Category Archives: Science

Curiosity on Mars!

NASA Ames

Congratulations to Curiosity! As the New York Times says this morning,

In a flawless, triumphant technological tour de force, a plutonium-powered rover the size of a small car was lowered at the end of 25-foot-long cables from a hovering rocket stage onto Mars early on Monday morning.

A crowd of some 5000 people gathered on the plaza at NASA Ames Research Center late last night (it was only Monday Morning on the east coast) to watch presentations by mission scientists and finally the live broadcast, on the big screen.

This was a thrill.  Not only was the landing process itself incredible— watch this video, “Seven minutes of terror” if you haven’t —but it was amazing to be in a crowd of so many people excited to watch the landing as well.  Many of the people in the audience screaming and cheering had worked on various parts of the mission, including the ground-breaking (pun intended) scientific instruments aboard the rover and the new lifting-body heat shield to get it there.

Curiosity closes in on Mars

On Sunday night, the Mars Science Laboratory rover Curiosity (the one on the right; the biggest, baddest, most awesomest Mars rover ever) will attempt to land on Mars. Curiosity is a nuclear powered Mini Cooper sized robotic geologist, much bigger and more capable than previous rovers. It’s going to be a moment of great excitement when Curiosity touches down, and there are a number of ways that you can watch.

If you have the opportunity (Mars rover pun intended) check with your local science museum, planetarium or hackerspace to find out if they’re hosting a viewing party.

Curiosity model at Exploratorium

Here in California, the Exploratorium currently hasa special exhibition up, including the simplified full-scale model of the rover in the picture above. They will be airing a live webcast of the landing on Sunday night.  And, NASA Ames Exploration Center in Mountain View, is hosting a live broadcast on-site with over 5000 people. The free tickets for the event went very quickly.

And, if you can only watch on the internet, NASA TV is NASA’s official video channel.  Star Talk Radio has a list of places to watch online. Space Industry News has a similar lineup, which includes a link to a google map of events.

Viewing the Transit of Venus

Transit of Venus with binoculars

Venus is just now passing between the earth and the sun, and so we stepped outside to take a look. We brought out a pair of binoculars to use to project the image of the sun onto a piece of paper on the ground. We also took a solar viewing film, but it turns out that the binoculars were a great way to see it as a group. These pictures were taken just after Venus crossed over the edge, and the speck you can see at the edge is much clearer if you click through to the large size on flickr. Over there, you may also be able to make out a couple of sunspots that we were also able to see with the binoculars, but not with the viewing film. Remember, don’t look directly at the sun without proper safety equipment! (See our earlier post for more details on viewing techniques.) The transit is still underway, so you still have a chance to get outside and see it!

Transit of Venus Closeup

 

Update:  Part II, with a slightly different method.

Venus Transit 3

To get a slightly better view, we used a simple telescope mounted to a tripod.

Aside: This is the Galileoscope, a high-quality, very low cost telescope for $50 (or as little $25 in classroom packs).  It’s designed to let you discover everything that Galileo could see with his telescope, including craters on the moon and the moons of Jupiter, albeit with modern optics that dramatically improve image clarity.

 

Venus Transit 2

Now, the one thing that you really don’t want to do with a telescope is directly look at the sun through it. (It’s bad enough to stare into the sun; it’s much worse to concentrate the light into a tiny spot.  That’s a good way to start fires, not view the Transit!)

What you can do is to project the light from the telescope onto a piece of paper or matte-white plastic. Adjust the focus until the edges are sharp and— poof! —suddenly, you can see the sunspots.

Venus Transit 1

And the image quality isn’t half bad.  This picture was taken right at the “peak” of the Transit, when Venus was as far into the disk of the sun as it went.  Our image on the screen is about two inches (five cm) across, and it’s easy to make out the features.

Most stunning of all is the incredibly rare opportunity to see a planet in the sky not just as a “point of light” but to see it for what it is: another planet just like ours, slowly orbiting around the same sun.

A Spectacular Speck on the Sun

Today, Tuesday June 5, 2012, the planet Venus— the planet in our solar system that is closest to the shape and size of Earth —will leisurely pass squarely between the Earth and sun.

The Transit of Venus, as it is called, is a once (or maybe twice) in a lifetime event. If at all possible, make an effort to see it today, because you won’t have another chance… at least until the year 2117.

While it will not be visible everywhere in the world (see map), it will be visible for all of North America, Asia, Australia, and eastern Europe. (The latter, towards sunrise on June 6.)   The transit begins at 22:09 UTC, peaks at 01:29 UTC, and ends at 04:49 UTC.  Here in the PDT time zone, that’s 3 PM, peaking at 6:30 PM, and finishing below the horizon. (More at the LA Times.)

Now, how to actually view it?

If you were clever, you might have stashed away an eclipse-viewing filter from the recent solar eclipse.  If not, another option— one that is cheap and easy to find at hardware stores —is a set of welding glasses with a #14 filter. (That’s black glass. Sadly, those dark green goggles that you found in the shed are likely not safe for direct solar viewing.)

But, as the Ontario Science Center warns you,

Be careful: there are many materials that may seem to block out the Sun’s rays, but which are not safe to use for solar viewing. DO NOT LOOK AT THE SUN THROUGH sunglasses, photographic neutral density filters, polarizing filters, photographic film, dark plastic such as garbage bags, or smoked glass.

 

The other approach to consider is indirect viewing. You can build a pinhole projector, or a simpler yet version.  You can also use a telescope set of binoculars to focus sunlight onto a surface for indirect viewing. (Using binoculars or a telescope for direct viewing requires a carefully chosen solar filter, to be safe.)

If all else fails— maybe you’re in cloudy Portland —NASA has got you covered. Head right over here for a “live” feed of solar pictures from the SDO spacecraft in orbit around the Earth, and updating every 15 minutes.

Update: A nice summary of the historical background of viewing transits of Venus is here.

[Image source]

Shadows of an Eclipse

Eclipse 2012- 5

There were a lot of amazing things that we saw this weekend at Maker Faire— everything from live demonstrations of snails creating artwork (by Presley Martin) to the DIY pick and place machine (from buildyourcnc.com).

There was also something special in the sky: the solar eclipse on Sunday.

Eclipse 2012- 9

Viewed elsewhere (e.g., further north in California) this was an annular eclipse, where the sun does not disappear entirely, but instead becomes a ring of fire (since the apparent size of the moon is not large enough to block the full disk of the sun).

For us at Maker Faire in San Mateo, it was a spectacular partial eclipse, which we were able to view through solar viewing filters, kindly handed out by the Exploratorium.


Eclipse 2012- 8

Of course, it turns out that you don’t actually need a solar filter to watch the eclipse. Any little aperture— in this case the cap between my hand and the camera —can act as the pinhole in a pinhole camera and project the image of the sun onto a surface.


Eclipse 2012- 4

Eclipse 2012- 2

So if you’re not sure if an eclipse has started, or how much of an eclipse it is, just hold out your hands and make some little apertures; the shadows will show up with little bright spots in the shape of the sun, whether that’s a circle, ring, or crescent.

Eclipse 2012- 1

Stranger yet is to look around at all the shadows that you see every day. Even the shadow of your hand takes on an unexpected shape when the sun is anything other than round.
There are actually five outstreched fingers on my hand here, but you can hardly tell that when every bit of light that seeps through (or around the edges) projects a crescent-shaped image.

We take for granted that the shadow of an object will the same shape as the object, but as you can see, that isn’t necessarily the case when the light source isn’t round.

Urban scientist: An unusual spider

Red-backed Jumping Spider 7

Red-backed Jumping Spider 3

It’s always good to keep your eyes open, ready to see new things. I came across this striking not-particularly-small spider with a bright red velvety abdomen, just hanging out on the concrete side of a building here in Sunnyvale, California.

I’ve never seen one of these before! How might you go about identifying it?

Continue reading Urban scientist: An unusual spider

A stunning display of natural birefringence

Penn Museum - 2

In a recent visit to the Penn Museum— the University of Pennsylvania Museum of Archaeology and Anthropology –we came across a most unusual artifact in their Chinese Rotunda: a giant crystal ball:

Penn Museum - 5

For a higher-quality image– without the display case– take a look here.

Here is what the display placard has to say:

Penn Museum - 3

Crystal Sphere
Rock crystal, Silver Stand
Qing Dynasty (1644-1911 CE)
China

An ornamental treasure of the Imperial palace in Beijing, the crystal sphere was said to have been a favorite possession of the Empress Dowager Cixi (1836 -1908 CE), under whose watch imperial China crumbled. The rock crystal originated in Burma and was shaped into a sphere though years of constant rotation in a semi-cylindrical container filled with emery, garnet powder, and water. The forty-nine pound flawless crystal sphere is believed to be the second largest in the world. The stand in the shape of a wave was designed by a Japanese artisan.

So, not only is it a giant crystal ball, but it’s a historically interesting giant crystal ball. But besides that– and its brief modern stint as a hat rack –what’s genuinely remarkable about this particular artifact is that it’s made from a chunk of rock crystal, better known as quartz crystal.

Now, those “crystal balls” that run-of-the-mill fortune tellers use are often just glass— glorified playground marbles or perhaps so-called lead crystal, which is actually just another type of glass.

Quartz crystal, on the other hand, has a structured atomic lattice that leads to some very interesting physical properties including piezoelectricity, triboluminescence, and birefringence. These properties arise from the crystal structure itself; they are typically minimal or absent in glasses such as fused silica (glass made by melting quartz crystal).

Penn Museum - 4

While the museum probably wouldn’t want you compressing or grinding their crystal ball for piezoelectricity or triboluminescence experiments, the birefringence is boldly sitting out on display.

Let’s look a little closer:

Penn Museum - 6

The sign, across the room reading “TEXTILES” is not just inverted like it would be with a spherical lens, but also– plain as day –appears as double image, even through our single camera lens.

Why? Quartz crystal is a birefringent material, which means that light rays entering the material experience two different indices of refraction, depending on their polarization and orientation with respect to the crystal lattice. In practice, our eyes see all polarizations, so this means that the crystal ball acts like a superposition of two glass balls with different indices of refraction– and light rays entering the sphere at any given point can follow two different paths to reach your eyes. Hence the double image.

It’s also worth noting that the two separate images are composed of photons with perpendicular polarization. If you were to look at this sphere through a linear polarizer (e.g., one lens of the 3D glasses that they use in modern movie theaters), you could turn it such that only one of the two images was visible at a time.

Birefringence is not particularly rare, and there are materials (like certain forms of calcite) that have huge, easily visible birefringence. Optical devices made from flawless natural calcite, exploiting this property, are tremendously important to scientific research and industry.

We tend to think of a quartz crystal as being perfectly clear– not something that gives you a double image when you look through it. That’s because quartz is only very weakly birefringent, especially when compared to calcite. Quartz is, however, still extensively used in industry in applications for which high transparency and very slight birefringence are key, such as optical wave plates. And, what’s truly remarkable about the Penn Museum sphere is that this tiny property– usually so hard to see –is so plainly visible to the human eye.

Penn Museum - 8

Finally, as we mentioned, the amount of birefringence depends on the orientation of light rays with respect to the crystal itself.

This means that if we walk one quarter circle around the sphere to a point where we’re closer to looking directly along (or perhaps, perpendicular to) the optical axis of the quartz sphere, the image suddenly becomes (if you’ll pardon the pun) crystal clear.

Field trip: Marine Mammal Center

Marine Mammal Center

The Marine Mammal Center, located in Sausalito, California, is an institution dedicated to the study and health of marine mammals, particularly seals, sea lions, otters, and whales. In their extensive veterinary programs, they rescue, rehabilitate and often release many of these animals, and work to identify causes of illness and injury.

Visitors to the center can see some of the healthier patients (not the ones in the ICU) in these outdoor hospital pens shaded by solar panels as well as the research labs and a great many exhibits about these creatures.

Marine Mammal Center

We were recently invited to a behind-the-scenes tour of the center to get a first hand look at some of the amazing equipment and machinery that is needed to run a hospital for these unique patients.

In what follows, we’ll show you some of the neat things that most visitors don’t get to see, from glowing purple plasma to Nike missile silo blast doors.

Continue reading Field trip: Marine Mammal Center

Gaunt and Glimmering Remains of Gastropods

1. Wetlands

Here at the southern end of San Francisco Bay, tall grasses and other slender plants thrive around the edges of our often-salty marshes.


2. Tall grass

Towards the end of every summer, as the grasses start to dry out, you’ll sometimes see a gleaming white jewel, shining from the top of a stem.


3. Mysterious shiny thing

And if you look closer, it becomes quite a puzzle what that might be. A chrysalis? A gall of some sort?


4. Isolated, white

But it turns out to be both simpler and stranger than that. The little jewels are actually the desiccated shells of brown garden snails, bleached by the summer sun.

5. Snails!

The common garden snail in this area is helix aspersa, the culinary snail of France, imported here in the gold-rush era by a Frenchman who intended to sell them as food. Normally, they are chestnut to ebony in color, with lighter striations.

4. At least eight

But the snails that we find in the grasses– I count at least eight in this picture –have dried up after their food sources, and have been left to sit in the sun for much longer than they would like. Seems clear enough that they climbed up the stem for a leafy snack while the plant was still green, but didn’t make it down in time.

9. Faded

7. Bleached

8. Anise

Depending how long it’s been, the shells may still be striped, faded, or fully bleached. In some cases the shell is long empty and backlit by sunlight. In others, the resident has only recently passed.

In some cases the surface luster weathers shiny like a jewel, catching your eye from a distance. And that’s how we end up with ornamented grasses, glittering with the gaunt remains of gallic gastropods.

The CO2inator

A guest project by Rich Faulhaber, contributing Evil Mad Scientist.

Setup

“Infusing unsuspecting whole fruit with gaseous CO2 in the entire Tri-State Area!


In an effort to make fruit fun for the kids, I built a carbon dioxide injector from parts in my garage with the purpose of carbonating whole fruit! With a common house water filter housing, a 16 Oz paintball CO2 canister, an old gas regulator, and some miscellaneous valves and fittings, I was able to bring this fizz fruit apparatus to life, and the kids love the results.


The principle
Carbon dioxide dissolves well in water, hence the reason you find it as the source of fizz in all your favorite soda drinks. When you open your soda and let it sit out on the counter you will find that after some period of time the soda loses its fizz and becomes “flat.” The rate at which the drink loses its fizz depends on pressure, temperature and the surface area of the liquid and the environment. Skipping the thermodynamics lecture, let me just tell you that the process works in reverse as well. To reverse this process, one needs only to have a high pressure CO2 environment, a medium to infuse (i.e., the fruit) and enough time to let the gas diffuse across the fruit skin and dissolve into the water inside. Refrigerating the fruit helps tremendously in the process as well.

Valve

Parts list


  • 16 Oz paintball cylinder (or a more proper CO2 tank if you happen to have one)
  • Gas Regulator
  • Household water filter housing
  • Some hose
  • Toggle or ball valve
  • Miscellaneous fittings to hook it all up
  • Fruit

This type of water filter housing is designed to withstand water pressures in excess of 100 psi, and it comes with two ports and an o-ring seal. These can be bought for about ten dollars at Lowes or Home Depot. Its ports are standard 3/4-inch type. Use Teflon tape (plumbers tape) on all the threads. Thread in a plug on one side and a valve on the other. I used a toggle valve with a quick disconnect to make everything easier. The hose can by any standard type rated for at least 100 psi. Small bundles are available in the plumbing section of your hardware store.

For gas handling I used an old single stage regulator. These can be quite expensive new but often times you can find deals at garage sales or in surplus stores. You don’t need anything fancy, just something to step down the pressure to something manageable– well below 100 psi. My CO2 source is a standard-issue paintball cylinder.

Pressure


Procedure:


  1. Pre-chill the fruit in the refrigerator. Get it nice and cold. My favorites are grapes, oranges and blueberries. However, just about any fruit with a large water content will work.

  2. Open the house water filter by unscrewing the lid. Place your cold fruit inside.

  3. Connect the CO2 tank to your water filter housing. This is where the quick disconnects come in handy.

  4. Adjust the regulator output to about 40-60 psi, the higher the better but make sure all your connections are extra tight and sealed or “it might get dangerous.” If you think you have a leak somewhere, you can apply some soapy water where you think the leak is and look for bubbles. If you see bubble just tighten until they stop forming.

  5. Start pressurizing the house filter by opening the toggle valve. On top of the water filter housing there is a pressure relief button. Depress this while you fill to get some of the residual air out.

  6. Once pressurized, shut the toggle valve and disconnect the CO2 line. You can store the unit in the fridge or somewhere out of sight.

  7. Then, you wait. Depending on the fruit, temperature, and pressure, carbonation should occur between 20-60 minutes. If you go too long at too high a pressure the skin of the fruit can burst and it will be a big mess, if you go too short and at too low of a pressure, the results will be unimpressive. Experiment with your fruit, pressure, and duration until it suits your tastes.

  8. Open the toggle valve to release the pressurized gas then unscrew the lid to the housing and enjoy your newly carbonated fruit.

Fruit

And of course, the kids love the “poppy fizz” inside the fizzy fruit.