Scientists warned about problems that orbital junk, or mankind’s mounting debris from decades of cosmic exploration, poses on current and future space missions.

In a conference in Germany last Tuesday, April 18, they sounded the alarm on the doubling risk of large fragments orbiting and potentially destroying a spacecraft. Tiny, hard-to-detect objects are a separate threat, as they are now estimated to reach about 150 million in number.

Growing Threat To Space Exploration

The problem, according to European Space Agency director of operations Rolf Densing, can only be solved on a global scale.

“We are very much concerned,” Densing said in an AFP report.

Back in 1993, ground-based radar monitoring revealed about 8,000 man-made objects in orbit that were bigger than 4.5 inches across. This size is huge enough to cause major damage, according to ESA.

At present, there are about 5,000 space objects with sizes bigger than 3.25 feet, as well as an estimated 20,000 objects sized bigger than 3.93 inches. Some 750,000 so-called “flying bullets” that are half an inch are lurking in space, too.

Hypervelocity makes space debris dangerous, as even the smallest debris traveling at up to 17,500 miles per hour could inflict enough damage on satellite or spacecraft surface. Collision risks are hardly likely, but chances increase as the bunch grows and more and more satellites are positioned in space.

For its part, ESA receives high-risk collision alerts every week on average for its 10 science satellites placed in low-Earth orbit. Each of them has to perform avoidance moves every year.

Satellite Launches

In addition, plans to launch “mega constellations” of communications satellites by the thousands — done mainly in the name of global wireless internet — is feared to add to the likelihood of collisions and further buildup of space junk.

Companies such as SpaceX and Google are just some seeking to launch international broadband networks and planning to deploy these tiny satellites into low orbit.

In his two-decade simulation dwelling on such climb in orbital traffic, University of Southampton senior lecturer in aerospace engineering Dr. Hugh Lewis discovered that it could create a 50 percent rise in the number of catastrophic collisions between satellites.

Is The ISS Protected Enough?

As the space laboratory in low-Earth orbit, the International Space Station is designed with the threat of small impacts in mind. The greatest potential for damage, according to a Quora reply from NASA instructor and flight controller Robert Frost, takes place when the ISS and oncoming debris travel in opposite directions since their velocities are combined.

“However, there isn't anything in the ISS orbit traveling in the opposite direction, because if there were, we would hit it every 45 minutes,” Frost explained, adding that the greatest threat hails from debris approaching from around 2 o’clock or 10 o’clock, a clearly different orbit but a truly huge relative speed.

The ISS’s best shielding, Frost continued, is dubbed Whipple bumpers and situated at the front of the station. These are multi-layered with spaces in between layers, aimed at slowing and hopefully breaking apart the projectile, making it harmless by the time it gets to the bottom layer.

In the event that a projectile punctures the hull into the station’s pressurized cabin, the ISS crew maintains patch kits to plug the resulting hole.

In a message presented at the conference, French astronaut Thomas Pesquet assured that the manned space outpost is shielded for objects up to 1 cm (0.4 inch) across.

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