chambers and
other detailed analysis with various
iterations because sometimes not
everything worked at the first try».
So let's imagine we are Rosetta and we
are traveling...
«The mission started from the ESA base in
Guyana (North of Brasil, close to the
Equator) with a normal Ariane Rocket
that pushed Rosetta outside the Earth's
orbit after dropping its stages. After the
launch we are outside the atmosphere and
we're traveling away from Earth. We have
to reach a moving object at a distance
superior to 400 millions of kilometers. A
distance of about 10000 times the
diameter of the Earth. Do we go straight to
the goal. No. We don't have engines or
batteries. So we take advantage of the
beauty and substance of the Universe the
planets' masses. It's the gravity assist. We
go around the destination, 1.2 billion
kilometers to an object which is 400
millions of kilometers away. The time was
a relative variable, we were focused in
arriving. We aim for the closest planet
which is Mars, designing an hyperbolic
flight path that uses the planet's
gravitational field to accelerate and change
direction. Then we go back to the Earth
and we do the same, increasing the speed
again. And then with Mars again. At that
point, the Mission Control shuts down
everything. We sleep for 10 years like the
Sleeping Beauty and we go adrift throughout
deep space. One year ago, there was a wake-
up call scheduled by a special clock and we
discovered that our navigation point was
wrong by several hundreds of thousands of
kilometers. Something like, 5 times the
diameter of Earth! It seems that the slight
mistake was due to a few grams of weight
difference (on a 400-kg total), to the fuel
used for the slight corrections going outside
the Earth orbit and to the loss - in empty
space - of part of the resins used in the pre-
impregnated fibers. From the Earth, Mission
Control orders a temporary ignition and
corrects the route. But there is no attrition
in space. If you accelerate too much, you get
to the side of the comet and pass it without
having the chance to come back. If you don't
accelerate enough, the comet runs away
because it is faster. So, being precise with
the few energy available is imperative. And
you have to be precise in using the minimal
amount of energy you have while staying
ready to correct the route because you can't
plan everything. From the Earth, the
technician try to use as little batteries and
hydrazine from the engines (there are strong
ties for the interplanetary explorations in
terms of emissions. Space is not only an
absolute heritage of the Mankind and
Universe, but together with time is the
condition by which we humans can explore
the Universe as it is). After getting
back on the right orientation,
we deploy our solar panels
like a chrysalis and we
collect, "drop by drop"
the sunlight because
when it's 400 million
kilometers away, there
is only a little of it.
With these few drops,
we re-orient the antennas
in order to communicate with
the Earth, we start the photographic
equipment and the on-board systems.
Imagine driving a car in an empty space, in
absolute darkness, having only a vague idea
of where you're headed, without any kind of
autonomy as you are following instructions
coming from far away. Now, imagine having
to tell the driver where you are and receiving
the instruction after about one hour. Well,
that can make you pretty anxious. From last
January until June, we get closer and closer,
down to about 30 kilometers. From July to
October, in four months, our photo cameras
capture the entire surface of the comet that -
surprise! - is not round. It's like a potato,
and 4 kilometers long with valleys, craters
and small hills. From the Earth, Mission