When I was young, I wrote for a paper. Check it out if you'd like to see how a I thought then.
5 points to the first comment with the song, band and album.
Wednesday, March 30, 2011
Monday, March 28, 2011
Apparently, the Fukushima reactor failures have cause some Americans to rethink their support for nuclear power. Even with the costs of Fukushima, good arguments have been made showing nuclear (fission) remains a very safe power source. That said, there is an upside of this recent (not exactly unfounded) wave of nuclear fear. It should spur public interest (and hopefully funding) in developing alternatives, primarily solar power. Other renewable sources work decently on a small scale, but tend to have serious, often unintended, impacts on the surrounding environment and population. Minimally, there are well reasoned arguments against large scale deployment of geothermal, hydroelectric and wind power. Furthermore, long term, I don't see how hydroelectric or wind power will ever produce enough power. I strongly doubt human society will decrease our energy appetite without a horrific population crash. Terrestrial solar power has its own problems, of course. It takes up a lot of space, it works best in sunny, low latitude environments, it doesn't generate power at night, efficient cells tend to cost a lot, etc. Still, it's the most direct of the sun driven renewables and the gives the ability to decentralize the grid (an advantage not all would agree with). Solar power is definitely worth investing time, thought and money in and I doubt many would disagree. But solar power doesn't have to be terrestrial. We can place solar power stations outside the atmosphere, in orbit where there are no clouds and there need not be night. There's no latitude affect in orbit, either. And there's a lot more, well, space. So space solar power solves all of the basic problems of terrestrial solar power and replaces them with different set: how do you build, locate and maintain a solar power satellite and how do you get the power back to earth? These are non trivial problems, but the basic answers are in place. The ISS proves we can build and maintain large scale structures in space, albeit expensively, but it's definitely possible. Power transmission can be done with low intensity microwaves* beamed down to rectennas on the ground. *Unfortunately, "microwave" tends to evoke thoughts of cooking and the ever frightening "radiation" so there is a small PR problem, maybe. Long term, space solar power is our best renewable energy source. Without it and with a still growing population, we are damned as a world to live in energy poverty. That poverty will eventually lead to a Malthusian disaster. It will, however, be a massive undertaking requiring Apollo program levels of investment. In brief, here's how I think we should proceed, as fast as possible. 1a) Develop a heavy launch capability (100 Mg to LEO) while also reducing launch costs, using different vehicles if necessary. We'll also need a manned launcher or very, very good robotic capability, but we have Soyuz now. 1b) Design and prototype a small scale solar power sat and rectenna. Demo these. An ISS experiment might be the fastest way to do this. 1c) Design and prototype an orbital broom. A working solar power sat would likely greatly ease the design and deployment of an orbital broom. This needs to be done ASAP, lest we hit the Kessler Syndrome. 1d) Continue to improve photovoltaics. This should be ongoing no matter what. 1e) Develop and improve effective high impulse thrusters like VASIMR. Like the orbital broom, these will benefit greatly from having large solar panels in space and enable us to efficiently mine near earth asteroids for resources. 2) Develop in-situ solar panel production if at all possible. The moon is a good candidate, but I suspect that some of the near earth asteroids might be better choices. The heavy launch capability is both the fall back if this doesn't work and the enabling mechanism -- we'll be able to launch factories into orbit to build the panels. 2a) Continue to refine power sat prototypes and rectenna systems. Demonstrate these and show that they're not dangerous. 3) Build and deploy the solar power sats. We could pull all of this off in 30 years, right? 3a) Develop a true "bridge to space" like a space elevator to really make this permanent and low cost. The good news is that NASA could be on this course with the Space Launch System and the ccDev space iniatives and the ISS provides a ready made platform to at least test LEO power sats. The bad news is that this requires a massive investment in resources, probably on an international level and there's almost no low hanging fruit to get the ball rolling. If at all possible, we* should leverage the current public awareness about power generation to drive the development of space solar power. *"We", I guess, is anyone who reads this, particularly those in charge of major media and awareness groups.
Sunday, March 27, 2011
Lawrence M. Krauss makes the argument that human exploration of space has become stagnant. After calling the ISS a "white elephant" he explains what he thinks caused the stagnation.
What happened? Why did the dream of unlimited manned space travel and a vast new universe of possibilities for humanity dry up and fizzle? The answer is relatively simple: reality prevailed. Human space travel is expensive and dangerous, and there is almost no scientific justification for it (a sobering realization for the child-turned-scientist).I'd like to see a quantification of "almost no scientific justification.*" Whatever it is, I figure it's smaller than the obvious justification: answering the question "What are the effects of the space environment on humans?" The question admits many possible falsifiable hypothesis as answers, so the process of answering them -- which requires humans in space -- would strike me as a perfectly scientific one. *What are the units of scientific justification?** **Asterisk/italics style taken from Joe Posnanski and used without permission. Krauss may have meant "no practical justification" -- a harder charge to defend, but one I am working on addressing in part in a not-yet-completed essay, so I'll put that off for now. Instead, I'd like to defend the ISS from the charge of "white elephant." Politically, it's a example of successful international collaboration to solve a complex problem. For science, it's a lab on the frontier, allowing experiments to be conducted in an environment not available on Earth, not just the experiment of having humans live in the LEO environment, but for a wide variety of scientific research. As advanced as our robotics abilities are, I strongly doubt any set of current automated experiments or labs could match the ISS's human crew for experimental flexibility. Having human beings on board greatly simplifies experiment design and allows for new experimental hardware to be more easily repurposed or repaired. Conservatively, I put the cost of having an astronaut on station with experimental tools for 180 days at 300 million dollars. That's about 5 times the cost to NASA of launching an astronaut on the Soyuz to the station. It's really hard to imagine a robotic mission that could conduct the variety of experiments with anywhere near a human level of flexibility or productivity for that cost. Additionally, the ISS serves as an engineering prototype for those of us learning to create self contained environments, not only in space, but anywhere humanity may need them: under the oceans, in the desert or any harsh environment we may encounter (or create if the more dire climate change and post nuclear war models are correct). These are really just quibbles, though, as Krauss's main point is that the space program is insufficiently inspirational. On that, I worry, he may be correct.
Sunday, March 20, 2011
Slate's Ray Fisman has an interesting piece on pay and motivation in workers. However, I'm going to focus on one section since it relates to the book project.
The experimenters checked in every 90 minutes to tabulate how many books had been logged. At the first check-in, the $20-per-hour employees had completed more than 50 books apiece, while the $12-an-hour employees barely managed 40 each. In the second 90-minute stretch, the no-gift group maintained their 40-book pace, while the gift group fell from more than 50 to 45. For the last half of the experiment, the "gifted" employees performed no better—40 books per 90-minute period—than the "ungifted" ones. The goodwill of high wages took less than three hours to evaporate completely—hardly a prescription for boosting long-term productivity.I'm sure the data logging here is probably uses a bit more information than I've been using for the book project. I doubt, however, that it includes the shelve/unshelve time or any time for moving books. So it's good to know that even at 2/3 my measured rate, I'm able to keep up with this baseline group. I'd hate to be wasting my time.
Saturday, March 19, 2011
I'm considering using this blog to host a sort of Introduction To Aerospace (Engineering) class. I think this will benefit me in a variety of ways: brushing me up on the basics of my field, helping me polish my rather tarnished writing skills, improve my equally tarnished pedagogical abilities, motivate me to build up a library of basic aerospace tools and possibly give me the opportunity to make promising contacts in the community and help me scout out promising candidates for any future "aerospace drafts." I'm planning on making the class as accessible as possible will still honestly covering the field. I figure assuming my readers have some knowledge of algebra is a good start. So I'm viewing this as "Aerospace (Engineering) for 9th graders." Were it a college class, it might be "Remedial Aerospace." I'm also going to rely on graphics as little as possible. I'll use them, but I'll do my best to explain all of the concepts adequately in the text. I'll likely include optional "advanced" content as well. Advanced posts will include Python and Haskell code -- Python, because it's so accessible and powerful and Haskell, because I think it has a lot of potential as a language for engineers. If this test post works out well, I'll post a link to it and any successor posts on aerospace.reddit.com. (My inspiration for this coming from this link.)If the Intro class works out, I'll continue trying to cover the field in greater and greater detail. I hope to have the first experimental post done sometime tonight. I'll be asking for feedback on the experimental post amongst my aerospace, engineering, teaching and other friends... if you fall into one of those categories, please feel free to speak up whenever. Laws of Motion, Coordinate Systems, Vectors Aerospace (engineering) may be viewed as the "art and science of making things move through air and space". To practice this art, we have to first understand how things move. It turns out that there's a simple set of physics laws -- rules the describe the physical world -- that quite accurately describe how all sorts of everyday objects move. These are called "Newton's laws of motion." Historically, there are three of them. Roughly stated, they are: 1. An object in motion keeps moving the same way unless it's acted upon by a force. An object at rest stays at rest unless acted on by an outside force. 2. Force equals mass times acceleration. 3. Every applied force has an equal and opposite applied force. Today, we usually only consider the latter two laws as modern scientists note that these laws apply, that is, are true, only in what's called an "inertial frame of reference." The first indirectly describes such a frame. Inertial frames of reference (alternatively, "Inertial reference frames") are "coordinate frames" that do not rotate or change velocity. Velocity has a specific meaning -- it's the speed of an object and it's direction. It can be written, for instance, as "5 kilometers per hour, due east." Since space is three dimensional, velocity can also be written as an object's speed in each dimension, for example "3 kph right, 2.5 kph up, -1.2 kph out." The left-right, down-up and in-out directions are given short hand names in math and physics, usually x, y and z. Each direction has it's own axis, or line running in that direction. All three axes (the plural for axis) intersect each other at one point called the origin. Each axis shares a name with it's corresponding direction: "x axis, y axis, z axis". Altogether, the axis, the origin and the space they sit in make up a "coordinate frame of reference," or coordinate frame for short. Inertial frames of reference are a special case of such frames. We call the individual values, 3 kph, etc, "coordinates." An object's position in space can be described the same way. "2 meters right, -10 meters up, 0 meters out." We call position, velocity and other properties that can be describe with magnitudes and directions "vectors." We often write vectors as three numbers inside parentheses. (2 meters right, -10 meters up, 0 meters out). We can set the order we mention the directions by convention, so we can write (2, -10, 0 ) meters and our meaning is understood to be the same as above. Furthermore, the directions don't have to be left-right, down-up and in-out, they can be tilted as well. Lastly, we can represent an unknown vector using variables. In the figure below uppercase X,Y and Z are the axis/direction names and x,y and z are variables representing the coordinates. A coordinate frame allows us to clearly state and quantify vector qualities like position and velocity. Without them, laws like the above laws of motion are pretty meaningless. Coordinate frames can have more than three axes and the axes can be in any direction or unit, not just distances or speeds. Some problems in physics, for instance, need coordinate frames that include a time direction, measured in units of seconds. Fortunately, we'll only have to deal with coordinate frames where all three axes define a direction in space. Our vectors, which are defined in relation to the coordinate frames, will have units of displacement (meters), velocity (meters/second) or acceleration (meters/second^2). We've covered velocity. Displacement is the vector describing the relative locations of two objects -- position is the displacement of an object from the origin. An object's acceleration describes how it's velocity changes over time -- the "time rate of change of velocity". Notice the pattern between displacement, velocity and acceleration. Each is a property of an object. Each successive property has the same units as the previous, but divided by seconds. That's because each successive property is the time rate of change of the previous one. Velocity describes the way displacement changes with time and acceleration describes the way velocity changes with time. All three are vectors. The first element (direction) of the velocity vector describes the time rate of change of the first element (direction) of the position vector. The second element of the velocity vector describes the time rate of change of the second element of the position vector. Velocity and acceleration relate in the same way. As a result, if we know the velocity of an object, we can predict how it's position will change with time and if we know it's acceleration, we can predict how it's velocity will change with time. To predict how an object will move, then, we can use the second law to find it's acceleration, which, along with a knowing the object's position and velocity at sometime in the past, we can use to describe how an object moves. Now we just need to know what force and mass mean, and what exactly that third law is saying. We'll cover those next time. Thanks to Jorge Stolfi for created in the coordinate frame image and to Wikimedia for hosting it.
Thursday, March 17, 2011
I've been planning to catalogue the household library for several years. I estimate we own somewhere between two and three thousand books, so it's always been a pretty daunting task. A couple of weeks ago, I actually got started on it. I've been using GCStar as my cataloguing software running on an Acer Aspire One netbook. The netbook allows me to have a very mobile station so I can move around the house as I catalogue. For the upstairs, I've been set up in the ping pong room using the ping pong table as my work space. I use banker's boxes to transport books to and from the shelves. They're nigh perfect for transporting and storing books. GCStar has been excellent software for the task. It's multiplatform (I'm running it on Ubuntu). It's straightforward to use and can usually pull book data and cover pictures from online servers such as Amazon's using only the book's ISBN. The process may take tens of seconds, though. So that can slow things down. As I log the books, I make sure to tag each with Post-It Page Markers, so I don't recatalogue the books. This also allows me to be put the books back on the shelves without worrying about a mix up. So far, I've logged 215 books. I timed a logging a boxful of books, including the shelving/unshelving and transport times and found that I could average about 1.1 books per minute. Including a 1.5 factor of safety, I figure my worst case average should be around 44 books an hour. So, as a conservative estimate, I figure it will take about 68.2 hours to log 3000 more books. As a baseline goal, I'm trying to log at least a hundred books a week, so that should take no more than 2.5 hours of book logging a week.