The Retirement of Discovery

The space shuttle Discovery took one last flight leaving from NASA's Florida spaceport this past Tuesday (April 17). After thirty years of service, it is going on permanent display at the Smithsonian Institution's National Air and Space Museum just outside Washington, D.C. Discovery was the leader of NASA's space shuttle fleet and, having launched in 1984, the oldest of the three shuttles remaining. Both Columbia and Challenger debuted earlier, but were lost along with their crews in tragic accidents.

Discovery is known as the world's most often flown spacecraft, having flown thirty-nine space missions and traveling a distance that is the equivalent of over 300 flights to the moon and back. Even more impressively perhaps is that it is the shuttle responsible for deploying the Hubble Space Station in April, 1990.

Eager viewers were able to snap photos on Tuesday as Discovery made its last flight, seen here on top a modified Boeing 747 jet.

Scientists develop ultra-thin solar cells

Today, Austrian and Japanese scientists have unveiled solar cells thinner than a thread of spider silk. These cells are still flexible enough to be wrapped around a single human hair. In the article on Physorg, Sekitani, from the University of Tokyo and one of the lead researchers, said the team hoped to increase the rate at which the device converts sunlight into electricity and put it to practical use in around five years.

So, what impact does this have on solar energy powered cars? Couldn't a car store the energy saved all day to charge the battery for later use?

Ignoring clouds, the daily average irradiance for the Earth is approximately 250 W/m² . A Toyota Camry is 4.805m long and 1.820m wide, for a total top area of ~8.75m² . That means every hour in the sun absorbs 2188W. Eight hours in the sun would get you 17,504 Wh.

But we have to take inefficiency in solar tech into account, which is currently around 10-20% efficient for most commercially available types. So we're only getting at most 3500Wh or 3.5kWh. Also that assumes no clouds and direct overhead sunlight, which is not often available, but for the purpose of the calculation we'll comply with. The Tesla Model S gets about 3.5 miles/kWh from it's battery back.

So covering your entire car with solar cells and leaving it in the sun for an entire day would get you at most 12.25 miles, but probably a lot less as not all the cells would be lit at the same time, the sun wouldn't be directly overhead, and there could be inclement weather, etc.

Now we just need to get the battery tech up to spec with the solar cell tech. It's no accident that the Oil & Gas giants have been scooping up patents to improved battery technology for years now. E.g. Chevron owning the large format NiMH patents. The truth is that while there is lots of anticompetitive and borderline illegal behavior in the industry. After all, it's a fiercely competitive industry so not unexpected. However, generally things are improving.

Plenty of technology has been developed over the last 10 years that is well outside the grasp of the Oil conglomerates and the $/kWh (cost per kilowatt hour) of renewables is steadily declining as the non-renewables costs are steadily increasing. Renewables will probably reach price parity with non-renewables for large-scale energy generation in the next 5 years or so and forward thinking countries like Canada, Germany, Denmark, etc... are certainly speeding up the process with their generous renewables subsidies too. So fret not, renewables are here to stay.

Wind Map

Earlier today I came across something incredibly cool: a US Wind Map. It is an interactive map of the US with forecast winds shown across the country. These near-term forecasts are updated once per hour, with data from the National Digital Forecast Database. The website describes it as a "living portrait."

There are handy keys detailing the wind speeds on the side bar, along with a note of the top and average speeds. It's unfortunate that it isn't shown where the top speed occurs.

The site proudly states that it is not associated with any corporation and is, in fact, a personal art project. A disclaimer expounds, "We've done our best to make this as accurate as possible, but can't make any guarantees about the correctness of the data or our software. Please do not use the map or its data to fly a plane, pilot a boat, or fight wildfires." So while the map may be fun to look at, don't use it for anything serious!

Jupiter and Io

The image above depicts Jupiter and its moon, Io. The tiny red dot on the surface of Io is a volcano, while the blue above it is the volcanic emissions.  According to NASA, "The Io image, taken on March 1st 2007, is an approximately true-color composite taken by the panchromatic Long-Range Reconnaissance Imager (LORRI), with color information provided by the 0.5 µm (“blue”) and 0.9 µm (“methane”) channels of the MVIC."

Since Io 's discovery by Galileo in 1610, it has continuously been both confusing and amazing scientists. First of all, it's larger than our own moon, and is also the most volcanically active object in the solar system. Io is home to volcanoes that erupt liquid sulfur dioxide, and has a molten iron/iron sulfide core due to the immense tidal heating associated with orbiting so closely to Jupiter at roughly 350,000 km. This happens because the gravitational field of Jupiter is so powerful that it squeeze Io, and that the magma inside Io is pushed outside because of the amount of pressure it induces.

The magnetosphere of Jupiter sucks off the dust and gasses emanating from Ionian eruptions at a rate of about 1 tonne per second. It has no magnetic field of its own, but instead has a magnetosphere created by Jupiter's. This is turn induces an electrical current along the magnetic lines of force from Jupiter's north pole, through Io, and back to Jupiter's south pole, which in turn creates an auroral glow similar to Earth's aurora. It's orbit is encased in a plasma torus of high-energy radiation and ionized sulfur, sodium, oxygen, and chlorine. Io's orbit is eccentric, since Io has the moons Europa, Ganymede, and Callisto pulling it back.

Happy (Belated) Pi Day!

Yesterday was "National Pi Day" -- March 14 (3.14). It has been declared by the U.S. House of Representatives as a way to introduce children and adults to the wonders of math and science (HR 224, in 2009). Pi is one of the most widely used mathematical constants in science and engineering, but only a relatively small fraction of the general public knows of its significance (perhaps beyond the circumference of a circle being pi times its diameter).



In honor of Pi day, I thought I'd introduce you to a website dedicated to your favorite mathematical concept: Pi! The wife of one of my favorite professors at Cal, Alex Filippenko, created a website designed an educational and entertaining website, piZone.org, in order to promote National Pi Day as a day to celebrate the fun facts, trivia, and uses of pi.

From an email I received from Alex:

The site has various videos, interactive games, and even pi-related t-shirts –- everything a person needs to celebrate pi. Moreover, you can enter to win an iPad (whichshe calls a "Pi-Pad") or t-shirts; click on the "Play" button, or "like" piZone on Facebook. (No purchase is necessary to win.)

The website is her social mission, and it was created as a crowd-source resource. Under the "pi it forward" program, $3.14 from every t-shirt sale goes to provide a pi-related t-shirt to a K-12 teacher.

I invite you to visit the website or Facebook (piZone) and help share the pi.
-Alex


Check out the site, it's pretty pi-tastic! And, because I can't resist, in honor of Pi day, my favorite Pi riddle:
Question: What do you get if you divide the circumference of a jack-o-lantern by its diameter?
Answer: Pumpkin Pi!

Introducing TED-Ed:

TED Talks is rolling out their new program: TED-Ed. This is set to be a series of TED Talks, under ten minutes in length, whose intention is to potentially rival Khan Academy.

I think the idea is fabulous, and the more well funded, educational services out there and accessible by students, the better. From the video description: TED-Ed's mission is to capture and amplify the voices of great educators around the world. We do this by pairing extraordinary educators with talented animators to produce a new library of curiosity-igniting videos.

In fact, they make it simple for you to nominate a teacher or animator. This can be done here.

The Most Astounding Fact

Neil DeGrasse Tyson was asked by a reader of TIME magazine, "What is the most astounding fact you can share with us about the Universe?" This is his video response, an incredible and humbling take on the universe: