Hands-on Activity Shielding from Cosmic Radiation:
Part 3 - Post-Launch Analysis

Learning Objectives

After this activity, students should be able to:

• Explain the concept of radiation shielding.
• Interpret radiation data.
• Suggest ways to optimize or improve their design for future launches.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each group needs:

• computer with access to the internet and equipped with Microsoft Excel
• printed copies of the following: Relative Humidity Graph, Air Pressure Graph, Wind Speed Graph, Temperature Graph, Radiation Graph, Shielded Payload Example Data, Control Payload Example Data, Post Launch Additional Resources

For the entire class to share

• main computer with screen and projector to watch onboard video footage, if video cameras were included in the payload

Worksheets and Attachments

Pre-Req Knowledge

• Knowledge of radiation and types of radiation (learned in the associated lesson, Shielding from Cosmic Radiation: Space Agency Scenario).
• Understand how radiation is measured.
• Identify and describe the types of materials can be used to block cosmic rays.
• Understand high-altitude ballooning and the conditions that the balloon will be exposed to (temperature, pressure, humidity changes, etc.).
• Understand how to build a payload/prototype of a device that attempts to shield radiation at high altitudes.
• Be able to graph data in an Excel spreadsheet.

Introduction/Motivation

It is time we looked at the data from the balloon flight! We will look at all of the data first, and then we will decide if the radiation shielding worked. Remember, the question we would like to answer by the end of our analysis is, “How well did the shields function?” We also want to look ahead by asking, “How could we improve upon the design for future flights?”

The Temperature Graph (see Figure 1) shows a surface temperature at the time of launch, which decreases to a minimum value and then increases again to the top altitude of our flight. This data clearly shows the division of the atmosphere into a troposphere, a tropopause, and a stratosphere. Can anyone tell me how to see these layers in the data? (Answer: The low temperature is the tropopause which separates troposphere from stratosphere.)

The Relative Humidity Graph (see Figure 3) shows that most moisture in the atmosphere is in the tropopause. Considering this, does it make sense when scientists say that the troposphere is where weather takes place? (Answer: Yes, because weather requires water vapor.)

The Radiation Graph (see Figure 5) shows a low value near surface, which increases with height to a peak value. There is a reason why the data look like this. Can someone explain what is going on? (Answer: The “Regener-Pfotzer Maximum” at 20-25 km above sea level is a real phenomenon. It results from secondary radiation from the atmosphere.)

The example temperature data from one particular launch displays a surface temperature near 4C, decreasing to –45C at 13,000m above sea level, and then rises back to 0C at bursting altitude showing the division of the atmosphere into a troposphere, a tropopause, and a stratosphere. The wind speed graph shows a variable wind that increases with altitude. The relative humidity graph shows most moisture in the atmosphere is in the tropopause. Pressure decreases with altitude because the density of air decreases along with the height of the air column. Radiation data show a low value near surface, which increases with altitude to a peak value.

Procedure

Background

(The first four questions and the video are optional; if you are only doing the data analysis, skip down to the data collection analysis.)

Let’s talk about the payload launch. To start with, what happened? [Let students offer suggestions. Answers will depend on what happened during the launch.]

What went well with the launch? [Let students offer suggestions. Potential answers: weather, air traffic, inflating the balloon, attaching payload harness, etc. Answers will depend on what happened during the launch.]

What went poorly with the launch? [Let students offer suggestions. Potential answers: weather, air traffic, inflating the balloon, attaching payload harness, etc. Answers will depend on what happened during the launch.]

How could the experience be improved? [Let students offer suggestions. Potential answers: weight of payload, weather/wind, balloon launch, etc. Answers will depend on what happened during the launch.]

(Optional) Let’s watch video footage captured by the onboard video cameras. [Play any video captured by the payload.] Now that data has been collected, it is ready to be analyzed. Let’s get to work!

In this activity students look over data their payloads collected, review the unit’s concepts and practices and provide feedback to the instructors. Students first examine all of their data, then answer the question, “how well did our shield function?” Next students examine temperature data. The example temperature data from a particular launch displays a surface temperature near 4C, decreasing to –45C at 13,000m above sea level, and then rises back to 0C at bursting altitude showing the division of the atmosphere into a troposphere, a tropopause, and a stratosphere. The wind speed graph shows a variable wind that increases with altitude. The relative humidity graph shows most moisture in the atmosphere is in the tropopause. Pressure decreases with altitude because the density of air decreases along with the height of the air column. Radiation data show a low value near surface, which increases with altitude to a peak value. Students should explain this finding, which might require some research to show if this observation is correct and why. Finally, a comparison of the shielded and unshielded, control Geiger counters show the shielding has produced more counts than the Geiger counter without shielding. The design didn’t work as intended. 

Now that data has been collected, it is ready to be analyzed. The radiation data was measured and recorded on the microSD card in units of microSieverts. If data were collected correctly, the radiation measurements should increase with altitude from about 0.1 microSiverts near the ground to over 2.0 microSieverts around 20–25 km above sea level. Above this, radiation measurements should slightly decrease. The peak in radiation measurements around 20–25 km above sea level is called the “Regener-Pfotzer Maximum” and is a real phenomenon that results from secondary radiation scattering that occurs when cosmic radiation particles interact with our atmosphere. For a further explanation of secondary radiation scattering (i.e., air showers), see: https://www.mpi-hd.mpg.de/hfm/CosmicRay/Showers.html. See the Post Launch Additional Resources for more details.

Building a radiation shield that effectively blocks both Beta particles and Gamma rays, those that are measured by the Geiger counter used here, is very challenging. You may find that the shields seem to work at lower altitudes but not at higher altitudes. In fact, at higher altitudes their shielded Geiger counters may actually measure slighter higher radiation measurements than if shields were not used at all. This can be confirmed by sending up a third payload that is unshielded to act as a control.

One explanation for this increase in radiation with the shielded Geiger counters is related to the shields themselves.  If composed primarily of thin sheets of steel and/or aluminum, this may cause additional secondary scattering to take place when they are hit by cosmic rays. Since secondary scattering of cosmic ray particles results in the production of high-energy Gamma rays, which can penetrate steel and aluminum, these additional Gamma rays produced when cosmic rays interact with the shielding would be measured by the Geiger counter and account for the increased radiation measurements. Additional research needs to be done to determine if this in fact occurs, however. To effectively shield against Gamma rays, wrapping the Geiger counter in a thick sheet of lead could help block some of the Gamma rays, but this is not feasible with weight considerations in regard to space travel, high-altitude ballooning, and budgets. Other more lightweight materials do exist, such as aluminum, that have shown the ability to shield against Gamma rays and could be considered for shields. Be prepared to discuss ways that the shielding could be improved (1) without making the payload too heavy and (2) going over budget.

Before the Activity

• (Optional) Prepare any onboard video footage and have it ready to be played.
• Gather all the onboard radiation data into a comma separated value (CSV) file, which can be opened in Microsoft Excel.
• (Optional) If you collected altitude data as well, you will likely have to interpolate that data to the radiation data in order to plot the radiation data as a function of altitude. The easiest way to do that is to use the linear interpolation method described here: https://www.datadigitization.com/dagra-in-action/linear-interpolation-with-excel/.
• Prepare to split the students into smaller groups of 2-3 to work on the data analysis together.

With the Students

1. Divide the students into groups of 2-3 students.
2. Have the students plot these contextual plots first:
1. Temperature vs. altitude
2. Wind speed vs. altitude
3. Pressure vs. altitude
4. Relative humidity vs. altitude
3. Next have the students plot the radiation data vs. altitude (radiation on x-axis, altitude on y-axis) in Microsoft Excel. They should be plotting the radiation dosage, which is in microSieverts per hour. Start with the measurements from one shielded payload, then the measurements from the other shielded payload. Finally, add in the measurements from the unshielded control payload. See Shielded Payload Example Data and Control Payload Example Data.

4. Ask the students to record their observations and note any interesting features of the plots. If using the example plots

1. Temperature data. The example temperature data is from a November 2019 launch and displays a surface temperature near 4C, decreasing to –45C at 13,000 m above sea level, and then rises back to 0C at bursting altitude showing the division of the atmosphere into a troposphere, a tropopause, and a stratosphere.
2. The wind speed graph shows a variable wind that increases with altitude.
3. The relative humidity graph shows most moisture in the atmosphere is in the tropopause.
4. The pressure graph shows that pressure decreases with altitude because the density of air decreases along with the height of the air column.
5. The radiation data show a low value near surface, which increases with altitude to a peak value. [Students should explain this finding, which might require some research to show if this observation is correct and why. Finally, a comparison of the shielded and unshielded, control Geiger counters show the shielding has produced more counts than the Geiger counter without shielding. The design didn’t work as intended.] 

5. As a group, discuss the student observations and questions:  
1. What do you see in your radiation vs. altitude data? [Answer: The radiation data was measured and recorded on the microSD card in units of microSieverts. If data were collected correctly, the radiation measurements should increase with altitude from about 0.1 microSiverts near the ground to over 2.0 microSieverts around 20–25 km above sea level. Above this, radiation measurements should slightly decrease. The peak in radiation measurements around 20–25 km above sea level is called the “Regener-Pfotzer Maximum” and is a real phenomenon that results from secondary radiation scattering that occurs when cosmic radiation particles interact with our atmosphere. For a further explanation of secondary radiation scattering (i.e., air showers), see: https://www.mpi-hd.mpg.de/hfm/CosmicRay/Showers.html.]
2. How well did the radiation shield work? [Answer: The shields seem to work at lower altitudes but not at higher altitudes. In fact, at higher altitudes their shielded Geiger counters may actually measure slighter higher radiation measurements than if shields were not used at all. This can be confirmed by sending up a third payload that is unshielded to act as a control. One explanation for this increase in radiation with the shielded Geiger counters is related to the shields themselves. If composed primarily of thin sheets of steel and/or aluminum, this may cause additional secondary scattering to take place when they are hit by cosmic rays. Since secondary scattering of cosmic ray particles results in the production of high-energy Gamma rays, which can penetrate steel and aluminum, these additional Gamma rays produced when cosmic rays interact with the shielding would be measured by the Geiger counter and account for the increased radiation measurements. Additional research needs to be done to determine if this in fact occurs, however.]
3. What material could effectively shield against Gamma rays? [Answer: To effectively shield against Gamma rays, wrapping the Geiger counter in a thick sheet of lead could help block some of the Gamma rays, but this is not feasible with weight considerations in regard to space travel, high-altitude ballooning, and budgets. Other more lightweight materials do exist, such as aluminum, that have shown the ability to shield against Gamma rays and could be considered for shields.]
4. How could the shielding could be improved…

• …without making the payload too heavy?
• …without going over budget?

Vocabulary/Definitions

altitude: The height of an object in relation to the ground or sea level.

electromagnetic radiation: ER composes the waves of the electromagnetic field, which includes visible light, x-rays, infrared, and gamma rays. Cosmic radiation includes gamma rays.

high-altitude: There are different definitions, but this generally includes 8,000 feet above sea level+. High-altitude balloons can reach altitudes over 100,000 feet.

particle radiation: Particle radiation is made up of alpha and beta particles. An alpha particle is basically a highly ionized helium atom. A beta particle is just a free electron. Alpha is deadly but is stopped much more easily than beta. We are working with cosmic radiation, which is composed primarily of beta.

secondary radiation: Radiation that intensifies after striking an object.

sievert: The unit of measurement for ionizing radiation and its effects on the human body.

Assessment

Pre-Activity Assessment

Review: Review terms and concepts from the previous lesson; may be informal verbal assessment. 

Activity Embedded (Formative) Assessment

Formative Assessment: Use the Post Launch Additional Resources to assess student knowledge on radiation and the designs they created, or to make connections in the data analysis.

Calculating and plotting the data graphs and plots.

Post-Activity (Summative) Assessment

Selecting a winning space agency: Students may be tested on their knowledge of concepts relating to radiation and cosmic rays. Additionally, participation in the group according to roles may be assessed. Delivery of products in a timely manner may be assessed. The team with the most effective radiation shield may be awarded a prize.

Investigating Questions

• How do the radiation measurements change with altitude? [Answer: The radiation data show a low value near surface, which increases with altitude to a peak value.]
• How much do they change? [Have students calculate how much the values change.]
• Why is there a peak? [Listen to student explanations. They may need to do some research on the Internet.]
• Did the shields cause a decrease in the measurements compared to the control payload? [Have students share their results.]

Troubleshooting Tips

Students may calculate incorrectly or interpret graphs incorrectly. Students will need to discern between signal and noise.

Activity Extensions

Students can begin to optimize their payload for “next time” by analyzing and troubleshooting materials and design. See an example.

Additional Multimedia Support

• Information about secondary air showers
• Linear interpolation in Microsoft Excel

References

Copyright

Contributors

Supporting Program

Acknowledgements

Much of the equipment and training to develop the Wyoming NASA Space Grant balloon program were provided by StratoStar.

This material was developed based upon work supported by the National Science Foundation under grant no. 1821566—the LIFT (Learning to Integrate Fundamentals through Teaching) Project, Wyoming NASA Space Grant Consortium, University of Wyoming. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.