Travel to Mars and killer cosmic radiation

An Inconvenient Radiation By David Galbraith  THE ARIZONA DAILY STAR , 5 Oct 16 Mars waxes large in our current imagination. Matt Damon provides a compelling performance as an astronaut botanist stranded on the Red Planet, in a Ridley Scott film lauded for its scientific accuracy. The future in space shines bright, it seems. But is this really so?……..

Cosmic rays are a puzzle. They are the remnants of atoms hurtling through the galaxy at inconceivable energies. Inconceivable is not used lightly here: the most energetic cosmic rays have energies roughly 40 million times greater than the particles we can produce in the Large Hadron Collider in Geneva. We do not know how they can be formed. And yet they exist, and they permeate the universe, continuously bathing the earth.
A major part of the magic of life on earth is associated with the atmosphere. Not only do we breathe it, but it also acts as a vital shield against cosmic rays since, when they hit the atoms in the atmosphere, their energies are converted into the harmless light that my father detected.

Why do we need protection? The most energetic cosmic rays pack a punch of a 56 mile‐per‐hour baseball. Just as a body can be damaged by a baseball, so a cell can be damaged by a cosmic ray. How much damage can it do? Scientists have recently tested this question, exposing mice to amounts of radiation that would be experienced by astronauts during a trip to Mars which has very little atmosphere and minimal protection from cosmic rays. Extensive destruction of the brains of these mice was seen, with drastic deterioration in cognitive tests.

Our astronauts have already described interactions with cosmic rays during brief trips to the moon, reporting random flashes of light, a consequence of the explosive interaction of a cosmic ray with the cells in the retina. During the much longer trip to Mars, and the establishment of a permanent colony there, the brains of the astronauts will experience lethal levels of cosmic radiation.

 So why not simply provide protection against cosmic rays? It’s easy to calculate the screening provided by the earth’s atmosphere at the surface. It’s equivalent to a 400-ton sphere, with the astronauts placed in the center. We cannot raise that amount of mass to earth orbit, or move it to Mars, or land it on the Martian surface. Plus, it is improbable that we will ever have that capability. Sending humans further into the solar system and beyond becomes impossible. The inconvenient conclusion is that humanity, in its biological form, is restricted, through the grand, inevitable, and total progression of time, to this planet only……..

An alternative, and very simple explanation of Fermi’s paradox, is that the universe is a sterilizing system: cosmic rays prevent access of living organisms, alien or human, to our immediate space neighborhood and beyond. Accepting and coming to terms with this disturbing concept will have far‐ reaching consequences, both practical, political, philosophical, and, perhaps, theological. The only things that remain shining, as we keep looking up, are the inaccessible stars, and my father’s ironic gift, the faint Cerenkov radiation in the night sky formed by cosmic rays.


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