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Explore the Satellite

Handouts

Use these pdf handouts to explore the satellite in the classroom, or with your kids at home! The handouts are available in English, French, German, Italian, and Spanish.

In the not too distant future...

Your friend has recently moved to Mars (surprise!), and it's time you paid her a visit. Still rubbing the sleep from your eyes as you roll your luggage through the shuttleport, you probably aren't thinking about what your early (too early!) morning lift-off has to do with mice in space. But we are.

The Mission: Mice In Space!

Put 15 Mice into Orbit on A Spinning Satellite for 5 Weeks. ...So why do we want to do this?

The spinning satellite will simulate the pull of gravity on Mars. By living with Martian gravity for 5 weeks, these pioneering mice will teach all of us about how our bodies might change if we were to move to Mars. And thanks to this research, humans may indeed be able to live on Mars one day.

Why don't we just pack up and move there now?

Well, for one thing, it would take us about 6 to 9 months just to get to Mars. And because of the way that Earth and Mars orbit the sun, you can only travel between them at certain times - when the planets are lined up correctly. Of course, after traveling all that way we'd want to stick around for a while and explore! We'd probably stay for about 15 months. Add 6 or more months for a return trip, and you're looking at a 2 to 3 year mission. That's a long time to survive away from our home planet. Think about all questions we have to answer before we can start out on that trip. Where will we get enough food for two years? What will we breathe? What if someone gets sick?... Feel free to list more questions - I'm sure you can think of some!

Another reason why we're still waiting to visit Mars is that we don't yet know what will happen to our bodies on a planet where gravity is not as strong as it is on Earth.

By now I'm sure you're familiar with the "pull" of Earth's gravity. If you've ever fallen out of a tree or off your bike, you may even have wished that Earth's gravity wasn't quite so strong. If you fell off of your bike on Mars, you would be pulled to the ground much more slowly. This is because Mars has less mass than the Earth.

Saying Mars has 'less mass' is a fancy way of saying that Mars is made up of less matter - less stuff - than Earth. This might seem obvious when you compare the sizes of the two planets.

However, size is not always a reliable guide to the amount of matter in an object. Small objects can have a lot of stuff packed into them! (Think about times when you've crammed just one more sweater into an already full suitcase or backpack. Or when you've crammed just one more empty milk carton into a full trash can, so that you don't have to empty it.)

Density is used to measure how much stuff an object contains. The more stuff (matter) that's crammed into an object, the more dense it is.

And as I was saying, before I got distracted by the wonders of density: Mars is made up of less matter than Earth, so you fall much more gently on Mars!

Why does the amount of matter make a difference? Gravity is an attractive force - a pull - between you and all other objects. The strength of this pull depends on a number of factors, including the amount of matter in an object. Planets are made up of a lot of matter, and so the pull between you and the Earth is much stronger than, say, you and a basketball. (There actually is a gravitational pull between you and a basketball. But it's too weak for you to feel.)

While it sounds nice to live on a planet where falling would be less painful, the lower gravity of Mars might actually be very difficult to live with for a long period of time. Our bodies are adapted to living with the pull of Earth's gravity, which we feel as our weight. Astronauts who go up into outer space for weeks or months at a time develop health problems because they are weightless.'

What are some of the changes experienced when weightless?

The fluids in the astronauts' bodies shift. Normally gravity pulls all the liquid in your body towards your legs and feet. When you take away that downward pull, more liquid can move up into your head and chest. This is similar to the way that blood rushes to your face when you stand on your head. Astronauts' faces actually puff up in space, because more fluid than usual has moved into their heads.

When the body senses that there's more fluid in the head and chest, it decides to get rid of some of this "extra" fluid. So it signals the kidneys to produce more urine. Their first day or two in space, astronauts find they have to pee much more often than normal because their bodies are trying to get rid of all the "extra" fluid in the upper body!

Over time, certain bones and muscles become weaker , because they are no longer working against the pull of gravity. This can cause problems when astronauts come back to Earth. Suddenly they are almost too weak to stand!

The longer astronauts are in space, the more bone mass they lose. Their bones get weaker and weaker until they return to Earth. As you might imagine, this is dangerous for astronauts. Astronauts on long missions can't afford to be breaking lots of bones.

So what will happen to you when you visit your friend on Mars?

Remember, these changes that we've been talking about happened to astronauts who were completely weightless, floating around in space. On Mars you won't just float around, you'll have some weight. But gravity on Mars will not pull you as strongly as gravity pulls you on Earth, so you'll weigh less on Mars than you do here.

The big question is: how will your body adapt to the lower gravity on Mars?

Will it be more like life on Earth, or more like life in outer space? Will you lose as much bone strength as weightless astronauts do?

What do you think?

You can see that these are important questions to answer before we pack our bags and blast-off for Mars! Mice in Space will help us answer these questions.