It seems that every week, another rocket is launched into space carrying rovers to Mars, tourists or, more commonly, satellites. The idea that “space is getting crowded” has been around for a few years now, but how crowded is it? And how crowded is it going to be?
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 died and burned up in the atmosphere, but thousands remain. Groups that track satellite launches don’t always report the same exact numbers, but the overall trend is clear — and surprising.
Ever since the Soviet Union launched the first man-made satellite – Sputnik – in 1957, humanity has been steadily putting more and more objects into orbit every year. In the second half of the 20th century, there was a slow but steady growth, with approximately 60 to 100 satellites being launched annually until the early 2010s.
But since then, the pace has been increasing dramatically.
By 2020, 114 launches have carried about 1,300 satellites into space, surpassing 1,000 new satellites per year for the first time. But no year in the past is compared to 2021. As of September 16, about 1,400 new satellites have already begun orbiting Earth, and this will only increase as the year progresses. This week, SpaceX deployed another 51 Starlink satellites into orbit.
Small satellites, easy access in orbit
There are two main reasons for this exponential growth. First, getting a satellite into space has never been this easy. For example, on August 29, 2021, a SpaceX rocket carried several satellites—including a satellite built by my students—to the International Space Station. These satellites will be put into orbit on 11 October 2021 and the number of satellites will increase again.
Another reason is that rockets can carry more satellites more easily – and cheaper – than ever before. This increase is not due to the more powerful rockets. Rather, the size of satellites has become smaller due to the electronics revolution. The vast majority – 94% – of all spacecraft launched in 2020 were small satellites – satellites that weighed less than about 1,320 pounds (600 kg).
Most of these satellites are used for Earth observation or communication and the Internet. Two private companies, Starlink by SpaceX and OneWeb, launched nearly 1,000 SmallSats in 2020 alone, with the goal of bringing internet to under-served areas of the world. They plan to launch more than 40,000 satellites, called “mega-constellations,” into low-Earth orbit in the coming years.
Several other companies are eyeing this US$1 trillion market, most notably Amazon with its Project Kuiper.
With the huge increase in satellites, the fear of overcrowded skies is starting to come true. A day after SpaceX launched its first 60 Starlink satellites, astronomers began to see them blocking the stars. While the effects on visual astronomy are easy to understand, radio astronomers fear they may lose up to 70% of sensitivity in some frequencies due to interference from satellite megaconstellations such as Starlink.
Experts are studying and discussing the potential problems posed by these constellations and the ways satellite companies can address them. These include reducing the number and brightness of satellites, sharing their location, and supporting better image-processing software.
As low-Earth orbit gets crowded, the concern about space debris increases, as well as the real possibility of a collision.
Less than 10 years ago, the democratization of space was a goal that has yet to be met. Now, with student projects on the space station and more than 105 countries with at least one satellite in space, one could argue that the goal is within reach.
Every disruptive technological advancement requires an update of the rules – or the creation of new ones. SpaceX has tested ways to reduce the impact of Starlink constellations, and Amazon has revealed plans to de-orbit its satellites within 355 days after the mission’s completion. With these and other actions by various stakeholders, I am hopeful that commerce, science and human efforts will lead to a lasting solution to this potential crisis.
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