Manned missions to Mars may seem like a long
way away, as NASA currently has their eyes set to get humans on Mars around the mid to
late 2030s. But in reality, this time scale is very small,
because there are a number of hurdles to overcome first, one of the most problematic being exposure
to radiation in space. So, how bad is the radiation in space and
on Mars? And what can we do about it? Radiation can mean a lot of different things. Light you are seeing now is a form of electromagnetic
radiation. Radiation is also heat emanating from your
central heating system. These are harmless or even beneficial to us
humans. But astronauts need to be aware of a number
of different types of space radiation. Types of radiation which can strip atoms from
your body, alter your DNA, and give you acute radiation sickness or even cause death. The main culprit for the dangerous radiation
in our Solar System is also our life giver, the Sun. It is constantly emitting light in many different
frequencies and has a steady outflow of solar wind, which is highly energised protons, electrons
and alpha particles, or in other words sub-atomic particles. These particles and wavelengths can be dangerous
to humans as it is, but every so often powerful events occur on the Sun’s surface called
solar flares and coronal mass ejections. This is where, through a combination of factors,
the Sun ejects billions of tons of highly energised particles into space. If a coronal mass ejection were to be aimed
at an astronaut without much in the way of protection, it would make them very sick. However, while bad, this is not the biggest
worry for scientists trying to overcome the obstacle of space radiation. There are particles hurtling through space
which travel even faster than those ejected from the Sun, known as Galactic Cosmic Rays. These are particles which were ejected from
extremely energetic events which could have occurred millions of years ago, like a supernova. They range from hydrogen atoms all the way
to heavy elements like uranium that have had their electrons stripped away, meaning just
the nucleus of the atom remains. These particles have been accelerated to almost
the speed of light, they can pass through an entire spaceship or body unimpeded, and
any atoms they pass through will be ionised. Luckily on Earth, we have a number of natural
protections which shelter us from all this radiation. The Earth’s magnetic field is one, deflecting
CMEs and some Galactic Cosmic Radiation around the planet and to its poles, where it impacts
the Earth’s ionosphere, producing beautiful aurora. This magnetic field also protects Earth’s
atmosphere from being stripped away by the Sun’s solar wind. And it’s this atmosphere which protects
us from any Galactic Cosmic Radiation that got through the magnetic field, as these particles
impact particles in the atmosphere before they reach us on the ground. So, how do scientists hope to protect future
astronauts outside of the Earth’s magnetosphere and atmosphere? The first hurdle to overcome is the trip to
Mars itself. Astronauts would realistically need at least
100 days to get to Mars from Earth, meaning they will be exposed to space radiation for
that long. Luckily, particles from solar flares and CMEs
can almost all be shielded by the spacecraft’s structure. However, high energy waves and Galactic Cosmic
Radiation can pass through the wall of a space craft. Recent rover missions to Mars measured how
much radiation an astronaut would absorb en route, about 0.66 sievert, or the equivalent
of getting a full body CAT scan every 4-5 days. In comparison, on Earth, we might expect to
absorb 0.0025 sieverts during the same period of time. The thing that really prevents radiation from
reaching you is putting a lot of mass in the way. However, simply adding more weight to the
walls of the spaceship itself would make lift-off prohibitively expensive. So, one of the methods currently being experimented
in NASA’s Orion capsule during periods of particularly high radiation is to hide in
a make-shift bunker, putting as many bags of supplies around you as possible. Interestingly, the best element for protecting
against Galactic Cosmic Radiation is hydrogen, so scientists are also experimenting with
the idea of storing water in the walls of the craft. Another method currently being investigated
that would also be useful on the surface of Mars is to have spacesuits made of or at least
lined with hydrogenated boron nitride nanotubes. This substance is strong, but also contains
hydrogen atoms which could protect astronauts from radiation. This material could even be used to make the
structure of the spacecraft, as it is also good at withstanding very high temperatures. However, testing still needs to be done before
it can be confirmed as a definite winner. The last option currently being experimented
with is building a forcefield within the spaceship, kind of like a little replica of Earth’s
magnetosphere. However, while something like this can be
built, it is not energy efficient enough to have on a spaceship just yet. But perhaps by the 2030s technology will have
advanced enough for this to become a real possibility. So, let’s say that astronauts have arrived
on Mars in the 2030s, will the radiation situation get any better for them there? A little, but not anywhere near like on Earth. Mars has no magnetosphere, and a very thin
atmosphere, meaning protection on the surface is minimal, although it should be mentioned
that the lower in altitude you go, the better you will be protected. Estimates put radiation exposure on the Martian
surface at 0.64 millisieverts per day, which is just over NASA’s acceptable radiation
limit. However, the plan is not just to dump astronauts
on the surface. One idea is that earlier missions could go
to Mars to fabricate a base using Martian regolith and 3D printing in preparation for
any future manned missions. Having the mass of Martian ground above any
future settlement would protect the occupants from radiation, especially from dangerous
CMEs. Should a CME come towards Mars, NASA’s fleet
of Sun observing spacecraft would warn astronauts outside the habitat to get inside with ample
time to spare. So, while perhaps we have a lot more testing
to do, it does seem like there are some workarounds in regards to space radiation. With all of them in place, it might be that
space radiation can be kept to a low enough level to allow longer term human exploration
outside of Earth’s magnetosphere. Do you think mankind will ever be able to
conquer space radiation? And what do you think of our chances to eventually
be able to colonise the solar system, or is it all a pipe dream? Is there an obstacle even more pressing than
space radiation? Let me know what you think in the comments! Thanks for watching! For more Astrum Answers, be sure to check
the playlist here. A big thanks to those of you that support
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