Space Travel
You’re strapped into a seat. You
hear a loud roar. Rocket engines fire and lift you into the sky. The rocket goes
faster and faster, pushing you harder and harder against your seat. Suddenly,
everything gets quiet. The engines stop. You take off your seat belt and start
to float around. You are almost weightless. This is what space travel feels
like.
GETTING INTO SPACE
Since ancient times, people have
dreamed of leaving Earth and exploring other worlds. But gravity holds
everything on the ground. Gravity is a pulling force between two objects. Earth
is a very large object, and its gravity is strong. Even airplanes that fly
thousands of feet above Earth can’t leave our atmosphere and go into space.
Scientists and engineers had to make a force much greater than gravity to travel
to outer space.
Finally, the dream came true.
Engineers built rockets powerful enough to lift a rocket into space. In 1957,
scientists from the Union of Soviet Socialist Republics (USSR) sent the first
artificial satellite, Sputnik 1, into space. The United States soon sent an
artificial satellite, Explorer 1, into space as well. The Space Age had
begun.
The first spacecraft just
orbited (went around) Earth. There were no humans on these spacecraft.
Then scientists sent robot spacecraft to the Moon. The spaceships carried
cameras that took pictures of the Moon’s surface. Some robot spacecraft even
landed on the Moon.
The first person went into space in
1961. Soviet cosmonauts and American astronauts made several trips into orbit
around Earth. The next goal was to send people to the Moon.
HEADING FOR THE MOON
After the Space Age began,
engineers worked hard to figure out how to send people to the Moon. They made
controls for steering spacecraft. They made spacesuits to allow astronauts to
breathe and keep them safe from heat, cold, and harmful rays.
Engineers made special rocket
ships for taking astronauts to the Moon. They named this series of spacecraft
Apollo. An Apollo spacecraft held three astronauts. It also carried a smaller
landing ship that looked sort of like a spider.
LANDING ON THE MOON
In July 1969, three astronauts in
Apollo 11 headed for the Moon. On July 20, they made history. Astronauts Neil
Armstrong and Buzz Aldrin climbed into the landing module, which was named
Eagle. They went down to the Moon. The spiderlike legs of the lander dug into
the Moon’s surface. Armstrong radioed back to Earth, “The Eagle has landed.”
When he stepped on the Moon, Armstrong said, “That’s one small step for man, one
giant leap for mankind.”
Astronauts in other Apollo
spacecraft landed on the Moon five more times. Astronauts in spacesuits walked
around on the Moon. They rode around in a kind of car called a lunar rover. All
the astronauts brought back moon rocks and soil for scientists to study.
VISITING OTHER PLANETS?
Astronauts haven’t yet visited
another planet. Robot spacecraft, also known as probes, have journeyed to all
the planets except Pluto. These space probes carried cameras and took pictures
of the planets. They studied gases around the planets. They can send these
pictures and other information back to Earth by using special radio
equipment.
Some of the space probes fly
quickly past other planets. Voyagers 1 and 2 took off in 1977 to fly by Jupiter,
Saturn, Uranus, and Neptune. After zooming by these planets, the Voyager probes
headed out of the solar system. They continued to explore the space between the
stars.
Some probes go into orbit around a
planet. Some also drop landers on these planets. Several Soviet probes dropped
landers on Venus. An American probe dropped a lander on Jupiter. More probes and
landers continue to be sent, designed to explore other planets.
EXPLORING MARS
Of all the planets in the solar
system, Mars is the most similar to Earth. Beginning in the 1960s, many robot
spacecraft visited Mars. The Viking mission in 1975 was the first probe to
safely land on Mars. A camera sent pictures of the surface to Earth. A robot arm
scooped up soil.
The Mars Pathfinder spacecraft
landed on Mars in 1997. It had a robot wagon called the Sojourner rover. The
rover moved around on Mars, taking pictures and studying rocks. Other probes,
landers, and rovers went on to study Mars.
Some people dream of astronauts
someday landing on Mars. Other people say it would be best to send more robots.
If astronauts do go to other planets, Mars would be the first one they
visit.
THE SPACE SHUTTLE
In the 1970s, the United States
developed a new kind of spacecraft called a shuttle. The shuttle blasts into
space on big rockets. Unlike previous spacecraft, which used lander ships and
could only be used once, the shuttle can land on Earth like an airplane and be
used again. The first shuttle flew into space in 1981.
The shuttle has a big area called
a cargo bay to hold large equipment. Astronauts on space shuttles launch
satellites from the cargo bay. Some satellites study Earth from space, while
others relay phone calls and other communications. Astronauts can also launch
space telescopes from the shuttle.
LIVING IN SPACE
Space travel is hard on people’s
bodies. Spending long amounts of time in space makes bones and muscles weak. It
is hard to eat in space. It is hard to sleep and take showers.
Scientists use space stations to
study how people can live and work in space. Space stations orbit around Earth.
The Soviets sent up several space stations. The first, Salyut 1, was launched in
1971. The first U.S. space station, Skylab, was launched in 1973.
The most famous Soviet space
station was Mir, which orbited Earth from 1986 to 2001. Astronauts from many
different countries visited Mir. Many of them performed experiments on the space
station. They learned many things about living and working in space.
In the late 1990s many nations
started working together to build an International Space Station. The space
shuttle carried parts for the station into space. Astronauts put the pieces
together. The goal is to have people living and working in the space station all
the time. Someday, maybe everyone who wants to will be able to travel into
space.
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Space
