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The goal of this guide is to help schools and amateurs get into space on a tiny budget with the minimum preparation necessary. Because this experiment needs to tie into the curriculum, we’ve talked to educators to make sure the guide is appropriate and easy to use. We’re also providing a set of questions you can use to help teach and get thoughtful discussion about the project. We’ve provided the questions below, but we’re not providing the answers in an easy format because we know how savvy kids are and don’t want them just copying the answers. Students should find most of the answers they need interspersed in the guide. If you have any questions, feel free to contact us or use the forum.

If you have additional recommendations or changes you’d like to see, please let us know.

A note on using hydrogen as a gas: we did it because it’s cheap and renewable and relatively easy to handle, but you may not have access to a supply store or be comfortable using it. You can easily replace hydrogen with helium throughout this guide.


Here you’ll find questions related to the balloon project, sorted into different subjects. Feel free to use these or modify them as necessary to fit into your curriculum.


  • What gases would make good lift for balloons?
  • What are the pros/cons of using hydrogen or helium?
  • What happens when a pure hydrogen balloon is ignited? What happens when oxygen is mixed with the hydrogen in the balloon and then ignited?
  • Why do batteries perform worse in the cold?


  • Why does a balloon rise?
  • What is the pressure of the gas inside the balloon?
  • Once the balloon pops, the payload will fall. Assuming no air resistance and that it falls from 20km, how fast will it be going when it reaches the ground?
  • Calculate the surface area of your payload.
  • Now add in resistance; how fast will the payload be going when it hits the ground (assume you are at sea level)?
  • Is it better to have a long tether or a short tether?

Earth Science

  • Where would be an ideal place to launch and recover a balloon?
  • How does the jet stream impact a balloon trajectory?


  • Calculate the volume of the inflated balloon given its diameter.
  • Calculate the distance traveled, both horizontally and along its trajectory.

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