DEPARTMENT OF AERONAUTICAL ENGINEERING

REPORT ON EARTH TO MOON NAVIGATION

SUBMITTED BY: SUBMITTED TO:

1. SURAJ KUMAR JAYSWAL MR. SIDDALINGAPPA PK

2. SAJAN SHRESTHA

3. RAMSAGAR MAHATO SIGNATURE:………………

4. PRASHANTH

CONTENTS:

1. RELATIONSHIP BETWEEN THE EARTH AND THE MOON

2. ORIGIN OF THE EARTH AND THE MOON

3. DIFFERENCES BETWEEN THE EARTH AND THE MOON

4. INTRODUCTION TO NAVIGATION

5. EARTH TO MOON NAVIGATION

A. HISTORY

B. SYSTEMS INVOLVED IN NAVIGATION

i. INERTIAL GUIDANCE SYSTEM

ii. OPTICAL NAVIGATION SYSTEM

iii. DIGITAL SYSTEM

6. LAUNCHING OF SATELLITE

7. STAGES INVOLVED IN LAUNCHING OF SATELLITE

A. BOOSTER STAGE

i. SERIES STAGING

ii. PARALLEL STAGING

B. JETTISON STAGE

C. SEPARATION OF SATELLITE FROM LAUNCH VEHICLE

D. DELIVERY OF SATELLITE INTO INJECTION ORBIT

E. SYSTEM TESTING

F. DRIFTING OF SATELLITE TO FINAL POSITION

8. SCHEMATIC DIAGRAM OF SATELLITE LAUNCH

9. A BRIEF INTRODUCTION TO GPS NAVIGATION

A. INTRODUCTION

B. WORKING

C. SIGNALS

D. DATA AND INFORMATION

E. SOURCES OF ERRORS

10. REFERENCES

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1. RELATIONSHIP BETWEEN THE EARTH AND THE MOON:

We think of ourselves as living on a single planet, but in reality we live in a system of two worlds.

Our sister world, the Moon, is easily visible in our sky, and we can see its daily effects on ocean tides.

The relationship between the two bodies was first appreciated in 1968, when humans started to

explore the other half of our system.

The Moon affects the Earth in several observable ways. Consider

the monthly movement of the Moon around our planet – we see the phases of the Moon cycle daily,

as different parts of the Earth – facing side of the Moon are illuminated by the Sun. Many people

superstitiously believe that the Moon influences human behaviour by some unknown force.

As Newton discovered, Earth’s gravity attracts the Moon toward

the Earth, and keeps it in orbit around the Earth. But gravity is a mutually attractive force. So the

Moon is attracting the Earth, too. Since the force of gravity depends on the inverse square of the

distance, the side of the Earth facing the Moon has a stronger force pulling toward the Moon than

the opposite side, because it is closer to the Moon. The two unequal forces cause a net stretching

force along the Earth-Moon axis, called a tidal force. Tidal forces occur any time there is a difference

between the gravity on the two sides of a celestial body caused by the attraction of another body. The

actual effect is to stretch the whole planet into a slightly football-like shape. This elongation of the

solid Earth is actually very subtle – it results in a difference in the radii at the poles and the equator

of only about 20 centimetres.

The Moon actually orbits the Earth in such a way that the same

side always points towards the Earth. This is because the force of gravity is working both ways – the

Moon is slightly elongated by its own tides, caused by the gravity of the Earth. Earth’s gravity has

forced the long axis of the Moon to face the planet, so that the Moon is tidally locked in synchronous

rotation.

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1. ORIGIN OF THE EARTH AND THE MOON:

By studying the Earth and the Moon, scientists have been able to piece together their linked histories.

Our planet and its satellite are a double system that formed 4.6 billion years ago. The Moon probably

originated during a gigantic collision in the late stages of planetary formation, after the Earth’s iron

core formed. The Moon formed close to the Earth from the ejected material, and it has been slowly

moving outward in its orbit ever since, due to tidal forces. The age of the Earth-Moon system and the

chronology of the Earth’s history are measured using the technique of radioactive decay. This well-

understood physical process also provides the energy that drives most of the Earth’s geological

evolution.

2. DIFFERENCES BETWEEN THE EARTH AND THE MOON:

Mass explains most of the difference between the Earth and the Moon. The Earth is so massive that

a lot of energy is released by radioactive decay within the interior rocks. This heats and liquefies the

rock, which then drives the activity of the crust. The Moon is 80 times less massive, so it has

proportionately less energy from radioactive decay. The heat generated within the Moon is

insufficient to melt rocks and drive geological activity. This simple difference illustrates the

fundamental contest between internal and external forces in determining the surface conditions on

planets. In general, a massive planet is more likely to retain a hot interior, and internal geological

forces win the contest to shape the surface. Smaller worlds lose their heat and have little internal

geological activity, so external impacts play the dominant role in shaping surface features.

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3. INTRODUCTION TO NAVIGATION:

Navigation is a field of study that focuses on the process of monitoring and controlling the movement

of a craft or vehicle from one place to another. The field of navigation includes four general

categories: land navigation, marine navigation, aeronautic navigation, and space navigation.

It is also the term of art used for the specialized knowledge used by navigators to perform navigation

tasks. All navigational techniques involve locating the navigator's position compared to known

locations or patterns.

Navigation, in a broader sense, can refer to any skill or study that involves the determination of

position and direction.

4. EARTH TO MOON NAVIGATION:

Plotting the path from launch pad on Earth to a landing site on the moon-and back again-was made

possible in the 1960s by using what we know of the mechanics of the two bodies. These are not easy

calculations. After all, the Moon and Earth are moving along their own trajectories, one of them

rotating quite quickly the whole time. Fortunately these movements are quite predictable, and there

aren’t many twists and turns along the way. Once you’re on the right trajectory, it’s smooth sailing

for several days.

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However, that “right trajectory” may require lots of small adjustments, especially when you get to

either end of the trip. To ensure the spacecraft doesn’t land on the edge of a crater on the Moon, or

burn up or skip off into space upon re-entry into the Earth’s atmosphere.

Navigating to the moon requires data about current position and velocity with respect to some frame

of reference. A large antenna on Earth, for example, can determine the distance from itself to the

spacecraft by measuring the delay of a signal sent from Earth to the capsule and back. It can also

determine radial velocity, or the rate at which the spacecraft is moving along the line between the

antenna and spacecraft, using the “Doppler Effect” to calculate the frequency difference of that

signal and its returned version. Radio tracking is incredibly precise in the neighbourhood of

Earth, measuring a distance to less than 30 meters of error.

A. HISTORY:

Plotting the path from launch pad on Earth to a landing site on the moon-and back again-was made

possible in the 1960s by using what we know of the mechanics of the two bodies. It is hard to

appreciate the technical challenges involved in putting a man on the moon, but 1960s computer

technology played a fundamental role.

But while they were no more powerful than a pocket calculator, these ingenious computer systems

were able to guide astronauts across 356,000 km of space from the Earth to the Moon and return

them safely.

The lunar programme led to the development of safety-critical systems and the practice of software

engineering to program those systems. Much of this knowledge gleaned from the Apollo programme

forms the basis of modern computing.

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The so-called Apollo Guidance Computer (AGC) used a real time operating system, which enabled

astronauts to enter simple commands by typing in pairs of nouns and verbs, to control the spacecraft.

It was more basic than the electronics in modern toasters that have computer controlled

stop/start/defrost buttons. It had approximately 64Kbyte of memory and operated at 0.043MHz.

The importance of this computer was highlighted in a lecture by astronaut

David Scott who said: "If you have a basketball and a baseball 14 feet apart,

where the baseball represents the moon and the basketball represents the Earth,

and you take a piece of paper sideways, the thinness of the paper would be the

corridor you have to hit when you come back."

B. SYSTEMS INVOLVED IN NAVIGATION:

Astronauts use three navigation systems to determine the proper flight paths to the Moon and back

to Earth. These systems are used jointly or separately. Together they form the Primary Guidance and

Navigation System.

i. INERTIAL GUIDANCE SYSTEM:

The inertial guidance system include accelerometers that sense every change in the spacecraft's

velocity or direction. An on-board computer receives data pertaining to the flight plan from the

inertial system and from ground tracking stations on Earth. In addition, the astronauts can give the

computer new information while in flight.

ii. OPTICAL NAVIGATION SYSTEM:

An optical navigation system consists of a scanning telescope and a sextant. With these instruments

the astronauts can take sights and plot the position of their spacecraft. All guidance and navigation

information is transmitted to Earth-based computers that calculate any necessary course or velocity

changes.

iii. DIGITAL SYSTEM:

This station includes a digital computer that stores data and provides solutions to guidance and

navigation problems. The right side of the computer faces into the command module. It contains the

eyepieces of the scanning telescope and the sextant and, at the far right, the display and keyboard

panel which is used to enter information and display answers. The back of the station connected to

the Command Module's systems.

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5. LAUNCHING OF SATELLITE:

In order to deliver spacecraft into orbit safely and with utmost accuracy and

precision, we really do need rocket science, the most advanced space technology,

the highest technical skill and experience and a fair amount of shear power.

Varieties of rockets are used to launch the rocket into the orbit.

The satellites are carried in rocket’s nose collop, just a small part of whole launch

vehicle, the rest is composed of engines, control devices and mainly fuel to generate

thousand tons of thrust to power the huge rocket in the space. Each launch vehicle

has an individual flight profile depending on size and number of stages. As each stage

completes its task, it is jettisoned and the engine of next stage begins to fire. Once the

launch vehicle has left the Earth’s atmosphere behind, nose cone fairing is also

jettisoned, so much less weight to carry but still a long way to go.

When the last stage of the rocket has completed its burn, separation occurs and the

satellite is set free in space. After some flight duration, the satellite is delivered to an

injection orbit, which is a giant ellipse. After delivering to the injection orbit, the giant

solar panels are deployed to generate electrical energy and the antenna swings out.

From control stations down on the Earth, the thrust systems, power systems,

communications and control systems, that allow the spacecraft to manoeuvres out in

space, are all tested for the liable operation. The payloads, transponders, antenna

and all the associated equipment which will feed signals and relay them to the Earth

are also fully tested.

Once all systems are confirmed fully operational, the satellite is drifted to its final

position where it begins its operational service in space.

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6. STAGES INVOLVED IN LAUNCHING OF SATELLITE:

To place a satellite at a height of 300 km, the launching velocity should at least

be about 30600 km per hour. If this high velocity is given to the rocket at the

surface of the Earth, the rocket will be burnt due to air friction. Moreover, such

high velocities cannot be developed by single rocket. Hence,

multistage rockets are used.

To be placed in an orbit, a satellite must be raised to the desired height and given

the correct speed and direction by the launching rocket.

At lift off, the rocket, with a manned or unmanned satellite on top, is held down

by clamps on the launching pad. The clamps are then removed by remote control

and the rocket accelerates upwards.

To penetrate the dense lower part of the atmosphere, initially the rocket rises

vertically and then tilted by a guidance system.

A. BOOSTER STAGE:

The study of rockets is an excellent way for students to learn the basics of forces and the response of

an object to external forces. All rockets use the thrust generated by a propulsion system to overcome

the weight of the rocket. For full scale satellite launchers, the weight of the payload is only a small

portion of the lift-off weight. Most of the weight of the rocket is the weight of the propellants. As the

propellants are burned off during powered ascent, a larger proportion of the weight of the vehicle

becomes the near-empty tankage and structure that was required when the vehicle was fully loaded.

In order to lighten the weight of the vehicle to achieve orbital velocity, most launchers discard a

portion of the vehicle in a process called staging. There are two types of rocket staging, serial and

parallel.

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i. SERIES STAGING:

In serial staging, shown above, there is a small, second stage rocket that is placed on top

of a larger first stage rocket. The first stage is ignited at launch and burns through the

powered ascent until its propellants are exhausted. The first stage engine is then

extinguished, the second stage separates from the first stage, and the second stage engine

is ignited. The payload is carried atop the second stage into orbit. Serial staging was used

on the Saturn V moon rockets. The Saturn V was a three stage rocket, which performed

two staging manoeuvres on its way to earth orbit. The discarded stages of the Saturn V

were never retrieved.

ii. PARALLEL STAGING:

The parallel staging, as shown in this figure, several small first stages are

strapped onto to a central sustainer rocket. At launch, all of the engines are

ignited. When the propellants in the strap-on's are extinguished, the strap-on

rockets are discarded. The sustainer engine continues burning and the

payload is carried atop the sustainer rocket into orbit. Parallel staging is used

on the Space Shuttle. The discarded solid rocket boosters are retrieved from

the ocean, re-filled with propellant, and used again on the Shuttle.

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B. JETTISON STAGE:

Each launch vehicle has an individual flight profile depending on size and number of

stages. As each stage completes its task, it is jettisoned and the engine of next stage

begins to fire. Once the launch vehicle has left the Earth’s atmosphere behind, nose

cone fairing is also jettisoned.

C. SEPARATION OF SATELLITE FROM LAUNCH VEHICLE:

When the last stage of the rocket has completed its burn, separation occurs and the

satellite is set free in space.

D. DELIVERY OF SATELLITE INTO INJECTION ORBIT:

After some flight duration, the satellite is delivered to an injection orbit, which is a giant

ellipse. After delivering to the injection orbit, the giant solar panels are deployed to

generate electrical energy and the antenna swings out.

E. SYSTEM TESTING:

From control stations down on the Earth, the thrust systems, power systems,

communications and control systems, that allow the spacecraft to manoeuvres out in

space, are all tested for the liable operation. The payloads, transponders, antenna and

all the associated equipment which will feed signals and relay them to the Earth are

also fully tested.

F. DRIFTING OF SATELLITE TO FINAL POSITION:

Once all systems are confirmed fully operational, the satellite is drifted to its final

position where it begins its operational service in space.

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7. SCHEMATIC DIAGRAM OF SATELLITE LAUNCH:

8. A BRIEF INTRODUCTION TO GPS NAVIGATION:

A. INTRODUCTION:

The Global Positioning System (GPS) is a satellite-based navigation system made up of a

network of 24 satellites placed into orbit by the U.S. Department of Defence. GPS was

originally intended for military applications, but in the 1980s, the government made the

system available for civilian use. GPS works in any weather conditions, anywhere in the

world, 24 hours a day.

B. WORKING:

GPS satellites circle the earth twice a day in a very precise orbit and transmit signal

information to earth. GPS receivers take this information and use trilateration to calculate

the user's exact location. Essentially, the GPS receiver compares the time a signal was

transmitted by a satellite with the time it was received. The time difference tells the GPS

receiver how far away the satellite is. Now, with distance measurements from a few more

satellites, the receiver can determine the user's position and display it on the unit's electronic

map.

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A GPS receiver must be locked on to the signal of at least 3 satellites to calculate a 2-D position

(latitude and longitude) and track movement. With four or more satellites in view, the receiver can

determine the user's 3-D position (latitude, longitude and altitude). Once the user's position has been

determined, the GPS unit can calculate other information, such as speed, bearing, track, trip

distance, distance to destination, sunrise and sunset time and more. The 24 satellites that make up

the GPS space segment are orbiting the earth about 12,000 miles above us. They are constantly

moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of

roughly 7,000 miles an hour. GPS satellites are powered by solar energy. They have backup batteries

onboard to keep them running in the event of a solar eclipse, when there's no solar power. Small

rocket boosters on each satellite keep them flying in the correct path.

C. SIGNALS:

GPS satellites transmit two low power radio signals, designated L1 and L2. Civilian GPS uses

the L1 frequency of 1575.42 MHz in the UHF band. The signals travel by line of sight, meaning

they will pass through clouds, glass and plastic but will not go through most solid objects such

as buildings and mountains.

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D. DATA AND INFORMATION:

A GPS signal contains 3 different bits of information - a pseudorandom code, ephemeris data

and almanac data.

i) The pseudorandom code is simply an I.D. code that identifies which satellite is

transmitting information. You can view this number on your Garmin GPS unit's satellite

page, as it identifies which satellites it's receiving.

ii) Ephemeris data, which is constantly transmitted by each satellite, contains important

information about the status of the satellite (healthy or unhealthy), current date and time.

This part of the signal is essential for determining a position.

iii) The almanac data tells the GPS receiver where each GPS satellite should be at any time

throughout the day. Each satellite transmits almanac data showing the orbital

information for that satellite and for every other satellite in the system.

E. SOURCES OF ERRORS:

Factors that can degrade the GPS signal and thus affect accuracy include the following:

Ionosphere and troposphere delays - The satellite signal slows as it passes through the atmosphere.

The GPS system uses a built-in model that calculates an average amount of delay to partially correct

for this type of error.

Signal multipath - This occurs when the GPS signal is reflected off objects such as tall buildings or

large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby

causing errors.

Receiver clock errors - A receiver's built-in clock is not as accurate as the atomic clocks on-board

the GPS satellites. Therefore, it may have very slight timing errors.

Orbital errors - Also known as ephemeris errors, these are inaccuracies of the satellite's reported

location.

Number of satellites visible - The more satellites a GPS receiver can "see," the better the accuracy.

Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal

reception, causing position errors or possibly no position reading at all. GPS units typically will not

work indoors, underwater or underground.

Satellite geometry/shading - This refers to the relative position of the satellites at any given time.

Ideal satellite geometry exists when the satellites are located at wide angles relative to each other.

Poor geometry results when the satellites are located in a line or in a tight grouping.

Intentional degradation of the satellite signal - Selective Availability (SA) is an intentional

degradation of the signal once imposed by the U.S. Department of Defence. SA was intended to

prevent military adversaries from using the highly accurate GPS signals. The government turned off

SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.

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REFERENCES:

www.wikipedia.com

www.google.com

www.nasa.gov

www.allthingsnav.com

www.nmit.ac

www.moonzoo.org

www.quora.com

www.youtube.com

www.explainthatstuff.com

www.stackexchange.com

www.space.com

www.ask.com

www.answers.yahoo.com

THE END

THANK YOU…