Wednesday, November 29, 2006

Fabricating LEGOs, the Toy of the Century

BusinessWeek|Online has a great article and slide show on how LEGGOs are fabricated. Read the whole story here to see how they convert ground plastic

into many many little bricks and parts.

From Lego:
LEGO Group is producing 15 billion components a year--that's 1.7 million items an hour, or 28,500 a minute. Tire production accounts for some of that number; the factory also produces 306 million tiny rubber tires a year. In fact, going by that number, LEGO is the world's No. 1 tire manufacturer.

The bricks are so versatile that just six of them can be arranged in 915,103,765 ways.

Tuesday, November 28, 2006

Two Micro-controller Starters

I'm always on the lookout for good starter educational kits for students to learn electronics through their own hacking project, and I hit the mother load this week. First, this month's Wired magazine had a plug for the new Micro-controller kit from Thames and Kosmos, which you can purchase here at Amazon.

The $136 price tag is a bit steep compared to the raw cost of all the parts, but everything is ready to go with almost no effort or overhead whatsoever, including all the necessary interface cables and whatnot.

Secondly, for those more intrepid (or budget conscious), there is the path for the purist. This link over at Instructables will send you on your way to building your first prototype systems from scratch including your own interface cables. On the up-side, total cost to start doing fun stuff can be managed within a $10 budget or so as long as there is an old PC with a parallel port lying around somewhere. The canonical first project it to light up an LED and control it.

This Instructable also include links to Cornell, where the devices are used in a class, complete with links and blogs about the student's final projects, and there is an extensive web reference site called AVR Freaks.

Go forth and Compute!

Sunday, November 26, 2006

Moore's Law Marching On

For those of you unfamiliar with Moore's law, Gordon Moore, the founder of Intel predicted that semiconductor technology would advance at a rate that doubled the number of transistors that would fit on a chip every 18 months or so.

Now, the University of Delft and IMEC have fabricated a MOSFET device (a type of transistor) with wires so small (around 35 nanometers across, or roughly 1/200 the size of a human hair) that the conductivity and other electronic properties of the material depended on the flow of electrons around a single dopant atom of arsenic.

FinFET transistor

Obviously, classical electromagnetics, which are based on the assumption that materials can be modeled as a continuum with homogeneous properties starts to break down when you need to consider individual atoms. But fortunately, we are headed towards quantum computers which might map very nicely to the quantum atomic properties.

Rube-Goldberg Honda Ad

If you didn't happen to catch this when it was live on television, YouTube has come to the rescue. Check out this amazing Rube-Goldberg machine from a couple-year-old Honda ad:

"This Advertisement for the new Honda Accord was shot in real time with no CGI involved in the sequence. It required 606 takes and cost $6 million to shoot and took 3 months to complete.

The equipment was so precisely set up that the crew literally had to tip toe around the set for fear of disturbing things, which led to some unexpected problems. "As the day went on, the studio would get hotter," says Steiner. "It meant that the wood would expand and the cog or exhaust that spins around would move slightly faster." These tiny changes made big differences to the precision set-up of the equipment......

.....The sequence where the tires roll up a slope looks particularly impressive but is very simple. Steiner says that there is a weight in each tire and when the tire is knocked, the weight is displaced and in an attempt to rebalance itself, the tire rolls up the slope."


Clearing Orbital Paths

After all the hoopla about Pluto being demoted to "Dwarf Planet" status a few months back, I've gotten a lot of questions about what qualifies a hunk of rock as a planet. One of the criteria which Pluto failed to satisfy, was that of having attained sufficient mass and thereby gravitation pull so as to have cleared its orbit of other debris.

Well it turns out that a very nice image illustrating the principle turned up a few days ago. NASA's Cassini spacecraft just turned in a very nice closeup of Saturn's tiny moon Pan in the midst of the planets network of rings.

The tiny moon, little more than 16 miles in diameter, has swept clean a 200 mile-wide gap in the rings which we now call the Encke gap. Incidentally, we saw the gap first, and deduced that there must have been some sort of gravitational object to have caused the sweep, and then later found the moon.

Original Source at NASA.

A Shooting Satellite?

Jim Faketselis of Huntington, NJ took this short 18 minute movie of the famed Orion Nebula, only to find what looked like a shooting star. But actually, it is the star field that is rotating about as the earth spins, made still by the motor drive the the telescope. What looks like a shooting star here is actually a geosynchronous satellite. These satellites are launched into a very specific orbit that circulates around the earth at the same angular rate that the earth spins to hover stationary with respect to a single point on the ground.

Here is another image of the Orion Nebula moving past four geosynchronous satellites but with the motor drive disengaged.

Original images courtesy of

Tuesday, November 21, 2006

Teen Creates Fusion in His Basement

Back in my teaching days, whenever some jaded, burned-out high school teacher would tell me something like, "...that's just too hard for the kids! Why do you make it so hard?" I generally ended up showing them the projects that actually ASKED to do and saying, "...well these students didn't think it was too hard. Check out the telescope and photometer that Jennifer built, and she didn't think she was good at either Physics or Math." And true, it might have been hard for some of the students, but not for all of them. The key was always to keep both ends of the intellectual engagement spectrum challenged.

But I just can't resist highlighting real teen achievement in such a way as to show that the main limitations in many of our science curricula are the limited breadth and depth of the curricula themselves when the main mechanism for pedagogy is the lecture. This story shows the true power of unlimited guided and independent innovation.

Thiago Olson put in over one thousand hours over a couple of years to create a fusion reactor in his basement. This is no mean feat, given that there are only a few dozen working fusion reactors in the world, with most of them at multi-million dollar research institutions. Thaigo, in the true spirit of scrappy innovation scoured EBay for the parts and built it on a shoestring with a little help from Dad.


My favorite quotes from the article come from his mother:

Thiago's mom, Natalice Olson, initially was leery of the project, even though the only real danger from the fusion machine is the high voltage and small amount of X-rays emitted through a glass window in the vacuum chamber -- through which Olson videotapes the fusion in action..

But, she wasn't really surprised, since he was always coming up with lofty ideas.

"Originally, he wanted to build a hyperbolic chamber," she said, adding that she promptly said no. But, when he came asking about the nuclear fusion machine, she relented.

"I think it was pretty brave that he could think that he was capable to do something so amazing," she said.

Thiago's dad, Mark Olson, helped with some of the construction and electrical work. To get all of the necessary parts, Thiago scoured the Internet, buying items on eBay and using his age to persuade manufacturers to give him discounts. The design of the model came from his own ideas and some suggestions from other science-lovers he met online.

Someday, he hopes to work for the federal government -- just like his grandfather, Clarence Olson, who designed tanks for the Department of Defense after World War II. Thiago, who is modest and humble about his accomplishment, said he knew from an early age what he would do for a living.

"I was always interested in science," he said. "It's always been my best subject in school."

But, his mom had other ideas.

"I thought he was going to be a cook," Natalice Olson said, "because he liked to mix things."

Read the full article here.

Sunday, November 19, 2006

A Potentially Lethal Electrostatics Lesson

I pulled into a Chevron station a few years back to gas up my ride, when a rather graphic flier taped to the pump caught my eye. It was a laser-printed page with a picture of a charred car complete with melted tires, glass and all, sporting a headline that said "BEWARE OF GAS TANK FIRES AT FILLING STATIONS! THIS COULD HAPPEN TO YOU!"

There followed a couple of dense paragraphs that I simply couldn't resist reading at that point, outlining a horrific story of the author's wife who inadvertently killed herself by starting a fire at the pump after topping-off her car.

The flier went on to explain that while this hazard was quite common, it was generally underreported. "Please pay attention and change any dangerous habits so that forewarned, you don't loose your wife like I did," it said.

I was completely hooked on the curious phrasing at that point. Why were women in particular at risk? The flier went on to claim an "extensive" level of post-accident research that determined the filling-station fire hazard beset a population heavily skewed towards women because they tended to get back in the car while waiting for the tank to fill, whereas men tended to stand around outside the car while waiting.

This seemingly innocuous relaxation is indeed a very real risk because the very act of getting into or out of your car can transfer or induce a rather large electrostatic charge to your body. I suspect most people have at one time or another felt a tiny shock of static discharge getting in or out of their car. Just imagine if that spark arises at the wrong time and place. And when people wear think-soled (insulating) shoes, and particularly when the air is dry, there are no fast mechanisms to bleed off the accumulated charge, which will then be retained until some connection to a ground is established.

The gas tank pumping risk is managed automatically for those who stay out of the car for the duration, because the pumps are grounded, and when the fueling operation is initiated, the driver is grounded when he/she first touches the pump before any pumping begins. The danger begins when someone releases their ground connection, and gets charged up electrostatically-speaking by getting back in the car. If the first contact to ground after re-emerging from the car happens near the pump nozzle, the resulting spark can ignite any fumes that had been released during fueling. (This, incidentally, is one of the principle reasons why all modern gas pumps have sleeves to trap fumes in the tank, and it is important to be sure the sleeve seal is fully engaged and mated to the gas tank pipe.) If enough fumes have been released over a protracted or poorly-sealed fill-er-up type operation, the resulting explosion could set fire to anything flammable nearby, like the poor late woman mourned in the flier.

So the first thing I did upon returning home, was to ask my wife what she tended to do while waiting for the gas tank to fill up at the self-serve gas station. To my surprise, she said, "I just sit in the car and wait." I personally NEVER get back into the car. I then went on to relate the story, and physical explanation. My hope at this point is that she will keep herself grounded forever more whenever near any gasoline pumping operations.

For those of you in any doubt as to the serious nature of this warning, here is a YouTube video that I found this morning for your review entitled "Always Ground Yourself at the Pump."

So what should you do, using your newfound electrostatics knowledge to stay safe at the gas station? Well, there are a few options.

1.) If you can afford the price premium, you might consider staying inside the car and having someone else pump the gas who is always outside and stays grounded.

2.) If you do get out to pump your own gas as I generally do, stay outside of the car until the filling operations is complete, and the gas tank is capped off.

3.) If for some reason you HAVE to go back inside the car, make sure to ground yourself to the outside of the car, and the pump FAR from the junction between the pump and the car before you approach the nozzle.

Remember, Physics is your friend!

Saturday, November 18, 2006

The Future of Automobiles

My wife and I were car shopping last weekend, and we saw the future of automobiles. It was both an inspiring and depressing view, all at the same time.

Being a little bit of a car and driving nut, I've always tended towards the performance and handling side of the car market. Even my wife's current "grocery getter and kid hauler" is a sport model mini-station wagon Audi A4 that in some ways is more fun to drive than my old '95 Porsche 911. And while I've always been intrigued by the prospects offered by advancing hybrid gas-electric technologies, the earliest commercial efforts towards "green" cars like the Honda Insight and the Toyota Prius always left me underwhelmed despite the amazing gas mileage because the performance just wasn't there.

But last Saturday, after test driving the latest crop of performance autos Audis, Beamers, and Volvos, we drove the new Lexus Hybrid mini-SUV.


My first impression as the salesman pulled the car up in front of us was a momentary visceral response of surprise and fear of being run over. The car was completely silent as over a ton of steel rolled up right next to me solely on battery power. It was just unnatural how so much mass could move without a gas engine that you could hear coming, and before I could help myself, I actually looked to be sure that someone was at the wheel of the car, and that it wasn't rolling out of control to crush us. My second thought, after noting the salesman at the wheel, was that I was going to need to immediately adjust the care with which I looked both ways when crossing the street.

Despite my skepticism, I climbed into the car to find pretty much what you would expect in any luxury SUV from Japan or Germany: great fit and finish, fine materials, clearly organized controls and labels, 8-way adjustable leather seats. The salesman made a point of telling me immediately that the car was already running. "How the hell can you tell? It's utterly silent!" I thought. Ahh. A tiny blue light on the dashboard.

So off we rolled, out of the lot and onto the busy streets of weekend Concord, CA. The only sound that accompanied the start of our journey was the whisper of the air and the tiniest of rumbles from the rubber meeting the road. At irregular intervals, the engine would start, and to my surprise, while you could hear the engine start and stop if you paid attention, there was no hitch or vibration or change in the ride whatsoever as it shifted from electric to gas power.

Then the salesman turned on the in-vehicle information display with an active diagram showing where the power was coming from at any moment, with a schematic of the car showing the effects of the engine, battery, and regenerative braking. High cool. My wife's comment at the time was, "...well, we clearly can't have THAT on if we expect him to pay any attention to the road."

Overall, the drive wasn't high on the handling ladder (admittedly it was an SUV) though there was plenty of horsepower. But it was remarkable that there wasn't anything different or troubling from the new hybrid technology other than the 30% improvement in gas mileage (a much better rating, in fact, than our little sport wagon of one half the size) and the freaky stalking behavior of the silent motor. Now we're not likely to get such a big vehicle at this point, but when the technology makes it into the smaller sports oriented cars, it will be a no-brainer. And it is clear to me that hybrid technology will eventually comprise the future of ALL automobiles, and that they have already become a viable quality consumer products now.

So what was the depressing part? The fact that this 3rd-generation hybrid from Japan was so freakin' fantastic, and that the American companies are just getting started (and headed towards bankruptcy). But maybe there is hope for a US auto maker if Tesla Motors can get their car into production. I met a couple of the company's founders a few weeks ago, and we commiserated that they were going through the NSTA crash test trials. The thought of building 20 of these sexy little $100k numbers just to destroy them was depressing. Be sure to check out their web page. They might not have the impressive window-rattling vroom vroom when you throw down at a stop light drag, but they will kick-ass in a very quiet and sneaky way.

A Nice Online Electronics Intro: FEEE

Several people have asked me lately about book recommendations for students and high school teachers to learn basic electronics. And while there are plenty of texts suitable for the college student, there are precious few works that can present aspects of electronics in a clearly simple form that is not dumbed-down to the point of silliness and is still fundamentally correct. There are always canonical references such as Horowitz and Hill's "The Art of Electronics" to help the teachers out, but more than 60% of that material will be virtually out of reach for the typical secondary student.

But just this morning, I stumbled upon a very nice online reference / textbook on introductory electronics called "The Fundamentals of Electrical Engineering and Electronics."

Although I though the ordering and organization of some of the chapters fell a little out of the sequence I would have used, the material is concise and simply stated, mostly correct, and replete with useful photos, examples and web links to take some of the basic theories and mathematics and translate them into working circuits, complete with descriptions of necessary lab equipment and how to use the tools, meters, scopes, and whatnot.

Any of you would-be circuit or robotics hackers should check it out!

Monday, November 13, 2006

A Photographic Periodic Table

I was talking to a friend from MIT a few years back, when she told me about this guy she used to date and what an incredible geek he was. Given her own tenure at MIT and her resultant accrual of a rather high level of nerd pride, it was indeed noteworthy to hear her cast such aspersions.

She went on to say "...he had even spent years collecting samples of most of the elements in the periodic table, and built a display case to hold them in the same layout." Though I didn't share it at the time, my first thought was "geeky or not, I would love to see it...maybe even build one of my own..." So I guess I'm a geek too.

What partly set off my imagination at the time, though, was the fact that the elements seemed very abstract to me when we first learned about them in high school chemistry. It wasn't until decades later in my technical career when I had been exposed to all the uses and applications of the different elements that there was any physical grounding for the abstract table. A little extra time studying the applications of the elements, and a physical sample of each one seem like a capital idea!

I never did manage the meeting or the initiative to build my own collection, but now I can get pretty close with a lot less effort. Check out this photographic table of the elements.

27x53 Poster
(click on the image for an enlarged version)

I particularly like the titanium turbine blade, the hydrogen in the nebula, and the neon bulbs for the noble gases. I'd still like to see more examples per element, including things like integrated circuits for silicon and aluminum and so on. But at least it's a start.

You can get all the posters and place mats you want here. Every chemistry classroom should have one!

ISS, Our Foothold in Space

I found a great video on UTube this morning. It is a time-lapse view of the International Space Station's evolution compressed to about 25 seconds.

Keep in mind that the ISS is still a work in progress with at least 17 additional flights planned to complete the station. After those missions and the planned Hubble Telescope rescue, the shuttles are to be retired and replaced by the yet-to-be-built Orion launch vehicle.

Sunday, November 12, 2006

A Great Hackable Robot: Roomba from iRobot

All you wanna-be robot hackers take note. Tod Kurt's new book on hacking the Roomba robot vacuum cleaner is available for pre-order on amazon.


It's a great platform with a decent processor and interface, very well-engineered sensors and motor systems, and is relatively cheap for all the hackable robotic excellence it contains. $180 for the robot, and $17 for the book seem like a good deal. The book highlight all sorts of projects including adding a camera and making the robot draw on paper and so on. Every high school should have four or five of these suckers.

Thursday, November 09, 2006

Air Shower Cuts Water Use By 30%

Water conservation is a particularly contentious topic in California what with the farmers battling the city-folk for every drop. And yet I know several otherwise "green" individuals who still revel in their luxurious high-volume "drenching" showers.

I will even admit that when we first moved into our new home, the master bedroom shower head afforded wonderful, though short showers that completely drained our water heater in about 10 minutes. So I did what any good scientist would do. I engaged in an extensive shower-head survey experiment.

It turned out to be a rather depressing exercise. Of the 12 or so shower heads that were available in our immediate area, the contenders generally fell into one of two camps: no flow restrictor and great showering, or great water economy with heads that would blow at you and not really get you wet enough to shower comfortably.

Image of a showerhead tied in a knot.

But now, Australian scientists claim they have solved this uncomfortable trade-off by developing a device that can be inserted into existing shower heads, which fills the water droplet with bubbles of air instead of blowing the air around the droplets.

Developed by a team led by Dr Jie Wu, the aeration device is a small nozzle that fits inside a standard showerhead. The nozzle uses a small Venturi tube – a tube for which the diameter varies, creating a difference in pressure and fluid speed. Air is sucked into the Venturi tube as a result of the partial vacuum created, causing air and water to mix, forming tiny bubbles within the water stream.

“The nozzle creates a vacuum that sucks in air and forces it into the water stream,” Dr Wu says.

“We make the water droplets in the stream hollow and the bubbles expand the volume of the shower stream.”

Small-scale experiments using the aeration device found that people detected no difference in water pressure, sensation, or overall perception of showering.

Sounds great, but I'll reserve judgment until my chill-prone wife approves the technology in her rigorous goose bump test. But I would feel very green indeed, if I could reduce household water consumption by 30%.

Spectacular New Orion Nebula Image

Here is the latest composite image from Hubble and Spitzer, this one of the famous Orion nebula. I love the fact that now, with better instrumentation, it really does look like a giant cloud of gas.

Spitzer/Hubble image of Orion nebula

From the NASA web site:
NASA's Spitzer and Hubble Space Telescopes have teamed up to expose the chaos that baby stars are creating 1,500 light years away in a cosmic cloud called the Orion nebula.

This striking infrared and visible-light composite indicates that four monstrously massive stars at the center of the cloud may be the main culprits in the familiar Orion constellation. The stars are collectively called the "Trapezium." Their community can be identified as the yellow smudge near the center of the image.

Swirls of green in Hubble's ultraviolet and visible-light view reveal hydrogen and sulfur gas that have been heated and ionized by intense ultraviolet radiation from the Trapezium's stars. Meanwhile, Spitzer's infrared view exposes carbon-rich molecules called polycyclic aromatic hydrocarbons in the cloud. These organic molecules have been illuminated by the Trapezium's stars, and are shown in the composite as wisps of red and orange. On Earth, polycyclic aromatic hydrocarbons are found on burnt toast and in automobile exhaust.

Together, the telescopes expose the stars in Orion as a rainbow of dots sprinkled throughout the image. Orange-yellow dots revealed by Spitzer are actually infant stars deeply embedded in a cocoon of dust and gas. Hubble showed less embedded stars as specks of green, and foreground stars as blue spots.

Stellar winds from clusters of newborn stars scattered throughout the cloud etched all of the well-defined ridges and cavities in Orion. The large cavity near the right of the image was most likely carved by winds from the Trapezium's stars.

Located 1,500 light-years away from Earth, the Orion nebula is the brightest spot in the sword of the Orion, or the "Hunter" constellation. The cosmic cloud is also our closest massive star-formation factory, and astronomers believe it contains more than 1,000 young stars.

The Orion constellation is a familiar sight in the fall and winter night sky in the northern hemisphere. The nebula is invisible to the unaided eye, but can be resolved with binoculars or small telescopes.

This image is a false color composite where light detected at wavelengths of 0.43, 0.50, and 0.53 microns is blue. Light at wavelengths of 0.6, 0.65, and 0.91 microns is green. Light at 3.6 microns is orange, and 8.0 microns is red.

Image credit: NASA/JPL-Caltech/STScI

Images from Yesterday's Mercury Transit

For those of you who missed the planetary excitement yesterday, here is a collection of images of Mercury's march across the face of the sun along with equipment and process details.

Howard Esklildsen of Ocala, FL took this image with a
Meade 6-inch telescope capped with a Baader solar filter. The perfectly circular silhouette of Mercury appears at bottom, the ragged expanse of sunspot 923 at top. "It was a great view."
The image “” cannot be displayed, because it contains errors.
This image was taken by Adrian of San Jose, CA using a Coronado PST.

Wednesday, November 08, 2006

Gas Up Before the Inevitable Price Increase

Now that election day is passed, I expect the Republican administration to re-start the filling of the Strategic Petroleum Reserve, which will inevitably drive up gasoline prices.

Most of the economists I know were a little surprised that the country would stop filling the reserve when the prices were already at a multi-year low and the reserves had been depleted already partly due to the Iraq conflict. But as we now know, politics trumps economics, and they needed any weapon in the run-up to the election. Even then, it looks like the artificially-induced lower gas prices weren't enough to stave off congressional defeat.

The only real question remaining in my mind is when they will open the spigot, given the open-ended nail biters in Virginia and Montana to determine control of the Senate. It wouldn't surprise me if for some reason the SPR intakes remain closed until the election is completely resolved.

Tuesday, November 07, 2006

Avoid Bad Assumptions

Back in the day when I was a high school Physics teacher, I often struggled to decide how much detail and complexity to include in the lessons and laboratory exercises.

One of the critical principles I swore to instill concerns the power of abstraction and how to use it. The idea that one can make a simplified model of a more complicated system in order to illuminate fundamental properties and behaviors is central to the understanding of science and science history, and central to using those models to make useful predictions. I think most people eventually got that part. The real challenge, though, was teaching someone what sorts of things they needed to worry about in making their abstractions, what they could ignore, and how to tell the difference between the two.

So yes, simplifying assumptions are critical to solving complex problems, but if you simplify too much, you are solving a problem that no longer really helps you understand what is happening in the real world. So in teaching those intro Physics classes, I took extensive steps to be sure that the students understood what types of things we ignored when discussing topics such as Newton's laws, and we discussed at length why their lab experiments didn't quite come out as the simplified equations would have predicted. We would even work to improve experiments with things like vacuum chambers and lubricants to reduce troublesome complications like friction specifically so they could understand the abstract mathematical descriptions and where they broke down. Despite the fact that these same principles apply across any human endeavor even outside of science from relationship management to business strategy, students would often ask, "so what does this have to do with my life?"

Well today, with all the current hoopla around returning to the Moon and then heading on to Mars, NASA resurrected some old data that highlighted a catastrophic assumption they had made on prior Lunar missions, so that hopefully, we can re approach the Moon with improved confidence.

You see, back in 1972 during the Apollo 16 mission, the Astronauts launched a small satellite called PSF-2 into a low Lunar orbit (only about 60 km above the Moon's surface) in order to continue extended observations even as the manned mission returned to Earth.

see caption

To make a rather longer story short, the satellite ended up crashing into the moon despite the fact that there was no atmosphere to induce drag that would have eroded the orbit. So what happened?

It turns out that the scientists of the seventies had made a catastrophic assumption that tremendously simplified the orbital path planning calculations to get the spacecraft to the Moon and back. And as long as the command module was in a short-term lunar orbit and cruising all the way from Earth and back (a trip mostly far away from planetary or Lunar mass), there was no noticeable deviation from the planned paths that would indicate any problem with the simplified models. Everything was fine.

But when the tiny satellite was left in a long-term orbit close to the surface of the moon, its actual flight path began to deviate quite substantially from what the simplified model had foretold. Eventually it crashed into the Lunar surface. So, what was the simplification? What happened?

The problem was that the scientists of the day had assumed that the density of the entire Moon was roughly uniform. In retrospect, anyone who has dug a hole would know that earth is composed of loose material, water, pebbles, all of varying density, and it wouldn't we all that much of a stretch to realize that those inhomogeneities might extend to larger scales. But in truth, those deviations from the average density had never been an issue before, because in interplanetary (or earth-to-moon) travel, the distances from the planets were typically large enough, and the durations of orbits short enough, that the simplified models proved quite accurate for those purposes.

It wasn't until a new experiment that "looked" much more closely at the Moon for a longer period was conducted that we discovered that the heretofore ignored "higher-order" effects were indeed relevant. We now know that the Moon is quite lumpy.

"The Moon is extraordinarily lumpy, gravitationally speaking," Konopliv continues. "I don't mean mountains or physical topography. I mean in mass. What appear to be flat seas of lunar lava have huge positive gravitational anomalies—that is, their mass and thus their gravitational fields are significantly stronger than the rest of the lunar crust." Known as mass concentrations or "mascons," there are five big ones on the front side of the Moon facing Earth, all in lunar maria (Latin for "seas") and visible in binoculars from Earth.

The mascons' gravitational anomaly is so great—half a percent—that it actually would be measurable to astronauts on the lunar surface. "If you were standing at the edge of one of the maria, a plumb bob would hang about a third of a degree off vertical, pointing toward the mascon," Konopliv says. Moreover, an astronaut in full spacesuit and life-support gear whose lunar weight was exactly 50 pounds at the edge of the mascon would weigh 50 pounds and 4 ounces when standing in the mascon's center.

see caption
Above: Mascons on the Moon that make its gravitational field so lumpy, as mapped by the Lunar Prospector mission, are shown in orange-red. The five largest all correspond to the largest lava-filled craters or lunar "seas" visible in binoculars on the near side of the Moon: Mare Imbrium, Mare Serenitatus, Mare Crisium, Mare Humorum and Mare Nectaris. Image reference: Konopliv et al, Icarus 150, 1–18 (2001).

"Lunar mascons make most low lunar orbits unstable," says Konopliv. As a satellite passes 50 or 60 miles overhead, the mascons pull it forward, back, left, right, or down, the exact direction and magnitude of the tugging depends on the satellite's trajectory. Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. PFS-2 released by Apollo 16 was simply a dramatic worst-case example. But even its longer-lived predecessor PFS-1 (released by Apollo 15) literally bit the dust in January 1973 after less than a year and a half.

Original Post at NASA's Bizarre Lunar Orbits.

Friday, November 03, 2006

Mercury Transit in a Nice Notebook

A lot of people ask me what sort of thing would I like to see in a student's laboratory notebook, and this turns out to be harder to describe than you might imagine. Yes, I want to see all the typical experimental setup description, recorded data, and details about experimental method and error analysis sorts of things. But I also like to see some creativity and thought, and maybe a little artistic impression to aid visualization, and links to new creative ideas and perhaps thoughts on the NEXT experiment.....

But there is nothing like a good example. This kid gets an A for his notebook page on the last Mercury transit back in May of 2006.

Original source: Spaceweather

And now you can go make a similar one for the upcoming transit next week on November 8th! Here is an image from the NASA web site that tells you when to be observing, depending on where you are.

see caption

Please note that observing the sun without optical protection or filtering is still as dangerous as ever and can blind you, and that there are proper ways to safely observe the sun, including eclipse glasses, using a pinhole projector, using eyepiece projection through a telescope onto a piece of paper, or directly through a telescope equipped with a solar observation filter.

Make a Very Cool Battery

Sorry, I couldn't resist the ice tray pun. I just love simple and illuminating (yes, another pun) science experiments which don't require any expensive equipment. And you can even recover most of the investment in this one after the students are done with the cash.

From Make Magazine: a Penny and Dime-powered LED.

Img413 1352

287161767 B7A3D45Df0

The simple initial challenge of making a one cell battery with salt water, a dime and a penny can be easily extended to multiple cells in series to generate higher voltage. The LED allows experimentation with polarity. If you have a volt meter, students can measure voltages and design batteries for any number of applications from lighting an LED to powering a motor. They can measure the capacity of the battery, calculate the currents, and experiment with ways to improve the battery performance. (Bigger cells, polished electrodes, bigger multi-penny electrodes.) It's a great open ended exploration: "Okay, now make your battery better!" or, "Okay, now can you make the same battery cheaper?"

Chemistry, Physics, Electrical Engineering and Electronics in one simple and inexpensive activity! Woohoo!

Astronomical Numbers Around a Black Hole

Sometime you run into a number that is just so damn large that it is hard to really comprehend just how big and far reaching that number is. But it is rare that you run into so many of them in one place, specially a place that is describing something real and physically out there and measurable.

MS 0735.6+7421
(click on image to see a high-resolution version)

NASA's recent press release on a "Monstrous Black Hole Blast in the Core of a Galaxy Cluster" simply would not relent. The amazing web of all the staggering numbers involved were tied together with a composite image assembled from instruments on two different spacecraft and an earth-bound radio telescope array. The Hubble Space Telescope's Advances Camera for Surveys was used to take an optical spectrum picture of the cluster of galaxies which are all bound together by gravity and a super-massive Black Hole at its center. More recently, that image was augmented with X-Ray spectrum data from the Chandra Orbiting X-Ray Telescope, and the Very Large Telescope radio sensor array in New Mexico to include the hot interstellar (and intergalactic)gas in such a way that an otherwise invisible blast that spans several GALAXIES has been exposed. Check out all of the astronomical numbers in the NASA release text (I've added the highlights in bold.)

This is a composite image of galaxy cluster MS0735.6+7421, located about 2.6 billion light-years away in the constellation Camelopardus. The image represents three views of the region that astronomers have combined into one photograph. The optical view of the galaxy cluster, taken by the Hubble Space Telescope's Advanced Camera for Surveys in February 2006, shows dozens of galaxies bound together by gravity. Diffuse, hot gas with a temperature of nearly 50 million degrees permeates the space between the galaxies. The gas emits X-rays, seen as blue in the image taken with the Chandra X-ray Observatory in November 2003. The X-ray portion of the image shows enormous holes or cavities in the gas, each roughly 640 light-years in diameter -- nearly seven times the diameter of the Milky Way. The cavities are filled with charged particles gyrating around magnetic field lines and emitting radio waves shown in the red portion of image taken with the Very Large Array telescope in New Mexico in June 1993. The cavities were created by jets of charged particles ejected at nearly light speed from a supermassive black hole weighing nearly a billion times the mass of our Sun lurking in the nucleus of the bright central galaxy. The jets displaced more than one trillion solar masses worth of gas. The power required to displace the gas exceeded the power output of the Sun by nearly ten trillion times in the past 100 million years.
It is simply amazing to me that we can measure and visualize such things directly.

See the original NASA release here.

Wednesday, November 01, 2006

Slow Motion Bullet Impacts

Here's a cool slow-motion YouTube video of a series of object suffering projectile impacts. All you need to take similar photos is a sound trigger for a digital camera, just like for stroboscopic photos, and a high-speed video camera. Let me know if you need pointers to the manufacturers.

The Gas Tax, Hockey Penalties, and Time-outs

I found an interesting chart on the Foreign Policy web site this morning that highlights some of the conflicted logic surrounding US energy and tax policies.

The gasoline tax rate within the US is literally less than one-tenth the comparable tax in Europe while per-capita gas consumption is more than four times higher. The anti-correlation is very illuminating. And while there are clearly many factors driving gasoline consumption relative to Europe such as the very area over which Americans much drive being larger than the average European roaming distance, even a quick glance at the chart shows that if the US is really serious about immediately decreasing the dependency on foreign, there is a very simple policy decision that could have broad and immediate impact, and is probably worth an experiment. The US administration could substantially raise the gasoline tax to a meaningful level, and see what happens.

There is a reasonable likelihood that doubling the effective price of gas could dramatically reduce consumption just through price elasticity alone. For those of you not familiar with retail sales economics, price elasticity is the relationship between the price of goods and the volume of sales at that price. If you lower the price, you sell more (the volume increases), and conversely, if you price goods higher, your sales volume will decrease. So retail sales strategy is all about picking the right price so that your sales price times the volume of sales is maximized (to maximize total revenues). So if the US raises the price of gasoline with an aggressive tax, the sales volume should decrease substantially.

The other effect such a tax levy might induce is that alternative energy sources could immediately become more cost effective relative to gasoline, and that economic advantage combined with simple market forces would likely drive entire energy, automotive and aviation industries to undertake much more accelerated transitions to alternative renewable energy sources and further decrease gasoline consumption.

But of course, there is one giant sector of the US economy that has understandably dug in its heals at the prospect of such a tax. The Oil industry would clearly be decimated if the US's per-capita gas consumption was cut to one-quarter of its current rate, and they have understandably invested hundreds of millions of dollars in lobbying efforts and supportive politicians to vigorously resist the introduction of any tax that would have even the slightest deleterious effect on consumption.

But government is supposed to be about understanding, planning for, and managing the larger-scale and longer-term consequences of suborning the national economy to a single (even an important) special interest. A committed and creative administration could even come up with solutions such as applying the proceeds of such a tax to support the very industries that might suffer through such a transition that is critical to national interests. Imagine if that flood of tax proceeds was directed solely to the energy industry companies for use in transitioning to renewable energy sources? Then Chevron and Exxon/Mobile would have a lot less to complain about. Would they come along willingly? Probably not, because that sort of sea change would put their core business at risk, and even with a generous R&D and new infrastructure tax subsidy they might have to sacrifice some of their record-breaking profits to stay ahead of some smaller and more aggressive companies that are starting from the same level as far as renewable energy investment goes.

But I've always said that you can tell how serious someone is about fixing a problem by how seriously they will impose penalties to change someone's behavior. So far, our efforts at reducing foreign energy dependence strike me as so much lip service. Yes, the analogy is a stretch, but I find the situation strikingly similar to Hockey. The sporting industry's half-hearted testimonials that hockey really is about the sport don't jibe with the fact that purposefully splitting someone's head open with your stick and then taking several swings at someone to start a bench-clearing brawl results in a few minutes in the penalty box. That just strikes me as not all that different from giving your toddler a 3 minute time-out for taking a switch blade to a playing companion. As they say in the Big House, the time must fit the crime. So examining the longstanding lax discipline in hockey, one can only conclude that they aren't all that serious about fixing any problem with the sport and that perhaps they need the sensationalism to draw crowds, as with Circus Maximus at its peak. If someone is really serious about fixing problem behaviors, discipline must be meaningful.

If Brazil can become energy independent in about 12 years through strong government direction, how long should it take the US? When will our government finally begin to lead a concerted effort. I bet we could cut that time in half if we just quadrupled the gasoline tax.

Anyone else have other suggestions or comments?