The Kessler Cascade

Or: In Space, No One Can Hear You Take out the Trash

My family goes to a lot of movies. We're not film buffs, by any means. Usually, we're looking for snappy dialogue and explosions. A couple years ago, we saw the film “Gravity.” For those who haven't seen it, a runaway debris cloud destroys satellites and space stations. Even though the science in that movie was pretty badly off, in a lot of ways, something like it does have the potential to occur.

Kessler Syndrome is a hypothetical scenario dreamed up by a NASA scientist named Donald Kessler in the 70s. Essentially, it proposes that if enough objects are in low Earth orbit, collisions between them will eventually result in an enormous cascade of debris.

It's a pretty simple process: one piece of space junk slams into another, which sends debris scattering about. Some of that debris hits another piece of space junk, creating another burst of debris, which slams into more space junk, and then maybe into a satellite. Eventually, you have an enormous cloud of debris traveling through orbit. Each piece would be widely spaced, but even tiny bits can have insanely destructive power when moving that quickly. The cloud wouldn't take out every satellite, of course; it would stay in the same orbit, and many satellites would be in a higher or lower orbit.

A Kessler cascade could potentially make space travel impossible for millennia, completely blocking off that orbit. The debris wouldn't orbit forever. The drag from the miniscule amount of air at that altitude, along with a few other factors, would eventually clear the orbit again, though the process could take thousands of years.

Governments take the threat quite seriously. Satellites aren't allowed to launch unless they can be safely disposed at the end of their lifespans. The two most common techniques for doing so: dropping it back into the atmosphere or raising it up into a higher graveyard orbit. People also have proposed gadgets for clearing the debris, including a device called a laser broom, which is precisely as cool as it sounds.

It all really just goes to show: proper waste disposal is important, no matter where you are.


Dust Busting in Space

fullmoonFor all of the billions of dollars spent getting to the moon, and with all of the challenges NASA had to overcome getting there, one of the most aggravating problems didn't crop up until astronauts had already landed: moon dust.

Moon dust has a perfect storm of properties that’s an absolute nightmare to deal with. It's extremely fine grained, yet simultaneously abrasive, like someone ground up bits of sandpaper. The best way to think of moon dust is like powdered glass. It also has severe static cling, thanks to the solar wind continuously bombarding it, so it sticks to every bit of equipment—suits, lenses, you name it. Moon dust also gums up spacesuit joints, wears through layers, and gets all over habitats.

Part of the reason the stuff is so difficult to deal with is that it’s formed by meteor and micrometeoroid bombardments, unlike earth dust. Since there is no wind or water to erode the dust, it stays just as sharp as the day it was shattered off.

Moon dust even causes its own health condition, known as lunar hay fever, causing severe congestion and other problems. Long-term exposure to the dust could likely cause health problems very similar to silicosis.

That's not to say NASA hasn't been researching solutions for dealing with all that moon dust. Each grain contains a small fragment of metallic iron, which means that we can collect it with a magnet. The grains also melt quickly and easily with a microwave. One scientist even envisions placing microwaves on the front of lunar rovers, so that our astronauts could create “roads” as they travel.

The Moon hardly has a monopoly on dusty conditions. The dust on Mars is believed to be such a strong oxidizer that it can burn your skin, much like lye or bleach. Martian dust on your skin would leave burn marks.

Orchid Hunting

Or: How I Chose Something Else

I like to keep a lot of houseplants around—it really helps make a house feel like a home.

Maggie used to give me a lot of guff about my taste in houseplants. She said that I could easily get a job as a hotel decorator because I had the same taste in plants. So, just to please her, I decided to pick up a couple flowers…orchids, in this case.

I'd avoided orchids for years, since I'd heard many stories about how difficult they are to keep. So, before I bought some orchid plants, I decided to do my research. And that’s when I stumbled across something incredibly weird.

There is an enormous black market for orchids. Seriously! Orchids are a multibillion-dollar market with a large percentage of that value being illegal.

Orchids have been wildly popular since the 1700s, largely due to their extreme variety. There are literally thousands and thousands of species, with new ones being discovered all the time. Some species go for incredible prices—one rare orchid species, The Gold of Kinabalu, sells for over five grand per stem on the black market. This one commands its high prices due to its unique appearance, its protection by the government of Malaysia, and the fact that the plants take 15 years to bloom.

Eventually, the extreme demand resulted in rare and delicate orchid species being driven extinct in the wild, all over the world.

Governments quickly began passing laws to prevent their smuggling from countries or harvesting by unauthorized personnel. But: since most of the countries involved merely punish offenders with fines—or short jail terms—at most, the legal threat isn’t a huge deterrent; potential profits are simply too large.

Some orchid species are being wiped out by orchid hunters before they even have a chance to be described by science.

I ended up going with a couple Cyclamen plants instead.

On Living Bridges

I've blogged a lot about bridges, I know (Sir Bridges Blog-a-Lot, eh?) but I haven't yet explored living bridges.

Meghalaya, a state in north-eastern India, is one of the wettest places in the world, getting close to 500 inches of rainfall a year. Almost three-quarters of the state is forested. One of the indigenous tribes living there, the War-Khasi, build living foot bridges from the roots of the Ficus elastica — a variety of rubber tree.

thebridgePhoto by Arshiya Urveeja Bose [CC BY 2.0], via Wikimedia Commons

To grow the bridges, the Khasis create root guidance systems out of halved and hollowed betel nut trunks. The roots are channeled to the other side of the river, where they are allowed to bury themselves in the soil on that side.

The bridges take 10 to 15 years to grow strong enough for regular use; once they do, they last incredible amounts of time with no maintenance: since they're still growing, they actually continue to grow stronger and stronger over time. Some of the older bridges are five centuries old. Many of the older, stronger bridges can support 50 or more people at once.

mfthoughtThe most famous of the bridges, the Umshiang Double-Decker Root Bridge, is actually two of those bridges, with one stacked directly over the other. Local dedication to the art has kept the bridges alive and prevented them from being replaced with steel. (Steel, frankly—and with all respect to those dealing with, ahem, yard ramps—don't have anything near the lifespan of the root bridges and aren't nearly as sturdy.)

The root bridges aren't the only living bridges around. In the Iya Valley in Japan, there are bridges woven out of living wisteria vines. They're much less common, and only three remain. They're built by growing immense lengths of wisteria on each side of the river before weaving them together—a process that must be repeated once every three years.

These wisteria bridges are much less sturdy than the Khasi root bridges, with wooden planks spaced over seven inches apart, and they apparently shake wildly while you're on them. By all accounts, these things are terrifying to cross, which makes sense: they’re widely thought to have been designed originally for defense. The original bridges didn't even have railings.

Hutton’s Geology

James Hutton

James Hutton

Everyone knows about Charles Darwin and Galileo Galilei. They're the closest thing to science rock stars. One battled the Catholic Church at the height of its power and performed experiments involving dropping objects off buildings. The other took a voyage around the world and developed a whole new science. They have fascinating, memorable, and dramatic life stories. They’ve earned rock star status.

Geology has its own Darwin, but he's hardly as well known.

James Hutton was far from an adventurous man. In fact, most of his discoveries came about from exploring the same small area close to where he lived.

Hutton was a Scottish gentleman farmer, commonly known as the Father of Modern Geology. By observing layers of dirt and stone, he was the first to consider that these layers might indicate great age.

Man of Rocks

Man of Rocks

In his day (the mid and late 1700s), most other geologists looked to various theories involving floods to explain the layers. Hutton, though, theorized that the Earth was incredibly hot inside, and that sediment swept into the ocean melted and was pushed upwards. Which wasn't too far from today’s consensus, at least compared to most of his contemporaries.

Part of the reason that Hutton isn't well remembered today is that he was a much worse writer than other prominent geologists of the time. Hutton's book Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe was much less readable for the general public. Plus, the title is just less catchy than, say, On the Origin of Species. Much, much less catchy.

Another reason? Rocks just aren't that interesting to most people.