Monthly Archives: February 2012

Our Fancy Coffee Machine

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During the flight of STS-126 in 2008, we carried upthree refrigerator-sized pieces of equipment. One was a toilet for the NASAside of space station. There was already one on the Russian side, so this onegave us redundancy. In the past, when the toilet broke, all work had halteduntil we fixed it. No other single piece of equipment fell into this categoryof importance. The oxygen generator could break, and maybe in a day or two wewould fix it; same with the carbon dioxide scrubber. But when the toilet broke—nowthat was serious.

The second piece of equipment we carried up was a smallchemical plant. It contained a distillation apparatus, catalytic reactors,pumps, filters, and plumbing. It was a chemical engineer’s dream. The liquideffluent from the toilet was plumbed to the inlet of this machine.

The third piece of equipment was a new galley. Itsported an injection port for filling our drink bags and rehydratingfreeze-dried food with our choice of hot or room-temperature water. It also hada hot box for warming thermally stabilized meat pouches (canned meat withoutthe can) and a small refrigerator—not for science samples, but for the crew’sfood. The inlet to the galley was plumbed into the outlet of the chemicalplant. This completed what we call our regenerative life support system. Simplyput, what goes out one end is processed, reworked, and put back in the otherend.

Water is an essential ingredient not just for us, butfor all life forms that we recognize. And water is always in short supply on aspacecraft. There may be water shortages in some places on Earth, butspaceflight redefines the meaning of the word “desert.” Closing the water loopwill therefore be essential technology when humans venture away from Earth forlong periods of time. If the toilet fails on a mission to Mars, the crew willrun out of water and die. Earth orbit, where spare parts and engineeringknowledge are close by, is the ideal place to refine this technology andproduce equipment that is truly robust. I call this engineering research; it iscomplementary to scientific research, and is one of the more importantactivities that we conduct on space station.

Nowhere on Earth do we recycle urine using portablemachinery. Not in Antarctica, not on ships at sea, not in our driest deserts.We choose to let Earth do the recycling, not a machine. Our recycling system onspace station is not a one-time demonstration, nor a test of astronauts’ability to handle the “yuck factor.” It’s a day-in, day-out operation, designedas an integral part of the overall spacecraft water balance. With thistechnology, we are truly on the frontier, and we have serial number 001 of acomplex machine. Of course it breaks down—constantly. And of course, we arealways fixing it. Of course there is a steady stream of spare parts arrivingfrom Earth. Any new technology is like this. The first crews arriving at Marswill thank us for our urine-stained hands.

Morning is a time for comfortable habits, and so it ison space station. Each morning I float out (“getting up” is obviously agravity-centric expression) and do my daily routine. I can hear the rumbles ofthe chemical plant. It vibrates the deck rails and gives your feet a massage atthe same time. Then I float over to the galley and make a bag of coffee. Konais one of my favorites; I can feel the caffeine race to my brain and stimulatemy thoughts. It occurs to me that our regenerative life support equipment isreally just a fancy coffee machine. It makes yesterday’s coffee into today’scoffee.

Don’s blog alsoappears at

Earth Photography: It’s Harder Than It Looks

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From my orbital perspective, I am sitting still and Earth is moving. I sit above the grandest of all globes spinning below my feet, and watch the world speed by at an amazing eight kilometers per second (288 miles per minute, or 17,300 miles per hour).


This makes Earth photography complicated.


Even with a shutter speed of 1/1000th of a second, eight meters (26 feet) of motion occurs during the exposure. Our 400-millimeter telephoto lens has a resolution of less than three meters on the ground. Simply pointing at a target and squeezing the shutter always yields a less-than-perfect image, and precise manual tracking must be done to capture truly sharp pictures. It usually takes a new space station crewmember a month of on-orbit practice to use the full capability of this telephoto lens.


Another surprisingly difficult aspect of Earth photography is capturing a specific target. If I want to take a picture of Silverton, Oregon, my hometown, I have about 10 to 15 seconds of prime nadir (the point directly below us) viewing time to take the picture. If the image is taken off the nadir, a distorted, squashed projection is obtained. If I float up to the window and see my target, it’s too late to take a picture. If the camera has the wrong lens, the memory card is full, the battery depleted, or the camera is on some non-standard setting enabled by its myriad buttons and knobs, the opportunity will be over by the time the situation is corrected. And some targets like my hometown, sitting in the middle of farmland, are low-contrast and difficult to find. If more than a few seconds are needed to spot the target, again the moment is lost. All of us have missed the chance to take that “good one.” Fortunately, when in orbit, what goes around comes around, and in a few days there will be another chance.


It takes 90 minutes to circle the Earth, with about 60 minutes in daylight and 30 minutes in darkness. The globe is equally divided into day and night by the shadow line, but being 400 kilometers up, we travel a significant distance over the nighttime earth while the station remains in full sunlight. During those times, as viewed from Earth, we are brightly lit against a dark sky. This is a special period that makes it possible for people on the ground to observe space station pass overhead as a large, bright, moving point of light. This condition lasts for only about seven minutes; after that we are still overhead, but are unlit and so cannot be readily observed.


Ironically, when earthlings can see us, we cannot see them. The glare from the full sun effectively turns our windows into mirrors that return our own ghostly reflection. This often plays out when friends want to flash space station from the ground as it travels overhead. They shine green lasers, xenon strobes, and halogen spotlights at us as we sprint across the sky. These well-wishers don’t know that we cannot see a thing during this time. The best time to try this is during a dark pass when orbital calculations show that we are passing overhead. This becomes complicated when highly collimated light from lasers are used, since the beam diameter at our orbital distance is about one kilometer, and this spot has to be tracking us while in the dark. And of course we have to be looking. As often happens, technical details complicate what seems like a simple observation. So far, all attempts at flashing the space station have failed.

Don’s blog also appears at

Leonardo’s Closet

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On space station, we have a closet module. Its prosaic name is PMM, an acronym that has metamorphosed beyond the original assemblage of words to become a noun on its own, pronounced pee-em-em (only at NASA can we create new words without vowels). In a former life, it was an MPLM (another vowel-less word), a special transport container that flew up and down to space station in the back of the Space Shuttle. Made in Italy for NASA, the PMM was formally christened Leonardo—obviously named after a Teenage Mutant Ninja Turtle.

On my STS-126 Shuttle flight, I had the pleasure of moving Leonardo from the Shuttle payload bay and berthing it to the nadir hatchway on the station’s Node 2, using the Canadian robotic arm. Operating the Canada arm is a bit like working with a fancy backhoe, and requires its own skills. Once the module was berthed, we opened the hatch and unloaded many tons of much-needed equipment and supplies over the next 12 days.

For its return voyage, we loaded it up with garbage and trash. Included in the trash were bags of urine left over from human physiological experiments. These weren’t ordinary bags of urine; these were eight-month-old bags of urine. I did not need to read the label—my nose could identify the contents. We brought garbage-laden Leonardo home, but due to bad weather at the Cape, we landed at Edwards in California. It took another week before the Shuttle was transported home, and another week after that before Leonardo was removed from the payload bay and placed in its holding fixture. That was followed by the Christmas holiday. By the time folks got around to opening Leonardo, it had been sitting for well over a month, and some of the bags had leaked all over the inside of the module. I happened to be at the Cape the day after the technicians opened the hatch. It was not a pretty sight. I felt partly responsible, since I had been the one who did the orbital packing. I offered, but the technicians would not let me help clean up the mess.

Inside the PMM

In orbit, the Leonardo module is for me a special place. It is cool, quiet, soothing—a good place to reflect and recharge. But like most closets on Earth, the PMM is a total mess. The crew is so busy maintaining and utilizing space station that no one has time to properly arrange things, despite our good intentions. A typical clutter-creating scenario might go like this: Say you are in the middle of working on the station’s control system. Swapping out motherboards is a delicate task, akin to doing computer brain surgery. If you bend a pin while inserting a card, you can fry the whole works, and there are precious few spare parts. In the midst of this intensity your stomach starts rumbling, with the associated low blood sugar shakes. Your watch shows that you have been at this for hours without a break. So you fly over to Node 1 and dive into the module where the primary stocks are located, only to find that the pantry is down to vegetables and tofudibeast. You need meat and potatoes to keep going, so you float over to the PMM and pull out a new “meats in pouches” package. At the galley, you cut open a meat pouch, only to have a big bloop of gravy squirt out and make a mess. Reaching for the wipes, you discover that the last one had been dispensed to clean up the previous gravy squirt. Flying to PMA 1 (the connecting tunnel between the U.S. and Russian segments), where the hygiene supplies are kept, you find that the staging bag for dry wipes is empty. Once again you dive into the PMM, searching for the mother lode of dry wipes. You refill the PMA 1 staging bag, and clean up your mess.

All of these packages have a nine-digit bar code. We are required to log these in our inventory management system, but often the bar code reader does not work. For this case of 20 dry wipe packages and a meats-in-pouches package, you have to write down 189 alpha-numeric characters (without a mistake). These numbers must later be typed up in a crew note or called down to mission control. So you think, “I will do all this inventory paperwork later.”

That’s how the PMM gets to be a mess.

When spare moments present themselves, I will go into the PMM and straighten up the clutter. Floating among the bags undulating on their anchor chords, I have the sensation of scuba diving in a kelp bed thicket. Then I catch up on the inventory paperwork. With luck, I’m able to scribble down all those nine-digit bar code numbers correctly.

Don’s blog also appears at

Jelly on Both Sides

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Whenyour slice of bread falls on the floor, everyone anxiously looks to see if itlanded jelly side up or jelly side down. Simple probability gives a 50-50chance either way, but it seems more correlated to the difficulty of cleaningthat particular section of flooring.

Onspace station the probabilities are still the same, but the results aredifferent. I fumbled my bread after spreading a generous layer of my favoriteconcoction, peanut butter and honey. It sped toward the overhead panel and hitit before I could intervene. Fortunately, it landed jelly side out (it’s interesting how many figuresof speech have gravity-oriented references), so the 50-50 odds were in my favorthis time.

Unfortunately, it ricocheted and sped off in a different direction.I noticed that the angle of incidence equaled the angle of reflection. Myearth-honed intuition anticipated a different motion, so I was not able to keepup with the errant slice. Like a real-life version of the game “asteroids,” itwent on to hit a second panel. Jelly side was out again, so the 50-50 statistics were still in my favor. One moretime my hand was lagging the trajectory. Like failing to flip heads three timesin a row, the third collision was jelly side in, which immediately halted all motion. And just like on Earth,the outcome seemed related to the difficulty of cleaning the landing zone.After having hit two easy-to-clean aluminum panels, it landed on a white fabriccovering on a patch of Velcro pile.

Thefatalist in me accepts the inevitable Zero-G result of landing jelly side“down,” so I decided to make sure the probability would always be 100%.Realizing that the bread is merely a vehicle for conveying peanut butter andhoney, I decided to spread it on both sides. In weightlessness, it’s easy tobalance your slice on its edge so that it can be parked on the galley tablewithout any fuss. And the result is pure tastebud heaven. I do it this waybecause I am in space, and I can.

Don’s blog also appears at

A Lab for Science, and for Thinking

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The International Space Station was conceived and constructed through the cooperation of fifteen nations. Now, with it’s construction complete, we can focus on how best to use it.

We have built a laboratory located on the premier frontier of our era. Our Earth-honed intuition no longer applies in this orbital environment. On frontiers, things do not behave the way we think they should, and our preconceived notions are altered by observations. That makes it rich in potential for discovery. The answers are not in the back of the book, and sometimes even the questions themselves may not be known.

Getting ready to insert biological samples in the Minus Eighty Laboratory Freezer for ISS (MELFI-1) in the Kibo lab.

On the Station we can use reduced gravity as an experimental variable for long periods of time. We have access to high vacuum, at enormous pumping rates. (The rate at which space can suck away gas, hence its ability to provide a region devoid of molecules, far outpaces anything we can do on Earth.) We are beyond the majority of our atmosphere, which lets us touch the near-space environment where solar wind, cosmic rays, and atomic oxygen abound. Such cosmic detritus, unavailable for study within our atmosphere, holds some answers to the construction of our universe and how our small planet fits into the picture.

The Station as a laboratory offers most of the features that Earth-borne laboratories have, including a good selection of experimental equipment, supplies, and a well-characterized environment (temperature, pressure, humidity, gas composition, etc.). There is generous electric power, high data-rate communications, significant crew work hours (the fraction of hours spent on science per crew day on Space Station is commensurate with the fraction for other science frontiers such as Antarctica and the deep ocean), and extended observational periods ranging from weeks to years. All this is conducted with a healthy blend of robots and humans, working together hand-in-end-effector, each contributing what each does best. Only on Earth is there a perceived friction between robots and humans.

In this orbital laboratory, we can iterate experimental procedures. We can try something, fail, go back to our chalk board, think, (we now have the time for this luxury) and try it all over again. We can iterate on the iteration. We now have continuous human presence, and time to see the unexpected and act upon it in unplanned ways. Sometimes these odd observations become the basis for studies totally different from those originally planned; sometimes those studies prove to be more valuable. And on this frontier the questions and answers mold each other in Yin-Yang fashion until reaching a natural endpoint or the funding runs out, whichever comes first. This is science at its best, and now, for the first time, we have a laboratory in space that allows us to do research in a way comparable to how we do it on Earth.

So what questions are ripe for study on the Station? What possible areas of research might bear fruit? We have a few ideas.

One area is the study of life on Earth. Life has survived for billions of years, during which temperatures, pressures, chemical potentials, radiation, and other factors have varied widely. Life always adapts and (mostly) survives. Yet there is one parameter that has remained constant for billions of years, as if our planet was the most tender of incubators. Now for the first time in the evolution of life, we humans can systematically tweak the gravity knob and probe its effect on living creatures. And we can change the magnitude of gravity by a factor of one million. Try changing other life-giving parameters, perhaps temperature, by a factor of one million and see how long it takes a hapless life form to shrivel up and die! The fact that gravity can be changed by many orders of magnitude and life can continue is, in itself, an amazing discovery. So now we have a laboratory to probe in-depth the effects of microgravity on living organisms.

The discovery of fire (or rather its harnessing) was a significant advance that allowed humans to transcend what we were to become what we are now. Well before Galileo and Newton dissected the basic formulations of gravity, humans intuitively understood that heat rises. We empirically learned how to fan the flames. But fire as we know it on Earth requires gravity. Without gravity-driven convection, it will consume its local supply of oxygen and snuff itself out as effectively as if smothered by a fire extinguisher. Questions about fire (up here we prefer the term “combustion”) are ripe for a place where we can tinker with the gravity knob.

Another invention, the wheel, literally carried us into the Industrial Age. Ironically, that particular tool is rendered obsolete on a frontier where one can move the heaviest of burdens with a small push of the fingertips. In space the problem is not how to move an object, but how to make it stay put. Perhaps the invention of the bungee cord and Velcro will be the space-equivalent to the development of the wheel on Earth. Such shifts in thought and perspective, some seemingly minor, happen when you observe the commonplace in a new and unfamiliar setting.

We are now told that we may only be seeing about 4 percent of the stuff that our universe is made of (which raises the question, what is the other 96 percent?). Some questions about fundamental physics can only be made outside our atmosphere or away from the effects of gravity. The International Space Station, contaminated with human-induced vibrations, may not be the ideal platform for these observations, but it is currently in orbit and is available to be used. Many of these experiments are like remora fish, latching onto an opportune shark for a sure ride instead of waiting for the ideal shark to swim by. And we pesky humans, even though we cause vibration, occasionally come in handy when some unexpected problem requires a tweak, a wrench, or simply a swift kick.

Although we have preconceived ideas about how the International Space Station can be utilized, benefits of an unquantifiable nature will slowly emerge and probably will be recognized only in hindsight. The Station offers us perspective; it allows us to question how humans behave on this planet in ways that you can’t when you live there.

The Expanding Universe of Trash

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It is not surprising that the humble garbage can, essential for Earth-borne civilization, is likewise essential for space station. Unlike the kitchen wastebasket, an omnivore that will eat just about any trashy thing, on space station our wastebaskets are picky eaters.  We sort our trash into a number of different categories different from the standard earthly recycle bins of paper, plastic, and glass.  The main categories are: dry trash (paper towels, food packaging, empty drink bags, paper items, etc.), wet trash (pouches and wrappers with food residue), spent batteries, life support systems expendables (fluid sample bags, toilet hoses, connectors, etc.), experimental expendables (used medical supplies, containers filled with leftover nasty things, etc.), and toilet waste (sealed buckets of you know what).  Some of our trash items have bar codes and serial numbers and require bookkeeping paperwork at the time of disposal.  Like happens at home, sometimes an item is tossed that is later discovered essential so we go orbital dumpster diving for its recovery.  Like passing through a miniature asteroid belt, in weightlessness such an operation can create a cloud of floating debris that is challenging to put back into its container.


One characteristic of an orbital trashcan is that it is always full.  When I change out a trash bag, within a short time it is once again full.  Like a gas expanding into a vacuum, items placed inside expand into the available volume thus giving the appearance of a full bag.  Unlike an ideal gas expanding into a vacuum, here the change in entropy is not zero.  Placing new items into such a bag is really an act of compression.  The trash is squeezed and compressed until the placing of one more item requires greater strength than your arms can supply.  At that point the bag is sealed with duct tape.  The final disposal is via Progress, the spent Russian cargo vehicle (and now we also can use ATV and HTV, the European and Japanese cargo vehicles).  The ultimate disposal of our garbage is thus via deorbital cremation.

Flying without Wings

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During interviews from space station with school children I am often asked what on Earth I miss the most.  On one occasion a little girl asked a most astute question, “What from space will you miss the most once you return to Earth”?  I had to think for a moment.  Was it the views of Earth, a blue jewel surrounded by inky blackness, the heavens filled with stars that don’t twinkle, or perhaps the aurora, pure occipital pleasure seen on the length scale of half a continent?  I decided it was none of these.  Such wonders can be experienced in some form from Earthly perspectives.  What is truly unique to living in orbit is a byproduct of being weightless.  Here I can fly.  I can fly without wings dictated only by Newton’s laws of motion without the complications of aerodynamics.


As subjects of Earth, we grow up with no innate knowledge of maneuvering in weightlessness.  This is a skill that has to be learned on the job.  In a matter of minutes, we can learn to move about but to gracefully conduct ourselves takes a few weeks.  During my first expedition, after a month I thought, “Wow, I am really getting good at this”.  Then another month went by and I would think, “Last month I thought I was really good but now I am really getting good”.  I found this pattern repeated over the six month mission.  When I returned to space station as a space shuttle crew member on Endeavour, our mission was only 16 days, a mere flash in the pan by space station standards.  Sixteen days is barely enough time for your bowel to become regular let alone learn how to translate in weightlessness.  Newly arrived Shuttle crew members typically would miss a hand rail and bounce off of a rack panel with the same grace as an albatross coming in for a landing.  There would be a cloud of items knocked off of their Velcro wall tacking in their wake.  The station crew members were constantly following our shuttle crew picking up the flotsam.  One station crew member mocked, “Next time before the shuttle arrives I will have to kid-proof the stack”.   


To improve your translation skills, it helps to apply some basic concepts of physics.  When flying like “Superman”, the first and most natural method for beginners to translate, your arms are outstretched in front thus grasping onto any fixed object in which to give a little push or pull as well as offering a measure of security for protecting the tender parts on top of the head.  But this is not the best way to fly.  In this position your center of gravity is located somewhere around the belly button so controlling motion with outstretched arms also imparts rotational components and complicates the movement.  Beginners flail with these yaw and pitch motions and struggle to compensate for their unwanted effects.  Thus I learned the best way to fly is head first with arms at your side like “Ironman”.  Pushing and pulling from this position goes nearly through your center of mass, thus does not impart rotation.  On space station Ironman becomes your role model for flying, leaving Superman for the comic books. 


With practice I progressed from flying like Ironman to fly-walking.  Fly-walking looks like normal walking with the body “standing upright” and motion perpendicular to the chest.  In fly-walking your motion is controlled by the legs through tactful forces exerted through the feet when hooked under a deck mounted handrail.  This motion does not seem possible, however; when pressed into a new environment, humans readily discover, learn, and adapt.  Fly-walking offers a real advantage because it frees your arms for carrying loads.  


There is recreational flying.  This is fun flying, perhaps in a gymnastic pike, an iron cross, or a cannon ball.  You try to shoot down a module corridor without touching anything thus having a visceral experience with the First Law of Motion.  We fly like this for no reason other than you are in space and you can.  It is the equivalent of a kid skipping to school.  In the frontier we once again become school kids.

Absence of g

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He flies through the air with the greatest of ease 

goes the daring young man, without his trapeze 

Drifting around, unconstrained by his girth 

free of the weight he acquired by birth 

A place where you won’t be skinning your knee 

where the biggest problem is “How does one pee?” 

(it is best to avoid preflight coffee or tea) 

Like flying in dreams, which you know can’t be 

yet it’s real as life, in the absence of g