The phenomenon you're referring to is known as space debris or orbital debris. While the Earth's gravitational pull does exist in space and affects objects within its range, several factors contribute to why space debris doesn't immediately fall towards Earth.
Orbital Velocity: Objects in orbit, including satellites and space debris, travel at extremely high speeds. These speeds are known as orbital velocities. To maintain a stable orbit, the orbital velocity must match the gravitational pull. The combination of the object's speed and the curvature of its orbit creates a balance between gravitational attraction and centrifugal force, keeping it in orbit rather than falling towards Earth.
Altitude: Space debris typically orbits at various altitudes above the Earth's surface. The altitude at which an object orbits affects the strength of the gravitational force it experiences. Objects at higher altitudes experience a weaker gravitational force compared to those closer to Earth. Consequently, while the force of gravity is present, it may not be sufficient to pull the debris down immediately.
Lack of Atmospheric Resistance: In space, there is a near-vacuum environment with an extremely thin atmosphere. Unlike objects within the Earth's atmosphere, space debris encounters minimal air resistance, which would otherwise cause it to slow down and eventually fall towards Earth. The absence of significant atmospheric drag allows space debris to maintain its orbital velocity over an extended period.
Collisions and Fragmentation: Space debris is a result of human-made objects, such as defunct satellites, spent rocket stages, and fragments from previous space missions. Over time, collisions between these objects can occur, further generating smaller debris fragments. These fragments can disperse in various orbits, creating a cloud of debris that poses an ongoing risk to operational satellites. However, even though they may be subject to gravitational forces, they can remain in orbit due to the factors mentioned above.
Despite these factors, space debris is indeed a significant concern. As the amount of debris continues to increase, efforts are being made to mitigate the problem through measures such as space debris tracking, active debris removal, and designing satellites and rockets with the consideration of reducing debris generation.