 When you think of space, you think of just that, space, emptiness, the void. But when it comes to the space around Earth, it's actually not that empty. It's filled with a whole bunch of junk or space trash. In fact, experts think that there are millions of pieces of debris in orbit, ranging in size from bigger than a softball to smaller than a marble. So what is all of this junk hanging out around our planet? Well, that's the awkward part. It's all our stuff that we've put into space that we just don't use anymore. Sorry, Mom. That can be satellites that are no longer working, leftovers from rockets, or stuff that's come off spacecraft over time, like panels or even flecks of paint. Space debris has included some rather unique items, too. There's a tool bag still up there that was lost by an astronaut during a spacewalk, a lipstick-sized capsule of Gene Roddenberry's ashes once orbited the globe for a while, too. Even frozen pee used to make the rounds. Before pee recycling systems were put in place, astronauts used to dump their urine out into space, where it immediately turned into beautiful, shiny ice crystals that reflected the sun. Sure, that's lovely and all, but just like trash here on Earth, debris and space can be a big problem. It makes the space around our planet a congested and potentially dangerous place. You may think space debris is just floating out there all slow-like, but this stuff isn't really floating at all. It's actually zooming around Earth at more than 17,000 miles per hour. That wouldn't be a big issue if everything was moving in the same direction, but there are a bunch of different types of orbits that space trash can be on. Some go around Earth's equator, while others go around the poles, for instance. That's where you run the risk of getting T-boned. It happened in 2009 when a U.S. satellite collided with one from Russia, putting thousands of pieces of debris into space. A similar event occurred in 2007, when China destroyed one of its satellites with a missile, creating a whole mess of trash. Okay so, a little different scenario, but the same result. Even the smallest piece of trash traveling at such a high speed can cause a whole lot of damage if it crashes into something. And if collisions happen too often, then we run the risk of something called the Kessler Syndrome. It's a simple concept. Colliding space objects create even more space objects, and the more debris there is, the higher odds of more collisions. So if we don't keep these accidents in check, it's all gonna snowball until we get so much litter in space that the entire area is basically gonna be hostile to spacecraft for generations. Our best defense against collisions is to basically know where all of this space trash is. Right now, tracking space debris is the job of the Defense Department. It uses something called the Space Surveillance Network, an array of telescopes entirely dedicated to tracking objects in space and figuring out what they are. The network is capable of tracking anything that's bigger than 10 centimeters, so about the size of a baseball. And right now, more than 22,000 objects of this size are being tracked. Once an object is spotted by the network, trackers must determine its orbit and then see if it's in the catalog. To get in the catalog, trackers have to be able to identify a piece of debris all the way back to its launch. If you can't, it's called an uncorrelated track, or basically, we don't know what it is. But ultimately, the main goal is to know the odds of these pieces running into each other. If a satellite has a 1% probability of collision, that's way too high, and you're gonna want to perform some orbit correction maneuvers with your thrusters to avoid an accident. Even the space station has to move out of the way sometimes when debris is in the area. Of course, correction maneuvers are really only an option for spacecraft with fuel to spare. Nothing can be done for debris without thrusters. Plus, there's a whole ton of small objects that the surveillance network can't see. For those, experts have to create theoretical models to predict where these tiny pieces are gonna be. So how do we clean up this mess? Well, for the satellites in lower Earth orbit, chances are they will come down eventually. There are still air molecules in the upper atmosphere that create drag on spacecraft, pulling them back down to our planet. Those vehicles will mostly burn up on the way back down to Earth, but just in case, the US has a policy that satellites must have a plan to deorbit safely when the time comes. That means no satellites are gonna fall on your head. That only works for satellites in lower Earth orbit, though. Many of our communications satellites are in a much higher region, 22,000 miles above Earth, called geostationary orbit. Those are way too high to come back down, so when they run their course, we put them into a graveyard orbit. It's an orbit that's 200 miles up. The hope is that they'll be far enough away to not interfere with our operating satellites. And those satellites will basically stay up there forever. As for getting rid of the rest of this stuff, people have come up with some creative and little kooky ideas. There's a concept known as the terminator tether. It's a miles-long cable that interacts with Earth's magnetic field, inducing a current along the tether. This creates drag on spacecraft in orbit, causing them to fall back down to Earth. It's similar to an electric whip that Japan recently sent to space for clearing out debris. Other ideas include adding balloons or sails to spacecraft to slow them down when they're done, or even shooting them with lasers. The photons would impart a small thrust on the object enough to bring it down. There are a lot of other ideas too, but there isn't anything really viable to solve this problem right now. So in the meantime, our best option is to get better at tracking all this stuff. And that job may soon switch hands. The Federal Aviation Administration has been very vocal about wanting to take over the job of debris tracking from the Defense Department. So soon, the FAA may be the traffic cops of air and space. There's also another way to protect against small debris that's moving pretty slow. It's called the Whipple Shield, and it acts as like a bumper shock for things moving at 1 to 11 miles per second. And the space station has over 100 Whipple Shields on it. So it's good to go.
 When you think of space, you think of just that, space, emptiness, the void.
 But when it comes to the space around Earth, it's actually not that empty.
 It's filled with a whole bunch of junk or space trash.
 In fact, experts think that there are millions of pieces of debris in orbit, ranging in size
 from bigger than a softball to smaller than a marble.
 So what is all of this junk hanging out around our planet?
 Well, that's the awkward part.
 It's all our stuff that we've put into space that we just don't use anymore.
 Sorry, Mom.
 That can be satellites that are no longer working, leftovers from rockets, or stuff
 that's come off spacecraft over time, like panels or even flecks of paint.
 Space debris has included some rather unique items, too.
 There's a tool bag still up there that was lost by an astronaut during a spacewalk, a
 lipstick-sized capsule of Gene Roddenberry's ashes once orbited the globe for a while,
 too.
 Even frozen pee used to make the rounds.
 Before pee recycling systems were put in place, astronauts used to dump their urine out into
 space, where it immediately turned into beautiful, shiny ice crystals that reflected the sun.
 Sure, that's lovely and all, but just like trash here on Earth, debris and space can
 be a big problem.
 It makes the space around our planet a congested and potentially dangerous place.
 You may think space debris is just floating out there all slow-like, but this stuff isn't
 really floating at all.
 It's actually zooming around Earth at more than 17,000 miles per hour.
 That wouldn't be a big issue if everything was moving in the same direction, but there
 are a bunch of different types of orbits that space trash can be on.
 Some go around Earth's equator, while others go around the poles, for instance.
 That's where you run the risk of getting T-boned.
 It happened in 2009 when a U.S. satellite collided with one from Russia, putting thousands
 of pieces of debris into space.
 A similar event occurred in 2007, when China destroyed one of its satellites with a missile,
 creating a whole mess of trash.
 Okay so, a little different scenario, but the same result.
 Even the smallest piece of trash traveling at such a high speed can cause a whole lot
 of damage if it crashes into something.
 And if collisions happen too often, then we run the risk of something called the Kessler
 Syndrome.
 It's a simple concept.
 Colliding space objects create even more space objects, and the more debris there is, the
 higher odds of more collisions.
 So if we don't keep these accidents in check, it's all gonna snowball until we get so much
 litter in space that the entire area is basically gonna be hostile to spacecraft for generations.
 Our best defense against collisions is to basically know where all of this space trash is.
 Right now, tracking space debris is the job of the Defense Department.
 It uses something called the Space Surveillance Network, an array of telescopes entirely dedicated
 to tracking objects in space and figuring out what they are.
 The network is capable of tracking anything that's bigger than 10 centimeters, so about
 the size of a baseball.
 And right now, more than 22,000 objects of this size are being tracked.
 Once an object is spotted by the network, trackers must determine its orbit and then
 see if it's in the catalog.
 To get in the catalog, trackers have to be able to identify a piece of debris all the
 way back to its launch.
 If you can't, it's called an uncorrelated track, or basically, we don't know what it
 is.
 But ultimately, the main goal is to know the odds of these pieces running into each other.
 If a satellite has a 1% probability of collision, that's way too high, and you're gonna want
 to perform some orbit correction maneuvers with your thrusters to avoid an accident.
 Even the space station has to move out of the way sometimes when debris is in the area.
 Of course, correction maneuvers are really only an option for spacecraft with fuel to
 spare.
 Nothing can be done for debris without thrusters.
 Plus, there's a whole ton of small objects that the surveillance network can't see.
 For those, experts have to create theoretical models to predict where these tiny pieces
 are gonna be.
 So how do we clean up this mess?
 Well, for the satellites in lower Earth orbit, chances are they will come down eventually.
 There are still air molecules in the upper atmosphere that create drag on spacecraft,
 pulling them back down to our planet.
 Those vehicles will mostly burn up on the way back down to Earth, but just in case,
 the US has a policy that satellites must have a plan to deorbit safely when the time comes.
 That means no satellites are gonna fall on your head.
 That only works for satellites in lower Earth orbit, though.
 Many of our communications satellites are in a much higher region, 22,000 miles above
 Earth, called geostationary orbit.
 Those are way too high to come back down, so when they run their course, we put them
 into a graveyard orbit.
 It's an orbit that's 200 miles up.
 The hope is that they'll be far enough away to not interfere with our operating satellites.
 And those satellites will basically stay up there forever.
 As for getting rid of the rest of this stuff, people have come up with some creative and
 little kooky ideas.
 There's a concept known as the terminator tether.
 It's a miles-long cable that interacts with Earth's magnetic field, inducing a current
 along the tether.
 This creates drag on spacecraft in orbit, causing them to fall back down to Earth.
 It's similar to an electric whip that Japan recently sent to space for clearing out debris.
 Other ideas include adding balloons or sails to spacecraft to slow them down when they're
 done, or even shooting them with lasers.
 The photons would impart a small thrust on the object enough to bring it down.
 There are a lot of other ideas too, but there isn't anything really viable to solve this
 problem right now.
 So in the meantime, our best option is to get better at tracking all this stuff.
 And that job may soon switch hands.
 The Federal Aviation Administration has been very vocal about wanting to take over the
 job of debris tracking from the Defense Department.
 So soon, the FAA may be the traffic cops of air and space.
 There's also another way to protect against small debris that's moving pretty slow.
 It's called the Whipple Shield, and it acts as like a bumper shock for things moving at
 1 to 11 miles per second.
 And the space station has over 100 Whipple Shields on it.
 So it's good to go.