May 8, 2012
March 9, 2012
Gold, silk, and spices were tangible treasures from past exploration. The Conquistadors were particularly good at extracting gold from the local inhabitants. Sir Francis Drake, before he acquired the title of “Sir,” brought back enough treasure from his circumnavigation of the globe to provide more than half the income for the British crown for an entire year. The frontiers of space likewise offer treasures won from exploration, treasures that will enrich our lives and enhance our standard of living. These treasures are golden but not gold. They contain secrets about the biochemistry of life, and will allow us to increase our understanding of how life functions. No more silver and gold; from Space Station we have blood, spit, and urine, treasures that contain secrets more valuable than a chest filled with pillaged Aztec gold.
On Space Station, we are human guinea pigs for a wide variety of medical experiments. The weightlessness of space offers a biochemical challenge to our bodies, which develop a host of fascinating maladies such as bone decalcification, cataracts, retina swelling, eye focus shifts, smooth muscle atrophy, fluid imbalance, gross weight loss, cardiovascular degeneration, and more. In spite of these maladies, humans can thrive in space, proving that as a species, we are a hardy lot and can explore places where we were never meant to go.
The microgravity of Space Station allows for yet one more experimental variable, offering an amazing and unique environment in which to study human physiology. Mother Earth throughout time has tormented creatures with every possible variation of environmental parameters. She has tweaked temperatures from hot to cold, pressures from high to low, chemical compositions from reducing to oxidizing and acid to base, and more. She has thrown stones at us from space and spewed out molten rock and ash from within. The layers of rocks are littered with fossils of hapless creatures that could not make the grade, or, through no fault of their own, were simply caught in the wrong epoch of geologic time. The history of life on Earth is the story of species extinction, a fascinating thought for those of us that are still here and can contemplate such a construct.
With all this change, with all this process, throughout all the evolution, the one factor that has been constant for billions of years is the magnitude of Earth’s gravity. Now we can venture off the planet and for the first time in the history of life, vary the influence of gravity by a factor of one million. The fact that we can survive in space is in itself an amazing discovery. We truly are off in a new frontier, one that life has never seen on Earth, and it is on this frontier that physiological secrets can be pried from the people who go there.
As the crew of Space Station, we routinely puncture veins, drool on cotton swabs, and urinate in bags. These samples are processed in centrifuges, sprinkled with preservatives, placed in tubes, and stored in MELFI, better known as “the freezer.” Kept at -98° C, these samples are stored for months before return passage to Earth can be arranged. To ensure safe passage of these treasures through the ride back to Earth, NASA has developed a special cold box that keeps them frozen for several days, ensuring unthawed recovery by ground crews, happy life science researchers, and crew members relieved to know that their bloodletting was not in vain.
The cold boxes themselves are an engineering marvel. They are nearly equal in thermal conductivity to a vacuum dewar (Thermos bottle) with only a fraction of the mass. They are made from truly space-aged materials; aerogel and Mylar. Aerogel is the most gossamer solid material known. Appearing more like solid smoke, aerogel has a density only 10 times greater than that of air (steel has a density 7,000 times greater than air) making it one of the best thermal insulators known, bested only by vacuum. Aerogel is brittle, readily crumbing into dust. To prevent this eventuality, it is placed inside a skin of Mylar (plastic) film. The air is then sucked out, making this structure as rigid as a vacuum-packed bag of coffee (which feels brick-hard until the package is opened). These Mylar-packed aerogel structures can be made into odd shapes, enabling cold boxes to fit in unused pie-shaped spacecraft volumes.
When new technology is developed, other unintended uses often surface. Such was the case for the cold box. Developed for space, it ended up in Antarctica, not for keeping things cold but for keeping them warm. In 2006-2007, I had the good fortune to live in a tent about 200 miles from the South Pole during a scientific expedition to Antarctica as part of a meteorite gathering team called ANSMET (Antarctic Search for Meteorites). The conditions found in Antarctica preserve and concentrate meteorites, a discovery not realized until the early 1970’s. They accumulate on the surface of the blue glacier ice, and because they appear as strongly contrasting black specks from a distance, they can be recognized from afar and gathered like cosmic Easter eggs. For the last 30 years, annual expeditions working during the short Antarctic summers have gathered over 20,000 meteorites. During our six-week stay, we advanced this number by 850.
Living in a tent under primitive conditions, the ambient temperature danced around -20° C throughout the continuous daylight of the Antarctic summer day. Including wind chill, the effective temperature was -40° C. At such temperature levels, it does not matter what scale is used. In our tents, the floor temperature stayed at -20° C and the chimney varied from -20° C to +20° C, depending on whether the stove was lit. Any water-based substance became a frozen lump. Most electronic devices refuse to operate under these conditions; from batteries that do not make sparks (lithium-ion batteries do not like to be charged if less than 0° C), LCD displays that give only blank stares, or hard drives that do not turn at the right speed.
The Antarctic hot box in its former life was an engineering test article used to make thermal measurements for the design of the spaceflight units. Having served that purpose, I found it in a dank NASA cabinet, itself in cold storage and seemingly of no further use. Brought out from retirement, this high-tech space cooler found itself strapped to a Nansen sledge, pounding through the Antarctic interior over snow structures known as sastrugi. In a sea of cold, it offered a small oasis of warmth. We also kept our Tabasco sauce and sourdough starter in the hot box, demonstrating the value of having small comforts when living on the frontier.
Thus we behold the new treasure garnered from the frontier of space. Not gold or spices, but knowledge. Knowledge always has value, even if we don’t immediately know or recognize it. The real treasure of new exploration is the larger knowledge base and the expanded imagination we develop from it. In time, all knowledge shows itself to be useful in some way. The fact that today it is difficult to pinpoint the value of space exploration shows that it is truly venturing into terra incognita, unknown territory.
February 8, 2012
Editor’s Note: Don Pettit demonstrates some weird physics onboard the space station for the Physics Central educational site.
February 1, 2012
The International Space Station was bought and paid for by a large group of nations. Now, with 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.
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.