Letters to Earth: Astronaut Don Pettit

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.

Don’s blog also appears at airspacemag.com.

“It is amazing to see an eclipse from orbit,” NASA Astronaut Don Pettit said. “The shadow on Earth looks just like what you see in the physics books and the astronomy book where those folks figured all that out without ever having seen what that shadow looks like.”

› Watch video of the solar eclipse

› Listen to the conversation from the space station about the eclipse

 Don’s blog also appears at airspacemag.com.

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.

Don’s blog also appears at airspacemag.com.

If my family and friends were to write me a letter, what address wouldthey use? When I type my name on one of my stories, what address should Igive?

It occurred to me that Space Station is a place as deserving of anaddress as other frontier stations like McMurdo Base or theAmundsen-Scott South Pole Base in Antarctica. These places have formaladdresses, complete with zip codes. Even Navy ships have addresses. Withthe future development of commercial spaceships, I could realisticallycontemplate 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 wecreate a new category of “rocket mail” stamps? If Space Station were tohave an address, instead of writing letters to Santa Claus asking forstuff, kids could write letters to astronauts asking questions aboutscience and engineering.

My sleep station, a coffin-sized box, is located in the fifth deckspace of Node 2. From an Earth-based perspective, I pop out of my sleepstation as if I were coming out of the floor. I am thus situated on theInternational Space Station (ISS) in Low Earth Orbit (LEO) with anorbital inclination of 51.6 degrees (the angle of our orbit plane to theequator) and an average altitude of 400 kilometers. It occurred to methat my address should be: Node 2, Deck 5, ISS, LEO 51.603. The firstthree digits of your space zip code would be your orbital inclinationand the last two a designator for your particular space station, withISS being the third in this location (after the Salyut series and Mir).This zip code nomenclature should suffice, at least until there are morethan 99 different space stations in orbit.

Don’s blog also appears at airspacemag.com.

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
     Embrace me!

Don’s blog also appears at airspacemag.com.

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.

Space is a desert unlike anything encountered on Earth. The humanbody is not configured to be able to survive in the cold, dark vacuum ofthis unearthly realm; creatures of this planet were never meant to gointo space. We can only go there if we make machines to take and provideus with all the necessary things our bodies need to stay alive.

To survive and thrive in this machine-dominated environment, we needto know how those machines work and how to maintain them. This takes astrong background in technical subjects—mathematics, science, andengineering. These subjects are interesting, and for many people, mostlyfun. But they can be difficult to master.

The theoretical basis for our machines must be understood, but wemust also have the practical hands-on mechanical-electrical skillsneeded to keep them running and fix them when they break down. Crewmembers who work on their cars and do their own home repairs are wellprepared for what is required when they venture into space. Whensomething 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, youmust study and absorb the fundamentals of these subjects, and developthe hands-on repair skills needed to keep things running smoothly. As inany wilderness, be it on Earth or in space, if you should find yourselfwithout the necessary technical knowledge and skills, you will be atthe mercy of the elements. You will have compromised your ability tocomplete the mission, and perhaps even decreased your chances ofsurvival.

Don’s blog also appears at airspacemag.com.