Monthly Archives: September 2010
I have a conflicted relationship with the Red Cross. On the one hand, I like donating blood (provided that I never actually see the needle), and believe it’s the right thing to do and indeed that I have a responsibility to do it. On the other hand, I wish they would stop calling me at totally inconvenient times, and that the finger stick didn’t hurt so much, and that I didn’t fail the hemoglobin test so often.
In space, this might get weird for me, because of space flight anemia.
Even in the 60s, they noticed that astronauts who spent time in space often had decreased red blood cell mass afterwards:
FIG. 1. Red blood cell mass changes after spaceflight. Each point represents one individual. Data are expressed as percentage of change from preflight red blood cell mass (mL/kg of body mass).
(from Smith, linked above)
Interestingly, despite invoking the word “anemia,” which to me suggested that the astronauts had iron levels that were too low, Smith says that:
Although the weight of evidence now indicates that iron storage and availability increase during space flight, space food systems provide excessive amounts of dietary iron (about 20 to 22 mg Fe/d).[13 and 26] Expert panels have recommended that iron intake of men and women be reduced to less than 10 mg/d during space flight.  Even with the typically reduced, overall dietary intake, iron consumption exceeds this recommendation ( Fig. 3A). Dietary fiber intake decreases during flight compared with before flight (Fig. 3B), further increasing the risk of elevated iron absorption.
Overdosing on iron can actually be dangerous, in that it can kill you. Could be awkward in space.
Also, it appears to be the case that anemia refers to the amount of red blood cells you have, not your internal iron content, explaining why it’s called “anemia” even if they have extra iron.
So why does it happen? I was struggling through a bunch of blood terminology I didn’t understand until I found this abstract, italics added by me for the important parts:
Upon entering microgravity, the blood volume in the extremities pools centrally and plasma volume decreases, causing plethora and erythropoietin suppression. There ensues neocytolysis, selective hemolysis of the youngest circulating red cells, allowing rapid adaptation to the space environment but becoming maladaptive on re-entry to a gravitational field.
“Hemolysis” means that the cells break open and their contents go floating happily into the bloodstream. Red cell count: decreased. Cue anemia. On the other hand, these people at the Vanderbilt Center for Space Physiology suggest that it’s just decreased production, not hemolysis, that causes space flight anemia.
As pointed out in one of the articles above, it’s hard to study because opportunities to fire people up into space and test their blood aren’t just lying around. Nevertheless, that it happens is pretty clear, so before our future space travelers set out we’ll have to figure out how to deal with it, as will Space Red Cross.
At some point… perhaps around now… you will probably want to know what’s up with this blog. Director, what’s my motivation?
There are a couple of things.
One: space is cool. There’s just no way around it. Space is cool, and the idea of living in space is also cool, and has been so to me for as long as I can remember. I have had a copy of Earthrise for a long time, and it sits framed in a place of honor with my Splatasaurus model. Sometimes at night I fall off the sidewalk because I’m looking at the stars instead of where I’m going. I want to walk on the moon. I want to ride go hiking on Mars. I want to skim across the surface of Saturn’s rings. Until that’s possible, I’ll have to make do with writing about it.
Two: science is cool. I majored in physics because I was captivated by it even when it drove me totally up the wall. I took a class on the history of evolution and electromagnetism (yes, both at the same time in the same class) and it changed the direction of my life. Science tells me things from the shape of the universe to why I stay in my seat when the coaster goes upside down even though I haven’t held onto a handle since the 90s.
Three: people in space needs a lot of science. When I prepare for a hiking trip there’s stuff I need to make sure I’ve accounted for: food, water, appropriate clothing, ICE information, maps. But I don’t need to worry about where the air I’m going to breathe is going to come from, or how to get more food if it’s been a while since my last trip to the store. For people in space, the problems only start with “where is the air coming from.”
Given my statements about the coolness of One and Two, this makes “people in space needing a lot of science” cool2.
So that’s why. Because these concepts have a temperature slightly lower than normal for me. And it’s fun. I hope that, with all the things I write about here, someday we will be able to go hiking on Mars.
Back in the day, people thought the dark patches on the moon were bodies of water, which is why they’re called maria: pronounced mahr-ee-a, not like the name. ‘Maria’ is Latin for ‘seas.’ If there were big bodies of water on the moon, it’d be a lot easier to grow things there.
It’s not just an issue of the lack of carbon dioxide, which plants need in order to perform photosynthesis and sustain themselves. Earth’s atmosphere blocks a lot–a lot–of electromagnetic radiation; in fact, it takes out almost everything except a narrow window around the visible range of light, called the optical window, and another window in the radio range whose name you can probably guess. The atmosphere also blocks a lot of space debris from hitting Earth, since the debris generally burns up the atmosphere and can show up as a shooting star, or meteor. Most of the time, anyway; sometimes pieces of debris run into people’s stuff or largely obliterate the dinosaurs. The moon, lacking an atmospheric shield, would be more vulnerable to these impacts.
Given these problems, it will be tricky to grow food on the moon, especially on its surface.
Sure, you run into the where-does-the-sunlight-come-from problem again, but on the other hand, a plant can actually live there. The CEAC prototype, according to the press release, takes up eighteen feet of tunnel space but can be collapsed to just 4 feet for transport.
I hope you all had a mental image of a slinky just now.
The manufacturing company claims 10 minutes for setup and 30 days until vegetables, and when working:
The lunar greenhouse contains approximately 220 pounds of wet plant material that can provide 53 quarts of potable water and about three-quarters of a pound of oxygen during a 24-hour period, while consuming about 100 kilowatts of electricity and a pound of carbon dioxide.
It would also be growing the vegetables hydroponically, aka in water.
CEAC also designed a unit which is used to grow vegetables at the South Pole, so they have some experience with making greenery grow in inhospitable places. They’re applying for additional funding in hopes of carrying the experiment on to Phrase II.
One thing it’ll be interesting to see in the future is how the light-usage issue in space agriculture is handled. Plants are adapted to use the light available on Earth for photosynthesis, which in space wouldn’t necessarily be available- either because the plants themselves are literally shielded from the light, or because the light isn’t bright enough even if it is there. So will it be easier to engineer efficient lights to maintain the plants, or to engineer the plants to take advantage of efficient lights?
When I think of food in space, I think of things like astronaut ice cream, sold in fine science museums everywhere.
It looks delicious, right?
Um, right. I like it, but it does have a texture weirdly reminiscent of styrofoam and sometimes it makes my teeth feel strange.
But it seems that “food in tubes” is no longer an accurate description for what astronauts have to eat. (Project Mercury astronauts weren’t so lucky) Modern astronauts even get some fresh food, though they have to eat it in the first couple days since there’s no fridge on the space shuttle.
All this revolves around the idea that astronauts take all their food with them. While that might work for hanging out close proximity to Earth for a limited period, it’s not really workable for a trip to, for example, Mars. Especially if you wanted to stay on Mars for a while.
At this point farming sounds like a good plan for food production. And it is, if you can overcome issues like “microgravity inside a spacecraft won’t hold the plants down,” “there is no sunshine inside the spacecraft,” and “where is the rain going to come from.”
People are working on that.
Like these people:
I want to know what happened to those strawberries after this photo (larger version). Did they go splat sadly on the floor? Did anyone apply the five-second rule? They look delicious even airborne and blurry.
This is Gioia Massa, Cary Mitchell and Judith Santini from Purdue University, who studied a variety of strawberries with the goal of determining which of them might be most suitable for space growing. They did this by comparing three strawberry types (Tribute, Fern, and Seascape; I had no idea strawberry cultivars had names like roses do) when the strawberries were given different amounts of light: 14 hours a day, 17 hours a day, or 20 hours a day.
After this test, Seascape “was the most consistent producer, typically with the largest, most palatable fruit.”
To figure the palatability, they had volunteers rating the deliciousness of the strawberries. Sign me up.
Anyway, after this initial experiment, they grew Seascape again at 10, 12, and 14 hours of light daily for 33 weeks, finding that “Photoperiod again had no significant effect on total fruit weight…” meaning it put out the same total amount of fruit regardless of daylight. Less light meant fewer individual fruits, but they were larger. Using less light means using up less energy, an important consideration when you’re on a space ship.
Fewer individual fruits also means the astronauts have to do less work. Bonus.
So the (NASA-funded) quest to grow space strawberries marches on. Mitchell and Massa plan to look at Seascape’s response to LED lighting, hydroponics growing, and different temperatures next.
Mitchell pointed out that strawberries might be the only sweet space crop being considered. I hadn’t thought about it before, but the others he lists – radishes, tomatoes, lettuce – are, well… veggies. Except for tomatoes, technically. They’re good for you, but does anyone look forward at the end of the day to a nice leaf of lettuce? Or a radish? Going to Mars is cool, but it’s pointless if you’ve gone insane from food monotony by the time you get there. Strawberries might help with that.
The article: Gioia D. Massa, Judith B. Santini, Cary A. Mitchell, Minimizing energy utilization for growing strawberries during long-duration space habitation, Advances In Space Research, February 2010; doi:10.1016/j.asr.2010.02.025