CHAPTER 19 Exploring Space - WRUSD #8 / Homepage

Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Missions to the Sun and the MoonWhat is the future for space exploration? Scientists at

NASA and other space agencies around the world are working together to decide.

A major goal is to expand human space travel within the solar system. Two steps leading to this goal are sending probes to the Sun and sending probes to the Moon.

Solar ProbesThe Sun emits high-energy radiation and charged

particles. Storms on the Sun can eject powerful jets of gas and charged particles into space. The Sun’s high-energy radiation and charged particles can harm astronauts and damage spacecraft. To better understand these hazards, scientists study data collected by solar probes that orbit the Sun. The solar probe Ulysses, launched in 1990, orbited the Sun and gathered data for 19 years.

Lunar ProbesNASA and other space agencies also plan to send several

probes to the Moon. One of the more recent lunar probes is the Lunar Reconnaissance Orbiter. It was launched in 2009. As it orbits the Moon, the Lunar Reconnaissance Orbiter collects data that will help scientists choose the best location for a future lunar outpost.

What do you think? Read the two statements below and decide whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if you disagree. After you’ve read this lesson, reread the statements to see if you have changed your mind.

Before Statement After

5. Humans have landed on Mars.

6. Scientists have detected water on other bodies in the solar system.

Key Concepts • What are goals for future

space exploration?• What conditions are

required for the existence of life on Earth?

• How can exploring space help scientists learn about Earth?

Sticky Notes As you read, use sticky notes to mark information that you do not understand. Read the text carefully a second time. If you still need help, write a list of questions to ask your teacher.

Key Concept Check1. Describe What is a goal of future space exploration?

Recent and Future Space Missions

Exploring SpaceLESSON 3

CHAPTER 19

338 Exploring Space Reading Essentials

C190_014_020_RE_L3_889407.indd 14C190_014_020_RE_L3_889407.indd 14 1/11/10 8:26:54 PM1/11/10 8:26:54 PM

Copyri

ght

© G

lenco

e/M

cGra

w-H

ill,

a d

ivis

ion o

f T

he

McG

raw

-Hil

l C

om

pan

ies,

Inc.

Missions to the Inner PlanetsThe inner planets are the four rocky planets closest to the

Sun: Mercury, Venus, Earth, and Mars. Scientists have sent many probes to the inner planets, and more are planned. These probes help scientists learn how the inner planets formed and what geologic forces are active on them. They also help scientists learn if any of the inner planets could support life. Some recent and current missions to the inner planets are described in the chart on the next page.

Missions to the Outer Planets and Beyond

The outer planets are the four large planets farthest from the Sun: Jupiter, Saturn, Uranus, and Neptune. Pluto also was once considered an outer planet. It is now included with other small, icy dwarf planets observed orbiting the Sun outside the orbit of Neptune.

Missions to the outer planets are long and difficult because the planets are so far from Earth. Some missions to the outer planets and beyond are described in the chart on the next page. The next major mission to the outer planets will be an international mission to Jupiter and its four largest moons.

Reading Check2. State What do scientists want to learn about the inner planets?

Look at the figure above. It shows all of the inner and outer planets in the solar system.

Visual Check3. Identify the outer planets.

Planets in the Solar System

Neptune

UranusSaturnJupiter

MarsEarthVenusMercury

Sun

Use a Venn diagram to compare and contrast space missions to the inner and outer planets.

Inner

Outer

Both

Reading Essentials Exploring Space 339


Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Studying the solar system remains a major goal of space exploration. The table above describes some missions to the inner planets, the outer planets, and beyond.

Future Space Missions Do you think there will ever be cities or communities

built outside Earth? That is looking very far ahead. No person has ever been farther than the Moon. But human space travel remains a goal of NASA and other space agencies around the world. The first destinations for human space travel are the Moon and Mars.

Planetary Missions

Name Description

Spirit and Opportunity

The first flyby reached Mars in 1964. Since then, many probes have been sent there. In 2003, two robotic rovers, Spirit and Opportunity, began exploring the surface of Mars for the first time. These solar-powered rovers traveled more than 20 km. They sent data—and thousands of photos—to Earth for over 5 years.

Messenger

Messenger is the first probe to visit Mercury—the planet closest to the Sun—since Mariner 10 flew by it in 1975. Messenger was launched in 2004. Before reaching Mercury, Messenger made two passes of Venus. The probe will fly past Mercury several times before entering Mercury’s orbit in 2011. Messenger will study Mercury’s geology and chemistry. It will send images and data back to Earth for one Earth year. On its first pass by Mercury in 2008, Messenger returned over 1,000 images in many wavelengths.

Cassini

Cassini was the first orbiter sent to Saturn. It was launched in 1997 as part of an international effort involving 19 countries. Cassini traveled for 7 years before entering Saturn’s orbit in 2004. When it arrived, it sent a smaller probe to the surface of Titan, Saturn’s largest moon. Cassini is so large—6,000 kg—that no rocket was powerful enough to send it directly to Saturn. Scientists used gravity from closer planets—Venus, Earth, and Jupiter—to help power the trip. The gravity from each planet gave the spacecraft a boost toward Saturn.

New Horizons

New Horizons is much smaller than Cassini. It is heading toward Pluto. Like Cassini, New Horizons is using gravity from Jupiter to help propel it along. Though New Horizons was launched in 2006, it won’t reach Pluto until 2015. It will leave the solar system in 2029. Without a gravity assist from Jupiter, it would take New Horizons 5 years longer to reach Pluto.

Interpreting Tables

4. Distinguish Which planet has been explored by rovers?


C190_014_020_RE_L3_889407.indd Page 16 4/4/11 8:16:45 PM userC190_014_020_RE_L3_889407.indd Page 16 4/4/11 8:16:45 PM user /Volumes/114/READING_ESSENTIALS_SCIENCE/iScience_Reading_Essentials.../Volumes/114/READING_ESSENTIALS_SCIENCE/iScience_Reading_Essentials...

P rinter P DF

Copyri

ght

© G

lenco

e/M

cGra

w-H

ill,

a d

ivis

ion o

f T

he

McG

raw

-Hil

l C

om

pan

ies,

Inc.

Studying and Visiting MarsA visit to Mars will probably not occur for several more

decades. To prepare for a visit to Mars, NASA plans to send additional probes to the planet. The probes will explore sites on Mars that might have resources that can support life. One of these probes is the MAVEN spacecraft. MAVEN will study the atmosphere of Mars and how it has evolved over time. Astronauts will need secure housing once they establish a suitable landing area on Mars. One of the options being tested is an inflatable structure that could serve as housing for astronauts. It has been tested in the harsh environment of Antarctica.

Studying JupiterThe largest planet in the solar system is going to be

studied by the Juno spacecraft. It will take Juno five years to reach the gas gaint. Juno will study Jupiter’s atmosphere, gravity, magnetic fields, and atmosphere conditions.

The Search for LifeFor a long time, people have considered the possibility

that life might exist beyond Earth. This has a name. Life that originates outside Earth is extraterrestrial (ek struh tuh RES tree uhl) life.

Conditions Needed for LifeAstrobiology is the study of life in the universe, including life on

Earth and the possibility of extraterrestrial life. Scientists study the conditions for life on Earth to help them predict where they might find life elsewhere in the solar system. Astrobiology also can help scientists find environments in space where humans and other Earth life might be able to survive.

Life exists in a wide range of environments on Earth. Life-forms survive on dark ocean floors, deep in solid rocks, and even in boiling-hot water. But no matter how extreme their environments, all known life-forms on Earth need at least three things to survive:

• liquid water

• organic molecules

• some source of energy

Scientists assume that if life exists elsewhere in space, it would also need these three things.

ACADEMIC VOCABULARYoption(noun) something that can be chosen

Key Concept Check

5. Identify What is the purpose of the probes being sent to Mars?

6. Predict Do you think scientists will ever find evidence of extraterrestrial life? Explain your answer.

Key Concept Check

7. Consider What is required for life on Earth?



P rinter P DF

Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Water in the Solar SystemEvidence from other space probes suggests that water

vapor or ice exists on many planets and moons in the solar system. A lunar space probe found water in a crater on the Moon. Enough frozen water was found in a single crater to fill 1,500 Olympic swimming pools.

NASA plans to launch the Mars Science Laboratory in 2011 to sample different types of soils and rocks on Mars. This mission will consider the possibility that life exists or once existed on the planet.

Some of the moons in the outer solar system, such as Jupiter’s moon Europa, might also have large amounts of liquid water beneath their surfaces. The dark patches on photos of Europa might show areas where water from an underground ocean has seeped to Europa’s surface.

Understanding Earth by Exploring Space

Space provides frontiers for the human desire for exploration and discovery. We have also learned things about planet Earth by exploring space. For example, information gathered in space has helped scientists understand

• how the Sun and other bodies in the solar system influence Earth;

• how Earth formed;

• how Earth supports life.

In addition, looking for Earthlike planets outside the solar system helps scientists learn if Earth is unique in the universe.

Searching for Other PlanetsAstronomers have detected more than 300 planets

outside the solar system. Most of these planets are much bigger than Earth. They probably could not support liquid water. They also probably cannot support life. To search for Earthlike planets, NASA launched the Kepler telescope in 2009.

The Kepler telescope orbits the Sun. It focuses on a single area of sky containing about 100,000 stars. Kepler might be able to detect Earthlike planets orbiting other stars, but it will not be able to detect life on any planet.

Reading Check

8. Name two places in the solar system (besides Earth) where water might exist.

Reading Check

9. Describe What have scientists learned about Earth by exploring space?

Reading Check

10. Contrast How are most of the known planets outside the solar system different from Earth?



P rinter P DF

Copyri

ght

© G

lenco

e/M

cGra

w-H

ill,

a d

ivis

ion o

f T

he

McG

raw

-Hil

l C

om

pan

ies,

Inc.

Understanding Our Home PlanetNot all of NASA’s missions are to other planets or moons

or to look at stars and galaxies. NASA and space agencies around the world also launch and maintain Earth-observing satellites. Satellites, like the one in the figure below, orbit Earth and provide large-scale images of Earth’s surface. These images help scientists understand Earth’s climate and weather. For example, in 2005, scientists used satellite images to track changes in ocean temperature associated with Hurricane Katrina, one of the deadliest storms in U.S. history.

Visual Check12. Define In the figure, the satellite’s path indicates its _________. (Circle the correct answer.)a. ageb. missionc. orbit

Satellite Orbiting Earth

Path

Key Concept Check11. Explain How can exploring space help scientists learn about Earth?



Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Mini Glossary

Reread the statements at the beginning of the lesson. Fill in the After column with an A if you agree with the statement or a D if you disagree. Did you change your mind?

What do you think

END OF LESSON

Log on to ConnectED.mcgraw-hill.com and access your textbook to find this lesson’s resources.

ConnectED

astrobiology: the study of life in the universe, including life

on Earth and the possibility of extraterrestrial life

extraterrestrial life: life that originates outside Earth

1. Review the terms and their definitions in the Mini Glossary. Write a sentence that explains how astrobiology and extraterrestrial life are related.

2. Fill in the diagram to show the destination for the various space missions indicated.

3. What evidence suggests that life might once have existed on Mars?

Messenger Spirit Cassini New Horizons



46 Exploring Space

Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Name Date Class

Recent and Future Space MissionsDirections: Answer each question on the lines provided. You must include the terms below in your answer.

astrobiology dwarf planet extraterrestrial life option

1. Pluto was once considered an outer planet, but this is no longer the case. Why not? Which term now describes Pluto? Why is the term appropriate?

2. What is astrobiology? In your answer, include three examples of Earth environments that support life-forms studied by astrobiologists.

3. Imagine you are working on a NASA planning team. Your team must decide whether they should work to send people to Mars or the Moon. Which option would you choose? Explain.

4. Does extraterrestrial life exist? How does the existence of water on many planets and moons affect hypotheses regarding the existence of extraterrestrial life?

Content Vocabulary LESSON 3

C190_045_051_CRF_L3_891448.indd 46C190_045_051_CRF_L3_891448.indd 46 12/15/09 4:20:08 PM12/15/09 4:20:08 PM

Exploring Space 47

Copyri

ght

© G

lenco

e/M

cGra

w-H

ill,

a d

ivis

ion o

f T

he

McG

raw

-Hil

l C

om

pan

ies,

Inc.

Name Date Class

Lesson Outline LESSON 3

Recent and Future Space MissionsA. Missions to the Sun and the Moon

1. People from different countries have set the goal of working together to

human space travel within the solar system.

2. People can reach this goal by sending probes to the and

the .

a. Data from probes sent near the can help scientists understand the hazards of solar radiation.

b. By using information from probes, scientists hope to figure out a good place to set up a future outpost on the Moon.

B. Missions to the Inner Planets

1. The inner planets are the four rocky planets closest to the Sun; in order, they are

, , Earth,

and .

2. Probes to these planets helps scientists learn how these planets

, what geologic are acting

on them, and whether any of these planets can

support .

C. Missions to the Outer Planets and Beyond

1. The outer planets are the four large planets farthest from the Sun; in order, they are

Jupiter, , Uranus, and .

2. was once considered an outer planet, but now it is considered an icy dwarf planet.

3. Missions to the outer planets take a(n) time and are

difficult because these planets are so from Earth.

4. Missions to some of the outer planets and to Pluto have used a technique

called .

D. Human Space Missions

1. Early destinations for human space travel are the Moon

and .


48 Exploring Space

Copyrig

ht ©

Glen

coe/M

cGraw

-Hill, a d

ivisio

n o

f The M

cGraw

-Hill C

om

pan

ies, Inc.

Name Date Class

2. Future visits to the Moon will not be , as in the past.

The mission will be to build a lunar , where people can

and do research in the harsh lunar environment.

3. NASA plans to send several more to Mars to explore sites that might have resources that can support life.

E. The Search for Life

1. The study of life in the universe, including life on Earth and the possibility of

extraterrestrial life, is called .

a. Using astrobiology, scientists are searching for environments in space other than Earth where humans and other Earth life might be able

to .

b. Life exists in many extreme environments on Earth as long as they have

liquid , organic molecules, and a source of

.

2. Evidence from space probes suggests that several planets and many moons have

or ice on or near their surfaces.

F. Understanding Earth by Exploring Space

1. Studying other planets helps scientists understand how the Sun and other

planets affect , how Earth formed and how Earth

supports .

2. Scientists are looking for other Earthlike planets in the universe to try to figure out if extraterrestrial life might exist or if life on Earth is likely to

be .

a. Most of the 300 planets scientists have discovered so far outside the solar system

are larger than Earth and probably could not support

water or .

b. NASA has launched a space called Kepler to study an

area of the sky containing about 100,000 to look for Earthlike planets orbiting other stars.

3. NASA and space agencies around the world have satellites that orbit Earth

and help scientists understand Earth’s

and .

Lesson Outline continued


CHAPTER 19 Exploring Space - WRUSD #8 / Homepage

Documents