Space Debris

Context:

A Chinese satellite had a near collision with one of the many chunks of debris left by the fallout of a recent Russian anti-satellite missile test, state media reported.

More than 27,000 pieces of orbital debris, or “space junk,” are tracked by the Department of Defense’s global Space Surveillance Network (SSN) sensors.
Much more debris — too small to be tracked, but large enough to threaten human spaceflight and robotic missions — exists in the near-Earth space environment. Since both the debris and spacecraft are traveling at extremely high speeds (approximately 15,700 mph in low Earth orbit), an impact of even a tiny piece of orbital debris with a spacecraft could create big problems.

The rising population of space debris increases the potential danger to all space vehicles, including to the International Space Station and other spacecraft with humans aboard, such as SpaceX’s Crew Dragon.

NASA takes the threat of collisions with space debris seriously and has a long-standing set of guidelines on how to deal with each potential collision threat to the space station.
These guidelines, part of a larger body of decision-making aids known as flight rules, specify when the expected proximity of a piece of debris increases the probability of a collision enough that evasive action or other precautions to ensure the safety of the crew are needed.

Space debris encompasses both natural meteoroid and artificial (human-made) orbital debris. Meteoroids are in orbit about the sun, while most artificial debris is in orbit about the Earth (hence the term “orbital” debris).
Orbital debris is any human-made object in orbit about the Earth that no longer serves a useful function. Such debris includes nonfunctional spacecraft, abandoned launch vehicle stages, mission-related debris, and fragmentation debris.
There are approximately 23,000 pieces of debris larger than a softball orbiting the Earth.
They travel at speeds up to 17,500 mph, fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft.
There are half a million pieces of debris the size of a marble or larger (up to 0.4 inches, or 1 centimeter) or larger, and approximately 100 million pieces of debris about .04 inches (or one millimeter) and larger. There is even more smaller micrometer-sized (0.000039 of an inch in diameter)

While space debris is unlikely to affect space travel, it will lead to significant problems for spaceflight around Earth.
The risk would be highest for objects orbiting at an altitude of around 1,000 kilometers (620 miles), which is used for communications and Earth observation.
“We will still be able to travel to Mars.

According to NASA, debris in orbits below 600 kilometers will fall back to Earth within several years, but above 1,000 kilometers it will continue circling the Earth for a century or more.

Source: THE HINDU.