Flying Without Wings
Flying without Wings
Feb 01, 2012 03:44:05 PM
Pictured on the front row are Russian cosmonauts Oleg Kononenko (right), commander; and Gennady Padalka, flight engineer. Pictured from the left (back row) are NASA astronaut Joe Acaba, Russian cosmonaut Sergei Revin, European Space Agency astronaut Andre Kuipers and NASA astronaut Don Pettit, all flight engineers. Credit: NASA
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.
Don Pettit floats weightless in the laboratory on the ISS as he prepares to insert biological samples in the Minus Eighty Laboratory Freezer for ISS (MELFI-1) in the Kibo lab. Credit: NASA / Don Pettit
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.
The Expanding Universe of Trash
Feb 01, 2012 03:45:07 PM
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.
Feb 15, 2012 04:46:52 PM
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.
The closet module, Leonardo, on the International Space Station. Credit: NASA / Don Pettit
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.
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 view of the Moon setting from the International Space Station. Credit: NASA
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.