Radiation Shielding for a Mission to Mars (Focus: Radiation) Preview Close Preview

Welcome to iLabs! (1/17)

Remote Online laboratories (iLabs) are lab instruments located at universities around the world that you can use through the Internet, allowing you to carry out different experiments from anywhere at any time.

Before we get started, we would really appreciate it if you would answer a few questions that will help us understand how we can better help students learn science.

Please click on this link: Click Here and answer the questions to the best of your ability.

Why We Can't Send Humans to Mars Yet (and How We'll Fix That) (2/17)

Now let's get started with your lab! The following sections will be a part of the assignment your teacher is giving you, and might be for points that count towards your class grade.

We have sent people to the moon, so why haven't we sent anyone to Mars? What makes sending someone to Mars so much more difficult?

mars

Read the following article to understand a bit more about the challenges faced by astronauts in making a trip to Mars, then answer the question below.

Here is the link to the article: Mission to Mars

After reading the article, which challenge do you think will be the most difficult to overcome? Why do you think that?

Radiation in Space (3/17)

As you discovered through the previous activity, conducting a successful manned mission to Mars requires a number of challenges to be successfully solved.

One of the biggest challenges of exploring the surface of the red planet comes from radiation astronauts would be exposed to during their mission.

Watch the video below to find out more about it:

How do spacecrafts protect astronauts from Galactic Cosmic Rays and Solar Energetic Particles? Do you think what they are using now is sufficient for a trip to Mars and back?

How is Radiation Measured? (4/17)

Radioactivity is typically measured by a Geiger counter. Different models of Geiger counters detect and measure different kinds of radiation.

GC

Geiger counters come in many forms, but they usually consists of three parts:

g

  1. Geiger tube – a gas-filled tube whose gas ionizes when charged particles or electromagnetic waves from a radioactive material pass through the gas. The ions create a signal that can be measured, allowing the Geiger counter to count the number of radioactive particles or electromagnetic waves that pass through the tube.

  2. Visual readout – a meter that keeps track of the number of radioactive particles or electromagnetic waves being detected by the Geiger counter.

  3. Audio readout – a meter that makes one “click” sound for each radioactive particle or electromagnetic wave counted by the Geiger counter. The clicks sound like this.

Let's Do an Experiment with Radiation (5/17)

The video you watched mentioned that spacecraft are built with different types of shielding to help protect astronauts from harmful amounts of radiation exposure.

Different materials are able to block different types of radiation. In this lab, you will have a chance to see which materials can block different types of radiation.

To investigate this, you can design your own experiment to learn about how different types of radiation moves through different materials. The instrument you will be using in this lab is located at the University of Queensland in Australia.

UQ

How does this lab work?

rva

What are radiation shields or absorbers? Radiation shields, also called absorbers, are any material that you place between the source of radiation and the radiation detection instrument to block radioactivity from traveling through space. Different materials have different efficiencies as absorbers.

The lab equipment consists of:

  1. A Geiger counter
  2. Three different radioactive materials: Strontium 90, Americium 241, and Cobalt 60
  3. Different types of absorbers including paper, different thicknesses of aluminum, and different thicknesses of lead

The things that you can change in order to design an experiment are:

  1. The type of radioactive material. Radiation from the material is measured in units of "particle counts", which means the number of particles emitted from the sample that were counted by the Geiger counter.
  2. The type or types of absorber(s) you wish to test.
  3. The measurement time in seconds that each measurement of particle counts will last.
  4. The number of trials that will be conducted at the settings listed above.
Research Question (6/17)

What are you trying to find out in this lab? What question are you trying to answer?

The last page gave you some information about the instrument you will be using to conduct an experiment about radiation. Now you need to develop the question you want to answer using this setup.

What is a research question? That is what your experiment is designed to answer. A “good” scientific research question is one that allows you to perform a test or experiment to show how your variables might be related. The results of the experiment will allow you to say something about how those variables are related. Your research question must be testable to make a strong statement about how the variables are related.

Your research question will guide your experimental design in the next step.

What is the independent variable in your remote labs experiment?

What is the dependent variable in your remote labs experiment?

Write your research question for your remote labs experiment.

Design Your Experiment (7/17)

Design your experiment by choosing a source of radiation and the absorbers you would like to test, and then selecting the duration of your trial(s) and the number of trials you would like to run. To learn more about each variable, click on the question mark icon next to the variable.

When you click "Run", the experiment will run on the instrument located at the University of Queensland in Australia.

Note that experiments are run one at a time, so you are being placed in a line or queue to run yours. If you don't want to wait, you can log out and come back later. Everything you have done up to now will be saved.

Radioactivity over Absorber
Source
Absorber
Distance (mm)
Duration (s)
Trials
View your iLab Results (8/17)

Now let's take a look at the data you got from running your remote experiment.

You can review both your experimental design and the data you generated from your experiment in table form by clicking on the tabs below. Take a look at your data.

Do you notice any patterns in your data? If so, describe what those patterns are.

Analyzing your iLab Results (9/17)

Let's take a closer look at the results from your experiment.

By clicking on the tabs below, you can see the variables you chose for your experimental design, your data in table form, and a graph of your data.

Take a close look at the graph of your data in order to determine which materials were able to block the radiation emitted from the source that you selected, and which materials were not.

Which shield or absorber seems to have done the best job at blocking radiation from the source you selected? Why do you think that is?

Which shield or absorber seems to have done the worst job at blocking radiation from the source you selected? Why do you think that is?

Let's Review Atomic Structures. (10/17)

You just explored what happens when you place a material between a source of radiation and a Geiger Counter, but what is really going on? What is radiation and how does it work?

To really understand what is happening with radiation, you need to understand a little about atomic and molecular structures. Let's take a moment to review these concepts. This will help some of the later concepts make more sense.

What is inside an Atom?

Atom

An atom is made up of 3 different particles: protons, neutrons, and electrons. An atom also contains as many electrons as protons.

  • A proton is a particle that usually stays inside the nucleus and has a positive (+) charge.
  • A neutron is a particle that usually stays inside the nucleus and has a neutral (0) charge.
  • An electron is a particle that orbits, or moves around, the nucleus and has a negative (-) charge.

Protons and neutrons are contained in the nucleus of an atom, or the very dense center.

Below is a diagram of a carbon atom to give you another example of the typical structure of an atom. As mentioned above, the nucleus is the center of the atom, which contains protons and neutrons, and the electrons typically orbit around the nucleus.

Carbon

A molecule is simply 2 or more atoms joined together.

For example, in the diagram of a water molecule below, two Hydrogen atoms bond with an Oxygen atom to make a water molecule.

water

What is Radiation? (11/17)

So what is radiation, really? This investigation is focused on minimizing the exposure to radiation by astronauts during a mission to Mars. In order to identify a solution to a radiation problem you must have a thorough understanding of what radiation is.

Radiation can be defined as "energy that travels through space either as electromagnetic waves or as moving subatomic particles." The amount of energy these waves contain falls along a spectrum where the shorter the wavelength, the more energy carried by the wave. Radiation can be both electromagnetic and particle radiation.

Elec

A more in-depth look at the electromagnetic spectrum can be found here:

Radiation can generally be classified into two types: ionizing and non-ionizing.

Radiation that has enough energy to move around atoms in a molecule or cause them to vibrate, but not enough to remove electrons or break the chemical bonds, is referred to as Non-Ionizing Radiation. The vibrations in the molecule can cause an increase in the temperature. Examples of this kind of radiation include visible light and microwaves.

Ionizing Radiation has enough energy to break chemical bonds in molecules, or remove tightly bound electrons from atoms, which creates charged molecules or atoms (ions). When this ionization happens, it releases energy that is absorbed by material surrounding the ionized atom. This is the type of radiation that people usually think of as 'radiation.' We take advantage of its properties to generate electric power, to kill cancer cells, and in many manufacturing processes.

Based on the information you have learned so far, which type of radiation do you think would be able to cause harm to living tissue? Why is that?

Do you think that solar energetic particles (SEPs) are a form of ionizing or non-ionizing radiation? Why do you think that?

Radiation vs. Radioactivity (12/17)

The terms Radiation and Radioactivity are often used interchangeably, but they are not the same thing! When people hear the term radiation, as in "The sun emits radiation that can affect people on Earth" they usually start thinking about ionizing radiation. Why is that so scary? Let's learn a little bit more about the different types of radiation.

Radiation is simply a name for energy that travels in particles or waves (like visible light from the Sun, for example).

Radioactivity is the process by which a nucleus of an unstable atom loses energy by emitting ionizing radiation. A material that spontaneously emits this kind of radiation—which includes the emission of alpha particles, beta particles, and gamma rays—is considered radioactive.

How does Radioactivity happen?

Types of Ionizing Radiation (13/17)

There are 3 main types of ionizing radiation: alpha, beta, and gamma.

Particles

Alpha Particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particles are 8,000 times more massive than beta particles, but do not travel very far- usually only a few inches in air.

Beta Particles are high-speed electrons ejected from a nucleus. Beta particles can travel much farther through materials than alpha particles- generally, beta particles can travel several feet through air.

Gamma Rays are highly energetic electromagnetic waves emitted from a radioactive nucleus, and are the type of radiation that can travel the farthest in air. Gamma rays are very penetrating - even a thick sheet of a dense material such as lead will not block them entirely.

Below is a diagram showing examples of how alpha, beta, and gamma radiation can travel through different materials:

penetration

Learn more about the different types of radiation in the following video:

How does ionizing radiation occur?

How are ionizing and non-ionizing radiation different?

What kind of radiation do you think the source you selected for your remote experiment was emitting?

Run the Experiment Again (14/17)

You now have a better understanding of how radiation works, and you might want to change your experimental design or try your experiment again.

As before, design your experiment by choosing values for the variables on the left. To learn more about each variable, click on the question mark icon next to the variable.

When you click "Run", the experiment will run on the instrument located at the University of Queensland in Australia.

Note that experiments are run one at a time, so you are being placed in a line or queue to run yours. If you don't want to wait, you can log out and come back later. Everything you have done up to now will be saved.

Radioactivity over Absorber
Source
Absorber
Distance (mm)
Duration (s)
Trials
Did you make any changes from your first experimental design? If so, why?

Analyze Your New Results (15/17)

Take a look at the results from your second experiment and answer the questions below.

Do you notice anything different from your previous results? Why or why not?

Planning a Mission to Mars (16/17)

As you have learned, radiation is one of the biggest concerns for NASA in planning a mission to Mars. In this experiment, you tested possible materials to shield astronauts from radiation in space.

rocket

From your results, which material would you use to insulate a spacecraft for a mission to Mars? Do you think that would be practical?

Are you confident in your results? Why or why not?

Can you think of any further experiments you might like to conduct to ensure you are using the best possible materials to block radiation? What would those look like?

Post-Survey (17/17)

Now that you have used iLabs to complete an assignment, we would like to again ask you some questions that will help us understand how we can better help students learn scientific concepts and how we can improve our product.

Please note, some of these survey questions are going to be very similar or even the same as questions we asked you before. We ask that you answer them honestly, as this will be a big help to us.

Please click on this link: Click Here and answer the questions to the best of your ability.