Chinese space docking

A three man crew landed in China today after almost 2 weeks in space with a successful docking with a lab module in space.  (link)  China is on its way to building its own space station.

Gumdrop and toothpick tower building challenge

The rules were, the base of the tower has to fit on a 8 1/2" square of paper (the paper could be cut into multiple pieces if wanted so that each part of the base fits on it).  Whoever builds the tallest, freestanding, tower out of gum drops and toothpicks at the end wins.  At first everything seems stable, but after a certain height it deforms uncontrollably, which is exactly what I was going for.  M went for a 3D grid.  T built a « ring » with triangles worked in in the horizontal plane.  After a while, T's construction sprouted arms, hands and eyes and he named it "tower man."  T was also being funny by saying things like "work harder not smarter" and "spare every expense!"  They both talked almost the entire time despite eating the gumdrops.  In the end M won by taking her tower apart and stacking four independent cubes. 

Arizona's immigration law

V alerted me to the Supreme Court's ruling striking down parts of Arizona's controversial law.  Here is a news link. 

While I would like for the world to be free and open so that anyone could live and work anywhere, I understand this is not the reality of the situation and we are bound by the circumstances of our birth which results in our citizenship, or lack of citizenship, status.  It is hard to think of anything more arbitrary and unfair in the modern world's laws. 

Anyway, countries have a legal right to deport illegal immigrants.  If anything, living as a non-citizen immigrant in Europe has made me less tolerant of illegal immigrants in the US (I know that may sound counter intuitive).  However, we should have humanitarian limits to this.  The part of the law that the courts upheld, that police check the immigrant status of people they interact with, worries me.  This means that if illegal immigrants are being unfairly treated or taken advantage of they can not go to the police for help, much in the same way blackmail is used to prevent people from going to the police.  This makes illegal immigrants targets for extortion.  There should be an immunity clause where immigrants can not be deported as a result of going to the police for protection, to help solve this situation.

Lion dance practice

T is still enjoying his Kung-Fu lessons.  He now has a « little brother » in the school that is a six foot tall man in the military.  Last week he was sparring with "a huge Jamaican dude with big muscles."  V told me the « Jamaican dude » is a black-belt and has long dreadlocks.  Also, on Friday T went to his first lion dance practice.  In China lion dances are used for good luck, like at the new opening of a business, and are associated with Kung-Fu schools.  They use a lot of the same moves as Kung-Fu so it is good practice, not to mention the strength and balance involved.  There was a little kid playing the drums and T started off as the lion's « butt ».  They learned how to trade off places, roll over, etc.  Two more advanced dancers were there, they practiced things like standing the lion up on its back legs (the front guy jumps backwards onto, and is supported by, the guy behind him) and scratching its ear with a foot (which requires holding one leg way up and way out in a pose while balancing on the other foot).   Actually this is all related to me by T and V.  I stayed home with the girls on Friday during his practice.  I don't have any pictures of him yet but below is a link to the lion dance world championships in Malaysia so you can see some of the advanced moves.

Fun with plasma!

As I hinted at in an earlier post, we combined high voltage with a vacuum!  I drilled a small hole in the side of a glass bottle to run a loop of wire through to the inside.  Actually this was the second attempt.  The first bottle shattered when I tried to drill the hole.  I even used a small triangle shaped bit designed for drilling glass, tile, etc.  V suggested I put tape over the spot to drill to help prevent it from cracking.  So I put tape on the glass and drilled through the tape, sure enough, it worked.  Then I epoxied the hole around the wire to seal the bottle's side back up.  For the top cap I drilled a 1/2" hole for a brass hose barb adapter (now I'm thinking of using nylon so it doesn't possibly conduct electricity to the outside) into a plastic aspirin bottle cap (it fit well over the end of the bottle).  I also drilled a second smaller hole to pass a wire through for the other side of the high voltage circuit.  Then I epoxied around the holes in the cap and the cap to the bottle.  After that it was just a matter of pumping it down and firing it up.

First attempt

The bottle had specks of some kind of tar-like substance stuck to it, which I tried to remove with rubbing alcohol. 

Epoxy is setting over the drilled hole.

It worked better to mix the epoxy on a flat plastic lid then apply it.  Here I am sealing the hose connector to the aspirin lid.

An initial attempt.  If you look closely you can see some purple glow and sparks.

I was a bit worried that the electrons might travel down the vacuum in the hose to the pump and ground there, bit it didn't seem to happen. 

You can see the glow in the space around the lower wire.

Below, testing the plasma deflection from a magnet. 

In low air pressure the electrons can jump long distances through the partial vacuum.  They are very energized from the voltage potential and moving fast.  In the process ions are produced from the low density nitrogen and oxygen atoms remaining, which race in the opposite direction (although this is still AC so particles are oscillating back and fourth).  This resulting ion gas is a plasma, like the sun is made from, and it doesn't behave like a gas because it is strongly affected by electromagnetic fields.  From time to time electrons will rejoin the ions and emit light, the purple glow.  The plasma is not working entirely as I want yet, I want to accelerate the electrons with some amount passing through the center of the wire loop, overshooting and continuing down the bottle, but instead it bent and went for a section of wire that was closest to the cap (it was impossible to get the wire even by passing it through a tiny drilled hole). Next we need a diode bridge rectifier to convert the AC to DC.  I also suspect the vacuum needs to be even lower so there is not as much interference from the air that is left.  What we made is something like a Geissler tube (invented in 1857).  But what I am ultimately going for is a Crooks tube, which was developed from that.  Anyway, this is just the first pass. 

The peak voltage difference is 12,000 volts, so, in theory, what speed are the electrons accelerated to by the field⸮  The result was surprising to me.  In classical mechanics E = 1/2 m v^2 , or kinetic energy is equal to half the mass times the velocity squared.  The mass of an electron is a tiny 9.11 x 10^-31 kg.  The energy is the charge of a particle multiplied by the voltage, the charge of an electron is -1.60 x 10^19 columb.  Multiplying this by 12,000 volts gives a kinetic energy of 1.92 x 10^-15 joule per electron.  Now that we have the energy and mass of an electron we can work backward to solve for the velocity.  This works out to about 65,000 kilometers per second.  To put it into perspective, the speed of light is about 300,000 kilometers per second.  In other words, this voltage can accelerate electrons (in a vacuum and full velocity) to 22%, or just over 1/5, the speed of light.  I didn't really expect this starting out so I double checked my calculations a few times.  This is starting to get fast enough that the results from classical mechanics begin to diverge from predictions under relativity.  So the speed will be off by a small amount.  However, I did a quick calculation and the Lorentz factor (a measure of how distorted space, time, mass and momentum become due to special relativity effects) at this speed is only gamma=1.02.  So, for example, there is only a 2% time dilation (time moves 2% slower for the electrons than for us at these speeds).

Special relativity is funny.  Because energy adds mass the faster you move something (adding kinetic energy) the more it weighs, and the harder it becomes to move it faster.  As you approach the speed of light most of the mass comes from the energy rather than the object itself.  It is not off by much but I wanted to try to calculate the velocity of the electrons under relativity rather than classical mechanics.  It took a while but I finally came up with, and found in the literature (to verify), the relationship v = c * sqrt[1-(mc^2/(mc^2+E))^2].  Buried in this you can see the famous E and mc^2.  Solving this gave a speed of 63,900 km/s.  So the electrons are predicted to be moving at « only » 21% the speed of light due to relativistic effects and not 22% as I calculated above.  In the full calculation the numbers are off by only 1.7% between classical mechanics and relativity at this speed.

In the graph above I plotted the electrons predicted speed (under ideal conditions at full acceleration in a vacuum...) as a function of the voltage potential.  In classical mechanics, the blue line, the electron's velocity keeps increasing with more voltage in a parabola shape (remember kinetic energy is a function of velocity squared).  At a little over a quarter of a million volts the electrons pass the speed of light, the yellow line.  Under relativity there is an extra downward bend in the curve, from the mass added by the energy, and the velocity will never exceed the speed of light.  However, for small voltages, in other words low velocities, either calculation works fine. 

The average speed of movement of particles can also be considered the temperature.  This leads to another curious number.  Ignoring the ions for a moment and focusing only on the more numerous electrons.  The kinetic energy is related to temperature in thermodynamics by E=(2/3)BK, where B is Boltzmann's constant, 1.38 x 10^-23 J/K, and K is the temperature in Kelvins.  If we plug in our particle energy estimate of 1.92 x 10^15 J from above, we can solve for the temperature in Kelvins.  This gives us a staggering 93 million Kelvin! --if I have not made a mistake somewhere in my assumptions or calculations.  Keep in mind the plasma is at a very low pressure, so the particles are rare and spread out, so when they impart their energy to the much much denser atoms in the glass, for example, it has a much smaller effect than we might otherwise expect.  (However, the jar was very hot and the copper was glowing red... )  Imagine the point of a pin and the base of an iron skillet heated up to the same 500 degrees.  It is the same temperature but there is a huge difference in which one you would rather touch.  Room temperature is 296 Kelvin.  The surface of the sun is « only » 5,800 Kelvin.  Lightning, a plasma at atmospheric pressure, is 28,000 Kelvin.  The core of the sun, which is under tremendous pressures, is 15 million Kelvin.  It would seem, according to calculations, that we have made something, in a bottle in our house, that has a potential to be six times hotter than the core of the sun, at which time we start to wonder about our fire insurance...(which reminds me of a joke I heard in Kenya; I'll write about that later).  However, these are unfair examples; the temperature of electrons in a plasma can easily be several orders of magnitude higher than ions and neutral atoms, because they are so easily accelerated. Temperatures, in a thermodynamic sense, can be misleading when we think about temperature in the everyday sense.


And then just as a final note, what is the relative mass of the electrons to the glass wall⸮  The transformer puts out 0.032 amps of current.  A flow of one amp is made up of 6.24 x 10^18 electrons per second.  So in this case there are 2 x 10^17 electrons moving along per second.  As stated above, an electron's mass is 9.11 x 10^-31 kg.  So the mass of electrons moving by each second is 1.82 x 10^10 grams.  Regular soda-lime container glass has a density of 2.52g per cubic centimeter.  Dividing one by the other we can see that a cubic centimeter of glass is 1.39 x 10^10, or 10 billion, times as dense as the electrons flowing over a second of time.  So simplistically ,(and perhaps this is a completely wrong way to think about it but) if we completely and 100% efficiently transferred the 93 million Kelvins of energy from one second of electrons at this voltage and amps to a cubic centimeter of glass, it would add 671 Kelvins after the kinetic energy is diluted 10 billion times out amongst the greater mass.

Quad-rotor controller board

In the latest development with our quad-rotor project, we attached the main controller board.  It has three gyros to maintain its orientation.  These types of gyros don't spin like we are used to thinking.  They have components that vibrate back and forth.  When something is vibrating it tends to vibrate in the same plane and is resistant to rotation.  The potential problem is the rotor motors can put out a lot of vibration into the frame.  This vibration could interfere with the gyros (although I have heard that some people have had success not worrying about it).  To dampen vibration from the gyros, instead of mounting the main board directly onto the frame, T cut out part of a "Dr. Scholls" foam shoe liner and I mounted the board to it with 1/2" 6-32 nylon machine screws (I am trying to avoid metal for weight and radio interference considerations).  Then this was mounted to another cut out shoe liner, which is attached to the frame (in this case temporarily with small binder clips).  I could have just glued the parts together but at the moment I want to keep things flexible so I can take it apart and redo it if necessary.  Anyway, the plan is that this set up will be sturdy enough to work, but will fully insulate the board's gyros from motor vibrations.

Above shows the main controller board partially attached. 

Below, the main board fully attached using the shoe liner vibration insulation.  This one also has one of the rotor motor micro-controllers plugged in.  That is the next thing to get sorted out. 

Local school funding

Why are public schools in the US primarily funded by local property taxes?  It is hard to think of a clearer example of class discrimination in this country.  People with higher educations tend to have higher incomes and can live in areas where property is more expensive, which means the local schools are better funded so that their children have better educations and the process continues to repeat.  Lower income people can only afford areas with lower property values and less well funded public schools for their children.  The US system works to separate people by class and strongly reenforces this generation after generation.  Why do we allow this?

I have seen arguments that it is « unfair » for richer school districts to spend more on poorer school districts, but the poorer ones don't have the money to spend in the first place.  It is not like they are cheating the system and keeping extra money somehow.  Also, we are talking about children's education here; a part of the population that has no say in how the system is set up and is not allowed to make these choices that are critically important to the rest of their lives. 

It is like the argument that retired people should not pay taxes for schools because their children are not in school.  Does anyone ask people that are still working and do not have children if they would like to not pay taxes⸮  Should people pay more taxes for each child they have⸮  Of course not.  It is better for everyone if we all live up to our fullest potential.  Do retired people not care about their grand-children's generation⸮  When retired people have medical issues and go to the hospital they want the personnel to have a good education, but some are trying to get out of paying for it.  Similarly, people in rich areas complain about crime in poorer areas, but they want to keep their public education taxes local and reenforce the negative cycle in poorer districts. 

Being limited in education and thus job opportunities from generation to generation is like creating a caste system.  Funding for public schools needs to be disconnected from local taxes.  Is there any reasonable argument to the contrary?

US citizen, in the US, denied sale because of ancestry!

Here is a link to a news article pointed out to me by V.  A woman, who is a US citizen, in Georgia was denied the sale of an ipad in an Apple store because she spoke Farsi.

Fun with a vacuum and peeps!

Earlier I posted about playing with a vacuum pump and mini-marshmallows.  I used a small bottle and rubber gasket for the vacuum container.  The problem was the seal wasn't very good and the small neck didn't allow large objects to be placed inside.

I asked V to save one of her pasta sauce jars.  I drilled a 1/2" hole in the top and threaded a brass barbed nozzle through with a connector on the other side.  Then I used some epoxy to seal around the drilled hole from each side.  

The I used some teflon tape and hose clamps to get a tight fitting with the brass connectors on the pump end. 

At first we tried some trusty old mini-marshmallows to see how they expand in the vacuum. 

Compare the two pictures below to see how much they have expanded. 

And now for the peeps.  I saved a box from Easter just for this.  They were getting a bit stale so I was worried they might not expand well, but see for yourself. 

In the end they are warped and wrinkled and have shrunk down even smaller than when they started.  I presume this is because air has escaped from bubbles inside the marshmallow. 

And again, with five peeps in a row.

Above, peeps after being exposed to a vacuum.

The problem with electric arcs is that air is such a good insulator.  It would be fun to combine high voltage and a vacuum later on.

New headlight bulbs

The latest work on the car, but not that exciting.  When driving at night, especially in areas that are well lit, it was hard to tell if the headlights were on or not.  I doubt the bulbs have ever been changed before.  I picked up some new bulbs that are supposed to be 25% brighter.  I did not get the super bright « BLUE DAWN » bulbs.  Not only are they amazingly expensive, I really don't like them in other cars.  I have been blinded before when another car is coming toward me with those bulbs in it so that I couldn't see the road.  (I am surprised they are legal; we are so obsessed with « safety first » in the US, but somehow these fell through the cracks.)  So got the cheaper less bright ones.  I wrestled the plug out of the back of the headlight and showed the kids how to replace the bulbs.

We could already tell a difference driving to the grocery store last night.  The light from the headlights was visible on the road ahead and lit up the signs reflecting back to us.

Jacob's Ladder

In Genesis, there is a story about Jacob having a dream about a ladder from earth to heaven.  This is also the name used to describe a high voltage traveling arc that rises over and over.  To get a decent spark through air you need around 10,000 volts to get started (it takes 30,000 volts to jump a centimeter).  However, once the spark is established it ionizes the air and makes it more conductive. 

Finally, some high voltage to play with!

Over the last few months I collected two old CRT TVs and a computer monitor.  These are easy to get for free because everyone is replacing them with flat screens.  They are on the curbs everywhere on junk pickup days.  What I wanted was the flyback transformer, you can see one on the near left corner of the table (it is all that is left of the CRT monitor I took apart).  I tried wrapping my own wire and hooking up a driver with a transistor (one can be seen next to the flyback transformer) but they tend to overheat.  I also tried hooking up the high voltage output directly from the TVs in the background using the built in board as a driver, they worked for a few minutes then burned out (I found out later it was because I had a bad ground connection; I hooked up another ground to use).  One was very dramatic and a capacitor started smoking and burned in two.  (I hooked up the highly insulated wire from the suction cups that were attached to the tube to one side and a ground to the other.)  It should go without saying that everything has to be discharged and grounded before messing with it.  I used a fiberglass « chicken » stick with a grounded wire connected to the end.

All I was trying to do was set up a Jacob's Ladder.  It is two vertical, uninsulated wires (in this case I cut them from coat-hangers) with a high voltage potential across them.  They spark across but the spark rises from heated air.  The wires are angled so that they slowly spread apart as the spark rises.  Eventually it breaks and a new one forms at the bottom.  They are commonly seen in old science fiction movie.  Here is a clip from the 1931 Frankenstein classic where there are several in the background.



Anyway, in the end a different approach worked best.  I hooked up the wires to a transformer from a neon sign.  M was indignant, she said I wasted some perfectly good TVs.  (I don't allow TV watching in our house despite the kids protests.)  While taking the monitor apart into a many little pieces, sometimes with a hammer, to salvage some parts T told V, "wow, dad really hates TVs doesn't he."  While the larger of the TVs worked it gave some very nice long sparks, but it buzzed very loudly before burning out.  This neon sign transformer can output up to 12,000 volts so it will do for now.

Here is a top view of the setup with a nice arc. 

By now the wires are very rusty (I've tinkered around to try to get this to work for several months now).  I suspect some of the yellow color is the rust burning off.  And by the way, don't read this and try to set one up if you don't know anything about electricity--this can be dangerous if you don't know what you are doing. Umm, also don't use anything flammable as a base, like the cork board I used; the arc can start a fire. 

Even though the kids complained about their « ruined » TV (I say it's an improvement) they still got a kick out of the sparks.

'Ihi (Portulaca molokiniensis)

Photo credit, Forest and Kim Starr

Photo credit, Forest and Kim Starr

  Off the coast of Maui is a small crescent shaped bird sanctuary island called Molokini.  It is the edge of a volcanic crater that rises just above sea level.  A succulent plant called the 'ihi is only found in the wild in two places, one is on Molokini and the other is on the nearby small island of Kaho'olawe, that was used as a live fire target by the US military and today is also off limits. 

'Ihi (Portulaca molokiniensis) is in the « purslane » family, portulacaceae.  It is estimated that there are only about 1,000 of these plants in the wild (link).  So, naturally, I tried growing one.

At first the plant did very well.  It quickly plumped up and put on some new growth.  But it started sagging to the side and soon couldn't hold itself up.  Then the leaves at the base started falling off.  I was watering it too much and rot had set in in the stem.  I cut all but the base of the stem off and trimmed away all of the black rot that I could.  I let the cut stem surface dry out in the air for 24 hours before planting them.  Also, I was careful this time to water them infrequently and let the soil completely dry out in between.

In this picture the plant at the lower left is from a piece of the stalk that I replanted after trimming it down to healthy tissue.  To the upper right are some remnants of the original over-watered stalk with rot in the stem (I left it to see what would happen).

Below are some additional plants I have established from cuttings of the original.

They are all putting on some new growth so I am hopeful.

Venus' Transit of the Sun

The transit of Venus is historically important.  It allowed the first accurate estimate of the size of the solar system, and was a world wide effort.  It is also a very rare event.  In 1716 Hubble first came up with the idea to measure the distance from the Earth to the Sun using the transit of Venus and the parallax of the transit time from two points on Earth, but he did not live long enough to see it.  Capt. James Cook (who was, along with his crew, the first historical westerner to land in Hawai'i) was sent to observe the transit in 1769 from Tahiti.  The next transit wasn't until 1864.  On Tuesday we were prepared; the next opportunity will not be until over 105 years from now, in December of 2117. 

First of all we needed shaded glass to view the sun with.  I ordered shade 14 lenses to go into welders goggles (we couldn't find any solar viewing level lenses locally), plus a replacement plate for a welders mask--to hold over the camera--and I saw some special solar viewing glasses for a few dollars so I ordered one of those as well.  I figured if I ordered three contingencies at least one would arrive on time.  All three made it!  V and the kids had a lot of fun trying them on. 

Hawai'i was in the perfect spot to view the transit.  Enthusiasts were traveling here from all around the world.  I took off from work on Tuesday.  We arranged to pop popcorn.  I charged up the camera battery.  Everything was ready.

Early in the morning before the transit I was able to get pictures of some sunspots.

However, as noon approached (the beginning of the transit), the clouds rolled in.

For over an hour I couldn't get a clear view of the sun.  I told V, "we have a problem" and she understood exactly what I meant.  So we suited up the kids and loaded them into the van.

We headed toward the interior of the island and then north toward the shore to try to get ahead of the mountains.  Also, there were more breaks in the clouds apparent to the north.  Noon, and the beginning of the transit were approaching.

I managed to get a picture at 12:11:16pm local time and Venus was not apparent.  At 12:22:08 I got another picture (which was very fuzzy and had clouds moving over it) but you could clearly see a bite taken out of the edge where Venus was moving in.

I took this image a few minutes later; it is a bit clearer.  The mottled pattern over the sun is caused by the clouds.  Venus is at the lower left.  At 12:22:20 Venus was still touching the edge:

Sorry, the picture is shaky.  This was taken handheld beside the van on the side of the road as the clouds opened up.  There was an optical « teardrop » effect, where the edge of Venus seemed to connect to the edge of the sun longer than anticipated, that vexed astronomers during the first international transit measurements.  By 12:41:40 Venus was clearly off the edge and had moved fully inside the suns disk. 

Here it is at the upper right.  I was at a different angle (again parked on the side of the road) taking the shot.  And yes, there was a lot of cloud cover we were dealing with.  V was driving and I was watching the sky.  Whenever it opened up we pulled off to the side of the road to check it out.  The kids found it exciting but I think they still question my sanity.

Above is a clearer image from later on.  Venus is at about 4 o'clock.  We could see it with just the shades and without enlarging the image.  We stopped in some parking lots and more than once strangers came up to me to ask if I could see it.  I gave them the shades and told them where to look so they could have a look for themselves.  I told them that Earth is about the same size as Venus and that is what we would look like it we switched places.  It helps drive home how large the sun really is.  Also keep in mind, Venus is much closer to Earth than it is to the sun.  Stars are really big!  Below is the same image enlarged to help show the sunspots.

We stopped for lunch and I ran out intermittantly as a break came in the clouds to capture and image.  This is at 3:37:36 PM when Venus is more interior.

Here is a later image at 5:02:24 PM as Venus is approaching the opposite edge.  Again it is visible at about 4 o'clock without enlarging.

Later in the day we returned home where the sky had cleared up a bit.  As the sun approached the horizon more objects came into the foreground which gave some perspective. 

Above is the sun with a power line crossing in the foreground.  Venus is at 4:30. 

 

Above you can see my reflection with my camera taking a picture of the sun through the welder's visor filter. 

By 6:23:50 I was able to catch an image of Venus touching the other edge of the sun.  The image below is from a few moments later when it was clearer. 

Here F is catching the last few moments. 

 

The last image I caught with Venus making a dent was at 6:35:04 PM

Here is an illustration of using the parallax and difference in times of transit from two points on Earth to estimate the distance.

From our observations I would hazard the start of transit at 12:16:22 and the end at approximately 18:36:00.  This gives a transit time of 6 hours, 19 minutes, and 38 seconds; or approximately 22,778 seconds from W 158 degrees and N 21 degrees 30 minutes.  If someone has an estimate from another position on Earth, and if we know the distance between us, we can make our own estimate of the distance to the sun.