ROCKETS
FOR SATELLITE COMMUNICATION.
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The
world needs a telecommunications system which could give constant field
strength at all times over the whole earth. Although it is possible to
provide telephone links between any two points on earth, the ionosphere can
make long distance communication difficult. |
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5 |
A rocket
flying at 8 km/sec outside the earth's atmosphere would stay in orbit. It
would be like a second moon, going round the earth without using power. If
the rocket were in orbit 42,000 km above the earth, it would circle the earth
once every 24 hours. It would stay above the same spot on the earth. |
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10 |
It would
be possible to build a space station in such an orbit by carrying up
materials in rockets. The station could be provided with transmitting and
receiving equipment, and could act as a repeater to relay transmissions
between any two points on the hemisphere beneath |
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15 |
For a
world service at least three stations would be needed, placed at equal
distances around the earth. This is the only way to transmit around the whole
world, using beams in an unlimited number of channels. The station would have
very low power needs, and even if it were expensive at first the system would
be much cheaper to run than present ones. |
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The
first manmade satellite was launched on |
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20 |
Intelsat
I had only 240 telephone channels, but now satellites like Intelsat V relay
75% of international telephone calls. New satellites have high capacity, long
life, and can be used for telephone. television or computer data
transmissions. Intelsat V has 12,000 circuits for all types of
telecommunications. |
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25 |
Transmissions
from a satellite can give global or spot beam coverage, but they are received
by all earth stations in sight of the satellite. Each station selects the
channels or carriers which are addressed to it. In the same way, all stations
in sight of a satellite can use it simultaneously, and this is known as
multiple access. |
|
30 |
Earth
stations must be capable of detecting very low level signals. Their parabolic
antennas, which track the satellite automatically, feed the signal to a low
noise first stage amplifier, which may be followed by a second stage
travelling wave tube amplifier. The earth station transmitting equipment is
very powerful, emitting signals at up to 10 kW. In some cases it is possible
to control the satellite transponders and antennas from an earth station.
This process is known as telecommanding |
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35 |
INTELSAT
was formed in 1964 to operate and maintain the global satellite
communications system. The agency designs and builds satellites, and
organizes their launching. |
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NASA,
the |
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40 |
E.S.A.,
the European space agency, has produced the Ariane launch vehicle as a rival
to Titan. For a 1.2 tonne geostationary satellite an Ariane launch costs $30
million, compared to $75 million by Titan. However, although it is more
costly, Titan is also more reliable with 119 successful launches out of 122. |
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45 |
The
Ariane consists of three stages, each of which is a pair of fuel tanks with
one or more rocket engines. The fuel from the two tanks burn when mixed in
the engine. The large first stage lifts, the vehicle through the atmosphere,
and when the fuel tanks are empty the section falls away, igniting the second
stage. The process is repeated by the second stage, then the third stage,
which carries a computer and directional equipment in its front end, and
manoeuvres the satellite into position |
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50 |
Expendable
launch vehicles such as Titan and Ariane now face strong competition from
NASA’s new generation of re-usable "Space Shuttle" launch vehicles.
Although the cost of a shuttle is as high as a billion dollars, the aeroplane
like spacecraft is designed to go into orbit repeatedly, thus reducing the
cost of launching a satellite to around $16 million. |
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55 |
The
space shuttle is launched with the aid of two booster rockets and an external
fuel tank. When the boosters are no longer needed they fall to earth by
parachute, to be picked up from the sea and used again. Later the fuel tank
is released, but this is not recovered. Once In orbit, the orbiter uses its
own engines to manoeuvre. After the mission the shuttle re-enters the earth's
atmosphere and lands on a runway in the same way as an aircraft.(Text adapted
from Telecommunications Developing Reading Skills in English. by D. Oxford,
Pergamon Press, 1985) |
EXERCISES.
1.
Comprehension exercises.
1.1 Main
ideas.
a) Which two of the following subjects do you think the author deals
with in this text.
1.
To build
space stations.
2.
Use of
rockets for launching satellites.
3.
Description
of the Ariane and the Titan.
4.
A world
service telecommunications system.
5.
Role of
satellites in modern communications.
b) Answer these questions.
1.
Is it
possible to have today worldwide communications? Why/why not.
2.
How are
satellites put into orbit?
1.2 Questions
on the text.
1.
Why does
the ionosphere make long distance communication difficult?
2.
To what
does the author compare a rocket orbiting without power?
3.
How are
space stations built in an orbit?
4.
What is
the function of a repeater?
5.
Why would
satellite systems be cheaper to run?
6.
What are
the main characteristics of new satellites?
7.
Which
earth stations receive transmissions?
8.
What is
the name of the International Satellite Communication Organization?
9.
What are
the names of the American and European Space Organizations?
10. Which is the cheapest way to launch a satellite? Why?
11. Which is the most expensive and the most reliable
vehicle?
12. How frequently can a space shuttle be used?
1.3
True/False questions.
Decide
whether the following statements are true or false by referring to the
information in the text. Then make the necessary changes so that the false
statements, become true.
1.
A space
station acts as a repeater.
2.
For a
world service only two stations are needed.
3.
The
Telstar was launched in 1957.
4.
Satellites
are used only for T.V. and telephone transmissions.
5.
Earth
stations can control satellites.
6.
INTELSAT
was formed in 1964 to send monkeys to the moon.
7.
INTELSAT
designs and builds satellites, and organizes their launching.
8.
After the
mission the shuttle desintegrates.
1.4 Find
and give the Information:
1.
Distance
from the earth needed by a rocket to circle it once every 24 hours.
2.
The year
in which the first telecommunications satellite was launched.
3.
The
duration of a Telstar transmission.
4.
The
capacity of Intelsat I.
5.
The
percentage of international telephone traffic relayed by Intelsat V.
1.5
Locating Information
Find the
passages in the text where the following ideas are expressed. Give the line
references.
1.
The
ionosphere poses problems to communications.
2.
To cover
the whole world several stations are needed.
3.
The first
satellites had a very limited capacity compared to the new ones.
4.
The
signals sent off by the satellite are received by some earth stations.
5.
Not all
rockets cost the same.
6.
One type
pf launching vehicle can be used more than once.
2.
Vocabulary exercises. Understanding words.
2.1
Synonyms antonyms.
Refer back
to the text and find synonyms (1-5) and antonyms (6-10) for the following
words.
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1. give
(line 3) |
6. above
(line 11) |
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2.
require (line 12) |
7. cheap
(line 14) |
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3. kind
(line 22) |
8. low
(line 21) |
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4.
principal (line 36) |
9.
before (line 56) |
|
5. he1p
(line 53) |
10. take
off (line 57) |
2.2
Matching words.
Match each
word In A with the meaning in B that comes closest to it.
|
A |
B |
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1. beam |
a)
somebody or something that may be depended upon. |
|
2. spot |
b)
supply, put in. |
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3. track |
c)
directed electromagnetic waves. |
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4. feed |
d)
particular place or area. |
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5.
reliable |
e) get,
capture a signal. |
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6. tank |
f)
container for liquid or gas. |
2.3 Content
review.
Find words
with this meaning in the text.
1) Rocket
used to give initial speed to a missile, after which it drops and leaves the
missile to continue under its own power.
2) The
planet on which we live.
3) Object
for relaying back to the earth telephone messages, radio o TV signals.
4) Band of
frequencies within which signals from a transmitter must be kept to prevent
interference.
5) Outline
from which something will be made.
2.4
Replacing terms.
Choose a
word or phrase from the text to replace the underlined word.
1. To
provide a link between two locations.
2. The
ionosphere can produce difficulties in telecommunications.
3. Some
satellites orbit the earth once every 24 hours,
4. A
satellite could relay transmmissions to one half of the earth.
5. Earth
stations are able to detect very low level signals.
6. The
Ariane is composed of three stages.
3 Text
organization.
3.1
Linking words.
Choose one
of the words below and fill in the blanks. There are some extra words.
|
but,
and, when, nevertheless, for, such as, if, in order to |
1.
INTELSAT was formed in 1964 operate and maintain the global satellite
communication system
2. There
are several space agencies NASA, ESA.
3. The
Telstar had the capacity for about 60 telephone circuits the Intelsat 1 had 240
telephone channels.
4. we
compare the Ariane and the Titan we will see that the Titan is more expensive
it is more reliable as well.
5. The
boosters fall to earth by parachute they are no longer needed.
3.2
Contextual reference
Look back
at the text and find out what the words in bold typeface refer to.
|
1. …
system which could give… |
(line 2)
|
|
2. It
would be like a second moon |
(line 5)
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3. …
cheaper to run than the present ones. |
(line
15) |
|
4. but they
are received … |
(line
24) |
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5. … which
are addressed to it. |
(line
25) |
|
6.
although it is more costly … |
(line
41) |
|
7. The
process is repeated |
(line
46) |
|
8. …
uses its own engines … |
(line
56) |
4. Summary
skills.
4.1 Text
summary.
Refer back
to the text and choose the six most important points from this list in order to
get a summary.
1.
Intelsat I had only 240 telephone channels.
2. The
first manmade satellite was launched in
3. At
least three stations are needed for a world service.
4. The
world needs a telecommunications system.
5. The
shuttle system reduces the cost of launching a satellite.
6. It is
possible to control the satellites from an earth station.
7.
INTELSAT organizes satellite launching.
8. Space
stations can be built in an orbit.
9. The use
of satellites in today's world communications is a must.
10.
Rockets are used for putting the communications satellites into orbit.
4.2
Schematic representation of data.
Make a
table listing the satellites and another listing the rockets mentioned in the
text, adding in each case relevant information (date of launching, channels
available, nationality, price etc).
5 Focus.
5.1 Passive
voice.
A
Examples:
|
The
world needs a telecommunications system (line 1) |
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A
telecommunications system is needed by the world. |
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Transmissions
are received by all earth stations (lines 24/25) |
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All
earth stations receive transmissions. |
|
Subject |
Active
Verb |
Object |
|
The
world |
Needs |
a
telecommunications system. |
|
a
telecommunications system |
is
needed |
by the
world |
|
Subject |
Passive
Verb |
Agent |
5.2
Exercises.
A Here you
have a summary of the text. Fill in the blanks using the suitable form of the
passive voice of the verbs between brackets.
The earth
can (circle) by satellites. New satellites can (use) for telephone, television
or computer data transmission. Transmissions (send) from the satellite and they
(receive) by all earth stations in sight of the satellite. The Ariane (build)
by the Europeans and the Titan (make) by the Americans. The global satellite
communication system (maintain) by INTELSAT.
B. Change
the following sentences from active to passive as in the example.
Example:
We need a telecommunications system
A
telecommunications system is needed
1. We need
at least three space stations for a world service.
.
2. The
shuttle reduces the cost of launching a satellite to around $16 million.
.
3. Titan
rockets safely launched all ten Gemini manned spacecraft.
.
4. They
have designed the shuttle to go into orbit repeatedly.
.
5. U.S.
Air Force will use five planned shuttles to launch ten military satellites per
year.
.
C. Here
you have three dates: 1957, 1962, 1964. Say what happened in these years
according to the text. Use the passive voice.
1. .
2. .
3. .
D. Read
this passage and complete the exercises which follow using the passive voice.
In the early days of space travel every pound weight added a £100 to the
cost of the flight so food had to be as light as possible. One way of making
food lighter was to extract all the moisture from it by a process known as
freeze drying.
Raw or
cooked food (freeze) inside a vacuum chamber and then (heat) a little. During
the freezing process, moisture in the food (turn) into ice crystals; these
(then convert) into gas by the heat, and the gas (finally suck out). During the
flight, water (add) to the dried food to make it more or less like normal food:
hot water produces hot food.
E.
Complete this text using either active or passive as needed.
A G. Bell
(invent) the Telephone in 1876 and some years later, the radio (develop) by
Marconi. Both breakthroughs (become) essential to men and since then many other
advances (achieve) in the field of communications.
5.3 Focus
review. Conditionals.
A Complete
the sentence choosing one of the clauses given.
1.
If a
rocket flies around the earth
a.
it would
be like a second moon.
b.
it will be
like a second moon.
c.
it were
like a second moon.
2.
If
materials were carried in rockets
a.
a space
station could be built in the orbit
b.
a space
station will be built in the orbit
c.
a space
station can be built in the orbit
3.
If we want
a world service telecommunications system
a) at least three stations would be needed
b) at least three stations were needed
c) at least three stations will be needed
4.
If
transmissions from a satellite can give global coverage
a.
they will
be received by all earth stations in sight of the satellite
b.
they would
be received by all earth stations in sight of the satellite
c.
they could
be received by all earth stations in sight of the satellite
B. Choose
one clause from the right as an answer to the problem posed:
When
launching a new space vehicle the space experts are worried about these things:
|
1) What
if the booster rocket did not work. |
a) A new
satellite can be sent to the space to bring it down. |
|
2) What
If the cost were too expensive. |
b) it
would be repaired immediately. |
|
3) What
if the booster did not fall to earth. |
c) a
cheaper satellite will be built. |
|
4) What
If the shuttle did not re-enter the earth's atmosphere. |
d) a new
satellite would be sent to the space to bring it down. |
|
|
e) it
would be a catastrophe |
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f)
people would have to pay more taxes to launch the satellite |