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STS-110 PESTO Payload
Question and Answer Board

Ed from Omaha
Considering we are testing wheat on this flight, does the ISS have the equipment, like a bread making machine, to bake on board? What challenges will there be in the cooking process? Specifically combining the ingredients and the process of rising bread? Since we have tried Coca-Cola why not bread?
Let's see. First of all, we do not have a bread machine on ISS yet. Unfortunately, the crew members don't have much time to cook, either. Kind of like your parents, though - they're probably ordering takeout food to be delivered. There are a lot of challenges with growing wheat in space, specifically trying to make bread. And a lot of those challenges, such as with the bread machine, we haven't gotten that far yet. Right now we're just trying to learn how the wheat plants themselves will grow. Later on we'll take a look at the development of the bread-making machine...about six or seven years ago they did do a fluid dynamics experiment using the Coca-Cola syrup and carbon dioxide that makes it fizz.
Wes from Wellesley
Is it possible to build structures on Mars? Could you try and grow something on Mars?
Well given our experience with the Moon, I'm sure that if they gave the astronauts the right tools, they could build structures on Mars. With respect to growing plants, we've already built a Martian simulator here on Earth, and we have already begun to test plants in that simulator. So, yeah, we will.
Greg from Milford, NH
Why is wheat the plant of choice? Is it the same strain of wheat that gets processed into flour? Is it germinated on earth or in space? Is it grown in dirt or hydroponically?
Let me see if I can catch each of those components. The first one was, why is wheat the plant of choice? Well, wheat is the plant of choice for many reasons. First of all, it has grown in space successfully before, so we know that it can be grown. Secondly, it's a food crop. So that would be very good, to learn some more information about the wheat plant. This specific strain of wheat is called Apogee. And we picked it because it's a dwarf-based wheat that doesn't get as tall, and also goes through its development cycle rather quickly, so we can learn more about the plants. Is it germinated on Earth or in space? Actually, the first set of plants is grown with four different chambers right now on its way to orbit, and each of those chambers was germinated here on Earth. The next eight chambers will all be generated while in space. And finally, is it grown in dirt or hydroponically? Well, kind of a combination of both. We are using some porous tubes, and also a matrix-type solution which is a dirt substitute kind of like kitty litter that will retain moisture for longer periods of time.
Ryan from NY
How do you water plants in space?
Well, we kind of just touched on that a minute ago, Ryan. There are a couple different methods, actually. In the first, what we do is - here on Earth how we water plants you just pour water in the soil. Obviously you can't do that in space; we don't have gravity to hold the water down in the soil. We use a matrix solution kind of like dirt, as a dirt substitute. In this case we're using a product very much like kitty litter, and it will retain the moisture. But the way that we're getting the moisture into the solution is by using porous tubes. So here the seeds will be coming in contact with a fibrous-type paper, and that fibrous paper will carry the liquid up to the seed and the seeds will then germinate. And then we've got that matrix solution with the water in it, and the nutrients, that will help continue to provide moisture to the plant as it absorbs it and keeps growing.
Chris from Pembroke Pines
Why is it important to learn about how plants grow in space?
Plants are a crucial component of our ecosystem that supports human life. They are machines that produce oxygen for us and they also purify our water. So we are definitely going to need plants for long-duration space travel, and also, hopefully, they'll provide a food source as well. So plants are very important for us to learn how to grow in space. Also there's a component here on Earth. The more we use these crop plants - which we are with this wheat - we can gather more insight into the fundamental biological systems and processes inside the plant so that we can learn more about wheat growth here on Earth, and improve our crops.
Michelle from La Grange
Do the plants grow in soil??
They do not necessarily have to have soil. What they really need is a nutrient source and some kind of a structure for the root to hold on to. Of course, we know that soil can do that here on Earth, but also porous tubes can do it. So we've got those two methods. We've got the porous tubes, which is hydroponically, and the solution which is more of a substrate matrix.
Arnold from Chicago
How do plants orient their growth without gravity?
Well let's see Arnold, there are a couple different ways - actually I should say a couple different parts of the plant that orient themselves independently. The roots grow toward the nutrients. That's one of their primary means is to bring those nutrients up to the plant, and a lot of times, gravity will certainly affect the root growth. That's why most roots grow down - not just towards the nutrients but also in the direction of gravity. The shoots and the leaves, on the other hand, are only concerned with growing towards the light. So when plants grow, the shoots grow towards the light, and the roots grow towards the nutrients.
Peter from Charleston
What will be done with the wheat after it returns to Earth?
We're going to do a lot of things. First thing we're going to do is take lots of photographs to document what the plants look like. Then we're going to put them through a physical, if you will. We're going to poke them and prod them and measure their heights, how wide they are, how much they weigh. We're also going to look at them under a microscope and look at the cellular structure to see if that has changed. We're going to measure their color. We're also going to do some biochemical analysis and genetic analysis. We're going to compare all that data to the same plants that were grown here on Earth. And that's how we'll determine the effects of spaceflight and gravity...but we're not going to make bread.
Luigi from Naples
What does PESTO stand for?
It's kind of funny, we have a lot of fun making up these different acronyms. And this one, PESTO, what it stands for is Photosynthesis Experiment and System Testing Operations. Not necessarily what you put on your the initial, original proposal, that's what it was titled, PASTA. So when the experiment got changed to a long-duration space station experiment, we had to come up with a new name. So we went from the original name of PASTA to the long-duration space station experiment that we call PESTO.
Beasleigh from Tinker AFB
What type of medium is the space program's top choice to cultivate plants? Is it Hydroponics, Zeoponics or some other technique? Please explain...
Well we've talking about both of them so far, the hydroponics and the zeoponics. And again, the hydroponics is using porous tubes, and the zeoponics is using a substrate solid-based type solution. Really, there's no number one choice within NASA; we use both methods because they each have their own advantages. In a lot of cases we use a combination. For example, in the PESTO experiment, we are using porous tubes, and we're also using the matrix solution. We're using that for a couple of different reasons. One is it provides a redundancy. We're initially pushing the moisture through the porous tubes, and then into the matrix solution. So the matrix will provide more of a larger water mass volume to be available in case there's a control problem with the porous tubes. And we also have the matrix solution to back it up. We also have the fertilizers within the matrix.
Mary from Wauwatrosa
Is it possible to get a description of the plant growth chamber that is being carried on today's (4/8/02) launch? I teach biology and would like to describe this to my students. Thank you.
Thank you, Mary. Let me see if I can give you a good visual. We've got a clear Plexiglas cube, it's about eight inches cubed. And on the very bottom of that cube that's where we imbibe the plants; we have the root structure in the root zone, that's where we pump in the moisture, and then from the top of course is where the light comes in. We also control the temperature, the relative humidity, the carbon dioxide levels, the amount of light that's in the chamber, and then we also filter for ethylene.
NASA's John F. Kennedy Space Center