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Space is, if nothing else, a health hazard. Extreme
temperatures, radiation, space debris, starvation, suffocation, and vacuum all
face the unprepared or unlucky.
Radiation
Near Earth or any planet with a spinning metal core, the
planet's magnetosphere shields spaceships from the copious ionizing radiation
that floods interplanetary and interstellar space. There are three main sources
of such radiation: planetary radiation belts, solar flares, and cosmic rays. Of
those, the lattermost is the most dangerous because it is the hardest to
protect against. Solar flares are also a real risk, despite being lower energy,
because of the sheer quantity of radiation. Planetary radiation belts, while
extremely dangerous, are usually the weakest around Earth-size planets;
however, the belts about gas giants can dwarf even the largest solar flares.
Indeed, Jupiter's belt is so horrific that for every two hours spent orbiting
Io, a person would receive radiation exposure similar to that of a coronal mass
ejection at Earth.
Protecting against ionizing radiation has always been an
immense challenge. Early attempts typically involved placing as much mass as
possible between astronauts and the radiation, but even still, some cosmic rays
penetrated. Over time, more compact power sources and more efficient
superconductors emerged allowing for the creation of electromagnetic shielding.
This has the benefit of not being mass-dependent, which permits smaller
vessels, while not compromising crew safety – as long as it has power.
Vacuum
Vacuum is associated with a number of hazards. There is no
air, so a human will suffocate in it. It is an amazing insulator, so objects in
the shade can approach absolute zero (the local temperature around Earth in the
shade is -250° F), and in the sun, can reach millions of degrees (near Earth,
sunlit objects reach about 250° F). But most dangerous to an unprotected human
is the lack of pressure. Under such conditions, blood boils, air expands,
forcing itself out of the lungs, and nitrogen narcosis sets in with a
vengeance. All of these combine to create a swift and painful death long before
a person can suffocate or suffer a lethal sunburn.
Since the advent of space travel, mankind has found ways
around these problems, but even today, the solutions still rely on providing
astronauts with what amounts to an environmental suit. They may be lighter,
more comfortable, more durable, and more flexible than in the days of early space
exploration, but the concept remains fundamentally the same. Spaceships
dedicate the majority of their mass to keeping the crew alive, as well. Food
stores, water stores, air stores, heating and cooling systems, and a
pressurized hull all serve to protect a
ship's inhabitants. Some larger ships – and stations, in particular – even house
entire farms for crop production and air scrubbing. Still, they all boil down
to sealed, pressurized environments vulnerable to power failure and breaches.
Space Debris
While not much of a hazard beyond the orbital space of
inhabited planets, where there are people, there is junk, and debris doesn't
have to be very large to cause a lot
of damage. For instance, a 50 microgram (that's roughly fifty thousandths of a thousandth
of a raisin) at a typical orbital velocity of 4.9 miles per second has roughly the
same energy as a rifle bullet. And during the first decades of spaceflight,
there were estimated to be over 20,000 pieces of debris larger than 4", 500,000
pieces of space debris between 1/2" and 4", and tens of millions of
objects under 1/2". Chance collisions with such space junk can rip through
hulls, damage equipment – and when encountered in clouds – even alter a
spacecraft's course.
While debris removal is an ongoing effort around most
populated worlds, spaceships still find it necessary to employ some
preventative measures. Most craft have an armored hull to fend off chance
collisions and protect against the erosive effects of extended exposure to
space dust. Some also use high energy lasers to divert or vaporize larger
debris before it can impact the craft. Lastly, foreign ships are often escorted
by local orbit tenders who know which orbits are freest of clutter and the
safest approaches to a planet's surface.
Trapped
No matter how much technology has progressed, and no matter
how creative the solutions to the problems presented by space travel may be,
always remember that when you are floating between the stars, you are alone. If
anything fails, if anything goes wrong, the only thing between you and death is
your ship and your wits.
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