'Tragedy of the commons' in space: We must act now to avoid an orbital debris crisis, scientists say

Humanity must start tackling the growing problem of space junk now, before it spirals out of control, scientists say.

Earth’s orbit is becoming more and more crowded, with both satellites and pieces of debris. There are so many things up there that it’s far from alarmist to start worrying Kessler syndromea nightmare scenario in which one or two collisions lead to many more, dramatically increasing the amount of waste surrounding our planet.

“We need to take this seriously and recognize that, if we do nothing, we are in imminent danger of wiping out an entire part of our Earth unusable environment,” said Dan Baker, director of the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder (UC-Boulder), during a panel Wednesday (Dec. 11) at the 2024 meeting of the American Geophysical Union (AGU) in Washington, DC.

Earth’s orbit is home to more than 10,200 active satellites, according to the European Space Agency (ESA). Most of these spacecraft are found low earth orbit (LEO), a shell that lies approximately 125 to 1,250 miles (200 to 2,000 kilometers) above our planet.

Most of these LEO satellites… about 6,800 of them — belong to a single constellation: that of SpaceX Star link broadband network.

These numbers continue to grow and the figure could soon reach staggering levels. SpaceX, for example, wants the Starlink network to eventually host more than 40,000 spacecraft.

Other players also aim to build their own broadband constellations in LEO. China has started to build its Qianfan (“Thousand Sails”) megaconstellation, which will have around 14,000 satellites if all goes as planned. Additionally, Amazon intends to build its own LEO broadband network of 3,200 satellites, called Project Kuiper.

And these are just the active satellites; the amount of waste in Earth orbit is much higher. For example, the ESA estimates that there are around 40,500 pieces of debris at least 10 centimeters wide circling our planet. THE space debris the population includes an additional 1.1 million pieces between 0.4 inches and 4 inches (1 to 10 cm) in width, and 130 million in the 1 millimeter to 0.4 inch range.

Even these tiny fragments can cause considerable damage to a satellite or other spacecraft, given the speed at which objects in orbit move. At International Space StationFor example, at an average altitude of 250 miles (400 km), the orbital speed is about 17,500 mph (28,160 km/h).

These fragments are too small to be tracked using ground radars. That’s a shame, scientists say, and not just because the shards are potentially dangerous.

“If Kessler syndrome starts to occur and we start to see some sort of cascade of collisions, we will see it first in the smallest grains,” said David Malaspina, a space plasma physicist and assistant professor at the ‘UC-Boulder. Wednesday’s AGU panel. “They’re our canaries in the coal mine.”

Quantifying the risk of Kessler syndrome is difficult, Malaspina and other panelists said, because the orbital environment is dynamic on several different levels.

For starters, the orbital population keeps growing, as rockets launch more and more satellites into space, so calculations tend to become obsolete almost as soon as they are made. And Earth’s atmospherewhich slowly drags LEO satellites downward over time by friction, also changes – expanding, for example, in response to an increase solar activity.

As expected, these satellites come into closer and closer contact with each other and with debris. Indeed, there are about 1,000 collision warnings per day on average in LEO, according to Thomas Berger, director of the Space Weather Technology Research and Education Center at UC-Boulder.

“So it becomes difficult for satellite operators to determine which of these warnings are important and which ones they should pay attention to,” Berger said during Wednesday’s AGU panel.

The vast majority of these warnings involve Starlink satelliteswho are far from being easy targets. These spacecraft use onboard software to spot potentially worrying encounters and perform evasive maneuvers if necessary.

But not all satellites that reach orbit are equally capable; there are no globally applicable rules requiring responsible behavior from satellite operators. This regulatory void leads to a situation of “tragedy of the commons”, according to Baker.

“Simply put, the tragedy of the commons is that individuals acting rationally and individually in their own self-interest will deplete a shared resource, even if doing so is contrary to the best interests of the group,” he said. “And I believe we are watching the tragedy of the commons unfold in low Earth orbit, right before our eyes.”

Some of the depleting resources are scientific, Baker said, noting that large satellite populations can interfere with observations made by visible light and radio telescopes. And some are cultural or societal – the pleasure an ordinary person enjoys in a dark night sky, for example.

Baker believes the United States should take the lead in instituting guidelines that could help stave off Kessler syndrome and the tragedy of the near-Earth commons. There is progress in this area, he noted, citing the recent introduction of Bipartisan Orbital Sustainability Act (ORBITS) in Congress.

“I think it starts at home and I believe we all need to play our part,” Baker said.