May 30, 2012
Last weekend I asked if I could use one of the research freezers onboard Space Station during my off-duty time. I made thin sheets of water about a millimeter thick (sort of like a soap film, but without the soap), and froze them. Then I looked at the ice under polarized light, using a laptop display as the light source for one direction of polarized light and a filter I just happened to have in my personal kit to make “crossed polarizers.”
When the ice sheets were placed between the filter and the laptop screen, the crystal structure became vividly visible. I do not know at this time if the crystal structure is any different than normal ice, but I will find out.
Meanwhile, we were unloading the supplies from Dragon.
May 21, 2012
Weightlifting in weightlessness is now my favorite oxymoron. (It has surpassed my previous favorite: reality TV.) Living in weightlessness causes our bodies to slowly degenerate, and for long-duration missions something has to be done to prevent, or at least mitigate, this degeneration. While the reasons are not fully understood, we have discovered an empirical solution, which also is not fully understood: an intense blend of cardiovascular and weightlifting exercises.
To accomplish the weightlifting—properly called resistive exercise—NASA has invented a machine that provides forces of up to 270 kilograms (600 pounds) that remarkably mimic the experience of weightlifting on Earth. When I finish a 1½-hour session on this machine, my muscles have been turned into salty limp noodles. (Heavy lifting also makes for heavy appetite. Here, I can truly claim to be able to eat my weight in barbeque). The weightlifting machine is called ARED, an acronym whose meaning I have long forgotten. I like to refer to this machine as The Beast.
When we lift weights under the influence of gravity, the force throughout the motion is constant. On Earth, we are used to this feeling. Normal weightlifting machines use springs, bows, bungees, or pneumatic cylinders to provide the load, with the resistive force increasing in proportion to the distance traveled. Most weightlifting machines rely on simple pulleys and weights, which of course do not work in weightlessness.
To make a resistive exercise machine for space that feels like lifting weights on Earth requires a different approach. It is possible to design springs that yield a constant force over a small displacement, but to make these operate over large motions, with user-selected loads that remain calibrated, leads to complicated mechanisms.
The invention in The Beast that solves the spring problem (giving force independent of displacement) uses something we have plenty of in space: vacuum. There are two large cylinders, with a vacuum behind each piston. The atmospheric pressure in the cabin pushes on the other side of the piston, thus creating a force independent of displacement (vacuum behind a piston does not “compress” like air does). Using a simple lever with a ball screw adjuster gives continuously variable, calibrated, and reproducible forces. These forces are transferred to a standard weightlifting bar through a yoke. When I stand on a platform attached to The Beast, the forces from my exercise are balanced within its structure, so that no unwanted vibrations are transferred to Space Station, which could spoil the environment for scientific experiments. The Beast is an engineering marvel that is central to maintaining crew health.
When living on a frontier, we move away from the standard way of doing things. The frontier spawns a class of invention that would never materialize if we remained comfortably surrounded by that which is familiar.
May 16, 2012
What space station crews call our “mission” is a bit more complicated than what you might think. Under normal operations, there are six crew members living on board station. We send up a three-person crew in the Russian Soyuz spacecraft four times a year, and the launches and landings are generally timed for spring and fall, to avoid severe weather in Kazakhstan.* This results in Soyuz crew overlaps of either four months or two months, with each three-person crew staying for about six months.
There are a number of advantages in this scheme, particularly during handover, when the newly arriving crew (we’re expecting one tonight) learns from the seasoned crew all the onerous nuances impossible to know except by being onboard.
Crews on space station are called “Expeditions,” a fitting name for a collection of explorers living on the frontier. Since there are two possible three-crew overlaps for each expedition, there are two possible expedition numbers that span a set of nine individuals. In addition, each crew of three arrives in a Soyuz with a designated engineering number, plus a space station mission number and a crew-chosen call sign. Thus, for my mission, I am Expedition 30 for four months, Expedition 31 for two months, and a crew member for Soyuz TMA-03M and Soyuz 29s, with call sign Antares.
This all gets multiplied by two, since we automatically function as backup crews for the mission that flies six months before us. So I am also backup crew for Expedition 28/29, on Soyuz TMA-02M and Soyuz 27s, with call sign Eridianus.
Then there are the management teams on the ground. These are people who work relentlessly through weekends and holidays to support the lucky crew members on space station. These management teams are called “Increments,” and they have numbers that usually correspond to the expedition numbers. Sometimes, though, these can get shifted to adjacent mission numbers. Of course, the nomenclature for increments, like expeditions, also gets multiplied by two, since every prime crew participates as backup crew for an earlier increment. When talking to crewmembers, people will speak in expeditions; when talking to NASA planners, they will speak in increments. Like the blind men feeling the elephant, we tend to describe our work from our immediate perspective. It is understandable that these subtleties can lead to confusion.
That’s why, when someone asks me what mission I am flying, the answer might lead to a conversation something like this: “I am backup crew for Expedition 28/29, also known as Increment 28/29, in Soyuz TMA-02M, or Soyuz 27s, called Eridianus, but am prime crew for Expedition 30/31 in Increment 30/31 for Soyuz TMA-03M, or Soyuz 29s, called Antares.” This kind of answer baffles even my fellow astronauts. I have decided that my mission identity is simply going to be dictated by the one with the largest three-crew overlap. Hence, I call myself Expedition 30. If you want the details, be prepared to settle in for a long conversation.
*There are exceptions. Expedition 29 (also known as Expedition 30, Increment 29, Increment 30, Soyuz TMA-22, or Soyuz 28s, with call sign Astraeus) slipped two months and launched in a November snowstorm so severe that from the viewing station only 1½ kilometers away, neither the rocket nor the launch pad were visible. At engine ignition, the TV cameras discovered they were pointed in the wrong direction, and quickly panned to the rocket, which appeared like a giant, slowly moving road flare—which was visible for perhaps 15 seconds before becoming completely obscured.
May 15, 2012
If my family and friends were to write me a letter, what address would they use? When I type my name on one of my stories, what address should I give?
It occurred to me that Space Station is a place as deserving of an address as other frontier stations like McMurdo Base or the Amundsen-Scott South Pole Base in Antarctica. These places have formal addresses, complete with zip codes. Even Navy ships have addresses. With the future development of commercial spaceships, I could realistically contemplate someone sending me a letter. So what address would they use? Do they need a zip code? Do you affix an “airmail stamp” or do we create a new category of “rocket mail” stamps? If Space Station were to have an address, instead of writing letters to Santa Claus asking for stuff, kids could write letters to astronauts asking questions about science and engineering.
My sleep station, a coffin-sized box, is located in the fifth deck space of Node 2. From an Earth-based perspective, I pop out of my sleep station as if I were coming out of the floor. I am thus situated on the International Space Station (ISS) in Low Earth Orbit (LEO) with an orbital inclination of 51.6 degrees (the angle of our orbit plane to the equator) and an average altitude of 400 kilometers. It occurred to me that my address should be: Node 2, Deck 5, ISS, LEO 51.603. The first three digits of your space zip code would be your orbital inclination and the last two a designator for your particular space station, with ISS being the third in this location (after the Salyut series and Mir). This zip code nomenclature should suffice, at least until there are more than 99 different space stations in orbit.
May 11, 2012
A poem written after my Soyuz TMA-1 landing in 2003.
Oh Mother Earth, embrace me
with all of your weight.
I am pressed into your bosom
and like Atlas, I carry the World’s load.
I leave the comforts of an orbital womb
and am born a second time.
Rudely thrust into the world of weight,
my chest sinks from heavy load
my arms do not move at my command
and my head spins.
But there is work to do, we must keep our wits.
We want to survive this test to prove our
worthiness for life on Earth.
And finally, our just reward,
the sweet smell of freshly tilled earth
and of crushed spring grass.
The Sparrow’s song greets our ears.
Did we perish and land on Heaven’s door?
I spew bile and mucus into desert soil,
a reminder that I am still among the living.
Oh Mother Earth, I have returned
May 8, 2012
May 4, 2012
It was time to get new socks. Mine had been worn for a week, and had reached their pull date. Groping in the bag of socks, I pulled out a pair of women’s (small) ankle socks by mistake. Not wanting to fold them up and put them back, I decided to just try them on – maybe they would stretch. They covered my toes, but only reached just past the ball of my foot. I quickly concluded, “This will not work.”
But that was based on my experience on Earth. It occurred to me that up here, you use your feet differently. In zero-g, you hook your feet under “handrails,” thus shifting the load from the bottom to the top of the foot, just behind the toe knuckle. After about two months in orbit your feet molt, and like some reptilian creature the callused skin on the bottom of your foot sheds, leaving soft pink flesh in its place. In the weightless environment, calluses apparently have no use, at least on the bottoms of your feet. However, the tops of your feet become red-rubbed raw and gnarly. And the bottom calluses shed faster than the top calluses can grow. Perpetually raw and hypersensitive, your foot tops can use a bit of padding to ease the pain.
Serendipitously, I discovered that these short socks provide the necessary protection for toes and toe tops while leaving your heels out where they can breathe. They are the zero-gravity equivalent to flip-flops. The more that I wore them, the more I liked them. I have dubbed this new space fashion “toe koozies” – they are perfect for lounging around in a Node or the Cupola.
May 2, 2012
Being in “outer space” has the connotation of being far from Earth. But here on Space Station, we are only 400 kilometers (240 miles) above the planet—not that far away considering the distances we deal with on a daily basis. Space Station is only about as far from Earth as Houston is from Dallas.
So why is being in low Earth orbit such a big deal? It’s not the distance, but the energy.
Rockets are momentum machines. They spew hot gasses out their nozzles at high velocity, and the rocket moves in the opposite direction. If the thrust is pointed correctly, and the rocket burns long enough, the rocket will go into orbit.
To achieve the required momentum takes energy, and this energy comes from rocket fuel. A rocket sitting on the launch pad is mostly propellant; only 15 percent of the mass is the actual rocket and payload. Turning that 15 percent into something that can withstand the dynamics of spaceflight, carry people and payload, and perform a meaningful mission—and bring everyone safely home—is right on the edge of our engineering ability. By comparison, airplanes, at about 70 percent fuel and 30 percent structure, are easy to design and build.
Once the type of rocket fuel has been chosen (and we only have a few choices), the required rocket propellant fraction to achieve orbit is dictated by the magnitude of Earth’s gravity. And there is very little we can do about Earth’s gravity. As long as rockets are the mode of transportation for traveling into space, we are stuck with a vehicle that is 85+ percent propellant.
Reaching orbit also requires a precision rarely seen in any form of travel. If the rocket engines miss their target by as little as 0.2 percent, achieving your desired orbit will not be possible and the Earth will repossess your spacecraft in a not-so-gentle way. This is like being two pennies short of a 10-dollar purchase. For the space shuttle, the difference between a trans-Atlantic abort to Spain and reaching orbit happened in the last eight seconds of powered flight. For both bull riders and astronauts, eight seconds is a long time.
The momentum balance that governs rocket dynamics is aptly called “the rocket equation,” and it holds a tyrannical grip on anyone who desires to leave this planet. During our ascent to orbit, our rocket transfers momentum to the vehicle and the crew. My body has stored about 32 mega-joules (7.6 million calories) per kilogram of energy that originated from the rocket fuel in our Soyuz booster launched last December. This is five times more than the energy stored in an equivalent mass of nitroglycerin, and seven times more than the energy stored in TNT. Thus, the energy now stored in my body is seven times greater than what would be in an 80- kilogram pile of TNT.
For my return to Earth, this energy must be removed slowly, in a controlled manner, or we risk explosive results with an equivalent bang. No wonder spacecraft accidents are so spectacular. Any perturbation to the carefully designed and engineered atmospheric entry, and you will be torn limb-from-limb, with the torched remains sprinkled as cosmic croutons on the garden salad of Earth.
This is why being in space is being “out there.” The remoteness of the space frontier comes not from the distance of separation, but from the enormous quantities of energy expended and dissipated. Thus, the tyranny of the rocket equation creates a separation that makes low Earth orbit a frontier with no parallels.
For more of my thoughts on this subject, see my longer essay on the NASA website.
April 27, 2012
Space is a desert unlike anything encountered on Earth. The human body is not configured to be able to survive in the cold, dark vacuum of this unearthly realm; creatures of this planet were never meant to go into space. We can only go there if we make machines to take and provide us with all the necessary things our bodies need to stay alive.
To survive and thrive in this machine-dominated environment, we need to know how those machines work and how to maintain them. This takes a strong background in technical subjects—mathematics, science, and engineering. These subjects are interesting, and for many people, mostly fun. But they can be difficult to master.
The theoretical basis for our machines must be understood, but we must also have the practical hands-on mechanical-electrical skills needed to keep them running and fix them when they break down. Crew members who work on their cars and do their own home repairs are well prepared for what is required when they venture into space. When something breaks on a spacecraft, you have to get your hands dirty.
If you want to fly into space and be a part of this new frontier, you must study and absorb the fundamentals of these subjects, and develop the hands-on repair skills needed to keep things running smoothly. As in any wilderness, be it on Earth or in space, if you should find yourself without the necessary technical knowledge and skills, you will be at the mercy of the elements. You will have compromised your ability to complete the mission, and perhaps even decreased your chances of survival.
April 23, 2012
A poem for today—
Helen of Earth
An Alien force,
smitten by the sight of Earth.
Stunning occipital pleasure,
with a face of such beauty.
As to launch a thousand ships,
laying siege to our planet,
until they can take her as their own.
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