Space Debris or "Junk" is garbage in space that humans are responsible for. It's made of old satellites, rockets, and other things that don't work anymore. Space junk can be dangerous for spaceships and astronauts because even small pieces can create big damage if they hit something.

It is important to learn about Space Junk because it's getting worse every year, and it can hurt people who go to space. We need to know more about Space Junk so that we can keep people safe, and make sure we can still go to space in the future. If we don't do something to remove Space Junk, it will make space really hard to explore and create even more problems.

Alongside the larger and more visible pieces of space debris, there are countless small and untrackable particles that float around in space. These tiny pieces of space debris, also known as micro debris or space dust, can be as small as a grain of sand, but they can travel at speeds of up to 17,500 miles per hour. They are too small to be tracked by radar or other detection systems, which makes them challenging to avoid and can pose a significant risk to space infrastructure.

It is estimated that there are at least billions of pieces of micro debris in orbit around the Earth. These particles can be generated by natural sources such as meteoroids and micrometeoroids, as well as by human activities such as satellite collisions and rocket launches. While they may seem insignificant, micro debris can cause considerable damage to satellites and spacecraft when they collide at high speeds. For example, a tiny paint chip can create a crater on a spacecraft's window or solar panel.

As the amount of micro debris in orbit continues to increase, there is a growing concern that it could create a runaway effect and generate even more debris, leading to an exponential increase in the risk of collisions and damage to space infrastructure. Therefore, it is essential to develop technologies that can detect and may solve these issues, such as shields and coatings that can protect spacecraft and satellites from impacts.

In space, there are many pieces of debris that are small, but large enough to be tracked and counted. These objects can include small parts of satellites, rocket stages, and other debris left over from past space missions. While they may not seem very large, they can still pose a threat to spacecraft and satellites in orbit.

It is estimated that there are tens of thousands of these debris objects in orbit around the Earth. To track and monitor them, ground-based radars and telescopes are used. These instruments can detect and track objects as small as a few inches in size and provide data on their movements and trajectories. This information is used to predict potential collisions and plan maneuvers to avoid them.

The United States Space Surveillance Network maintains a catalog of all objects in orbit that are larger than 10 centimeters (about four inches) in size. This catalog contains information on the objects' movements, orbits, and potential collisions with other objects. The catalog is updated regularly, and new objects are added as they are discovered. Space agencies and operators also use their own tracking systems and instruments to monitor and track space debris. By working together and sharing data, they can reduce the risk of collisions and help keep space a safe place for exploration and discovery.

The largest and most trackable items of space debris are defunct satellites, rocket stages, and other large pieces of debris left over from space missions. These objects can be as big as a school bus and weigh several tons. They orbit the Earth at high speeds, and their movements can be tracked and monitored by ground-based radars and telescopes.

As of 2021, there were over 3,000 large objects of space debris in orbit, according to the United States Space Surveillance Network. These objects can pose a serious threat to safety since they can cause catastrophic damage in case of a collision. The majority of these objects are in low Earth orbit, which is the region of space between 160 and 2,000 kilometers above the Earth's surface. To reduce the risk of collisions, space agencies and operators keep track of the large objects of space debris. They use this data to predict the objects' trajectories and plan maneuvers to avoid them.

Tracking and counting space debris is a complex and challenging task since the debris is constantly moving, and new debris is created all the time. However, ground-based radars and telescopes can detect and track objects as small as a basketball in low Earth orbit. This data is used for accurate tracking and counting of space debris, which is crucial for the safety of space activities.

Discarded rockets and rocket stages are some of the largest and most easily visible objects among space debris and space junk orbiting the Earth. These rockets are the remnants of space missions, including launches of satellites, scientific missions, and human spaceflight. Once a rocket or its stage has completed its mission, it becomes space debris, orbiting around the Earth for years and even decades.

There are currently thousands of rocket stages and other rocket-related debris in orbit around the Earth, ranging in size from small parts to several meters in length. Some notable examples of rocket stages causing problems include the Soviet Union's Sputnik-4 in 1960, which collided with its own launch vehicle, and China's Fengyun-1C satellite in 2007, which was destroyed in an anti-satellite missile test, generating thousands of pieces of debris.

Efforts are being made to address this problem, including removing discarded rockets and rocket stages from orbit. One notable example is the European Space Agency's Clean Space initiative, which aims to develop technologies to remove debris from orbit. Some rockets and rocket stages have been deorbited intentionally, while others have been removed through space missions to retrieve them. For example, in 2018, the European Space Agency launched a mission to retrieve a discarded rocket stage from orbit and bring it back to Earth for analysis. These efforts are essential to ensure the safety of space activities, and to prevent further pollution of Earth's orbit.

Satellites provide vital services, including communication, navigation, and research. However, satellites are also contributing to the problem of space debris. Currently, there are more than 3,000 defunct satellites in orbit.

Several solutions are being explored to address this problem, including launching spacecraft to rendezvous with these satellites and retrieve them, or using technology to deorbit satellites back to Earth. One notable example is the 2018 Space Sweepers mission, where a spacecraft was launched to retrieve a defunct satellite from orbit.

Despite efforts to address the problem, satellites continue to cause problems in space. For instance, in 2013, a satellite operated by the European Space Agency experienced a propulsion malfunction and could not be controlled, resulting in its uncontrolled re-entry into the Earth's atmosphere. In 2019, India conducted an anti-satellite missile test that created over 400 pieces of trackable debris. Also in 2019, the SpaceX Starlink satellite constellation was launched, with plans to launch up to 42,000 satellites to provide global internet coverage. The sheer number of satellites has raised concerns about the impact on space debris and the potential for collisions with other satellites.

Satellites provide an essential service, but they also contribute to the growing space debris problem, as shown by several events. This poses a major challenge for the space community.

Untrackable objects in space debris are a cause for concern as they cannot be accurately tracked. Without proper identification, it is difficult to determine the level of risk they pose to active satellites or space missions. Due to the limitations of current technology and the vastness of space, makes it a major challenge to identify every piece of debris. Every moment, there is a chance that some of these debris objects may cause a future accident or collision.

Space debris causes big problems on Earth. It poses a risk to human life and infrastructure, in the event of collisions with satellites or the International Space Station. Space debris contributes to the environmental impact of space exploration by producing more debris and increasing the risk of the Kessler Syndrome, a theoretical scenario where a cascade of collisions in space creates so much debris that it makes space activities unfeasible for generations.

Previous events where space objects have impacted Earth include the Tunguska event in 1908, the Sikhote-Alin meteorite impact in 1947, the 1972 Great Daylight Fireball, the 2013 Chelyabinsk meteor, and the 2018 Green Valley fireball, among others. Scientists are currently working to avoid specific and severe events such as collisions with operational spacecraft, collisions with the ISS, the creation of new debris through collisions, and the proliferation of space debris in low-Earth orbit. One approach is to track and monitor debris through ground-based and space-based sensors, and another is to actively remove debris through methods such as nets or harpoons.