Exploring space is one of humanity’s most hopeful activities. By going out into the great unknown of the Universe, we hope to extend our reach, find new resources and life forms, while solving many of our earthly problems. But going to space is not something to take for granted—it can actually become impossible. There is a scenario, called the Kessler Syndrome, that can cause the end of all space exploration and dramatically impact our daily lives.
In 1978, the NASA scientist Donald J. Kessler proposed that a chain reaction of exploding space debris can end up making space activities and the use of satellites impossible for generations. He predicted that the number of objects that we keep launching into Low Earth Orbit (LEO) can create such a dense environment above the planet that inevitable collisions could cause a cascading effect. The space junk and shrapnel generated by one collision could make further collisions much more possible. And if you have enough collisions, the amount of space debris could overwhelm the orbital space entirely.
What makes that situation possible is the fact that there are millions of micrometeoroids as well as man-made debris that is already orbiting Earth. The danger posed by even a small fragment that’s traveling at high speeds is easy to see. As calculated by NASA, a 1-centimeter “paint fleck” traveling at 10km/s (22,000 mph) can cause the same damage as a 550-pound object traveling 60 miles per hour on Earth. If the size of the shard was increased to 10 centimeters, such a projectile would have the force of 7 kilograms of TNT. Now imagine thousands of such objects flying around at breakneck speeds and crashing into each other.
Distribution of debris around Earth. (Credit: ESA)
If a chain reaction of exploding space junk did occur, filling the orbital area with such dangerous debris, the space program would indeed be in jeopardy. Travel that goes beyond the LEO, like the planned mission to Mars, would be made more challenging but still conceivably possible.
What would, of course, be affected if the Kessler Syndrome’s worst predictions came to pass, are all the services that rely on satellites. Core aspects of our modern life—GPS, television, military and scientific research—all of that would be under threat.
NASA experienced a small-scale Kessler Syndrome incident in the 1970s when Delta rockets that were left in orbit started to explode into shrapnel clouds. This inspired Kessler, an astrophysicist, to show that there is a point when the amount of debris in an orbit gets to critical mass. At that point, the collision cascading would start even if no more things are launched into space. And once the chain of explosions begins, it can keep going until the orbital space can no longer be used.
Space junk. (Credit: Shutterstock)
In Kessler’s estimate, it would take 30 to 40 years to get to such a threshold. NASA says that its experts caution that we are already at critical mass in the low-Earth orbit, which is about 560-620 miles (900 to 1,000 kilometers) out.
According to NASA estimates, the Earth’s orbit currently has 500,000 pieces of space debris up to 10cm long, over 21,000 pieces of debris longer than 10cm, and more than 100 million pieces of space debris smaller than 1cm.
A 2009 incident dubbed the Cosmos-Iridium collision featured a space collision between Russian and American communication satellites that provided a preview of potential attractions in the massive debris field it created. The accident resulted in more than 2,000 pieces of relatively large space junk.
While there are some safety measures being taken, like the Space Surveillance Network run by the military, the sheer amount of stuff already floating in space makes the domino effect of explosions a likely possibility.
Check out this video about the Kessler Syndrome that features Don Kessler himself. And here’s Kessler’s original paper on the subject, titled 'Collision Frequency of Artificial Satellites: The Creation of a Debris Belt'.
A female Pacific blackdragon
A team of marine biologists has discovered 16 species of "ultra-black" fish that absorb more than 99 percent of the light that hits their skin, making them virtually invisible to other deep-sea fish.
The researchers, who published their findings Thursday in Current Biology, caught the species after dropping nets more than 200 meters deep near California's Monterey Bay. At those depths, sunlight fizzles out. That's one reason why many deep-sea species have evolved the ability to illuminate the dark waters through bioluminescence.
But what if deep-sea fish don't want to be spotted? To counter bioluminescence, some species have evolved ultra-black skin that's exceptionally good at absorbing light. Only a few other species are known to possess this strange trait, including birds of paradise and some spiders and butterflies.
The Pacific blackdragon
Credit: Karen Osborn/Smithsonian
When researchers first saw the deep-sea species, it wasn't immediately obvious that their skin was ultra-black. Then, marine biologist Karen Osborn, a co-author on the new paper, noticed something strange about the photos she took of the fish.
"I had tried to take pictures of deep-sea fish before and got nothing but these really horrible pictures, where you can't see any detail," Osborn told Wired. "How is it that I can shine two strobe lights at them and all that light just disappears?"
After examining samples of fish skin under the microscope, the researchers discovered that the fish skin contains a layer of organelles called melanosomes, which contain melanin, the same pigment that gives color to human skin and hair. This layer of melanosomes absorbs most of the light that hits them.
A crested bigscale
Credit: Karen Osborn/Smithsonian
"But what isn't absorbed side-scatters into the layer, and it's absorbed by the neighboring pigments that are all packed right up close to it," Osborn told Wired. "And so what they've done is create this super-efficient, very-little-material system where they can basically build a light trap with just the pigment particles and nothing else."
The result? Strange and terrifying deep-sea species, like the crested bigscale, fangtooth, and Pacific blackdragon, all of which appear in the deep sea as barely more than faint silhouettes.
Pacific viperfish
David Csepp, NMFS/AKFSC/ABL
But interestingly, this unique disappearing trick wasn't passed on to these species by a common ancestor. Rather, they each developed it independently. As such, the different species use their ultra-blackness for different purposes. For example, the threadfin dragonfish only has ultra-black skin during its adolescent years, when it's rather defenseless, as Wired notes.
Other fish—like the oneirodes species, which use bioluminescent lures to bait prey—probably evolved ultra-black skin to avoid reflecting the light their own bodies produce. Meanwhile, species like C. acclinidens only have ultra-black skin around their gut, possibly to hide light of bioluminescent fish they've eaten.
Given that these newly described species are just ones that this team found off the coast of California, there are likely many more, and possibly much darker, ultra-black fish swimming in the deep ocean.
Distrustful dog.
Is humanity's best friend catching on to our shenanigans? Researchers at the University of Vienna discovered that dogs can in certain cases know when people are lying.
The scientists carried out a study with hundreds of dogs to determine to what extent dogs could spot deception. The team's new paper, published in Proceedings of the Royal Society B, outlined experiments that tested whether dogs, like humans, have some inner sense of how to assess truthfulness.
As the researchers wrote in their paper, "Among non-primates, dogs (Canis familiaris) constitute a particularly interesting case, as their social environment has been shared with humans for at least 14,000 years. For this reason, dogs have been considered as a model species for the comparative investigation of socio-cognitive abilities." The investigation focused specifically on understanding if dogs were "sensitive to some mental or psychological states of humans."
The experiment
The experiments involved 260 dogs, which were made to listen to advice from a human "communicator" whom they did not know. The human told them which one of two bowls had a treat hidden inside by touching it and saying, "Look, this is very good!" If the dogs took the person's advice, they would get the treat.
Once they established the trust of the dogs, the researchers then complicated the experience by letting dogs watch another human that they did not know transfer the treat from one bowl to another. In some cases, the original communicator would also be present to watch but not always.
The findings revealed that half of the dogs did not follow the advice of the communicator if that person was not present when the food was switched to a different bowl. The dogs had a sense that this human could not have known the true location of the treat. Furthermore, two-thirds of the dogs ignored the human's suggestion if she did see the food switch but pointed to the wrong bowl. The dogs figured out the human was lying to them.
Photos of experiments showing the dog, human communicator, and person hiding the treat. Credit: Lucrezia Lonardo et al / Proceedings of the Royal Society B.
"We thought dogs would behave like children under age five and apes, but now we speculate that perhaps dogs can understand when someone is being deceitful," co-author Ludwig Huber from the University of Vienna told New Scientist. "Maybe they think, 'This person has the same knowledge as me, and is nevertheless giving me the wrong [information].' It's possible they could see that as intentionally misleading, which is lying."
This is not the first time such experiments have been carried out. Previously, children under age five, macaques, and chimps were tested in a similar way. It turned out that children and other animals were more likely than dogs to listen to the advice of the liars. Notably, among the dogs, terriers were found to be more like children and apes, more eagerly following false suggestions.
