Earth is a bit of a hoarder, collecting trinkets and tchotchkes since they first started appearing in its orbit. A piece of the rocket that carried the Soviet Union’s Sputnik 1 was its first man-made possession, and since then Earth has amassed over 500,000 pieces of spent spacecraft and other debris. But gadgets and gizmos aplenty are creating an orbital minefield that can cascade into catastrophe.
Celestial junk doesn’t have to be big to be a threat: Debris the size of a marble traveling at high speeds could disable a working spacecraft or bore International Space Station (ISS) shields with the power of a hand grenade. Even flecks of paint, when traveling up to 17,500 miles per hour, can inflict damage. Amid fragments from artificial celestial junk are also naturally occurring meteoroid particles, but anything smaller than 5 centimeters (about 2 inches) is too hard to track.
The visualization above shows the 41,000 man-made objects the size of a softball or bigger tracked in Earth’s orbit since Sputnik sparked the space age over half a century ago. A mere tenth of them are still active. The Department of Defense (DoD) catalogs these objects at low Earth orbit and geosynchronous orbit. If one gets too close to the ISS, for instance, the DoD notifies NASA, and the station is gracefully maneuvered out of the way. The ISS has a pizza box-shaped perimeter that’s part of its warning system, and each invasive object is designated a cautionary level based on the likelihood of a collision. a flight controller described in an interview with Ars Technica.
And collisions do happen, because the past is still very much steering the present. (NASA even has a quarterly newsletter dedicated to the subject.) Fragments from explosions have caused the volume of junk to climb, and climb fast. Of more than 250 in-orbit explosions, only a handful have been known collisions, according to the European Space Agency (ESA). The first-ever accidental crash occurred in 2009 when an active Iridium satellite collided with a decommissioned Russian craft above Siberia, resulting in more than 2,200 trackable bits. Other blasts happen largely due to the fuel that’s left in tanks even after a rocket stage has been retired.
In 1978 A NASA scientist Donald Kessler authored a paper that predicted the chain reaction of pieces smashing into one another, leaving a belt of debris. This runaway scenario is called the Kessler syndrome, and it’s very much happening, a NASA scientist told Wired. Debris is a risk to every mission, manned or unmanned, and to people back on land, as pieces occasionally drop in from the sky. And launches, both scientific and commercial, show no sign of stopping anytime soon.
Scientists have been toiling over all sorts of solutions, from harpoons and lasers to fishing nets and robotic arms. Even game theory has entered the ring. NASA has hosted hackathons called the Space Apps Challenge for the last five years, which cultivates innovations to solve space problems. Mock satellites like DebriSat are destroyed in tests to assess impact risk. Switzerland looking to launch a conical net in 2018 to capture and de-orbit its defunct satellite SwissCube, and the ESA’s e.Deorbit mission is gearing up for flight in 2023. Till then, those involved with missions will have to keep their smiles plastered through Earth’s show-and-tell.