President Obama has asked for a whopping $18.5 billion in NASA’s budget, and rightly so! NASA has a lot going on. The Moon, Mars, Deep Space….and how “we” are going to handle it all.
There’s water, there’s oxygen, food, oh yeah and lethal space radiation. Lethal because here on Earth we have a magnetic field that is developed from deep inside, from the Earth’s core and extends far into space. That shields us from 99.0% of the harmful rays but the final piece comes in the form of an extra layer of protection added by the Earth’s atmosphere. But once you step outside of our protective shield, well that’s when things get messy and space radiation becomes a hazard.
This blog has previously dealt with the first two and even partially this concern when it covered habitation location. But there‘s a lot to know about radiation, what we can handle, what are the lifetime limits, all becomes important when you try to decide how to combat the lethal force that is present throughout the galaxy everywhere in varying amounts.
BASICS: So let’s start at the beginning-What is radiation? It is a form of energy that has many different forms – rays, electromagnetic waves, particles – sometimes visible sometimes not and only viewed via special equipment. Unfortunately radiation can have negative effects on our biological systems and even mechanical systems need protection as well.
MEASUREMENT of RADIATION:There are many different names for different quantifications of radiation. Each different method may be referring to a different property of the radiation involved. The Roentgen is just one sort to be followed by the rad (Radiation Absorbed Dose) and the Sievert.
ROENTGENS: Roentgens are the measurement used with Geiger Counters. Perhaps you have seen them in use in various SciFi movies through the decades. A more ‘popular’ (if you will) measurement is the millirem but seeing as 1 roentgen = 87.7 millirems, let’s go with the roentgen.
So roentgens tell you what is available to be absorbed by the body, but out of what is present some will go through the host body and some will get absorbed by the body’s organs. The portion absorbed by the body is referred to as RADs and has no straightforward relationship to the radiation as different particles (alpha, beta, gamma or neutron) absorb differently.
While both Ionizing & Non-Ionizing radiations exist – the Non-Ionizing radiation can simply be filtered out – but the Ionizing causes more damage and is more difficult to avoid. Ionizing radiation blasts through the body at the atomic level and leaves havoc behind. It changes the charge of the atoms it comes in contact with. (Additional damage is caused by the secondary particles it propels into motion.)
THE SIEVERT: There is another measurement you need to know to understand the below tables; the Sievert (Sv) – it is a unit of radiation absorption that takes into account the relative body effectiveness (RBE) of ionizing radiation. (Each type – gamma rays, X-rays, neutrons, has a slightly different effect on human tissue/organs.)
ARE THERE EXPOSURE LIMITS?Yes and the above tables show you not only the career limits by astronauts both male & female, but by age. Interesting to note ois that the suggested age limits are less for the uyounger as they take into account that the younger astronauts may live longer than the older and hence will have more time for negative effects.
NASA’s THOUGHTS? Well there are looking into this in twenty different ways. The most common way to deal with radiation is to simply block it. (Consider the thick concrete around a nuclear plant.) MoonDust can make up a concrete AND can easily by microwaved or heated into a hardened slab. Make a habitation out of 11-14 inches thick and you are protected. OR you could move the habitat under the ground and sleep better.
Other radiation blocking materials are Aluminum (which is present on the Moon) advanced plastics and liquid Hydrogen. But that’s if you try and block it.
What if you didn’t try and stop it but instead redirect it? Most of the dangerous radiation in space consists of high-speed protons and electrons that come from the Sun or positively charged atomic nuclei from distant supernovas. Since like charges repel, it stands to reason that a powerful electric fence would work to shield them. This is one idea that NASA’s institute of Advanced Concepts has invested some time and money into.
AND NASA has got more ideas, and they go after each one, from the easy
We live in a radioactive world. Every day we are exposed to radiation whether it is from materials in the earth itself or from naturally occurring radon in the air; It attacks us from outer space, and from inside our own bodies (as a result of the food and water we consume). I feel positive that not only will the idea to stop or repel radiation be surprisingly simple, our grandchildren or maybe their children won’t have to worry about it in quite the same way.