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Expert Voices

How many satellites are orbiting Earth?

Thousands of the satellites orbiting Earth are small – like this cubesat seen here being released from the International Space Station.
Thousands of the satellites orbiting Earth are small – like this cubesat seen here being released from the International Space Station. (Image credit: NASA, CC BY-NC)

This article was originally published at The Conversation. (opens in new tab) The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Supriya Chakrabarti (opens in new tab), Professor of Physics, University of Massachusetts Lowell

It seems like every week, another rocket is launched into space carrying rovers to Mars (opens in new tab)tourists (opens in new tab) or, most commonly, satellites (opens in new tab). The idea that "space is getting crowded (opens in new tab)" 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 (opens in new tab) and director of the Center for Space Science and Technology (opens in new tab) 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 (opens in new tab) that track satellite launches (opens in new tab) don’t always report the same exact numbers, but the overall trend is clear — and astounding.

number of satellites orbiting Earth

(Image credit: The Conversation)

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 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 (opens in new tab).

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 month, SpaceX deployed another 51 Starlink satellites into orbit.

The ever-shrinking size of technology has led to tiny satellites like the one students are working on here. (Image credit: Edwin Aguirre/University of Massachusetts Lowell, CC BY-ND)

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 (opens in new tab) — 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 smallsats — satellites that weigh less than around 1,320 pounds (600 kilograms).

The majority 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 (opens in new tab) together launched almost 1,000 smallsats in 2020 alone. They are each planning to launch more than 40,000 satellites (opens in new tab) 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 (opens in new tab), most notably Amazon with its Project Kuiper (opens in new tab).

A crowded sky

With the huge growth in satellites, fears of a crowded sky are starting to come true. A day after SpaceX launched its first 60 Starlink satellites, astronomers began to see them blocking out the stars (opens in new tab). While the impact on visible astronomy is easy to understand, radio astronomers fear they may lose 70% sensitivity in certain frequencies (opens in new tab) due to interference from satellite megaconstellations like Starlink.

Experts have been studying and discussing the potential problems posed by these constellations (opens in new tab) and ways the satellite companies could address them (opens in new tab). These include reducing the number and brightness of satellites, sharing their location and supporting better image-processing software.

As low-Earth orbit gets crowded, concern about space debris (opens in new tab) increases, as does a real possibility (opens in new tab) of collisions (opens in new tab).

Less than 10 years ago, the democratization of space (opens in new tab) was a goal yet to be realized. Now, with student projects on the space station (opens in new tab) and more than 105 countries having at least one satellite in space, one could argue that 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 (opens in new tab), and Amazon has disclosed plans to deorbit 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.

[The Conversation’s science, health and technology editors pick their favorite stories. Weekly on Wednesdays (opens in new tab).]

This article is republished from The Conversation (opens in new tab) under a Creative Commons license. Read the original article (opens in new tab).

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Professor of Physics, University of Massachusetts Lowell