The space age kicked off in 1957 with the Soviet Union’s launch of Sputnik 1, the world’s first artificial satellite. Since then, according to the European Space Agency’s (ESA) Space Environment Statistics, some 6,420 rocket launches have placed about 15,880 satellites into Earth orbit. About 10,590 of those are still in orbit and 8,900 of those are functioning today.
That’s a lot of hardware sent into orbit. The ESA estimates the total mass of all objects in orbit to be over 11,000 tons. But satellites don’t function forever. Some run out of fuel and die while others are decommissioned when the technology that they supported reaches obsolescence. More than 640 objects sent into orbit have broken up, exploded, or collided their way into fragmentation, resulting in clouds of debris.
The agency tracks about 35,530 debris objects, which have resulted from over 640 breakups, explosions, collisions, or other mishaps that caused fragmentation. However, many thousands of space debris objects up there are circling the Earth in all of the various orbital regimes from low-Earth orbit (LEO) to geostationary to high-altitude orbit.
Space debris ranges from items as small as flecks of paint to nuts, bolts, and tools, to large items like spent rocket stages and engines. Even the smallest of these objects, traveling at orbital speeds, can do significant damage to, say, a working satellite or the International Space Station. Aside from disruptions in services such as communication infrastructure, ISR coverage, navigation, or research, the proliferation of space debris can have a cascading effect if there’s a catastrophic collision or explosion.
So, what are we doing about it? Knowing where these things are located is the first order of business. As mentioned above, agencies like the ESA and NASA diligently track the orbits and location of thousands of debris objects. At its Operations Centre in Darmstadt, Germany, the ESA takes action when it’s alerted to a possible collision between an operating satellite and some chunk of metal. Often, an avoidance maneuver by the satellite can avert disaster, albeit at the expense of possibly shortening its lifespan through use of fuel.
An interesting effort mounted at Purdue University’s College of Engineering aims to investigate how LEOs and geostationary satellites can be “parked” safely in orbit. With an ever-growing number of satellite constellations being established, it’s bound to become more difficult to ensure the long-term survival of orbiting vehicles that are so critical to communications infrastructure. Purdue’s team is looking into modified orbital patterns, predominantly in the cislunar region between Earth and the moon, as safe havens.
Hopefully, the ongoing efforts to either predict catastrophic events or prevent them altogether will produce a space environment that’s conducive to orbital security for satellites of all varieties.