Space is big and the hardware that humans keep sending into the great beyond is comparatively small, but our habit of letting random bits of space vehicles, boosters, and defunct satellites hang around in orbit is starting to concern scientists more than ever before. Now, the European Space Agency is sounding the alarm and pleading with the space-traveling nations to pitch in and help clean up the estimated 150 million bits of debris with the capability to destroy or damage spacecraft that accidentally collide with them.

“Today, we find in space roughly 5,000 objects with sizes larger than 1 meter (3.25 feet), roughly 20,000 objects with sizes over 10 centimeters… and 750,000 ‘flying bullets’ of around one centimeter (half an inch),” Rolf Densing, director of operations at the ESA said at a conference regarding space junk, held in Germany. “For objects larger than one millimeter (0.04 inch), 150 million is our model estimate for that.”

The problem has gotten bad enough that some countries, like Japan, have been trying to find a way to clean up the junk with their own tools. Unfortunately, some technical difficulties held up that operation and proved to be a huge disappointment.

According to the ESA, the organization’s fleet of 10 satellites is constantly under threat from potential collisions with the junk floating around in orbit, and typically needs to make a couple of safety maneuvers each year to prevent problems. That might not sound like much of a burden, but as the volume of debris continues to climb, it will only become more and more common.