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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