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Hi, kids. I'm Mr. Gruner. How can I help you?

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Hi, Mr. Gruner. We're the Treehouse Detectives, and we're trying to design a Martian habitat.

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We realize that we have to grow our own food on Mars.

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Yeah, because we don't want to go hungry.

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And we need to know if plants grow differently in space than they do here on Earth.

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Well, sort of, but plants still need the basics like light, air, water, nutrients, and a nice temperature and humidity.

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We know that Mars is extremely cold.

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And that it doesn't have the same atmosphere as Earth.

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Does that mean that we can't grow anything on Mars?

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No, it just means you'd have to grow them indoors in a controlled environment.

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How do you do that?

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Well, here at NASA, we design plant growth chambers, or systems, to meet the plants' basic needs.

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Kind of like this one here.

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Do you have to use special seeds to make the plants grow in space?

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No, we use the same seeds as we do here on Earth.

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However, we do conduct experiments and collect data to see what effect low gravity and increased radiation has on the way plants produce seeds.

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Why is that important?

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We want to make sure that plants can reproduce in space.

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This will help astronauts who live there for a long time.

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Can the seeds produced on Mars grow here on Earth?

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Yes, and they're able to germinate and grow in the new plants just fine.

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Do you only use plants in space for food?

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No, we also hope to use plants to produce oxygen and water.

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That is so cool!

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During a process called photosynthesis, plants take in carbon dioxide and produce oxygen.

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We breathe oxygen and exhale carbon dioxide.

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Exactly. So you see, plants and people can live very well together, trading gases.

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Okay, I understand that. But how do they produce water?

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Through a process called transpiration.

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What's transpiration?

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Well, when a plant transpires, it releases water through tiny holes called pores that are mostly found in the leaves.

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And then the water evaporates into the atmosphere and we can collect it and turn it back into liquid water on a cold surface.

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Oh, you mean just like the water droplets on the outside of my glass of ice water.

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That's right. It's called condensation.

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I guess it is important to be able to produce water and oxygen since it takes a long time to get to Mars.

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You bet it is. It would be very expensive to send space vehicles to resupply the habitat.

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Therefore, it is very important for the habitat to be as self-sufficient as possible.

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What kind of plants are you growing in your lab?

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We are currently experimenting with grains like wheat and rice, legumes like peas and peanuts, potatoes, fruits, and salad crops.

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I love salad.

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That's good, because right now there are no plants to produce any meat.

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I don't like just vegetables.

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Well, don't get too discouraged. Meat will still be available in packaged form, but in small quantities.

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However, there are still lots of good foods you can make with fruits and vegetables.

45
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Like what?

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Like peanut butter from peanuts, jelly from strawberries, tortillas from wheat, and potato chips from potatoes.

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You could even make tomato sauce from tomatoes for pizza or spaghetti.

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Now you're talking. That's my kind of meal.

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And just like here on Earth, the most important thing is to eat a balanced and nutritious diet.

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That's true. My mom always tells me that.

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Would you like to see us harvest some carrots from our chambers?

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Yes!

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All right.

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Thank you, sir.

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Good luck with your project, kids.