Please forgive the editing. I was trying to get this out to you today by 1 PM PST. Radiation Shielding for Space Travel and Space Living By: David Shahal – Systems Engineer Date: 05/20/2019 When we think of Radiation we often think of going to the Dentist Office and getting ...
Please forgive the editing. I was trying to get this out to you today by 1 PM PST.
Radiation Shielding for Space Travel and Space Living
By: David Shahal – Systems Engineer
Date: 05/20/2019
When we think of Radiation we often think of going to the Dentist Office and getting an X-Ray of our mouth or going to the doctor to for an X-Ray for a possible broken bone. Electrical power is generated through nuclear power and Nuclear weapons are the stuff of nightmares only used twice in our history on Japan during World War II. The horrors of nuclear radiation became well known to the world after Three Mile Island had a partial melt down in 1979. Chernobyl suffered a meltdown in 1986, and Fukushima suffered a meltdown in Fukushima prefecture in Japan after a major earthquake and tsunami hit the area in 2011. In these three cases radiation was released into the surrounding area and atmosphere.
In Space radiation is abundant. Our own Sun, distant suns and planets all create radiation sending it out across space. We see evidence of this in our northern lights and solar winds. Todays Space Craft are monitored by various instruments that detect radiation. The Johnson Space Center monitors all radiation in the spacecraft and on the astronauts, they also monitor space weather for signs of incoming solar flares.
Types of Radiation:
There are four types of radiation. Alpha, Beta, Neutrons and Electromagnetic.
1. Alpha particles: These particles have two protons and two neutrons.
Common elements: Uranium and Thorium. In our homes we may have Radon.
Notes: Alpha particles wont go through paper, Human skin is shielding enough from alpha particles. Radon is used in Smoke detectors.
2. Beta particles: which is an electron that is not attached to an atom with a small mass and a negative charge.
Common elements: Tritium, which is produced by cosmic radiation and exists all around us. Carbon-14 which is used for Radio carbon dating also emits Beta particles.
Notes: Travel farther than Alpha Particles, these particles can go through your skin. Medical imaging devices use Beta Particles so they can see inside the body. Common use is in treating cancer.
3. Neutrons: These particles do not have any charge and is present in the nucleus of an atom.
Common elements: These are seen when an atom is split as in uranium atoms. Without neutrons, you wouldn’t be able to sustain the nuclear reaction used to generate power.
4. Electromagnetic: X-rays and Gamma rays. They have no mass or charge.
Common use: x-ray medical/dental equipment
Notes: Can pass through the body. Useful in medical devices to see broken bones etc. A common shield against Gamma/X-rays is lead. This is why the x-ray technician puts a lead apron over you and leaves the room. Too much gamma radiation will do a human body very much harm. An X-Ray or Gamma Ray burst from a nearby star could potentially wipe out all life on earth.
Calactic Cosmic Radiation (GCR) – originates from outside the solar system. These are ionized particles that consist of the entire element table. They travel at the speed of light and can pass through matter.
Solar Particle Events (SPE) – Solar flares or Coronal Mass ejections (CMEs), travel at various speeds and can arrive at Earth sometimes in a matter of as little as 10 minutes. These are full of electrons, protons, alpha particles and heavier particles.
How do we protect humans in space?
First lets talk about what a Spacecraft is made of. Since spacecraft needs to be light in weight, they are made of Aluminum and aluminum composites. Titanium and Titanium alloys are also used to strengthen it as well. Spacecraft also need some sort of heat shielding so they can survive reentry into Earth or Mars Atmosphere, This is called Thermal Protection.
The first line of Radiation shielding is what the spacecraft is made of, in our case Aluminum or Aluminum composites provide for some radiation shielding.
Some scientists and engineers think creating a space craft out of Hydrogen rich plastics could give better radiation shielding than that of Aluminum. Another example, liquid hydrogen to provide Material shielding. Hydrogen fuel tends to give good shielding by placing it between the crew and outside of the space craft. Another potential shield is that of Water (H20), again placing it between the crew and the outside of the space craft.
How about Electromagnetic fields (raise shields captain?), EM Shielding. The earth does this for us naturally. We can create a magnetic field around objects, but this would take more space and weight on the space craft. The two main issues are: 1. Needs a very large power supply. 2. In tests at NASA, they could only repel either positive ions or negative ions, however they attracted the opposite back to the test subject. More research needs to be done on this.
In order to protect humans’ we may have to provide a safe zone onboard each space craft, possibly behind all the water or liquid hydrogen we are carrying. Space is limited onboard our current space craft and the added weight would mean the creation of larger rockets to carry our space craft to into space.
Another type of protection being talked about is Drugs. These drugs would be taken to strengthen the human body, in order to repair the damage caused by radiation. A drug by the name of Retinoids – a vitamin with antioxidant properties which when taken could stop the division of cells damaged by radiation, giving the body time to repair itself.
Using Clay as a Radiation Shield for spacecraft is also an option. Clay from Asteroids would be mined and placed on the space craft, between the crew and outside of the ship. The clay is rich in hydrogen and would allow for better radiation shielding than aluminum. The major hurdle is mining in space, its never been done before and putting it on our space craft would be nearly impossible, we need a space dock or to land on the moon or Mars. Etc.
Mars or Moon Colony:
The radiation shielding of a colony on Mars or the Moon would boil down to using the materials we send to both bodies, i.e. space craft, landers etc. lined with Aluminum. The creation of an initial habitat would need to be brought with the first human’s. Placed on the ground, then built up. In the last section, I spoke of using clay from an Asteroid as Radiation shielding. Well, we could use Moon dirt and Mars dirt to create a habitat with. Forming bricks with the dirt and used to create brick structures. Of course, radiation is not the only thing we need to be mindful of, we have Mars and Moon quakes. On Mars we have dust devils larger than some of our biggest tornados and the falling of meteors.
References:
1. https://www.newscientist.com/article/2124676-asteroid-clay-is-a-better-space-radiation-shield-than-aluminium/
2. http://www.tp.umu.se/space/Proj_10/Daniel_H-10.pdf
