What are artificial satellites & why don't they drop out of orbit and fall back to Earth?

Artificial satellites are among the most technologically advanced inventions by human civilization. These artificial satellites have allowed humans to have better communication, better knowledge about space - and most importantly, the largest among them have shown that it is possible for life to exist in the inky black void for extended periods.

So what are satellites? 

Satellites are objects in high orbit around a planet. While innumerable natural satellites exist, including the Moon, humans have also launched artificially designed satellites to space. Gravity dictates the equation of a heavenly body and its satellites. The solar system's two most massive planets - Jupiter and Saturn - have its largest (the Jovian moons) and most numerous (4) natural satellites respectively.

Also read: Elon Musk's SpaceX to Launch 60 Starlink Satellites On Oct 21; Here's How To Watch Live

Artificial satellites

As per NASA's website, artificial satellites were invented in the middle of the 20th century. It is a space probe that orbits around a planet and has different purposes. The first-ever artificial satellite was Sputnik, a small beach ball-sized probe from Russia which was launched on October 4, 1957. On November 3 of the same year, a bigger size satellite Sputnik 2 with a dog named Laika made history. The US launched its first satellite Explorer 1 on January 1, 1958. With time, the satellites grew bigger and became more advanced, Russia launched its first satellite which served as a space station, named Salyut 1 in 1971.  Followed by Skylab from the US and Mir from the Soviet Union. Currently, the International Space Station (ISS) which is a joint effort by space agencies around the world has been a home to humans for two decades.

Also read: ISRO Gearing Up For Launch Of Small Satellite Launch Vehicles: Sivan

With satellites, telecommunication, live TV broadcasts and long-distance phone calls became a reality and feasible. At present, these artificial satellites are used for internet services, military surveillance, and also for detailed research in space, with the ISS housing numerous labs.

Also read: What Is Starlink SpaceX? How Does The Satellite Internet Constellation Work?

Also read: SpaceX Launches 60 More Starlink Broadband Satellites Into Orbit

Parts of satellites

According to NASA, an artificial satellite has four parts. The first one is the power system which has a solar or nuclear core that powers the satellite, a component that controls its orbiting path. Then there comes an antenna which sends and receives information and a payload which collects information like a camera or a particle detector.

Also read: ISRO Releases Draft Policy To Boost Private Players' Participation In Space Communications

Why don’t the satellites fall on the Earth?

Despite the Earth's gravitational pull, satellites don't immediately fall back on Earth as their angular velocity from launch is sufficient that the gravitational pull serves more as a string that keeps the body from being ejected out of orbit. Over time, however, many satellites lose their velocity and face degradation of their orbit, eventually burning up in the atmosphere.