early space exploration

sputnik

The USSR launched Sputnik 1 on October 4, 1957. This was the first artificial satellite ever put into orbit. Sputnik 1, shown in Figure 23.20, sent out radio signals, which were detected by scientists and amateur radio operators around the world. The satellite stayed in orbit for about 3 months, until it burned up as a result of friction with Earths atmosphere. The launch of Sputnik 1 started the Space Race between the USSR and the USA. Americans were shocked that the Soviets had the technology to put the satellite into orbit. They worried that the Soviets might also be winning the arms race. On November 3, 1957, the Soviets launched Sputnik 2. This satellite carried the first living creature into orbit, a dog named Laika.

the race is on

In response to Sputnik program, the U.S. launched two satellites. Explorer I was launched on January 31, 1958 and Vanguard 1 on March 17, 1958. National Aeronautics and Space Administration (NASA) was established that same year. The race was on! On April 12, 1961, a Soviet cosmonaut became the first human in space and in orbit. Less than one month later May 5, 1961 the U.S. sent its first astronaut into space: Alan Shepherd. The first American in orbit was John Glenn, in February 1962. And on it went.

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how rockets work

Rockets were used for centuries before anyone could explain how they worked. The theory came about in 1687. Isaac Newton (16431727) described three basic laws of motion, now referred to as Newtons Laws of Motion: 1. An object in motion will remain in motion unless acted upon by a force. 2. Force equals mass multiplied by acceleration. 3. To every action, there is an equal and opposite reaction. Which of these three best explains how a rocket works? Newtons third law of motion. When a rockets propulsion pushes in one direction, the rocket moves in the opposite direction, as seen in the Figure 23.12. For a long time, many people believed that a rocket wouldnt work in space. There would be nothing for the rocket to push against. But they do work! Fuel is ignited in a chamber. The gases in the chamber explode. The explosion creates pressure that forces the gases out of one side of the rocket. The rocket moves in the opposite direction, as shown in Figure 23.13. The force pushing the rocket is called thrust.

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a rocket revolution

For centuries, rockets were powered by gunpowder or other solid fuels. These rockets could travel only short distances. Around the turn of the 20th century, several breakthroughs took place. These breakthroughs led to rockets that could travel beyond Earth. Liquid fuel gave rockets enough power to escape Earths gravity (Figure 23.14). By using multiple stages, empty fuel containers could drop away. This reduced the mass of the rocket so that it could fly higher. Rockets were used during World War II. The V2 was the first human-made object to travel high enough to be considered in space (Figure 23.15). Its altitude was 176 km (109 miles) above Earths surface. Wernher von Braun was a German rocket scientist. After he fled Germany in WWII, he helped the United States develop missile weapons. After the war, von Braun worked for NASA. He designed the Saturn V rocket (Figure

satellites

One of the first uses of rockets in space was to launch satellites. A satellite is an object that orbits a larger object. An orbit is a circular or elliptical path around an object. Natural objects in orbit are called natural satellites. The Moon is a natural satellite. Human-made objects in orbit are called artificial satellites. There are more and more artificial satellites orbiting Earth all the time. They all get into space using some sort of rocket.

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how satellites stay in orbit

Why do satellites stay in orbit? Why dont they crash into Earth due to the planets gravity? Newtons law of universal gravitation describes what happens. Every object in the universe is attracted to every other object. Gravity makes an apple fall to the ground. Gravity also keeps you from floating away into the sky. Gravity holds the Moon in orbit around Earth. It keeps Earth in orbit around the Sun. Newton used an example to explain how gravity makes orbiting possible. Imagine a cannonball launched from a high mountain, as shown in Figure 23.17. If the cannonball is launched at a slow speed, it will fall back to Earth. This is shown as paths (A) and (B). Something different happens if the cannonball is launched at a fast speed. The Earth below curves away at the same rate that the cannonball falls. The cannonball then goes into a circular orbit, as in path (C). If the cannonball is launched even faster, it could go into an elliptical orbit (D). It might even leave Earths gravity and go into space (E). Unfortunately, Newtons idea would not work in real life. A cannonball launched at a fast speed from Mt. Everest would not go into orbit. The cannonball would burn up in the atmosphere. However, a rocket can launch straight up, then steer into orbit. It wont burn up in the orbit. A rocket can carry a satellite above the atmosphere and then release the satellite into orbit.

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types of satellites

The first artificial satellite was launched just over 50 years ago. Thousands are now in orbit around Earth. Satellites have orbited other objects in the solar system. These include the Moon, the Sun, Venus, Mars, Jupiter, and Saturn. Satellites have many different purposes. Imaging satellites take pictures Earths surface. These images are used for military or scientific purposes. Astronomers use imaging satellites to study and make maps of the Moon and other planets. Communications satellites, such as the one in Figure 23.18, are now extremely common. These satellites receive and send signals for telephone, television, or other types of communications. Navigational satellites are used for navigation systems, such as the Global Positioning System (GPS). The largest artificial satellite is the International Space Station. The ISS is designed for humans to live in space while conducting scientific research.

earth science satellites

Dozens of satellites collect data about the Earth. One example is NASAs Landsat satellites. These satellites make detailed images of Earths continents and coastal areas. Other satellites study the oceans, atmosphere, polar ice sheets, and other Earth systems. This data helps us to monitor climate change. Other long-term changes in the planet are also best seen from space. Satellite images help scientists understand how Earths systems affect one another. Different satellites monitor different wavelengths of energy, as in Figure 23.19.

types of orbits

Satellites have different views depending on their orbit. Satellites may be put in a low orbit. These satellites orbit from north to south over the poles. These satellites view a different part of Earth each time they circle. Imaging and weather satellites need this type of view. Satellite may be placed so that they orbit at the same rate the Earth spins. The satellite then remains over the same location on the surface. Communications satellites are often placed in these orbits.

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the space race

The Cold War was between the Soviet Union (USSR) and the United States. The war lasted from the end of World War II in 1945 to the breakup of the USSR in 1991. The hallmark of the Cold War was an arms race. The two nations spared no expense to create new and more powerful weapons. The development of better missiles fostered better rocket technologies.

rockets

Humans did not reach space until the second half of the 20th century. They needed somehow to break past Earths gravity. A rocket moves rapidly in one direction. The device is propelled by particles flying out of it at high speed in the other direction. There are records of the Chinese using rockets in war against the Mongols as early as the 13th century. The Mongols then used rockets to attack Eastern Europe. Early rockets were also used to launch fireworks.

exploring other planets

Both the United States and the Soviet Union sent space probes to other planets. A space probe is an unmanned spacecraft. The craft collects data by flying near or landing on an object in space. This could be a planet, moon, asteroid, or comet. The USSR sent several probes to Venus in the Venera missions. Some landed on the surface and sent back data. The U.S. sent probes to Mercury, Venus, and Mars in the Mariner missions. Two probes landed on Mars during the Viking missions. The U.S. also sent probes to the outer solar system. These probes conducted fly-bys of Jupiter, Saturn, Uranus, and Neptune. The Pioneer and Voyager probes are now out beyond the edges of our solar system. We have lost contact with the two Pioneer probes. We hope to maintain contact with the two Voyager probes until at least 2020.

reaching the moon

On May 25, 1961, President John F. Kennedy challenged the U.S. Congress: I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him back safely to the Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish. The Soviets were also trying to reach the Moon. Who would win? The answer came eight years after Kennedys challenge, on July 20, 1969. NASAs Apollo 11 mission put astronauts Neil Armstrong and Buzz Aldrin on the Moon, as shown in Figure 23.21. A total of five American missions put astronauts on the Moon. The last was Apollo 17. This mission landed on December 11, 1972. No other country has yet put a person on the Moon. Today, most space missions are done by

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instructional diagrams

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questions

Voyager 1 is the first human-made object to

a. leave Earths orbit

b. orbit the Sun

c. leave interstellar space

-->  d. leave the solar system

Which of the following is one of Newtons Laws of Motion?

-->  a. To every action, there is an equal and opposite reaction

b. An object in motion will remain in motion forever and always

c. Every object is attracted to every other object proportionately to its volume

d. Gravity equals mass times acceleration

A rocket has multiple stages so that it

a. can take humans into space

b. is able to orbit Earth

-->  c. reduces the rockets weight in steps

d. none of these

Which two countries were involved in the space race?

a. China India

-->  b. U.S.A and U.S.S.R.

c. Brazil U.S.S.R.

d. U.S.A. U.K.

For a rocket to enter Earth orbit, it must be launched

a. at the right speed

b. from the right location

-->  c. straight up

d. all of these

Humans first reached space at the beginning of the 20th century.

a. true

-->  b. false

Rockets were developed before scientists knew how they worked.

-->  a. true

b. false

The invention of gunpowder allowed rockets to travel to space.

a. true

-->  b. false

Only two nations have put a human on the moon: the U.S. and China.

a. true

-->  b. false

The first use of rockets in space was to land astronauts on the moon.

a. true

-->  b. false

A satellite is an object that orbits a smaller object.

-->  a. true

b. false

Most satellites launch themselves into orbit.

a. true

-->  b. false

Thousands of satellites are in orbit around Earth.

-->  a. true

b. false

It was only 12 years between when the first artificial satellite was launched and Neil Armstrong walked

-->  a. true

b. false

Landsat satellites make detailed images of continents and coasts.

-->  a. true

b. false

An object can go into orbit because of the law of conservation of momentum.

a. true

-->  b. false

Newtons Third Law of Motion helps explain how a rocket will travel in space.

-->  a. true

b. false

Imaging satellites are placed in high orbits over Earth.

a. true

-->  b. false

Alan Shepherd was the first astronaut to walk on the Moon.

a. true

-->  b. false

The U.S. has landed space probes on Mars.

-->  a. true

b. false

circular or elliptical path around an object

a. rocket

b. thrust

c. space probe

d. satellite

e. ISS

-->  f. orbit

g. NASA

force that pushes a rocket

a. rocket

-->  b. thrust

c. space probe

d. satellite

e. ISS

f. orbit

g. NASA

object that orbits a larger object

a. rocket

b. thrust

c. space probe

-->  d. satellite

e. ISS

f. orbit

g. NASA

largest artificial satellite

a. rocket

b. thrust

c. space probe

d. satellite

-->  e. ISS

f. orbit

g. NASA

U.S. agency in charge of space exploration

a. rocket

b. thrust

c. space probe

d. satellite

e. ISS

f. orbit

-->  g. NASA

vehicle pushed in one direction by particles flying out of it in the opposite direction

-->  a. rocket

b. thrust

c. space probe

d. satellite

e. ISS

f. orbit

g. NASA

spacecraft that explores space without people aboard

a. rocket

b. thrust

-->  c. space probe

d. satellite

e. ISS

f. orbit

g. NASA

Rockets were first used as early as the

-->  a. 13th century.

b. 17th century.

c. 19th century.

d. 20th century.

Isaac Newtons third law of motion states that

a. an object in motion will remain in motion unless acted upon by a force.

b. every object in the universe is attracted to every other object.

-->  c. for every action, there is an equal and opposite reaction.

d. force equals mass multiplied by acceleration.

The first rocket to travel into space was used during

a. the 1200s.

b. World War I.

-->  c. World War II.

d. the space race.

Satellites stay in orbit because of

a. thrust.

-->  b. gravity.

c. rockets.

d. propulsion.

The Global Positioning System (GPS) uses

a. communications satellites.

-->  b. navigational satellites.

c. weather satellites.

d. imaging satellites.

A satellite in a low orbit

-->  a. travels from north to south over Earths poles.

b. orbits Earth at the same rate that Earth spins.

c. moves in the same direction that Earth rotates.

d. remains over the same place on Earths surface.

The first American to orbit Earth was

a. Neil Armstrong.

b. Buzz Aldrin.

-->  c. John Glenn.

d. Alan Shepher

diagram questions

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