Archive for May 2019

A Textile cone snail

And you thought they were just garden pests or a French delicacy

One of my kids is really into both trivia and nature, and we’re routinely subjected to recitations of unusual facts about the animal kingdom. So we were reading through one of the innumerable lists of the world’s deadliest animals. And of course we saw all the usual suspects—venomous snakes, hippos, mosquitos (you know, because malaria), box jellyfish, and so on. Animals that are widely known to be deadly for fairly obvious reasons. (Humans rank high in some of these lists too, but that’s another whole story.) But one entry on this list made me do a serious double-take: a snail.

Depending on which list you look at, the cone snail is either the fourth-and-a-half, fifth, ninth, or twenty-second deadliest animal on Earth. But anyway: super crazy deadly. And that’s not even the world’s only deadly snail. The freshwater snail also makes a bunch of the deadliest animal lists, coming in at fourth on one list, seventh on a second, and sixteenth on another.

So I’m thinking, wait, what? Seriously? Snails? Those little guys that blaze along at speeds approaching one furlong per fortnight? How are they deadly? Do people step on them after a rain storm, slip, and break their necks? Do they choke on them because they weren’t cooked with quite enough garlic and butter?

Well, no. Here’s the scoop.

The cone snail is not merely venomous; various species can produce hundreds of different venoms. A sting with the snail’s harpoon-like “teeth” can cause paralysis followed by death—sometimes within minutes—and there’s no antivenin. These lovely creatures are found in warm coastal waters, in places like the Caribbean, Hawaii, and Indonesia. Yowch.

Freshwater snails are not harmful themselves, but they carry a type of parasitic worm called a blood fluke. If a freshwater snail—or even the water it was hanging out in—comes into contact with your skin, the parasite can get into your body through the skin. It can then lay eggs inside you and cause a truly gross disease called schistosomiasis. This condition is treatable, at least, but it still kills way more people each year (think: hundreds of thousands) than the cone snail (think: single digits).

So let’s be careful about there. There may be no good way to die, but I’m pretty sure you don’t want “snail” listed in your obituary as the cause of death.


Source: Interesting Thing of the Day

MS The World cruise ship

Making your home on the high seas

Back in 2006, my wife and I were living in San Francisco and bristling at the rapidly increasing rents (yes, even that long ago). We noticed the prices for homes in our neighborhood (much like the one we were renting) and couldn’t fathom ever being able to afford a mortgage for a tiny house in an unfashionable neighborhood of the city. Needless to say, that situation has gotten far, far worse in the intervening years. We do own a house now, but it’s a very small one, and nowhere near San Francisco. When looking for a home, we toyed with the idea of buying a condo instead, but even though they might cost a bit less, you pay monthly fees for maintenance of the building and common areas; yet you get less privacy and have less flexibility in how you can use or modify the space.

On the other hand, we love to travel, so I was intrigued by a notion that was all the rage in the mid-2000s: selling cruise ship cabins as condos. Roughly speaking, the sales pitch was that for just a bit more money than you’d pay for a luxury condo, you could travel the world in style without leaving home—or spending extra on airfare and hotel accommodations. In other words, if you were thinking about buying a condo anyway, if you like to travel, and if your work and lifestyle didn’t tie you to a particular location, you could have your cake and eat it too.

I speak about this in the past tense even though it’s technically still possible. But as I’ll explain in a moment, changing market conditions have largely taken the wind out of this idea’s sails.

Liquid Assets

Living full-time in a cabin on a cruise ship isn’t quite as simple as buying an expensive condo. For one thing, your average working middle-class couple—an ideal target market for a conventional condo—might run into difficulties living on a ship beyond merely paying for it. Most jobs require employees to show up at a particular location, for instance, and a ship could be highly problematic if you’ve got school-aged children, as we do. So retirees and the excessively rich are among those most likely to purchase a condo on a ship. On the other hand, living aboard a ship for a month or two at a time is well within the means of many ordinary, working citizens, and in some cases one can buy fractional ownership of a cabin—very much like a timeshare. Even those who purchase a cabin outright generally maintain land-based homes as well, and spend only a few months of the year on the ship.

When I say “cabin,” by the way, don’t think I’m talking about an ordinary ship’s cabin—as in a smaller and less comfortable hotel room. On the contrary, the homes you can buy on a ship range from simple studios to expansive suites with three bedrooms, sweeping verandahs, and every conceivable amenity. Most units have kitchens, though of course you’ll be somewhat limited in where you can shop for groceries. But naturally each ship has numerous restaurants as well, so you needn’t do your own cooking at all.

As just one of 200 or so owners, you’ll have little if any influence over the ship’s itinerary. But you can be assured that, over the course of two or three years, your home will visit nearly every major port on the planet. Some residential ships make a point of being in Cannes for the annual film festival, in Rio for Carnivale, or in other seasonally appropriate locations. But between ports, tenants may find the range of activities onboard a bit limiting; these ships have fewer shops, shows, and other diversions than vessels of similar size that cater to vacationing tourists. In addition, you’re bound to miss certain conveniences of home, such as a choice of medical and dental facilities, your favorite local businesses, and the proximity of friends and family. On the other hand, you won’t need a car, and you can hardly offer a more attractive vacation getaway for visiting guests.

A Titanic Investment

The first residential cruise ship to set said is called The World, and it launched from Norway in 2002. Although no prices are currently listed—the cabins are presumably all sold, though occasional turnover is inevitable—the last time I checked, prices ranged from US$825,000 to $7 million, plus a 6% annual fee to cover maintenance, utilities, landing privileges on the ship’s helipad, and so forth. Some units could also be rented for anywhere from $1,200 to $4,200 per night. The ship features the usual luxuries, such as a casino, a theater, upscale restaurants, and a spa. Unlike ordinary cruise ships, The World typically spends two to five days in each port, giving tenants plenty of time to explore the world off the ship. The itinerary changes each year.

Another cruise vessel currently selling units (though it isn’t scheduled to launch until mid-2020) is the MV Narrative, which advertises prices “from only $352,235.” That’s for a 172-square-foot (16 m2) cabin on a lower deck—not including the $70-per-person-per-day maintenance fee. If you want a large cabin on an upper deck, you’ll be looking at spending upwards of $3 million dollars, plus $200 or more per day, per person. This ship seems to offer everything, including t’ai chi classes. Hmmmm. I wonder if they’ve lined up an instructor yet. I know a guy.

At least two more such cruise ships are also reportedly in the works—The Utopia (still at least a couple of years out) and The Marquette, which is unique in being a river cruise ship rather than an ocean liner; the plan is for it to travel the inland waterways of the eastern United States.

However, I have to wonder how safe an investment something like this is. When I first wrote here about cruise ship condos in 2006, at least three other major vessels were in various stages of preparation, and all those projects were apparently cancelled—the websites have been taken down, and I’ve found no evidence that they ever set sail. Those were The Four Seasons (a ship owned by and named after the hotel chain), which was supposed to launch in the fall of 2007; The Orphalese, which was supposed to set sail in 2008; and The Magellan (which hadn’t even begun construction at the time but was already selling condos)—that one appealed to me especially because it promised an observatory with an astronomer on staff. Maybe they would have succeeded had enough people gotten on board with the idea, early enough, but…I guess that ship has sailed.

Because I’ll probably never have the sort of money that would make owning a cruise ship condo even a remote possibility, I can’t say whether it would be worth the expense. In some respects, you undoubtedly get what you pay for, but then, I don’t really want or need to be surrounded with luxury all the time. If someone came up with a middle-class condo ship that a mere mortal such as myself could afford, though, I’d certainly consider taking my home with me as I travel the globe.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 30, 2006.


Source: Interesting Thing of the Day

Hard to tell where the canal ends and the pavement begins, Venice floods 2012.

Atlantis redux

While on our first European vacation years ago, Morgen and I visited Venice, that beautiful Italian city where the streets are paved with water. We were there for only a few days, but we enjoyed every minute of it. The place oozes history, and it’s wonderfully romantic. When we took the customary gondola ride through the city’s canals, our gondolier casually pointed toward a small house and said, “Marco Polo used to live there.” And we could believe it—if it were not for the constant noise of motor boats, it would be easy to imagine that the city looked much the same way centuries ago as it does now. But it’s not quite the same as it was in Marco Polo’s time. Whatever other changes have happened, the most significant one is that the city, as our gondolier reminded us, is sinking.

Of course, the entire planet is doomed to be destroyed when the sun explodes in 500 million years or so, but I’m not losing any sleep over that. Why should I worry about Venice? It still looks OK to me, so it must be sinking very slowly, right? Well, not really. Venice is located in a lagoon on the edge of the Adriatic Sea. When Venice was founded in the year 421, the level of the Adriatic was about 5 meters (16 feet) lower than it is today. For centuries the water level rose very, very slowly, but in the last century or so the rate has increased dramatically. With each passing year, the difference between street level and water level shrinks faster. From time to time, the city gets a brief reprieve. As recently as 2005, unusual weather patterns caused Venice to experience exceptionally low tides—so low that boats could not navigate most of the city’s shallower canals. Nevertheless, the clear trend, as observed over centuries, is in a decisively downward direction. If nothing is done and the trend continues, by 2055, a significant portion of the city’s walkways, plazas, and ground-level floors will be submerged all the time.

That Sinking Feeling

For a long time I was puzzled about just what it meant for Venice to be “sinking,” because that doesn’t fit into my categories of things a city is capable of doing. This is in fact a somewhat simplistic description of a complex problem. One part of the problem is that the city is not built on a solid foundation. Venice was originally a collection of muddy islands. In order to construct buildings, workers drove millions of pilings—thin, sharpened poles made of alder trees—through the mud and into the marginally more solid base of sand and clay beneath. Oak planks were placed on top of the pilings, and on top of the planks, several thick layers of marble (which is impermeable by water) formed the foundations of the buildings. From there on up, most of the construction was done in ordinary brick or wood. At the time the buildings were constructed, the marble was well above the high water line, so there was nothing to worry about. However, over the centuries, the weight of the buildings has driven the pilings deeper into the mushy seabed. In addition, at one time there were hundreds of wells in the city, removing water from deep aquifers. Unfortunately, these aquifers had acted as a sort of balloon of water propping up the city; when it was “deflated,” the city began to sink even faster.

But the literal sinking of Venice, which averages something like a few centimeters per century, is only part of the problem. The other part is that the surrounding water level has been rising at an alarming rate. This is partly due to the effects of global warming and partly due to centuries of poor environmental management in the entire region. But in any case, the rising waters compound the sinking problem and make the net effect quite serious.

When It Rains, It Pours

Venice has always been subject to periodic flooding—mainly in winter, and especially at high tide. This is something that residents have come to regard as a fact of life, and not a terribly troublesome one; most of them get around in boats anyway. But whereas flooding used to be something that would happen a few times a year, now it happens on the order of a hundred times a year. Because the sea level has risen, even in a modest flood, the water level rises above the waterproof marble foundations of the buildings, rapidly wearing away the less-robust building materials.

In November, 1966, a particularly bad storm caused a devastating flood that put much of the city under 2 meters (over 6 feet) of water. This caused extensive damage to both buildings and the valuable artwork they contained, and began to impress upon Venetians the need to take drastic action.

In 1970, a plan was proposed that involved the installation of large, mobile gates at the three inlets of the lagoon; these would be raised as needed to keep out high water. But for the next 30 years, a series of excruciating delays prevented any significant progress from being made. There were, of course, significant engineering problems to be solved, not to mention the problem of financing such an ambitious undertaking. But political reasons, more than anything else, held up development. Many Venetians did not want to believe their city was in imminent danger—and even to the extent that they did, there was tremendous disagreement about how best to address the problem. Some wanted to address the problem at the base—to basically “jack up” the city and install new and improved foundations. Others wanted to build a series of dikes and locks around the city—the so-called “Dutch solution”—or use a different mechanism to hold back high waters.

Holding Back the Sea

At the end of 2001, a plan was finally put in motion to keep back the high waters. A project called MOSE (an acronym for Experimental Electromechanical Module in Italian, but also an allusion to Moses) involves the construction of 78 steel gates, hinged at the bottom, installed along the sea floor at the three inlets to the lagoon. The gates, which are hollow and normally filled with water, measure 20 meters wide, 3.6 meters deep, and 20 to 30 meters high. When water levels appear to be rising dangerously high, compressed air will be pumped into the gates, causing the ends to float up to (and slightly above) the surface. In effect, they will form a dynamic dam that will appear only when needed. The gates will be tall enough to hold back water quite a bit deeper than the 1966 flood.

Although construction has been underway for quite a few years and significant progress has occurred, there are still numerous problems ahead, and the completion date has been delayed repeatedly. One issue is the 5.5 billion euro (and counting) cost, and more specifically the vast portion of that sum that has disappeared due to corruption. There are also significant environmental concerns; the project was vigorously opposed by numerous environmental groups. Among their concerns is that any interference with normal tides will increase the levels of toxic chemicals such as mercury in the waters of Venice, seriously threatening both marine life and the health of people who consume the local fish. There are also basic worries about health and sanitation. Venice has no sewer system; household waste flows into the canals and is washed out into the ocean twice a day with the tides. No one is certain quite what effect the gates will have on the city’s natural waste treatment system.

An Uncertain Future

Under the most optimistic prediction, Project Moses will be fully operational by 2022, but given the city’s history of delays, few expect it to be finished that soon. And even if it works perfectly, it is not a complete or final solution. The city will continue to sink and the water level will continue to rise. Sooner or later, the gates will no longer be able to protect the city from deterioration.

In the meantime, Venice faces an uncertain and paradoxical existence. While tourism increases to record levels, the population of the city itself has plummeted. The historic old part of the city had about 184,000 residents in 1950; today, there are fewer than 55,000. A shocking percentage of Venice’s glorious old buildings stand vacant as owners move to more stable surroundings, yet real estate prices remain astronomically high, discouraging an influx of new residents. With no one to renovate and maintain the buildings, they will fall apart faster; but the more the city deteriorates, the fewer people are willing to live there and do anything about it. Project Moses may keep the floods out, but will it enable Venice to keep its head above water?

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on July 2, 2003, and again in a slightly revised form on March 21, 2005.


Source: Interesting Thing of the Day

Sirocco Winds over the Adriatic Sea

More than just a bunch of hot air

Our article about the Chinook winds discussed an unusual meteorological phenomenon, but one thing it didn’t touch on was the peculiarity of a wind having a name in the first place. That strikes me as odd, like a temperature or a humidity level or a barometric pressure having a name. I mean, I get it: we give hurricanes and certain other storms names, and that serves a useful purpose, but just calling the movement of air in a certain way at a certain time by a proper noun seems weird.

Be that as it may, we were able to find quite a few other examples of winds that have names. Here’s a representative sampling—by no means a complete list:

  • Bora: A cold, north-eastern katabatic wind that blows along the east coast of the the Adriatic Sea (including Greece, Russia, and Turkey).
  • Brickfielder: A hot and dry summer wind in Southern Australia.
  • Cape Doctor: A dry south-easterly wind that blows over part of Western Cape Province in South Africa, so named because of its apparent effect of clearing away pollution.
  • Chinook: A warm winter wind in the western United States and Canada.
  • Fremantle Doctor: A cool summer sea breeze on the coast of Western Australia.
  • Halny: A strong, warm föhn wind storm in the Carpathian mountains of Poland and Slovakia.
  • Khamsin: A hot, sandy wind in Egypt.
  • Mistral: A cold, forceful wind that blows in southern France and into the Mediterranean Sea.
  • Santa Ana: A hot, dry wind, usually in autumn, in southern California and northern Mexico.
  • Sirocco: A powerful wind that blows from the Sahara through North Africa and Southern Europe.


Source: Interesting Thing of the Day

ATK Space Systems' Solar Sail during testing at the Plumbrook Test Facility in Sandusky, OH

The next big thing in space travel

If you wanted to cross the ocean by ship, you’d probably choose an engine-driven vessel over a sail-driven vessel. The engine will get you where you’re going faster; it enables the ship to be much larger than it could be if it were driven by a sail; and it requires much less manual intervention to keep it going. Besides, you won’t be at the mercy of unpredictable winds. In oceangoing vessels, the technological progression from sails to internal-combustion engines solved a great many problems while creating only a few new ones, such as the need to obtain and store significant quantities of fuel and the pollution that results from burning that fuel. Of course, since the planet is conveniently spherical, you’re always a finite distance from the nearest port where you can fill up. If, on the other hand, you wanted to circumnavigate the globe without stopping for fuel, sails would be the way to go. The trip would take longer and the ship would be smaller, but you’d never have to worry about running out of gas.

This is the very thinking behind an ostensibly retro design for spacecraft: by ditching the fuel and engines you can enable much longer journeys, albeit with some trade-offs. Outfit your ship with a giant sheet of lightweight and highly reflective material, and you’ve got a solar sail, a propulsion system that can take you to the distant reaches of the galaxy without any fuel—pushing you along with the gentle power of light from the sun.

What Goes Around

Solar sails are by no means a new idea. In fact, German astronomer Johannes Kepler floated the idea by Galileo in 1610. Kepler imagined “heavenly breezes,” though, and had no concept of the scientific principles that would actually come into play. In 1871, James Clerk Maxwell, a Scottish physicist, predicted that electromagnetic radiation (including light) should exert a small amount of pressure when an object absorbs or reflects it; Russian physicist Peter Lebedev first demonstrated the effect in a laboratory in 1900.

A little more than 20 years later, another Russian physicist named Fridrikh Tsander proposed using this radiation pressure to push a spacecraft along using a large but very thin mirror. In the early 1970s, NASA funded research into solar sails, and for a while proposed that they be used to propel a probe that would rendezvous with Halley’s Comet in 1986 (though the necessary technology turned out to be unavailable at the time). Today, NASA and numerous other groups are actively developing solar sail designs, and several spacecraft powered by solar sails have already been deployed.

Light Pressure

The whole idea of light exerting pressure seems counterintuitive. I’ve personally stood in front of some very bright spotlights without so much as a wobble. And I know from my rudimentary understanding of physics that photons, the particles that make up light, have no mass. Nevertheless, under the right circumstances, light can indeed provide a push. The math, frankly, is beyond me, but according to scientists who seem to know what they’re talking about and can back it up with impressive-looking equations, photons do indeed exert a gentle pressure on objects they hit—and the pressure is roughly twice as great if the object reflects the light than if it absorbs the light, so solar sails would effectively be giant mirrors. But the key word here is gentle. I’ve read various analogies for the strength of the sun’s push, but one I particularly liked, on a NASA webpage, said that if you had a mirror the size of a football field, the pressure of the sun’s light would be about the same as the weight of a first-class letter.

In space, a small amount of pressure goes much further, because other factors such as gravity, air friction, and wind don’t get in the way. Even so, if a solar sail is going to push a spacecraft of any significant mass, it must be enormous. And therein lies a problem: with greater size comes greater mass—not so much from the sail itself but from the support structure that’s needed to keep it rigid and connect it to craft’s payload. The greater the mass to be pushed, the greater the size of the sail that’s needed, and so on. Thus, in solar sail design, thinner and lighter materials are almost always better. Sail thickness is measured in micrometres (µm)—millionths of a meter—with some being as thin as 2 µm. (By comparison, the average human hair is about 80 µm thick.) This brings up a second problem: fragility. You’ve got to fold or roll up a huge sheet of material that’s a zillionth of an inch thick, get it into space, and then unfurl it perfectly—without ripping or mutilating it, and without creating a support structure so massive that it’ll cancel out the sail’s low mass. One promising material is a type of porous carbon fiber that’s much thicker than the polymer films most researchers have used, and yet lighter in weight because of its unusual structure; it’s also highly rigid, durable, and heat-resistant.

Still More Uses for the Force

Proposed solar sail designs have used a wide variety of shapes, from simple squares to disks to pinwheels. As with wind sails, you can change the angle of a solar sail in order to steer the craft; designs that incorporate numerous smaller sails provide greater directional control. But one thing you will not see is a solar sail shaped like a parachute—since light travels in straight lines, that would make for a highly inefficient design. Interestingly, that’s exactly the shape of a certain fictional solar sail—the one used by Count Dooku’s spaceship in Star Wars: Episode II—Attack of the Clones.

Besides having an inappropriately shaped sail, that ship somehow managed to zip across the galaxy at a startling speed as soon as the sail unfurled. Real solar sails, because they generate so little force, accelerate quite slowly. On the other hand—and this is what makes them an intriguing option for long-term missions—the velocity continues to increase over time, there being no friction to counteract it. The result is that over a period of months or years, a craft powered by a solar sail could reach speeds far in excess of any rocket-powered design. However, as the craft gets farther and farther away from the sun, the radiation pressure also decreases, so it’s not as though the rate of acceleration can continue to increase indefinitely. Even so, a vehicle with a very lightweight solar sail could reach the orbit of Pluto in about 7 years. (The Pioneer 10 probe, launched in 1972, took 11 years to reach that point.)

Sail On

After many years of ground-based and suborbital testing, as well as a few noteworthy failures, an interplanetary solar sail spacecraft (Japan’s IKAROS probe) was first successfully deployed in 2010. NASA launched the NanoSail-D2 later in 2010. And The Planetary Society launched and successfully tested a small solar sail-powered spacecraft called LightSail 1 in 2015; LightSail 2 is scheduled to launch in June, 2019. Numerous other solar sail projects are in various stages of planning.

Among the future missions envisioned for spacecraft propelled by solar sails are probes sent to explore the inner planets, monitoring stations near the sun, and deep-space exploration. Some proposals even use a giant laser here on Earth, instead of the sun, to push the craft along. Manned missions, however, are a much more distant possibility; a spaceship big enough to hold passengers would require an unfathomably gargantuan sail, and the slow acceleration would be rather inconvenient considering human lifespans. But if we ever encounter a ship sent a long time ago from a galaxy far, far away, it may very well have been carried along by a solar sail.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 19, 2006.


Source: Interesting Thing of the Day