[ad_1]
If the Roman Empire had been able to launch a satellite into a relatively high low-Earth orbit – say about 1200 km (750 miles) above sea level – only now would that satellite be on the verge of falling back on Earth. And if the dinosaurs had launched a satellite into the farthest geostationary orbit – 36,000 km (23,000 miles) or more – it might still be up there today.
While we’ve only * really * launched satellites since 1957, these examples show how long objects can stay in orbit. With the growing problem of space debris accumulating in Earth orbit, many experts have stressed for years that satellite operators must figure out how to responsibly dispose of abandoned satellites at the end of their life.
The European Space Agency (ESA) and the United Nations Office for Outer Space Affairs (UNOOSA) have collaborated on a new infographic showing how long it would take for satellites at different altitudes to fall back naturally to Earth.
While the process of natural desorbiting can be relatively fast for low-flying satellites – taking less than 25 years – for satellites launched into orbit tens of thousands of kilometers away, it can take thousands of years before their return.
Gravity has little effect on a satellite’s return to Earth. The most important factor in which satellites decrease their orbit is the amount of drag they encounter from Earth’s atmosphere. A satellite can stay in the same orbit for a long time because the Earth’s gravitational pull provides balance to the experience of centrifugal force satellites in orbit. For satellites orbiting out of the atmosphere, there is no air resistance and therefore, according to the law of inertia, the speed of the satellite is constant, which results in a stable orbit around Earth for many years.
“If we look at our statistics, we have about 300 objects a year coming back to Earth, burning in the atmosphere,” Francesca Letizia, space debris engineer at ESA, said in a space debris podcast. “Below 500 km, under the effect of the atmosphere, the spacecraft can re-enter within 25 years. At 800 km above Earth, it will take approximately 100 to 150 years to fall back to Earth. “
Letizia said the greatest risk to older satellites that are not currently functioning is the risk of them exploding and creating more fragments, or hitting other satellites and causing damage or destruction and also to create additional objects in Earth orbit.
In detail: here’s what happens to spaceships when they reenter Earth’s atmosphere
This means that when we launch satellites into space, we have to think about how they will be removed at the end of their life, otherwise the area around the Earth will be filled with dead old spacecraft at risk of collision, explosion and almost certain. creation of large amounts of space debris.
Further reading: ESA
[ad_2]
Source link