Early Space Exploration Assignment (2)
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Jan 9, 2024
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Lesson 23.1: Early Space Exploration CK-12 Assignment (50 points) True or False Write true if the statement is true or false if the statement is false. Put a “T” for a true statement and a “F” for a false statement.
__T___ 1. The first rockets ever used were launched in the 20th century.
__T___ 2. The first liquid-fuel rockets to be built were designed by Robert Goddard.
__T___ 3. Wernher von Braun joined NASA and helped design rockets for space travel.
_F____ 4. The first satellite ever to orbit Earth was put into space by the United States.
_F____ 5. The scientist who first explained how satellites stay in orbit was Hermann Oberth.
__T___
6. Over the past 50 years, thousands of artificial satellites have been put into orbit around Earth.
___T__ 7. The speed of a satellite depends on how high it is above the object it is orbiting.
__T___
8. U.S. Mariner missions sent space probes to the outer solar system.
_F____
9. U.S. Voyager probes are now traveling toward the sun.
T_____
10. The U.S.S.R. sent probes to Venus and landed some of them on the surface.
Lesson 23.2: Critical Reading Read this passage based on the text and answer the questions that follow.
Types of Satellites and Their Orbits
Since the first artificial Earth satellite was launched more than 50 years ago, thousands of artificial satellites have been put into orbit around our planet. We have even put satellites into orbit around the Moon, the Sun, and several other planets. Depending on their purpose, there are four main types of satellites: imaging satellites, communications satellites, navigational satellites, and the International Space
Station.
Imaging satellites take pictures of Earth’s surface that are used for military or scientific purposes. For example, meteorologists use imaging satellites to study Earth’s weather. Astronomers use them to study the Moon and other planets.
Communications satellites are designed to 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 International Space Station (ISS), the largest artificial satellite, allows humans to live in space while conducting scientific research.
The speed of a satellite depends on how high it is above Earth’s surface. Satellites that are relatively close
to Earth are said to be in low-Earth orbit (LEO). Satellites in LEO are often in polar orbit. This means that
they travel over the North and South Poles and move in a direction that is perpendicular to the direction of
Earth’s rotation. Because Earth rotates beneath a polar-orbit satellite, the satellite is over a different part of Earth’s surface each time it circles the planet. Imaging satellites and weather satellites are often put in low-Earth, polar orbits. A satellite placed at just the right distance above Earth—35,786 km (22,240 miles)—orbits Earth at the same rate of speed that Earth spins on its axis. When such a satellite orbits Earth in the same direction as Earth’s rotation, it is always over the same position on Earth’s surface. This
type of orbit is called a geostationary orbit (GEO). Many communications satellites are in geostationary orbits.
Questions
1.
Identify four main types of satellites based on their purpose
.
Answer: Satellites can be categorized into four main types based on their purpose:
1. **Communication Satellites**: These satellites are designed for transmitting and receiving data, including television signals, internet connectivity, and telephone communication. They are often placed in geostationary orbits (GEO) to maintain a fixed position relative to the Earth's surface for consistent communication coverage.
2. **Earth Observation Satellites**: These satellites are used to observe and monitor the Earth's surface, atmosphere, and oceans. They provide valuable data for applications like weather forecasting, environmental monitoring, agriculture, and disaster management. Earth observation satellites can be in various orbits, including polar and sun-synchronous orbits.
3. **Navigation Satellites**: Navigation satellites, such as those in the Global Positioning System (GPS), provide precise positioning and timing information to users on the Earth's surface.
They are usually in medium Earth orbits (MEO) and are essential for applications like navigation,
mapping, and location-based services.
4. **Scientific and Space Exploration Satellites**: These satellites are used for scientific research, space exploration, and astrophysical observations. They include telescopes like the Hubble Space Telescope, planetary probes, and observatories studying phenomena in space. Their
orbits and configurations vary depending on their specific missions and objectives.
These are just a few examples of the many satellite types that serve various purposes, including military and defense satellites, space debris monitoring satellites, and more. Each type of satellite is designed to fulfill specific functions and contribute to a wide range of applications and industries.
2.
Describe a polar orbit, and explain why a satellite in a polar orbit is over a different part of Earth’s surface each time it circles the planet.
Answer: A polar orbit is a type of satellite orbit that takes the satellite over the Earth's poles on each orbit. In this orbit, the satellite travels from the North Pole to the South Pole and back on each revolution around the Earth. The key characteristics of a polar orbit are as follows:
1. **Inclination**: Polar orbits have a high inclination, which means the orbit is tilted relative to the Earth's equator. The inclination is typically close to 90 degrees, and the satellite passes directly over the poles.
2. **Low Altitude**: Polar orbits are often at relatively low altitudes, typically in the Low Earth Orbit (LEO) range, which can be a few hundred to a couple of thousand kilometers above the Earth's surface.
The reason a satellite in a polar orbit passes over a different part of Earth's surface each time it circles the planet is due to the rotation of the Earth itself. The Earth rotates on its axis from west to east. Here's how it works:
1. **Earth's Rotation**: While the satellite is in orbit, the Earth continues to rotate underneath it. This means that with each orbit, the satellite is effectively "chasing" the rotation of the Earth.
2. **Coverage**: Since the Earth rotates 360 degrees every 24 hours, and a polar orbiting satellite completes an orbit in less time, the Earth has rotated a certain amount by the time the satellite completes one orbit. As a result, the satellite's ground track shifts slightly to the west with
each orbit.
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3. **Repeating Coverage**: The combination of the Earth's rotation and the satellite's orbital path results in the satellite covering a different part of the Earth's surface on each orbit. Over time, the satellite will cover the entire surface of the Earth, providing global coverage.
This feature of polar orbits is particularly useful for Earth observation satellites, as it allows them to capture images and data from different parts of the planet with each orbit. It is also beneficial for scientific research, environmental monitoring, and other applications where comprehensive and repetitive coverage of the Earth's surface is essential.
3.
What is a geostationary orbit? What is required for a satellite to be in this type of orbit? Which of the four main types of satellites have geostationary orbits?
Answer:
A geostationary orbit is a specific type of orbit around the Earth in which a satellite orbits at the same rotational speed as the Earth. This means that the satellite appears to remain stationary relative to a fixed point on the Earth's surface. In other words, a geostationary satellite stays directly above the same point on the equator.
For a satellite to be in a geostationary orbit, it must meet the following requirements:
1. **Altitude**: It must be located at an altitude of approximately 35,786 kilometers (22,236 miles) above the Earth's equator.
2. **Equatorial Plane**: Its orbit must be in the plane of the Earth's equator.
3. **Synchronous Orbit**: It must orbit the Earth at the same rotational speed as the Earth's rotation, completing one orbit in approximately 24 hours.
The four main types of satellites are:
1. **Geostationary Satellites (GEO)**: These satellites orbit at an altitude of approximately 35,786 kilometers above the equator. They remain fixed relative to a specific point on Earth and are commonly used for purposes like communication, weather monitoring, and broadcasting.
2. **Medium Earth Orbit Satellites (MEO)**: These satellites orbit at an altitude between 2,000 and 35,786 kilometers above the Earth's surface. They are often used for navigation systems like GPS.
3. **Low Earth Orbit Satellites (LEO)**: These satellites orbit at an altitude below 2,000 kilometers. They are used for a variety of purposes including Earth observation, communication, and scientific research.
4. **Polar Orbit Satellites**: These satellites pass over the Earth's poles on each orbit. They are typically used for Earth observation, including environmental monitoring and climate research.
Among these, only geostationary satellites are in geostationary orbits. They have the unique characteristic of staying fixed relative to a specific point on the Earth's surface, which makes them highly valuable for applications that require a stable and constant connection, such as television broadcasting and weather monitoring.
Lesson 23.2: Multiple Choice Questions
Highlight the letter of the correct choice.
1.
The scientist who first developed the idea of multi-stage rockets was __________.
a.
Tsiolkovsky
b.
Goddard
c.
Oberth
d.
von Braun
2.
Newton’s law of universal gravitation explains __________.
a.
how the moon stays in orbit around Earth
b.
why objects on Earth always fall toward the ground
c.
why objects in motion stay in motion unless acted upon by a net force
d.
two of the answers above are correct
3.
Human beings have put satellites into orbit around ___________.
a.
Earth
b.
the sun
c.
the moon
d.
all of the above
4.
Satellites in low-Earth orbit generally orbit over the __________.
a.
poles
b.
equator
c.
same place on Earth’s surface
d.
two of the answers above are correct
5.
The space race was a competition to explore space that occurred after World War II between the U.S. and ___________.
a.
Germany
b.
Saudi Arabia
c.
the Soviet Union
d.
the European Union
6.
The first human being to travel into space was the U.S. astronaut _____________.
a.
John Glenn
b.
Buzz Aldrin
c.
Alan Shepherd
d.
Neil Armstrong
7.
The U.S. Viking missions landed space probes on ___________.
a.
Mars
b.
Venus
c.
Jupiter
d.
Mercury
Lesson 23.2: Matching Questions
Match each definition with the correct term listed below.
Definitions
_E____ 1. Any object that orbits a larger object
___D__ 2. Name of the force that pushes a rocket forward
__f___ 3. Type of spacecraft that does not have human occupants
__b___ 4. Law that explains how satellites stay in orbit
_a____ 5. Vehicle propelled by particles flying out of one end
___G__ 6. Law that explains how a rocket works
__C___ 7. Circular or elliptical path around an object
Terms
a. Rocket
b. Law of Universal Gravitation
c. Orbit
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d. Thrust
e. Satellite
f. Space probe
g. Third Law of Motion
Lesson 23.2: Fill in the Blank
Fill in the blank with the appropriate term from the CK-12 reading materials.
1.
According to Newton’s ___
third
_______
law of motion, to every action there is an equal and opposite reaction.
2.
To escape Earth’s gravity, rockets must use fuels in the _liquid___
state.
3.
One of the first uses of rockets in space was to launch _satellite_________
.
4.
__________
satellites.
5.
Earth’s largest artificial satellite is the _
_ISS
________
.
6.
An artificial satellite that orbits Earth at the same speed that Earth rotates has a(n) __geosationary________ orbit.
7.
The first artificial satellite ever put into orbit around Earth was named _sputnik_________
.
Lesson 23.2: Critical Writing
Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.
Explain how a rocket works and why multi-stage rockets are needed to escape Earth’s gravity.
Answer:
A rocket works based on the principles of action and reaction, as described by Newton's third law of motion: "For every action, there is an equal and opposite reaction." In the context of rocketry, this means that the rocket generates thrust by expelling high-speed exhaust gases in one direction, which propels the rocket in the opposite direction. This process is crucial for lifting off from Earth and overcoming its gravitational pull. Multi-stage rockets are needed to escape Earth's gravity for several reasons.
**How a Rocket Works:**
1. **Thrust Generation**: A rocket generates thrust through a propulsion system. Inside the rocket's engine, a combination of fuel and oxidizer (collectively called propellant) is burned in the combustion chamber. This chemical reaction produces high-speed exhaust gases.
2. **Action and Reaction**: As the exhaust gases are expelled from the rocket's nozzle at high velocity, they create a force in one direction. According to Newton's third law, the rocket experiences an equal and opposite force in the opposite direction, propelling the rocket forward.
3. **Continuous Process**: The rocket continues to burn its propellant and expel exhaust gases, providing a continuous source of thrust. This allows the rocket to accelerate and overcome Earth's gravity.
4. **Aerodynamic Control**: Rocket fins and control surfaces are used to steer and stabilize the rocket's trajectory during ascent.
**Why Multi-Stage Rockets Are Needed to Escape Earth's Gravity:**
1. **Weight Efficiency**: The main reason for using multi-stage rockets is the need for weight efficiency.
Rockets must carry not only their payload (such as satellites or crewed spacecraft) but also the propellant required for the journey. As the rocket ascends, it expends its fuel, making it lighter. Carrying the empty fuel tanks of lower stages becomes inefficient. Multi-stage rockets allow the shedding of empty stages, making the vehicle lighter and more efficient.
2. **Optimization**: Each stage of a multi-stage rocket can be optimized for the specific conditions it will encounter during different phases of the journey. For example, the first stage is designed for the initial push against Earth's gravity, while later stages may be optimized for the vacuum of space.
3. **Escape Velocity**: To escape Earth's gravity and reach orbit or travel to other celestial bodies, a rocket must achieve a speed known as escape velocity. On Earth, this is approximately 11.2 kilometers per second (about 25,020 miles per hour). Achieving this velocity requires a significant amount of energy and thrust, which can be provided by multi-stage rockets.
4. **Momentum Conservation**: Multi-stage rockets allow for the conservation of momentum. When a stage is jettisoned, the rocket maintains its forward momentum while becoming lighter, which improves overall efficiency.
In summary, multi-stage rockets are essential for space travel because they provide the necessary thrust and efficiency to escape Earth's gravity. By sequentially igniting and jettisoning stages, these rockets enable payloads to reach orbit, explore space, and conduct missions beyond our planet's gravitational pull.