Have you ever wondered how hard it is to land at a specific spot on the Moon, Mars or another planet? Find out in this activity by building a device that can zip down a line and drop a "lander" onto a target.

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See below for materials and step-by-step instructions. For more video tutorials and activities like this one, visit Learning Space.

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In this episode of Learning Space, you'll modify a paper-cup spacecraft so it can zip down a line and drop a "lander" onto a target. | Watch on YouTube

Materials for the Land a Spacecraft on Target activity


Animation showing how the Mars Perseverance rover will land itself on Mars

1. Learn how NASA lands spacecraft

NASA lands spacecraft in different ways depending on the goals of the mission. For NASA’s Perseverance Mars rover, a team of people wrote computer code that the spacecraft will use to land itself on the Red Planet! For other missions, a spacecraft might drop a probe onto the surface of the planet or Moon while the spacecraft continues orbiting from above. For example, the long-lived Cassini mission to Saturn dropped the Huygens probe on Saturn's moon Titan in 2005 so it could peer beneath the moon's thick, hazy atmosphere. When astronauts land on the Moon as part of NASA’s Artemis program, the lunar Gateway will remain in orbit while astronauts embark on their journey to the Moon’s surface inside a lunar lander.

It can be pretty tough to land on the Moon, Mars or another planet because both the spacecraft and the place it's landing on are moving! The Moon and planets are in constant motion, rotating on their axes and revolving around the Sun. The good news is that for this activity, your landing spot will be relatively stationary compared with your fast-moving "spacecraft."

About the image: This clip from the NASA video "How We Are Going to the Moon," shows how Artemis astronauts might travel from the lunar Gateway to the surface of the Moon. › Watch full video

A string tied to a door slopes down past a red and white target to the leg of a low chair

2. Set up your target and zipline

Use the smooth line to create a zipline about 9 feet (3 meters) long between two chairs or a door handle and a chair. One end of the line should be higher than the other.

Place the paper target under the zipline about 2 feet (1 meter) from the low end of the zipline. This will be the target you are aiming for.

Side-by-side images showing a person attaching a paper cup and paper clip to a sloping line, then the paper cup moving down the line

3. Hang your spacecraft on the zipline

Use the paperclip to hang your paper cup spacecraft from the zipline. You can decide how to do this so it will work with your design. Make sure the cup and paperclip can slide freely from the top of the zipline to the bottom.

A person sketches a design for their zipline lander on a piece of graph paper with various materials spread around them

4. Brainstorm and design

Figure out how to modify the paper cup to carry the marble down the zipline using the available materials or others you have on hand. Will the marble travel inside the cup? Outside of the cup on a platform? Underneath it? How will your spacecraft release the marble lander while zipping down the line? Consider whether you will use an automatic release system or a remotely-activated release system.

A person puts a wood ball into a paper cup as various materials are scattered about below them

5. Build it

Build your spacecraft based on the design you made in Step 4.

Three side-by-side animated images showing a wooden marble landing on a target

6. Test and evaluate

Starting at the top of the zipline, send your spacecraft down the line and try to land your marble on the target using the release system you designed. How close did you get? Use the numbered rings on the printed target to keep track of your accuracy. Repeat this step several times and try to get consistent results.

A person crosses out their first zipline lander design in red and writes "Design #2"

7. Redesign and try again

How might you improve your design? Does where you start your spacecraft on the zipline influence the landing?

A diagram shows the timeline and phases for NASA's Artemis program.

8. Explore More!

Learn how NASA plans to land astronauts on the Moon with the Artemis program and build your own astronaut lander!

About the image: This graphic shows the planned timeline for NASA's Artemis program, which is designed to land the first woman and next man on the Moon by 2024. + Expand image› Learn more