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Lesson 09 – Astronauts and Space Travel

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Read About Astronauts and Space Travel

Vocabulary

Read the vocabulary terms to understand the reading better.

An astronaut is a person who has been trained, equipped, and sent out to travel in space.

The atmosphere is a layer or set of layers of gases that surround Earth.

Energy is the ability or power to do work.

Gravity is the force that attracts objects toward one another (e.g., gravity pulls objects toward the ground).

Mass is the amount of matter in an object; the mass of an object remains the same no matter where it is.

Radiation is a form of energy that is given off as rays, electromagnetic waves, or particles; Earth’s biggest source of radiation is the Sun.

Astronauts and Space Travel

In space, you do not feel gravity. It is extremely cold, and there is no atmosphere to breathe or to protect you from the Sun’s radiation. It takes enormous energy to get there, and you have to take everything you need with you—even the air. Outer space is an extreme environment.

The first person in space orbited Earth for less than two hours in 1957. Less than 40 years later, another astronaut spent a record-setting 438 days in space. Space travel has changed a lot since then. Between 1969 and 1972, 12 astronauts set foot on the Moon. These are the only times a human has landed anywhere other than Earth.

After leaving Earth, life support is the most important function of a spacecraft. It must clean the air for astronauts to breathe and provide heat. It must also protect the contents from the X-rays and other radiation coming from the Sun. All things used in space are designed for low gravity. Tools are attached to surfaces so they do not float away. Even drinking becomes difficult. You do not think about it, but gravity keeps the drink in your glass. Without gravity, the drink floats in a ball. Meals must be eaten from containers that keep the food from floating away. Equipment must be protected from floating crumbs, too.

Gravity on Earth also makes your muscles work hard. This exercise helps the blood spread throughout your body. In space, blood does not circulate as well. Lack of exercise makes the body lose muscle and bone mass. Astronauts have to strap themselves into exercise equipment to keep fit without floating away!

Yuri Alekseyevich Gagar was the first human to travel into space
Meals must be eaten in containers, food and medical supplies need to be tied down

To learn more about astronauts, watch the video by SciShow Kids on Youtube.

Now Show What You Know!

Complete some questions about the reading selection by clicking “Begin Questions” below.