Rocket Science and Artificial Satellites

1. Rocket Science and Artificial Satellites Pgs. 128 – 131, 132 – 134

2. Rockets • A machine that uses escaping gas to move. • Around 1900, a Russian high school teacher named Konstantin Tsiolkovsky began trying to understand the reasoning behind the motion of rockets. • He could explain how rockets work, but never built one. • Robert Goddard, the father of modern rocketry, was the American physicist who began constructing rockets and advance space exploration.

3. Modern Rocketry • Goddard conducted several rocket experiments in Massachusetts from 1915 to 1930. • He moved to New Mexico in 1930 where he had more room for his experiments. • He tested over 150 rockets between 1930 and 1941. • By the time of World War II his work got a lot of attention from the United States military.

4. Rocket Bombs to Rocket Ships • During World War II, Germany developed the V-2 rocket to bomb England. • The design cam from Doctor Wernher von Braun. • Von Braun and his team eventually surrendered to the Americans at the end of the war. • The U.S. now had 127 of Germany’s best rocket scientists. • Research began to expand.

5. Birth of NASA • At the end of WWII, an arms race had begun between the Soviet Union and the U.S.. • On July, 1958 the National Aeronautics and Space Administration (NASA) was created. • This organization combined all of the separate rocket-development teams in the U.S. and combined their efforts to create a series of rockets. • These include the Saturn V rocket And those used to launch the space shuttle

6. How Rockets Work • Rockets work based on Newton’s third law of motion. • This says for every action there is an equal reaction in the opposite direction. • Think of air rushing backward from a balloon paired with the forward motion of the balloon. • The equality of the action/reaction is not obvious for rockets. • The mass of a rocket and its fuel is more than the gases that come out. • Since the hot gases are under extreme pressure they exert a tremendous amount of force. • Force that accelerates a rocket is called thrust

7. Combustion – A rocket’s combustion chamber in which hot gases are under high pressure are contained and at rest. Once there is an opening for the gas to escape, the force pushing against the wall of the chamber will push gas out of the rocket. • Pressure – When pressurized gas is released in one direction, the force of the hot gas against the top of the combustion chamber becomes greater than the opposing force of the air outside. Gas is force out of the rocket. • Thrust – The force of the gas pushing against the top of the combustion chamber becomes greater than the force of gravity holding the rocket down. The rocket moves upward

8. How Fast is Fast Enough? • It is not enough to have the rocket move upward, it needs to have enough thrust to achieve orbital velocity (the speed and direction a rocket needs to orbit the Earth) • The lowest possible speed for orbital velocity is 8km/s. • For Earth, all speeds less than 8km/s are suborbital speed. • Suborbital speed will have a rocket fall back to Earth. • Escape velocity is the speed and direction a rocket must have in order to completely break away from a planet’s gravitational pull. • This speed is 11km/s.

9. Rocket Fuel • Rockets burn fuel to provide the thrust that propels them forward. • In order for something to burn in space, oxygen must be present. • Rockets in outer space must carry oxygen with them to burn out in space. • The first rockets used gunpowder. • Goddard used liquid fuel for rockets, which also require oxygen.

10. Artificial Satellites • In 1955, President Eisenhower announced that the U.S. would launch an artificial satellite as part of America’s contribution to International Space Science. • An artificial satellite is any human-made object placed in orbit around a body in space, such as Earth. • The Soviet Union was working on a satellite program and launched theirs first.

11. Space Race • The first artificial satellite, Sputnik 1, was sent into space October 4, 1957 by the Soviets. • It carried instruments to measure the properties of Earth’s upper atmosphere. • One month later, they launched Sputnik 2 which carried a dog named Laika. • The U.S. attempted to launch their own satellite, but it exploded after only reaching 1 meter off the ground.

12. The U.S. Takes Second • The U.S. Army modified its military rockets to send a satellite into space on January 31, 1958. • Its name was Explorer 1, and it triggered the international space race. • The satellite carried instruments to measure cosmic rays and temperatures of the upper atmosphere. • Explorer 1 discovered the radiation belts around the Earth. • These are regions in the Earth’s magnetic field where charged particles from the sun have been trapped.

13. Into the Information Age • The first U.S. weather satellite, Tiros1, was launched in April 1960. • Weather satellites have given meteorologists an understanding of how storms develop and change by helping us study wind patterns and ocean currents. • After Tiros 1, The U.S. launched Echo 1, the first communications satellite. • Echo 1 could bounce signals from the ground to other areas on Earth. • It led to the development of TV signals and radio signals worldwide.

14. Choose Your Orbit • All of the early satellites were placed in low Earth orbit (LEO), which is a few hundred kilometers above the Earth’s surface. • This is still just within Earth’s outer atmosphere. • A geosynchronous orbit (GEO) is an orbit in which a satellite travels around the Earth at a speed that exactly matches the rotational speed of the Earth. • This keeps the satellite positioned above the same spot on Earth at all times. • Ground stations are in continuous contact with these satellites so television program or phone call is not interrupted.

15. Results of Satellite Programs • Satellites gather information by remote sensing. • This is gathering of images and data from high above the Earth’s surface. • The images and data help investigate the Earth’s surface by measuring light and other forms of energy that reflect off Earth. • Some satellites use radar which uses high-frequency radio signals to observe objects.

16. Military Satellites • The U.S. military used satellites for defense and spying purposes by pointing telescopes toward the Earth’s surface. • Between 1940 and 1980, the U.S. and Soviet Union built up military forces to prevent the other from becoming too powerful. • Both countries monitored the other with spy satellites. • The military also launched GEO satellites that served as early warning systems against missiles launched toward the U.S. • Spy satellites are still used today.

17. Eyes on the Environment • Satellites have given us a new vantage point for looking at the Earth in ways never possible before. • The Landsat program has given us the longest continuous record of Earth’s surface as seen from space. • The latest Landsat satellite was launched in1999 and will gather images in several frequencies of the Earth. • It will also gather information on global and regional changes on Earth. • We have also used remote sensing to perform large scale mapping of vegetation, urban development and the global environment.