Talking Trash (in Space)
It moves faster than a speeding bullet. Is it a bird? A plane? No, it’s space junk!
In less than 75 years, humanity has managed to leave an estimated 100,000 pieces of useless debris behind in space. Now, understand that some of this junk is very small. We’re talking bits as tiny as .5 millimeters wide. Still, even very tiny items moving at speeds of up to 17,500 miles per hour (no atmosphere to slow them down) can inflict damage when colliding with large objects, such as the International Space Station.
The first human-made object to reach space was launched by German scientists in 1942. To an average middle school student, this may sound like ancient history. But historically speaking, that was a recent event. Since then, more than 40,000 objects of human design have been sent into space. Some were meant to explore the outer reaches of our solar system, but about two-thirds of these objects stayed closer to home. That is, within 500 miles of our planet in what’s called Low Earth Orbit (LEO).
Geosynchronous orbit, about 22,000 miles above sea level, is another common location for satellites because they can match the Earth’s rotation and cover the same area at all times. This is handy if you want to assess weather or facilitate communications. The average distance between objects in this area is about 120 miles, according to the European Space Agency.
But with all of those human-made objects up there, things can get a bit crowded. Items break down or lose pieces of themselves. Sometimes astronauts lose gloves (what parent can’t relate?) or tools while floating outside their spacecraft. And some items, like rocket bodies, are intentionally ditched up there. This leads to a growing amount of space junk, or orbital debris.
Now, larger junk is less concerning to scientists and space agencies because it is more easily tracked and avoided by satellites and spaceships. Small debris, on the other hand, can cause damage to sensitive parts of the Space Station or to space suits. Even a tiny fleck of paint, whizzing by with no resistance at thousands of miles an hour, can do enormous damage. Think of what a tiny bullet can do here on Earth. Bullets, though, eventually hit the ground. A lot of tiny space junk does not.
Fortunately, there have been few major collisions, compared to the amount of debris. But there have been some significant encounters, according to NASA.
Your students are, no doubt, familiar with the “domino effect,” in which one action leads to a reaction, then another and so on. Astrophysicist and NASA scientist Don Kessler created an equation that describes the space debris equivalent of a domino effect, known as Kessler Syndrome.
For example, when China destroyed an old weather satellite in 2007 with a missile, more than 3,000 pieces of broken missile and satellite became trackable debris. Among the untrackable debris was a number of pieces less than two inches wide. This mess can result in many more crashes and explosions, which create more debris for even more collisions until, at some point, it may no longer be safe to send items into orbit (an already risky venture).
NASA recently added a debris impact sensor to the Space Station to monitor the very small objects that can’t currently be tracked be tracked from Earth. The agency hopes to collect data to help it better understand the dangers of small-scale debris. Learn more in this brief video.
Even if we stopped launching satellites and rockets into space, we would still face problems with the current level of space junk and usable items in orbit. In an effort to prevent a nightmare scenario, all spacefaring nations must work together to create guidelines and manage debris mitigation.
Some current potential solutions to solve problems related to orbital debris include:
- Using lasers to zap large pieces of debris (though as noted above, this can lead to other problems)
- Collecting space debris
- Establishing a recycling program
The ultimate solutions will need to be creative, but also grounded in science.
Here’s where young scientists come in. They are the Mars Generation; a cohort that will likely experience the thrill of space tourism. Heck, they might even launch their own satellites before they’re old enough to vote. It behooves them to both understand the pressing issues related to space junk and try to solve the problem. And if they start pondering the issue now, they might just have a great idea when it's time to enter next year's Young Scientist Challenge.