Thursday, April 28, 2011

Surface Power for Human Mars Missions

A human mission to Mars would require a substantial amount of electrical power on the surface. It seems there are two main options for producing a lot of power on Mars: solar and nuclear fission. Both a large array of solar panels and a nuclear reactor would be difficult to deliver to and deploy on the Martian surface.

Solar power has the advantage of being safe and technologically reliable. There is no public resistance to solar power. Since non-tracking solar panels have no moving parts, they do not frequently fail to operate. We can also expect solar panel technology to develop significantly over the next decades because there are a variety of terrestrial applications and initiatives that employ it. Unfortunately the solar flux at Mars is less than half what it is at Earth, and the amount of insolation will decrease at non-equatorial latitudes and during the Martian winter. Accumulation of dust on solar panels, a phenomenon for which Mars is notorious, will further decrease energy outputs. If solar panels are thin and flexible, a stern wind could lift unrestrained panels off the ground. Of course, solar power must be stored during the day with a battery or regenerative fuel cell for nighttime use.

Nuclear fission on the Martian surface can offer much more power per unit mass than solar power. It produces energy at a constant rate and could be used equally at any surface location. These characteristics make the fission reactor an attractive candidate to power a production plant for in-situ resource utilization—machinery that will surely consume loads of power. A nuclear reactor, of course, produces dangerous radiation and therefore must be placed a significant distance from crew members. Typical designs contain numerous moving parts to convert heat into electricity, which introduces complexity and risk of failure. Small-scale nuclear reactors have little application in terrestrial settings, so most development efforts may have to fall on space agencies like NASA. And we are all aware of the political obstacles to developing a nuclear reactor and launching it into space.

Monday, April 25, 2011

Smoking Bans

Smoking bans in private buildings, including bars and restaurants, are becomming increasingly common in Western countries. These bans are typically based on the idea that smoking is optional but breathing is not. There's no doubt that breathing second-hand smoke is unhealthy, so the function of the law is to protect those who do not want to inhale.

These laws seem to imply a right to be inside the building in question. There are some buildings with which the public is clearly entitled to have an association: court houses, public schools, or public transport stations to name a few. In fact, I can see the justification for smoking bans on outdoor public property like sidewalks or parks. If citizens are required to pay taxes to support these properties, why must they breathe second-hand smoke when they want to use them?

On the other hand, there appear to be no movements to ban smoking inside personal homes. This is presumably because the public doesn't have a right to enter somebody else's home, and it would be an injustice to violate a person's freedom to smoke so long as it's on his or her own property. Whether other people enter someone's home is considered to be up to the property owner, not the desires of the anonymous public. Why, then, is the law different for so-called workplaces? As I see it, this nonuniform application of the law can only make sense if you regard the public—whether employees or customers—as entitled to use these properties on their own terms. 

This appears to be a rather blatant example of public appropriation of private property. It seems entirely irrelevant to me that a majority of citizens support the bans. What's going on here is the public is voting themselves broader access to smoke-free restaurants, bars, and workplaces by forcing an eccentric minority—those weird indoor smokers—to conform to the dominant lifestyle. I find it hard to claim we live in a free society when some majority consensus can dictate whether you light a cigarette in your own building.

Friday, April 22, 2011

Review: Journey to the Center of the Earth

Jules Verne's 1864 Journey to the Center of the Earth is a classic adventure story with a scientific leaning. Three dissimilar characters—a stubborn old professor, a curious young kid, and a stoic Icelander—join forces to explore a subterranean world hinted at in an aged Icelandic manuscript. The emphasis in this book is on what the characters discover rather than what they feel.

Journey to the Center of the Earth by Jules Verne bookRead more reviews on AmazonAt some point in the story the sense of discovery becomes truly captivating. Verne really grasps the imagination as he describes the team stumbling across biological organisms of immense proportions, some of which hail from the seafaring monsters of the Jurassic period. Perhaps the apex of the journey is the sighting of primitive human beings hunting a herd of mammoths, a scene Verne apparently added after the original story was finished.

These possibilities are exciting not for the interior of the Earth, but for the vast unexplored cosmos ahead of us. I can't help but wonder whether intelligent beings lead lives greatly different from own, but with similarities as well—a need for food and drink, a desire for leisure, a fascination with nature.

Unfortunately, the explorers in Journey don't actually go underground until page 99 (out of 232). A number of scientific details have also not held up well with time, the most obvious being Verne's fabrication of an enormous open cavern with temperatures and pressures suitable for a diverse ecosystem. There's also a vague reference to an electrical phenomenon responsible for lighting the entire cavern and supporting photosynthesis. Finally, the plausibility of the story is further degraded when the team falls through a passage and rides a magma flow, on a flimsy raft, all the way through a volcano in Italy. It is perhaps unfair to judge Verne with the lens of scientific history; a better measure might be the impact Journey has had on inspiring scientists and explorers over the last 150 years—people who were motivated by Verne to go out and actually discover what's out there.

Monday, April 18, 2011

Io's Tidal Heating

Jupiter's moon Io is the most geologically active world in the Solar System. Its internal heat is generated by the friction of changing tides, heat that rides across the surface in lava flows and is blasted to orbital heights through a network of 400 volcanoes. The same internal processes are operating on another of Jupiter's moons—Europa—but its heat may go into warming a subsurface ocean.

Io's geologically-active surfaceTidal heating results from a shifting gravity differential between a moon's far side and its near side. The strength of gravity always diminishes as the distance from its source increases, but this discrepancy is negligible for moons in distant orbits around low-mass planets. Io is about the same distance from Jupiter as our own moon is from Earth, but Jupiter is about 318 times as massive as Earth. Under these conditions Io feels tremendous gravitational pull from Jupiter—it swings around the planet in only 1.7 Earth days. The pull from Jupiter's gravity, though, is stronger at the side of Io closest to Jupiter. This effect causes Io to deform slightly from a sphere into an egg-shaped form called an ellipsoid.

A static gravity differential will not cause tidal heating. The internal heat in Io is caused by a changing gravity differential. Since Io's orbit is not circular, the differential of Jupiter's gravity will be more significant at closer orbital distances from the planet; Io's ellipsoid shape will thus be more pronounced when the moon is passing close by Jupiter. The bulges of this moon wax and wane, creating frictional heat in the same way a paper clip will become warm if it is flexed a few times. This interior heat reaches the surface through volcanism and is then radiated away into the cool and refreshing cosmos.

Friday, April 15, 2011

Israel's Rocket Problem

Since 2002 Palestinians have fired thousands of rockets into Israel from the Gaza Strip. The rockets are unguided, currently have a range of up to 40 kilometers, and are typically packed with explosives and shrapnel. They can be considered a terrorist weapon because they are designed to cause indiscriminate damage and maximum disruption to daily life. Dozens of Israelis have been killed, mostly civilians because the rockets cannot be aimed with much accuracy. The Israel Defense Forces (IDF) usually retaliate against rocket attacks and kill disproportionately more Palestinians, though the Palestinian casualties are more targeted than the Israeli ones.

Iron Dome deployed in Israel
An Iron Dome missile battery
One of Israel's defensive strategies is to deploy a rocket interception system called Iron Dome. Iron Dome tracks projectiles fired from Gaza, analyzes their trajectories, and fire a guided interceptor called the Tamir missile. On April 7, 2011, Iron Dome successfully intercepted a rocket fired at Ashkelon—a coastal city with over 100,000 residents—marking the first time in history a short-range rocket was ever intercepted.

The problem with Iron Dome is not technical but economical. Each Tamir missile is estimated to cost between $35,000 and $50,000, while each crude Palestinian rocket could not cost much more than a few hundred dollars. The Tamir is created in advanced laboratories with state-of-the-art components; the Palestinian rockets are made in clandestine workshops with antiquated hardware. For each interception, the Palestinians effectively impose a cost on Israel something like 100 times their own. Without the threat of aggressive retaliation by the IDF, it seems Iron Dome could actually invite more rocket attacks. Israel clearly leads the world in this kind of defensive technology but I do not see their rocket problem being solved with technology alone.

Tuesday, April 12, 2011

Review: Woman with a Parasol

Claude Monet's 1875 painting Woman with a Parasol—Madame Monet with Her Son documents the rise of middle-class leisure in nineteenth-century Europe. Though Monet himself was one of the poorest Impressionists, he nonetheless witnessed the unfolding of modern life in all its splendid glory. A number of technological inventions allowed such Impressionist paintings to be created en plein air, or outdoors. Steam trains began transporting urban residents to city parks and outlying suburbs. Portable tubes of paint freed artists from their stuffy and dim studios.

Woman with a Parasol by Claude Monet art
The subjects in the painting are Monet's first wife, Camille, and their son. Using people as subjects is rare in Monet's works, probably because his obsession with the effects of natural light required him to paint the same scenes over and over. This interest is also evident in the reflections of light, known as highlights, on the right side of the woman's dress. Though carefully applied, these highlights comprise fully open and visible brush strokes. Likewise, the dabs of yellow paint in the grass are intended to be reflections of light rather than to capture the actual shapes of grass or flowers. This tendency is a defining characteristic of Impressionism.

The viewer may notice seemingly haphazard, almost reckless brushwork in the clouds to the left of the painting. I think it's a testament to Monet's skill that these brush strokes are not particularly distracting. It's also more evidence that he was primarily concerned with light and color as opposed to line or shape. Though I'm not typically moved by Monet's choice in subject matter, this painting has a tragic story behind it. Camille's health began a terminal decline in the same year Woman with a Parasol was painted, leaving this image a precious glimpse into a lost nineteenth-century moment.

Friday, April 8, 2011

On the Falcon Heavy

The Falcon Heavy is a rocket under development by the American company SpaceX. SpaceX is a launch services company—they are not selling rockets but are rather providing transportation services to destinations in space. As such the typical customer will not be selecting a rocket from a catalog, but will be selecting performance characteristics to meet his space launch needs. SpaceX will retain control of all launch operations, so customer demand is likely to be driven by the cold, hard numbers: the payload mass and the cost to get it to space.

Artist's depiction of the Falcon Heavy launch vehicle; image credit: SpaceX
The Falcon Heavy uses a
cluster of 27 engines
With this customer mindset, the success of Falcon Heavy will depend solely on its performance capabilities. As far as payload mass, SpaceX has advertised that the rocket can loft 53,000 kilograms into low Earth orbit. This is much greater than all currently operational rockets; even if Falcon Heavy was not cost effective in price per kilogram to orbit, it could attract customers based chiefly on its brute strength.

In the long run, though, the rockets that will become most common will simply be the most cost effective ones. Many future payloads—such as crew, fuel, and supplies—will not need to be launched on a single launch vehicle. If a smaller (or larger) rocket can deliver mass more efficiently than Falcon Heavy, then the former will prevail. Part of SpaceX's strategy to make this rocket cost effective, though, is to launch a dozen or so times per year—allowing the engine, which is also used on the smaller Falcon 9 rocket, to be mass-produced on an industrial scale.

Falcon Heavy's engine configuration has also been a source for skepticism. The challenge with using so many engines is igniting them at the same time and keeping them from failing during flight. Soviet engineers toiled without success to manage a cluster of 30 engines on their ill-fated moon rocket, the N1. I'm more confident that SpaceX can operate these engines, though, because they are properly testing testing them, and they plan to build tolerance for multiple engine failures into Falcon Heavy.

Tuesday, April 5, 2011

The Automobile and Happiness

I'm convinced that the invention of the automobile has led to a great deal of unhappiness. After a steady stream of technological precursors, the automobile finally freed man from the last bonds of daily toil. And he hasn't been happy since.

There's something decidedly uncomfortable about driving a car and working in an office. Ask yourself, "Does it feel right?" Muscles have been evolving on Earth for hundreds of millions of years, only to be tossed aside as obsolete in the last hundred. This is not how the vast majority of human beings, much less mammals, have felt as they lived out their lives. The discomfort of driving extends to the mind. Automobiles allow us to escape from our environment to an insular and artificial one. But we are very much not free inside a car; we are much of the time stuck helplessly in traffic and all of the time compelled to think about driving. Lastly, physical strength was one thing that made men useful to women. I would be willing to bet there's an inverse correlation between marriage longevity and use of an automobile. Do women not agree that easy life has left men altogether less necessary than they once seemed to be? And man did this to himself!

The answer to the problem is not to freeze technology—progress is an inspiring and beautiful thing. Our transportation paradigm is critical to our economic output, which gives us the food and medicine to survive, and the science and technology to explore the cosmos. No, the answer will require far more creative and subtle ways of integrating physical and mental struggle.

Saturday, April 2, 2011

Review: Capitalism and Freedom

Capitalism and Freedom will probably evoke a response consistent with the reader's pre-existing views on economics. It is more a book on economic ideology than predictive theory, although the author, the American economist Milton Friedman, attempts to take on rival theories—namely Keynesian economics—with his own empirical evidence. Keynesian economists are skeptical that the free market is always efficient and they typically advocate some intervention to keep everybody working. Although I was left unsure about the author's predictions, the ideological issues he raised should be of interest to all parties. Friedman says, "Underlying most arguments against the free market is a lack of belief in freedom itself." I would like to hear more of the author's critics address this claim head-on.

Capitalism and Freedom by Milton Friedman bookRead more reviews on AmazonFriedman is often labeled a libertarian but he takes some positions other free-market advocates may oppose. One is his willingness to endorse government interference to reduce harmful "neighborhood effects". Another is his idea of a negative income tax that would guarantee a minimum income for all citizens. His position on corporate monopoly also allows for eventual intervention to maintain "competitive conditions". The problem with these suggestions is that Friedman doesn't offer a methodology for determining when such measures are worth violating his core value: economic freedom.

The idealogical approach in Capitalism and Freedom is perhaps a weakness as well as a strength. For instance he mentions that tariffs on foreign goods do not help anybody. His point is that tariffs introduce inefficiencies, which is true, but what he seems to miss is that some workers do not care about efficiency and only want to continue their lifestyle. Friedman's ideology is rendered impotent when citizens impatient with or apathetic about capitalism vote to further their interests by means of government power, a problem for which the author admitted having no solution.

Despite using a generally accessible vocabulary, Friedman's writing is clumsy and rigid—nominalizations run wild when ordinary characters and verbs would do just fine. In short, Capitalism and Freedom is unlikely to convert a collectivist to an individualist, but it will push both to sharpen their arguments.