How many satellites are orbiting Earth?
7941 number of satellites orbiting earth as of 16 September 2021
It seems like every week; they launched another rocket into space carrying rovers to Mars, tourists or, most commonly, satellites. That “space is getting crowded” has been around for a few years now, but just how crowded is it? And how crowded is it going to get?
I am a professor of physics and director of the Center for Space Science and Technology at the University of Massachusetts, Lowell. Many satellites that were put into orbit have gone dead and burned up in the atmosphere, but thousands remain.
Groups that track satellite launches don’t always report the same numbers, but the overall trend is clear–and astounding.
Since the Soviet Union launched Sputnik–the first human-made satellite–in 1957, humanity has steadily been putting more and more objects into orbit every year.
Over the second half of the 20th century, there was a slow but steady growth, with roughly 60 to 100 satellites launched yearly until the early 2010s.
But since then, the pace has been increasing dramatically.
By 2020, 114 launches carried around 1,300 satellites to space, surpassing the 1,000 new satellites per year mark for the first time. But no year in the past compares to 2021.
As of Sept. 16, roughly 1,400 new satellites have already begun circling the Earth, and that will only increase as the year goes on. Just this week, SpaceX deployed another 51 Starlink satellites into orbit.
Small satellites, easy access to orbit
There are two main reasons for this exponential growth. First, it has never been easier to get a satellite into space. For example, on Aug. 29, 2021, a SpaceX rocket carried several satellites–including one built by my students–to the International Space Station. On Oct. 11, 2021, these satellites will deploy into orbit, and the number of satellites will increase again.
The second reason is that rockets can carry more satellites more easily–and cheaply–than ever before. This increase isn’t due to rockets getting more powerful. Rather, satellites have gotten smaller thanks to the electronics revolution.
The vast majority–94%–of all spacecraft launched in 2020 were smallest–satellites that weigh less than around 1,320 pounds (600 kilograms).
Most of these satellites are used for observing Earth or for communications and internet. With a goal of bringing the internet to underserved areas of the globe, two private companies, Starlink by SpaceX and OneWeb together launched almost 1,000 smallest in 2020 alone.
They are each planning to launch more than 40,000 satellites in the coming years to create what are called “mega-constellations” in low-Earth orbit.
Several other companies are eyeing this US$1 trillion market, most notably Amazon with its Project Kuiper. constellations–like SpaceX’s Starlink, seen in the video above–are set to dramatically increase the number of objects orbiting Earth and are already causing problems.
A crowded sky
With the enormous growth in satellites, fears of a crowded sky are coming true. A day after SpaceX launched its first 60 Starlink satellites, astronomers saw them blocking out the stars.
While the impact on visible astronomy is easy to understand, radio astronomers fear they may lose 70% sensitivity in certain frequencies because of interference from satellite mega constellations like Starlink.
Experts have been studying and discussing the potential problems posed by these constellations and ways the satellite companies could address them . These include reducing the number and brightness of satellites, sharing their location and supporting better image-processing software.
Less than 10 years ago, the democratization of space was a goal yet to be realized. Now, with student projects on the Space Station and over 105 countries having at least one satellite in space, perhaps that goal is within reach.
Every disruptive technological advancement requires updates to the rules–or the creation of new ones. SpaceX has tested ways to lower the impact of Starlink constellations, and Amazon has disclosed plans to de-orbit their satellites within 355 days after mission completion.
These and other actions by different stakeholders make me hopeful that commerce, science and human endeavors will find sustainable solutions to this potential crisis.
Supriya Chakrabarti, Professor of Physics, University of Massachusetts Lowell