Simulating space junk can help researchers design spacecraft to clean up orbital debris. 

Here are some ways to simulate space junk: 

• IOTA Simulates the movements of defunct satellites based on their size, orbit, and other factors 
• ESA’s Clean Space Initiative Observes objects in space to recreate their spin and develop plans to retrieve them 
• Adams simulation software Simulates the capture of space debris by origami mechanisms in a microgravity environment 

Other ways to detect and characterize small space debris include: 

• Radar systems 
• Optical telescopes 
• Data fusion algorithms 

As of May 2023, there are roughly 14,000 small, medium, and large debris objects floating about in low Earth orbit.

When a spacecraft dies, it loses the ability to maintain its direction in space. Additionally, as the spacecraft’s orbit begins to decay, the thin atmosphere interacts with the spacecraft, causing it to tumble unpredictably

Space junk, also known as orbital debris, is made up of many different types of objects: 

• Payload: Includes satellites and fragments from collisions and wear and tear 
• Rockets: Includes remains of stages used to propel missions into orbit 
• Mission-related objects: Includes dropped tools, screws, cables, and cameras 
• Debris: Includes launch canisters, dust, and paint flakes 
• Detritus: Includes debris from missiles and detritus left behind by astronauts 

Space junk can range in size from tiny paint flecks to decades-old, inoperative spacecraft. However, most space debris is relatively small, often no larger than a few centimeters in diameter. 

NASA has several methods for removing space junk: 

• ADRV: Removes large debris from low Earth orbit (LEO) 
• Ground- and space-based lasers: Push debris out of orbit 
• Space tugs: Manually move objects elsewhere 
• Rockets: Remove space junk 

NASA also designs satellites for controlled deorbiting at the end of their mission. 

Other methods for removing space junk include: 

• ClearSpace-1: A “space claw” that will capture and dispose of space junk 
• ELSA-d: A two-satellite mission that removes debris from orbit 

Space junk can also be removed by pulling it into Earth’s atmosphere, where it will burn up. Debris left in orbits below 600 km usually fall back to Earth within a few years.

Space junk is mainly detected by ground-based observation. The two types of ground-based observations are: 

• Ground-based radar observations 
• Ground-based optical observations 

Radars are used to characterize space debris in low Earth orbit (LEO). Optical telescopes are used for more distant orbital regions such as the geostationary ring (GEO). 

Other tools for tracking space debris include: 

• Lidar 
• Lasers 
• Returned spacecraft surfaces 

The U.S. Space Surveillance Network routinely tracks large orbital debris (> 10 cm). Ground-based radars can detect objects as small as 3 mm. 

It’s nearly impossible to spot individual pieces of space junk with the naked eye. However, it’s possible to observe larger objects, such as defunct satellites, as they reflect sunlight. (Full article source google)

Spacecraft can avoid space junk by: 

• Changing orbits Small satellites in low Earth orbit can change their orbits to avoid debris. They can do this by changing the surface area exposed to atmospheric drag. 
• Adjusting position Some satellites can adjust their position through a satellite operator. For example, the International Space Station (ISS) regularly adjusts its position to avoid space junk. 
• Using shielding The ISS uses a Whipple shield to protect against particles up to 3 mm in size. The shield breaks up the impacting object into smaller fragments. 

Other ways to reduce the growth rate of space debris include: 

• Making reusable rockets 
• Designing satellites for controlled deorbiting at the end of their mission 
• Preventing in-orbit explosions 

The UN asks companies to remove their satellites from orbit within 25 years after the end of their mission. 

Spacecraft can protect themselves from space debris in a few ways: 

• Whipple shielding: A multi-layer barrier that causes debris to disintegrate on impact 
• Multi-layer insulation (MLI) blankets: Placed on critical areas of the spacecraft, such as propellant and helium tanks 
• Shields: Designed to break up impacting particles into lower-mass dust 

Spacecraft can also avoid debris by: Changing orbits, Adjusting position.

The mesosphere is the layer of the atmosphere that protects Earth from meteoroids. 

Here are some ways that spacecraft protect themselves from space debris: 

• Whipple shields: These shields use multiple layers of metal to break up debris. The first layer breaks the debris, the second layer breaks the fragments, and so on. 
• Multi-layer insulation (MLI) blankets: These blankets are made of multiple layers of thin sheets. They protect spacecraft from micro-debris and provide thermal control. 
• Bumper shields: These shields use the impact energy to shatter debris.

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