Category: Science and Technology

Knock Yourself Out (Carbon Dioxide – The Diver’s Nemesis)

Most rebreather divers start off their diving career with open-circuit diving; that is, with scuba. And some of them pick up bad habits. I happen to be one of those divers.

With scuba you start the dive with a very limited amount of air in your scuba bottle. New divers are typically anxious, breathe harder than they have to, and blow through their air supply fairly quickly. More experienced divers are relaxed and enjoy the dive without anxiety, and thus their air bottles last longer than they do with novice divers.

So early in a diver’s experience he comes to associate air conservation with a sign of diver experience and maturity. When you are relaxed and physically fit, and your swimming is efficient, your breathing may become extraordinarily slow. Some call it skip breathing — holding your breath between inhalations.

I was once swimming among the ruins of Herod’s Port in Caesarea, and my dive buddy was a Navy SEAL. I started the dive under-weighted, so I picked up a 2000 year old piece of rubble and carried it around with me as ballast. In spite of the very inefficient style of swimming which resulted, my air supply still lasted longer than that of my SEAL buddy.

At first I was annoyed that I had to end the dive prematurely, but then I began to feel somewhat smug. I had used less air than a frogman.

As a physiologist I knew that I may well have been unconsciously skip breathing, which would have raised my arterial carbon dioxide level, potentially to a dangerous level. But all ended well, and I could not help being glad that I was not the one to call the dive.

It is important for rebreather divers to understand that they don’t have to be breathing elevated levels of carbon dioxide to run into physiological problems with carbon dioxide. It’s the carbon dioxide in your arterial blood that matters. It can render you unconscious even when you’re breathing gas with no carbon dioxide at all.

MK 16 rebreather diver

Normally the body automatically ensures that as you work harder, and produce more carbon dioxide in your blood stream, that you breathe more, forcing that CO2 out of your blood, into the lungs, and out through your mouth. It works like an air conditioner thermostat; the hotter it gets in the house, the more heat is pumped outside. In other words, arterial and alveolar CO2 levels are controlled by automatic changes in ventilation (breathing.) In fact you can predict alveolar levels of CO2 by taking the rate at which CO2 is being produced by the body and dividing it by the ventilation rate. This relationship is called the Alveolar Ventilation Equation, or in clinical circles, the PCO2 Equation.

Normally, CO2 production and ventilation is tightly controlled so that normal alveolar and arterial CO2 is about 40 mmHg, mmHg being a unit of so-called partial pressure. 40 mmHg of arterial CO2 is safe. [One standard atmosphere of pressure is 760 mmHg, so ignoring the partial pressure of water vapor and other gases, a partial pressure of 40 mmHg of CO2 is equivalent to exhaling about 5% carbon dioxide.]  

When a diver is working hard while breathing through a breathing resistance like a rebreather, as ventilation increases respiratory discomfort goes up as well. For most people, when the respiratory discomfort gets too high, they quit working and take a”breather”. But there are some divers who hate respiratory discomfort, and don’t mind high levels of arterial CO2. We call these people CO2 retainers.
Navy experimental deep sea divers; photo credit: Frank Stout

As an example, I once had as an experimental subject a physically fit Navy diver at the Naval Medical Research Institute during a study of respiratory loading. The test was conducted in a dry hyperbaric chamber under the same pressure as that at 300 feet of sea water. The experimental setup in the chamber looked somewhat like that in the figure to the right although the diver I’m talking about is not in this photo.

The diver was exercising on the bicycle ergometer while breathing through a controlled respiratory resistance at 300 feet in a helium atmosphere. The diver quickly learned that by double breathing, starting an inspiration, stopping it, then restarting, he could confuse the circuitry controlling the test equipment, thus eliminating  the high respiratory loading.

As he played these breathing pattern games my technician was monitoring a mass spectrometer which was telling us how high his expired CO2 concentration was going. The exhaled CO2 started creeping up, and I warned him that he needed to cut out the tricky breathing or I’d have to abort the run.

The clever but manipulative diver would obey my command for a minute or so, and then go back to his erratic breathing. He joked about how he was tricking the experiment and how he felt fine in spite of the high CO2 readings.

That was a mistake.

When you’re talking, you’re not breathing. Since his breathing was already marginal, his end-tidal CO2, an estimate of alveolar CO2, shot up in a matter of seconds from 60 to 70 and then 90 mmHg, over twice what it should have been. When my technician told me the diver’s exhaled CO2 was at 90 mmHg, I yelled “Abort the run”. But the diver never heard that command. He was already unconscious and falling off the bike on his way to the hard metal decking inside the hyperbaric chamber.

The diver thought he was tricking the experiment, but in fact he was tricking himself. Although he felt comfortable skip breathing, he was rapidly pedaling towards a hard lesson in the toxicity of carbon dioxide.

Keep in mind, this diver was breathing virtually no carbon dioxide. His body was producing it because of his high work level, and he was simply not breathing enough to remove it from his body.

In upcoming posts we’ll look at what happens when inspired CO2 starts to rise, for instance due to the failure of a carbon dioxide scrubber canister in a rebreather. I already gave you one example in the CO2 rebreathing study of my first post in this series. There’s lots more to come.

 

 

 

 

 

 

 

 

 

 

 

 

 

Carbon Dioxide – The Diver’s Nemesis Pt. 1 (Meduna’s Mixture)

Of all the gases humans excrete, the most bountiful, and arguably the most deadly, is exhaled carbon dioxide.

There is a forgotten bit of American medical history that reveals the bizarre features of the toxicity of carbon dioxide. In 1926, before the advent of modern psychiatric medications, some American psychiatrists began experimenting with the use of inhaled carbon dioxide for the treatment of schizophrenia and psychoses. At the time, there were no effective treatments other than electroshock.

Dr Ladislas J. Meduna

One of the most successful of these researchers was Dr Ladislas J. Meduna, a Professor of Psychiatry at the University of Illinois College of Medicine in Chicago.

High levels of carbon dioxide (CO2) did in fact have some success in treating schizophrenia, but it also produced Out of Body (OBE) and seemingly spiritual experiences. The following text is quoted from a book called Carbon Dioxide Therapy. A Neurophysiological Treatment of Nervous Disorders, published in 1950 and authored by Meduna.Meduna administered by mask between 20 and 30 breaths of a gas mixture of 30% CO2, 70% O2. From pg. 22 of his book we find,

“Any attempt to define the sensory phenomena during CO2 anesthesia, in terms of dream, hallucination, illusions, etc., would be futile. The actual material would support any hypothesis. Some of the sensory phenomena would direct us to define them as hallucinations. Some of these phenomena are felt by the patients as “real dreams”; others obviously are dreamy repetitions of real events in the past or of past dreams. I believe therefore that any classification of these phenomena in terms of dream or hallucination would be not only meaningless, but directly misleading; the patient is not “sleeping” in the physiological sense, nor is he in the state of consciousness which we usually assume to be present in true hypnagogic hallucinations.”

click to enlarge

“One subject, after 20 respirations of the gas, reported seeing a “bright light, like the sun.”

“It was a wonderful feeling. It was marvelous. I felt very light and didn’t know where I was. For a moment I thought: ‘Now isn’t that funny. I am right here and I don’t know whether I am dreaming or not.’ And then I thought that something was happening to me. This wasn’t at night. I was not dreaming. And then it felt as if there were a space of time when I knew something had happened to me and I wasn’t sure what it was. And then I felt a wonderful feeling as if I was out in space.”

“After the second breath” — reported a 29 year-old healthy female nurse who had taken a treatment – “came an onrush of color… then the colors left and I felt myself being separated; my soul drawing apart from the physical being, was drawn upward seemingly to leave the earth and to go upward where it reached a greater Spirit with Whom there was a communion, producing a  remarkable, new relaxation and deep security. Through this communion I seemed to receive assurance that the petite problems or whatever was bothering the human being that was me huddled down on the earth, would work out all right and that I had no need to worry.”

“In this spirituelle I felt the Greater Spirit even smiling indulgently upon me in my vain little efforts to carry on by myself and I pressed close the warmth and tender strength and felt assurance of enough power to overcome whatever lay ahead for me as a human being.”

Meduna summarized that preceding case by stating, “In this beautiful experience we can discern almost all the constants of the CO2 experience: (1) color; (2) geometric patterns; (3) movement; (4) doubleness of personality; and (5) divination or feelings of esoteric importance.”

Meduna went on to admit that “Not all of the sensory phenomena experienced by the patients are of celestial beauty and serenity. Some of them are horrifying beyond description.”

In 1971, Chris Lambertsen, M.D., Ph.D., from the University of Pennsylvania School of Medicine, and considered to be the father of special warfare diving by Navy SEALS, published a careful examination of the physiological consequences of the Meduna mixture. He found that inhalation of 30% CO2 in oxygen would cause unconsciousness and convulsions within 1-3 min. The precipitating event for loss of consciousness seemed to be a catastrophic increase in the acidity of the blood due to the large amount of carbonic acid produced by the CO2 inhalation. This raises the possibility that the experiences noted by Meduna were caused by pre-convulsive events within the brain.

Since then the medical community has deemed carbon dioxide “treatments” as not only dangerous but ineffective compared to modern psychiatric medication. Meduna’s mixture is no longer used.

While at the Naval Medical Research Institute, I was my own research subject in a study of the effects of rebreathing  CO2 concentrations up to 8%. That was a carbon dioxide concentration that some Navy SEALS had claimed could be tolerated without impairment.

The simplest scrubber canister in the simplest rebreather, Ocenco M20.2

I was not under water, but riding a stationary bicycle ergometer in the laboratory, simulating breathing on a closed-circuit underwater breathing apparatus (in diving vernacular, a rebreather.) Although oxygen was being added as I consumed it, there was no carbon dioxide scrubber (a container of carbon dioxide absorbing material), so the test was examining what happens when a scrubber canister is no longer functioning properly. At 7% inspired  CO2 I stopped the exercise, feeling a little abnormal. However, I was surprised at how unimpaired I seemed to be; that was, until I attempted to dismount the ergometer. I almost fell and needed help removing myself from the bicycle to a chair.

The single-minded and simple-minded task of exercising had hidden a growing central nervous system impairment. Like someone intoxicated with alcohol, I could not judge my level of impairment until a task requiring some coordination was required.

So we see that high levels of carbon dioxide intoxication can lead to profound disturbances of the central nervous system. In upcoming posts we’ll see how elevated carbon dioxide levels and the control of respiratory ventilation can interact to put rebreather divers at risk.

Much of the above is from a nonfiction book project currently under review. The working title for the book is “Collected Tales of the Spiritual and Paranormal.”

 

Google Noodling and other Technological Pleasures

I am easily bored.

Fortunately, I’m also easily entertained. In fact I have no trouble at all entertaining myself, especially if it’s at the expense of new technology. Especially if the technology has big names attached to it like Facebook and Google.

Now don’t misunderstand me. I love and use both Facebook and Google, a lot. But sometimes they just crack me up.

For example, there is a new Facebook app allowing you to leave a message behind after you die.

What a clever idea! No need for séances, or readings by psychic mediums. All you have to do is plan ahead for what you want to say, write it down, then tell your family and trusted friends to inform FB that you are indeed deceased. Voila, you get to have the final words, the last laugh, to have your say without being interrupted.

Of course, if your final thoughts as your life ebbs away are about changing your mind, or regretting what is about to be said, well, there’s simply nothing to be done. The cat will be out of the bag.

And you better not wake up in the morgue chiller if you’ve finally told the world what you think about your in-laws, or the wife, or your boss. You may not be technically dead anymore, but for all practical purposes, you are. Or you’ll wish you were.

But I can’t help thinking how much fun it would be to plan an after-life revenge on someone I consider despicable, but don’t wish physical harm on them. Let’s say their collected body of lies, fabrications and falsehoods have earned them a stint in Hell, but you’re not sure Hell really exists. Or perhaps you’re impatient.

Imagine then a Facebook farce where you reveal that you buried a  small fortune in gold, which is now worth a large fortune, at a vacant lot at some particular GPS coordinates. Of course, you’d not mention that the vacant  lot now had a McMansion built on it, by the very person from whom you seek after-life revenge.

Photo credit: hercules-online.com

Imagine the look on your archenemy’s face when people start gathering in front of his  home with GPS units, and backhoes. Do you think that would make him nervous?

I realize there are some logical inconsistencies with such a fabricated story, but I think you can count on the  ability of most people to dismiss logic if there is believed to be a fortune to  gain.

So thank-you Facebook; no more need for haunting and ectoplasm. Isn’t technology great?

The next technology that really is fun is Google’s screening of  any and all words in your Gmail. There is a way to play games with it —  I call it Google Noodling.

Photo credit http://www.catfishingtipstoday.com/catfish-noodling/

If you’re from the south you should know what noodling is. But if  you’re not, I’ll explain. Noodling is the reaching of bare hands into a catfish hole and hauling out a feisty catfish. It’s rough and tough fishing without a  pole, line, or hook. Your hand is the hook, and you hook the fish by feel through their mouth or gills. It’s a blood sport that Roman gladiators would  have enjoyed.

So, where does Google come in?

Both my wife and I have Gmail accounts, and I noticed when my wife  sent an email to me that there were certain subject relevant advertisements that accompanied that email. We all know by now, or should, that Google  computers read every word of our messages, and uses its proprietary algorithms to select ads that might be of interest to both sender and recipient. When one of those ads are clicked on, money goes into Google’s pocket. So much for privacy.

Enter into the mix my somewhat contrarian mind. I concocted an email from my wife to me, where the scenario is that I’m on travel and she is  complaining about certain female maladies that are irritating her. Well, faster than you can say itch, an ad popped up on the email after it was sent that offered over-the-counter antifungal remedies.

Well, since the ersatz wife had started a supposedly discrete discussion with her husband, I responded in a like manner, but of course with gender-appropriate words thrown in.

Bingo! Ads for things we commonly see on TV appeared in a flash.

Are we sure there is no panel of underpaid girls in Hong Kong intercepting our emails, laughing their butts off while pushing the Cialis ad button? I don’t know; I’m not convinced.

So I decided to run a test. Posing as my wife again, I concocted a fantastic email that combined a set of mixed-gender complaints, as if the person sending the email were a fully developed and functioning hermaphrodite. Then I hit the send button and waited for the first ads to show up. I checked my account — message received, but no ads. I checked her sent mail — message  sent, but no ads showing on the sent mail.

I had my hands in Google’s gills. Their snooping computers were mystified! How delicious, I thought; Google was stumped.

And then it happened. A few minutes later when I rechecked the sent mail it had an ad for a treatment for, of all things, constipation.

Google had the last laugh. Sure, their algorithms were getting ambiguous messages about gender, so the previously targeted ads could not be sent. But I hadn’t thought about the lowest common denominator among the sexes. And after spinning a few million compute cycles thinking, the Google computers decided on a sure course of action.

Those clever devils!

I suppose the message is, new technology is being spawned at a dizzying rate, designed to provide us “features” we never thought we needed, and to keep its inventors in the black, financially. But at the same time these innovations are fodder for the imaginative mind who sees the value in a good laugh. Count me in as one of those minds.

 

 

The Green Flash and Inspiration

Some say it is serendipity. In reality, maybe it is just the human ability to increase awareness once your attention has been attracted. For example, you’re thinking about buying a black Subaru when you suddenly notice how many black Subarus are on the road.

Photo credit, Mila Zinkova.

I had been thinking of late about the Green Flash, a rare optical phenomenon that I experienced once, years ago, on the Pacific shore at Monterey California. It was memorable not only because of its surprising appearance, and its brevity, but because it was one of the most monochromatically pure and intense visions I’ve experienced.

I have since watched many sunsets over the water, trying to witness again what I saw in Monterrey. I recently watched for it from the air, flying towards the Gulf of Mexico as the sun set. I have watched from an elevated pavilion at St. Andrews State Park in Panama City, Florida.

So far, nothing has come even close to matching what I once saw. That is one of the givens for the Green Flash; witnessing it is oftentimes considered a once-in-a-lifetime event.

The closest I’ve come recently was seeing a greenish tint on the top part of the sun as it appeared to be half way below the horizon. My wife confirmed what I was seeing, but the brilliant flash of emerald green I saw in Monterey has eluded me.

And then like the black Subaru, I saw the Green Flash again recently in a rented 2007 movie, “Pirates of the Caribbean: At World’s End.”

But it was not the same. The Green Flash appeared in the movie like the flash from a nuclear explosion, stretching from one side of the screen to the other. There were even sound effects.

That was not the Green Flash I know.

I don’t blame Hollywood for its hyperbole. After all, I don’t think the beauty of what I once saw would convey well on the silver screen, or the TV screen. In fact photographs, such as the ones above or on the Internet fail to capture the essence of it. The brilliance of color from the flash is otherworldly — it cannot be easily reproduced.

I chuckled at the point in the Pirates of the Caribbean script when the statement is made that the Green Flash means a soul is coming back from the dead.

Master Gibbs

“Ever  gazed upon the green flash, Master Gibbs?”

“I reckon I’ve seen my fair share. Happens on rare occasion; the last
glimpse of sunset, a green flash shoots up into the sky. Some go their whole lives without ever seeing it. Some claim to have seen it who ain’t. And some say—”

“It signals when a soul comes back to this world, from the dead!”

I’m as intrigued with the paranormal as the next person, but I know what 18th century pirates could not know; the green flash is a physical phenomenon, not a metaphysical one.

According to some bloggers, and Wikipedia, the purported association between souls and the Green Flash was promulgated  by Jules Verne through his fiction. Supposedly Verne claimed it to be an old Scottish legend in his 1882 novel Le Rayon-Vert, according to which, one who has seen the Green Ray is incapable of being “deceived in matters of sentiment,” so that “he who has been fortunate enough once to behold it is enabled to see closely into his own heart and to read the thoughts of others.”

Others have misquoted the passage to say that “if one were to peer in the light of the green flash they would gain the power to read the very souls of other people they met.” But that quotation is a no truer translation from the French.

As I said, Verne’s passage is a fictional myth. So, one good fiction leads to another. And of course a little Hollywood computer graphics and sound effects makes it that much better.

But what inspired me to write about the Green Flash is the resemblance, in my mind at least, between the Green Flash and inspiration.

Inspiration comes to me, and you as well I suspect, in a flash. It may be rare, but like the Green Flash it is all so clear, like a lucid dream; an “aha” moment. It is a revelation, perhaps.

Flashes of inspiration have power; they cause things to happen.  Flashes of inspiration have led me to write poetry, science fiction, and non-fiction. Some would call it the writer’s Muse: I just call it that flash of inspiration that seemingly comes from outside me.

Through a flash of lucidity, inspiration caused me to invent a new type of rebreather underwater breathing apparatus. It also caused me, at a young age, to hop on a tiny 50 cc Honda motor-scooter and ride from Atlanta to almost my destination, Kansas City. (50 cc Honda scooters are not really built for long distance cruising, but that didn’t stop me from trying and almost succeeding.)

Inspiration has caused me to raise my hands to the heavens and feel the very presence of God.

Inspiration has propelled me to pull a union thug out of a courtroom and tell him I forgave him for the assault that broke my jaw. Like the cross-country motor scooter ride, not all inspired events would be considered sane except by the person inspired. But they can be life-changing.

Unlike the Green Flash, inspiration can come anytime, anywhere. But like the emerald flash of the setting sun, inspiration can occur when you least expect it.

Both are gifts to be treasured for a lifetime.

Killer Optical Illusions — Size Does Matter

A discrepancy between what you see and what you expect to see can prove fatal.

In graduate school at Florida State University I drove a motorcycle between Tallahassee, FL and my home in Thomasville, GA almost every day of the week, an 80-mile roundtrip. I seldom took the heavily traveled direct route. One alternative route took me through the boonies along a road that apparently rarely saw a motorcycle. One summer day, somewhere between Miccosukee and Metcalf I approached a ramshackle, rusting tin-roofed house, and out of the yard came bounding a dog which apparently lived for the excitement of chasing cars.

As bikes go, a Honda CL 350 was not a large bike. It was a combination road/trail bike called a Scrambler. It was smaller than even a 500 cc Honda, and much smaller than a car. That disparity in size caused the charging dog to misjudge his distance from me. He was falling prey to an optical illusion: objects that are smaller than you anticipate seem farther away than they actually are.

As a pilot, and knowing something about firearm marksmanship, I can admire in retrospect the animal’s uncanny ability to properly lead and zero in on a fast moving target. He was on a collision course with my 346 lb bike traveling at highway speed. Of course, when intercepting hard steel with something as fragile as a skull, it is not a good idea to complete the interception.

I well remember the image of that dog, mouth open, tongue lolling happily to the side of his maw, seeming to relish the chase of a moving vehicle. And then in an instant his expression changed when he realized that he was actually going to catch a moving vehicle.

I don’t think he had thought through the consequences of completing his intended attack.

He applied his brakes —- front legs fully and stiffly extended, toes digging into the asphalt. But he was too late; his momentum carried him headfirst into the mid-section of the bike as our paths crossed.

His car chasing days were over.

We humans might smugly think we are not so easily confused by an optical illusion based on expected sizes and shapes. After all, we are highly intelligent creatures. But we would be wrong in our smugness.

There is a new airport in the Florida Panhandle built in the middle of millions of slash pine acres. It was a land donation designed to assist the land owners with developing sylvan land into valuable real estate. Unfortunately the real estate crash has stymied development around the airport, so an aircraft flying at night into the field which boasts a long 10,000 foot runway, sees only blackness around the airport. What results is the so-called black-hole illusion.

The black-hole illusion applies to unusually long runways lit up at night and surrounded by impenetrable blackness. The runway at ECP (Panama City) is about twice as long as the usual runways used by general aviation aircraft, and at 10,000 feet is far longer than the runway at the previous Panama City airport (PFN). The almost overpowering visual illusion is that you are closer to the runway than you actually are, and that you are considerably higher than you are in reality. On final approach the unwary pilot gets the impression that he is too high, and must push the nose of the aircraft down. In fact, nothing could be further from the truth. A pilot has to be on his game to resist the potentially deadly optical illusion.

In a black-hole situation, it is critical to fly by the aircraft instruments, with the altimeter being one of the most important. When in the grips of the black-hole illusion I find it very easy to fly the “pattern”, the rectangular visual approach that eventually leads you to the runway, at too low of an altitude. Now I am aware of the trap, but I still have to concentrate on the instruments and ignore the visual cues from the humongous runway. I also find new pilots flying my aircraft into the field for the first time falling into the same trap. Looks can be very deceiving.

A simulated black hole approach to a runway. Orbiter imagery from Guleit.com

Boeing engineers found through their night approach research that during a black hole approach flown solely by reference to the view out the windscreen, pilots will have an almost overwhelming urge to fly too low as they approach the airport. The result of such action is likely to be impact with the ground two to three miles from the runway. Details of that discussion, relying heavily on geometry, are aptly given in the following aviation news item from 2000. http://www.avweb.com/news/airman/182402-1.html.

Airline transport pilots using autopilots to fly an Instrument Landing System guided approach to the runway seldom have to worry about visual illusions. But even they can be fatally fooled when going visual. There have been at least two commercial crashes caused by the black-hole optical illusion; Alitalia Flight 4128and VASP Flight 168. (For more details, click on the Alitalia and VASP links.)

A depiction of a black hole feeding on stars and gas.

As we learn about astronomical black holes, we realize they destroy all things in their grip. However, much closer to home are personally destructive phenomena that result from nothing more than visual trickery, a vicious mental confusion between actual and perceived sizes of airport runways, and as it turns out, even between motorcycles and cars.

 

Six-Degrees of Freedom

Photo credit Paul Burger, Houston

I’ve had an epiphany of sorts.

I was flying with friends as night was falling. We were over a mile up, the air was clear and still, not a bump to be found. City lights and major roads could be seen from over 45 miles away. We seemed to be suspended in space, with only the movement of lights sliding below our wings betraying the fact that we were traveling at 145 knots over the ground.

The fellow sitting in the seat to my right seemed interested in taking the controls, something he had never done before. I first let him handle the yoke. With the autopilot holding track so we wouldn’t get too far off course I let him see how the elevator worked to raise and lower the nose, controlling pitch. Then as I turned the autopilot off completely, I had him experiment with the rudder pedals to see how that affected the aircraft. They made the plane yaw to the left and right. Next I showed him how the ailerons on the wings work with the rudder on the tail to smooth out turns by applying roll simultaneously with yaw. That created a coordinated turn which is the most efficient and comfortable way to change direction in the air.

He was getting a mini-lesson in flying, and doing quite well for a novice.

Then I told him to point the nose of our bird towards a light on the horizon that would keep us headed in the right direction, towards our home base some 90 nm away.

He had the plane swaying slightly from side to side, but I did not interfere or correct him. Now that I think about it, he may have been doing it deliberately as he learned how the ailerons and rudders work in unison. And then he said something interesting: “It’s six-degrees of freedom.”

Granted, my friend is a mechanical engineer, and in his student days he had done a project with wind tunnels and model airplanes. That was where he gained both academic and practical experience about the six-degrees of freedom in aviation.

Image credit: Horia Ionescu, Wikipedia Commons

The six degrees involve three degrees of translation, and three of rotation. In the following illustrations, aside from the three rotational axes commonly applied to aircraft, roll, pitch and yaw, the other three axes are also shown. In a ship, motion in those translational axes are called heave, sway, and surge. In an aircraft they have less colorful terms; motion fore and aft, left and right (port and starboard), and up and down. The figure to the right shows all six degrees of freedom irrespective of the craft or method of motion.

Illustration by S. W. Halpern

 

For me, the  epiphany was the realization that my favorite things on earth (or slightly above it) involve six-degrees of freedom. Physically, there can be no greater freedom, and that freedom is found in flying and diving. No wonder I love them.

Birds live in that six-degree of freedom world, and perhaps that’s why we envy them. While we may not envy fish, per se, perhaps it is the six-degrees of freedom that lures so many of us to diving underwater. I well remember the first time I glided over a vertical precipice in crystal-clear water and realized with supreme pleasure that the laws of physics no longer compelled me to tumble over that precipice. Even now, quite a few years later, I still enjoy diving in the Florida Panhandle Springs, and finning directly over a rock face that drops vertically towards a sand bottom some 25 or so feet below. I’ll float over it, looking down, then bend at the waist and glide effortlessly to the bottom.

This is the stuff of flying dreams, of which I am also enamored.

A soul floating in space prior to incarnation, an embryo floating in utero prior to implantation; these are ways we might have once had the same freedom of motion. But soon after becoming a fetus we lose that freedom. There is no where else that freedom of motion can be experienced in a sustained manner than by  flying and diving.

Photo credit: Mass Communication Specialist 1st Class Jayme Pastoric

 

The following video is the best example I’ve found to demonstrate the true meaning of six degrees of freedom. Go to full screen, high def, volume up, and enjoy! (Disclaimer: I have no connection to the featured company or equipment used in the making of this video.)

What I Would Miss on Mars

When I first saw images from NASA’s various Mars rovers, I was almost crawling out of my skin with excitement. As I spoke at a NASA sponsored conference where scientists and engineers were discussing plans for a Mars mission and colonization, I was enthralled with the thought that humans are actually planning for mankind to leave our planet for a foreign world.

Lately, I’ve been thinking about what I would miss if I were a colonist on Mars. I’ve decided, what I would miss the most is something we take for granted in most places of the world; water.

Of course, Martian pioneers would have to have abundant stockpiles of drinking water. But I sure would miss Earth’s oceans; their awe inspiring breadth and depth, their multitudes of sea life, and the gentle shades of blue-green in clear water along sandy coasts.

I would miss the sound of the surf, the laughter of children chasing and being chased by harmless but persistent waves.

I would miss the sound of clicking shrimp, and the clicking of dolphins corralling schools of fish.

I would miss being able to open the windows on a perfect day. I would miss feeling a breeze on my bare face.

I would miss never having to wonder if I had enough oxygen to breathe. I’d miss not worrying that toxic carbon dioxide would seep into my tiny house and suffocate me and my family in our sleep, or that my home’s pressure barrier would fail and our blood would essentially boil, releasing a flood of deadly bubbles stopping our hearts.

I am concerned that those attempting to colonize Mars woud sink into a chronic melancholy simply because the water that pleases and sustains so many of us is absent on Mars. Could these homesick astronauts survive, and even thrive?

If the first wave of colonizers did survive, procreate, and nurture the next generation, the first generation of true Martians, then I suspect that generation would fare much better psychologically than the first. After all, they would never have known the verdant forests and splendorous seas of Earth.

As I pondered what it would be like to be a third and fourth generation colonist on Mars, growing up knowing nothing else, I realized that rather than space exploration being a guaranteed and common place activity at that time in the not too distant future, a bleaker possibility exists.

It is entirely possible that war, disease, asteroid and comet collisions, or even the failure of mismanaged banking systems could so impoverish the Earth that space travel to the Martian colony might not remain economically sustainable. Eventually, to the stranded Martians our Earth could be little more than a distant memory, perhaps even a legend. Martian children might grow up on the red planet hearing tales of Sky People who came to Mars from a far away place, a world of indescribable beauty, with colors of blue and green that are not even imaginable on Mars.

Some native Americans have in the past recounted tales of Sky People coming to Earth. Wouldn’t it be ironic if the next generation of Earthlings becomes the fabled Sky People that populate the planet Mars?

If offered the chance to be one of those Sky People on a one-way trip to Mars, would I sign up for the mission? Frankly I don’t think I could leave the most beautiful planet in the solar system, perhaps in the galaxy, even for something as exotic as a trip to Mars. 

 

Another Rebreather Scrubber Thermokinetic Simulation

Compared to the previously posted video of a segment of a rebreather scrubber, this video shows a much larger, and therefore more realistic scrubber with axially aligned, CO2 rich gas flow passing from left to right. Due to the larger size of the simulation space, more widely distributed heat patterns are noticeable, as are fluctuations in heat. The flow of those fluctuations are most noticeable along the simulated boundary of the cylindrical scrubber bed.

The assumptions of this simulation are that CO2 production (diver workload) is constant throughout the simulation run, ventilatory flow through the canister is constant, the surrounding water temperature is constant at 50° F, and the canister was chilled to the water temperature before the “diver” started breathing through it.

The previous simulation conditions were similar except that the canister was toasty warm prior to immersion in frigid water.

To fully appreciate the fine detail of the imagery, click on the video frame then expand the video to full screen size (lower right symbol immediately after “You Tube”) and play back in 1080p High Definition mode.

 

 

 

 

The Mysterious Physical Attraction of Slash Pine Seeds to … Anything

Pine cones are falling from the sky and smacking the roof with a thud, with all the earnestness of a piece of reentering space debris. The sound reverberates among the rafters, giving the impression of a large falling limb, sending us scurrying outside searching for damage to the roof.

It is October in the Florida Pan Handle, the time of year when pine cones eject their winged pine seeds.  Once emptied, the cones are rejected by their parental trees like useless appendages.

Those seeds had begun their race towards destiny high in the outstretched branches of 100-foot tall slash pines, being nestled by the overlapping leaves of their natal cones. But once ejected from their nest, they were on their own, distributed by gravity, winds, and those always tricky helicopter aerodynamics.

Walking outside this morning I could see those seeds helicoptering down to the ground, or the pool. Those landing fruitlessly, without hope on the concrete were distributed forlornly like bodies on a battle field. But those landing in a pool, being swept towards the uncaring maw of the pool skimmer, did something interesting.

It reminded me of illustrations of the attempted fertilization of human eggs by sperm; all lined up, jockeying to be the first to the prize. The heavier seed end of the wing seemed to be attached to the pool ladder as if by magic, although I suspected some subtle electrical charge interaction with the metal.

This was not occurring in still water; there was a considerable flow carrying unattached seeds swiftly past those clustered around the ladder.

Click to enlarge.

But then I saw the seeds clustering around other objects, the walls of the pool, and in an almost Oedipal fashion, a pine cone floating in the pool. One cluster of seeds were touching their ends together as if in some group incest.

Keep in mind, each seed fluttered down on its own, singly. Yet when they met in the water they had an unexplained physical attraction, literally.

 

The last two photos made me suspicious that the attraction was not based on electrical charge, but on surface tension — somehow. In the photo of the pine cone you can see dimples in the water around the wings and seed, an observation that positively screams surface tension.

Just how surface tension works to orient these seeds in the way they do is unclear to me. However, I see an evolutionary benefit.

Concrete pools are not of nature. In nature, seeds falling in water might be benefited if surface tension orients the seed end towards the edge of whatever stream or pond the seeds fall into. If the seed ends can touch the soil of the earthen banks, then they have a chance to germinate.  If the seed ends pointed away from the soil, they would eventually become water logged and sink, thus drowning the potential pine seedling.

In the following short video clip we see the strange maneuvering of three separate seeds, unattached except through some invisible force, moving to and fro in the eddy behind a pool ladder in a relatively swift current.

[youtube id=”CDmWVLZOpu4″ w=”525″ h=”439″]

 

One of the many joys of being human is discovering the beauty and mystery in nature. You don’t have to understand it to appreciate it.

 

 

 

 

 

On the Odds of Being Struck by Falling Satellites

UARS satellite before deployment. Photo credit: NASA Johnson Space Center.

NASA says the odds that someone will be struck by falling space debris when the bus-sized NASA Upper Atmosphere Research Satellite comes down this week is 1 in 3200. Which got me to thinking … if I was struck while out walking Friday night, would I be unusually lucky because I beat the odds, or unlucky because I beat the odds?

Would my life insurance company pay off? Arguably it would not be an act of God, or an act of war, so I think the insurance company should pay. But I really don’t know if they would; admittedly, I don’t have a falling space debris clause in my policy. (As the space around our planet becomes increasingly crowded, perhaps space debris insurance would be a good investment.)

Now if the odds were 1 in 3200 for each of us, can you imagine the chaos? That would be a mass casualty event in the making. Those odds would be much higher than the odds of being killed by almost anything else I can think of.

From Dr. Strangelove. Click to activate the video.

I suspect there would be anti-NASA marches on the capitols of all the nations affected, which would be most of the world’s nations, by people demanding we nuke the satellite before it poses a hazard. Or maybe they’d demand we send space cowboys up to guide the careening space bus to a safer impact. (I’m not sure how those heroic bronco busters would get back; maybe they’d ride it down a la Dr. Strangelove.)

Fortunately, the odds are mighty small (1 in 21 trillion) that you or I would be hit by this particular satellite. There are much greater chances of winning a state lottery.

But assuming a piece did actually hit me without putting a hole through my head or chest, maybe simply winging me, could I profit from it? Would I become an instant celebrity? Would there be book deals? Can you imagine the television talk show questions, like “How did you feel about your impending death when you saw the fire ball heading your way?”

Let’s face it, with burning metal hurtling to Earth at 18,000 miles per hour I likely wouldn’t see it in time to react, and if I did see it, I undoubtedly wouldn’t have time to mentally compute its trajectory. Should I stand still or run? In fact, I think that calculation would be impossible. An incoming missile simply gets larger and larger in your field of view, giving you perhaps just enough time to say “Oh…” but not enough time to finish the four letter expletive you had intended.

But frankly, I’m not at all concerned. If it happens at all, it wouldn’t happen to me. It always happens to the other guy. Which I’m sure is what the insurance companies are hoping – it will be the other guy, and the other guy will be uninsured.

If pressed, I suppose I could see the insurance company’s point; If I did get squashed by supersonic satellite debris it probably would be an act of God.

Now, I’m trying to think, have I done anything to tick Him off lately?