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Space junk

Space junk (johan63, iStockphoto)

STEM in Context

Space Junk

Nathalie Ouellette

Summary

Litter isn't just a problem on Earth. When litter ends up in space, it can cause collisions and other consequences for satellites, the International Space Station and even for people on Earth!

Spotting a “No Littering” sign in your local park is pretty common. But would you expect to spot one in outer space? “Space littering” is a growing and increasingly dangerous problem. Let’s learn what this is, why it’s dangerous, and what scientists, engineers and politicians can do to solve it!

What is space junk?

Some things in space are supposed to be there, like working satellites and space stations. Other things are considered orbital debris, or space junk. It is hard to guess exactly how much space junk is in Earth’s orbit, but the European Space Agency estimated there was more than 8,500 tonnes of it in 2019. That means if you added all of that junk together, it would equal around 100 space shuttles.

NASA has been dealing with the space junk problem for years. In 2013, they kept track of over 500,000 pieces travelling at speeds of up to 28,000 km/h! These floating, trackable objects range from small pieces the size of a marble to entire broken satellites.

Space Debris: 1957-2015 (2015) by Stuart Grey (1 min.).

 

So what exactly is this junk? Lots of different things! For example, there are rocket boosters that have detached during rocket launches. There are the leftovers of accidental or intentional explosions. There’s even an odd collection of equipment lost by astronauts: a glove, a camera, tools and garbage bags!

Did you know?

One of the larger pieces of space junk currently in orbit is the broken-down Envisat satellite, which weighs 8 tonnes and could stay in orbit for up to 150 years!

The really dangerous stuff is often the tiny bits that NASA can’t keep track of. Most of the space junk scientists worry about is in a region called low Earth orbit (LEO). This is where the International Space Station and the majority of satellites are located because it takes less energy to get there than to orbits further away and because it’s easier to observe the Earth’s surface from (relatively) close by. It’s the area that lies between an altitude of 180 and 2 000 km above the Earth’s surface.
The closer you are to the earth when you are orbiting, the faster you go - LEO objects are travelling at nearly 28 000 km/h - going ¾ of the way around the earth every hour. (and if they’re colliding they’re often going in opposite directions). At those speeds even something as tiny as a fleck of paint can do a surprising amount of damage! 

This photos shows a chip out of the International Space Station’s window. This chip was probably caused by a flying object a few thousandths of a millimetre  across - a hundredth the width of a human hair!
This photos shows a chip out of the International Space Station’s window (Source: ESA/NASA).

 

Photograph - additional information

This chip was probably caused by a flying object a few thousandths of a millimetre across - a hundredth the width of a human hair!

 

But how bad can all this space junk really get?

Luckily for us on Earth, there’s a whole lot of space out in space! On average, you would have to travel about 125 km in low Earth orbit before coming across a piece of space junk large enough to be tracked by NASA. That’s like driving from Toronto to Niagara Falls.

Did you know?

On average, one piece of space junk has fallen back into Earth’s atmosphere every day for the last 50 years.

But that is not to say we have nothing to worry about! The 2013 sci-fi movie Gravity showed astronauts in the middle of a very possible scenario called the Kessler effect. That’s a critical point at which the space junk has gotten so dense that a single collision could start a domino effect of more and more collisions, eventually destroying almost everything out there!

This would be a disaster, since here on Earth we have grown very dependent on orbiting satellites. They help humans with everything from communications to navigation. This is why everyone from NASA to tech companies to entire governments are researching ways to get rid of the space junk that’s already out there.

Did you know?

There is no international law about minimizing space junk, although space agencies are working together on the problem.

How to get rid of space junk

One of the easiest ways to get rid of space junk is to change its orbit so it gets close enough to Earth that it hits the atmosphere - and at the speed they are travelling, small objects will just burn up. There are different possible ways to do this. For example:

  • Small rockets on the broken junk satellites themselves can push them into a lower orbit. 
  • Scientists can blast a laser at pieces of space junk to nudge them around. The laser could even be located on the Earth’s surface if it were built to be precise enough!

Right now, scientists are only using rockets to destroy space junk. They’re not using lasers yet because governments are worried about the dangers of lasers in space. After all, they could potentially damage things that aren’t space junk.

Some companies have proposed sending up a ship or giant net that could physically drag the space junk into falling orbits. That way, it could either burn up or fall into a sort of“graveyard orbit” far away from all the good, working satellites.

The latest idea from NASA is a brand new type of ‘space velcro’ that could grab all the space junk. This idea was inspired by geckos! Their feet can grip onto walls using small flaps that create a static electric charge. This is just like when you rub a balloon against your hair to create an electric charge and then stick the balloon to the wall. Astronauts tested this inside the International Space Station in 2017.

What’s next?

As humans push the limits of space exploration and send more and more people beyond Earth, fixing the problem of space junk is getting really important. Luckily, some of the world’s best scientists and engineers are on the case. Who knows? We may one day see the start of a brand new industry: space junk removal!

Attack of the Cosmic Space Junk! (2016) by “It’s Okay to be Smart” (5:56 min.).

 

 

Starting Points

Connecting and Relating
  • What do you do with the trash collected from all over your house before it goes out to the road on garbage day? Why do you do this? Why is it a problem when someone knocks over the garbage bin or runs over the garbage bags? 
  • If you were working on a long-term mission in space, what would you do with the garbage you created?
  • Would you like to work at a job where you kept track of the amount of space junk? Why or why not?
Connecting and Relating
  • What do you do with the trash collected from all over your house before it goes out to the road on garbage day? Why do you do this? Why is it a problem when someone knocks over the garbage bin or runs over the garbage bags? 
  • If you were working on a long-term mission in space, what would you do with the garbage you created?
  • Would you like to work at a job where you kept track of the amount of space junk? Why or why not?
Relating Science and Technology to Society and the Environment
  • Should there be international laws created to monitor and control space junk? How could littering in space be policed? 
  • Humans have done a lot to pollute the Earth. Do you think we have the right to now pollute space? Is it possible that we will damage space to the same extent that we have damaged the Earth with waste?
Relating Science and Technology to Society and the Environment
  • Should there be international laws created to monitor and control space junk? How could littering in space be policed? 
  • Humans have done a lot to pollute the Earth. Do you think we have the right to now pollute space? Is it possible that we will damage space to the same extent that we have damaged the Earth with waste?
Exploring Concepts
  • What is the Kessler effect? 
  • Why is there a growing problem with space junk? 
  • What are the current options available to get rid of space junk? What new options are being explored?
Exploring Concepts
  • What is the Kessler effect? 
  • Why is there a growing problem with space junk? 
  • What are the current options available to get rid of space junk? What new options are being explored?
Nature of Science/Nature of Technology
  • Our technological achievements have created the excess of space junk. Will science and technology be able to solve the space junk problem? Explain.
Nature of Science/Nature of Technology
  • Our technological achievements have created the excess of space junk. Will science and technology be able to solve the space junk problem? Explain.
Media Literacy
  • Have you seen a science fiction movie that includes a reference to space junk? What movie? What problem was encountered because of the space junk?
Media Literacy
  • Have you seen a science fiction movie that includes a reference to space junk? What movie? What problem was encountered because of the space junk?
Teaching Suggestions
  • This article and embedded video examine the issue of space junk and how it is impacting the environment of space and space exploration. It connects in science to the topic of space, the ISS and satellites. For senior physics courses it connects to the topics of collisions and orbital mechanics. These resources introduce the concepts of orbit, low Earth orbit and the Kessler effect. 
  • After reading the article and viewing the video, students in groups could complete a Pros & Cons Organizer learning strategy for weighing the pros and cons of different methods of space junk removal. Ready-to-use Pros & Cons Organizer reproducibles are available in [Google doc] and [PDF] formats.
  • To get a hands-on understanding of the Kessler effect, students could use simple materials, like dominoes, to visually replicate the increasing collisions that could take place. 
  • Senior physics students could also conduct further research about low Earth orbit and strategies for moving space junk into lower level orbits.
Teaching Suggestions
  • This article and embedded video examine the issue of space junk and how it is impacting the environment of space and space exploration. It connects in science to the topic of space, the ISS and satellites. For senior physics courses it connects to the topics of collisions and orbital mechanics. These resources introduce the concepts of orbit, low Earth orbit and the Kessler effect. 
  • After reading the article and viewing the video, students in groups could complete a Pros & Cons Organizer learning strategy for weighing the pros and cons of different methods of space junk removal. Ready-to-use Pros & Cons Organizer reproducibles are available in [Google doc] and [PDF] formats.
  • To get a hands-on understanding of the Kessler effect, students could use simple materials, like dominoes, to visually replicate the increasing collisions that could take place. 
  • Senior physics students could also conduct further research about low Earth orbit and strategies for moving space junk into lower level orbits.

Learn more

Space junk and a net-carrying satellite that catches it (2019)

Longer piece by PBS Newshour on the space junk problem, the RemoveDEBRIS satellite and other possible solutions. Article include a video (2:01 min.) with additional information.

Space Debris  

Facts, figures, images and regularly updated news from the European Space Agency.

Orbital Debris Program Office

Facts, figures, images and regularly updated news from NASA.

Sticky ‘space Velcro’ developed by NASA to clear up junk in orbit (2017)

Article by Sarah Knapton for The Telegraph about a technology developed to help clean up space debris.

Space Junk Crisis: Time to Bring In The Lasers (2011)

Article by Adam Mann for Wired about how lasers could be used to help deal with space junk.
 

References

Kessler, D., & Cour-Palais, B. (1978). Collision frequency of artificial satellites: The creation of a debris belt. Journal Of Geophysical Research, 83(A6), 2637. DOI: 10.1029/ja083ia06p02637

Jiang, H., Hawkes, E., Fuller, C., Estrada, M., Suresh, S., & Abcouwer, N. et al. (2017). A robotic device using gecko-inspired adhesives can grasp and manipulate large objects in microgravity. Science Robotics, 2(7). DOI: 10.1126/scirobotics.aan4545

National Research Council. (1995). Orbital debris: A technical assessment. National Academies Press.