Our Understanding of Space

1
Our Understanding of Space
The development of science generally has
developed very closely to our understanding of
the night sky and space. Revolutions in
scientific thinking coincide with revolutions
astronomy (the study of space). Space has always
given us something to think about and provided us
with more than enough inspiration to produce
useful science to further our understanding of
the world we live in. One of the first things we
notice is that not all heavenly bodies behave the
same way. The sun and moon seem like obviously
different things than the tiny dots of light. A
few of these dots of light move quite differently
than the vast majority of the rest and beg for
special attention.
2
One of the first major problems is that the night
sky is not full of stationary objects. The sun,
moon, and stars seem to rise from one horizon and
circle around to set in the opposite horizon.
Why would we see these circular paths?
Aristotle (384-322 BC) developed some of the
first theories of what composed the night sky and
space. He used common sense and logic to develop
most of his theory. Many of his ideas seem silly
today but they were successfully used for 2000
years before we finally improved on them.
3
Aristotles model of the universe use concentric
spheres with the earth at the center and the
moon, Venus, Mercury and the sun circling it.
Then, the other planets further out. A further
sphere had the stars fixed in place on the sphere
and the sphere rotated. With earth as the center
of the universe, this model is known as the
geocentric model.
4
In Aristotles geocentric model, the central
spheres were imperfect domains filled with the
four elements earth, water, air, and fire. These
4 elements had their natural place around the
imperfect earth. The heavenly spheres that were
outside the center were perfect. All motion was
in a uniform circle and was made of a perfect
incorruptible fifth element called quintessence.
The model worked well but occasionally the
wandering stars (planets) would speed up and slow
down or even go backward. This was called the
retrograde motion of planets. Planets also
become brighter and dimmer.
5
About 400 years later the Greek philosopher
Ptolemy (100 180 AD) suggested a system of
epicycles to explain the retrograde motion. An
even more complicated system of epicycles of
epicycles were use to explain some of the motion.
Ptolemys Universe had 3 main points. 1) All
motion is a uniform circle. 2) Objects are made
from perfect material. 3) The earth is at the
center (geocentric).
6
This model was used successfully for centuries
and is called the Ptolemaic model of the
universe. Nicoli Copernicus (1473-1543) then
suggested a different model where the sun was the
center of the universe (heliocentric). This was
a system that also explained retrograde motion in
a simpler way.
This made the earth just another planet (the
third planet) orbiting the sun. This also
suggested that the other planets might be made of
material similar to the earth.
7
Copernicus kept the idea that all motion was
still a uniform circle. This meant that he was
forced to still use epicycles in his model to
explain some of the motion. The heliocentric
model became known as the Copernican model.
Copernicus knew these ideas were not popular and
did not publish them until he was on his death
bed. Copernicus was not the first person to
propose a heliocentric model. Around 200 BC,
Aristarchus suggested the same idea. There were
objections however that easily dismissed the
heliocentric model. 1) If the earth must be
spinning and orbiting then why dont objects
simply fly off the earth? 2) How do the birds
keep from being left behind? 3) Why do we not
see evidence of parallax?
8
The parallax effect is a result of looking at an
object when the earth is in different positions.
If the earth circles the sun, then a star seen 6
months apart should appear to be in different
locations against the background of distant stars.
One of the explanations given to support the lack
of parallax in the heliocentric model was to
consider the idea that stars are very far away
making the parallax effect very small.
Very precise measurements are needed to see the
parallax effect.
9
Tycho Brahe (1546-1601) made the most precise
observations of the sky using new tools he
developed. He is also saw a supernova and
observed no parallax. This did however show that
the heavens do change. Brahe had a bright young
assistant named Johannes Kepler (1571-1630).
Brahe was a colorful person. For one, he
believed in the Copernican model. He also lost
his his nose in a duel over who was a better
mathematician so he had a silver and gold
prosthetic! Brahe deeply mistrusted Kepler and
wanted to make sure Kepler was never seen as a
greater astronomer.
10
In order to keep Kepler busy, Brahe only gave
Kepler the daunting and almost impossible task of
calculating the orbit of Mars keeping the idea of
circular motion and epicycles. Kepler was not
allowed to see any other data. By a ironic twist
of fate, it was exactly the Mars data that Kepler
needed to conclude the next major
breakthroughorbits are elliptical.

• This breakthrough gave rise to 3 laws
• Orbits are ellipses
• Orbits sweep equal areas in equal times
• The ratio is constant for any planet.
• (P orbital period R avg. distance from the
  sun)

sun
earth
11
Galileo Galilei (1564-1642) did many things for
our understanding of the universe and physics.
He did not invent the telescope that was done by
the spectacle maker Hans Lippershey. Galileo
refined the telescope and turned it to the sky to
observe the heavenly bodies.
Galileo made many observations that were much
more detailed than ever before using his
telescope. He observed that Jupiter had 4 moons,
which went against the theory that everything
orbited earth.
12
Galileo observed dark blemishes on the sun and
even saw them move to one side, disappear, and
reappear on the other side. This showed that the
sun rotated around an axis and that it was not
made of perfect uniform material. These spots
became known as sunspots. (So much sun observing
probably led to his later blindness.)
13
Galileo also observed that Venus displayed a
complete set of phases. This was huge because it
gave conclusive evidence that the Copernican
system was correct. In the Ptolemaic system,
Venus would display only a crescent when viewed
from a central Earth. Galileo saw that Venus
actually showed a complete set of phases just
like the moon. No number of epicycles could
explain the phases unless Copernicus was right.
14
Galileo saw that the cloudy regions of the sky
were actually made of stars. He saw the
mountains on the moon and the shadows cast by
them. He saw that Saturn had ears. The rings of
Saturn were not yet known to exist.
15
Galileo also made other discoveries that at first
didnt seem to have anything to do with how the
universe was organized. He discovered the hidden
force of friction and the principle of inertia.
Most of his discoveries were made by doing
experiments which was a huge shift in scientific
thinking. Aristotle believed that experiments
were useless because they only give you
information about experiments. If you wanted to
know something about the nature of the world, you
needed to observe the world. By changing the
incline and composition of a ramp, Galileo
diluted gravity to show that objects fell at the
same rate no matter what the mass and would
continue falling until friction stopped it.
Being such a revolutionary, Galileo was placed
under house arrest by the church for the last
part of his life.
16
Sir Isaac Newton (1642-1727) unified the thinking
of Copernicus, Kepler, and Galileo in a wide new
theory of universal motion. The theory was
summarized into 3 laws of motion for anything,
not just heavenly objects.
1.) Objects at rest will stay at rest. Objects
in motion will remain in motion unless an outside
force acts on them. 2.) If a force is applied to
an object, it will be accelerated inversely
proportional to the objects mass. 3.) Every
action will have and equal and opposite reaction.
17
To explain the elliptic orbits of the planets,
Newton identified a new force created between all
objects called gravity. Gravity pulled two
objects together and would cause a planet
traveling in a straight line to constantly change
direction and curve around the planet. So an
orbiting object can be thought of as an object
that is constantly falling.
Many of Newtons theories required new
mathematics and radical thinking. Using Newtons
formulas and precise measurements, Neptune,
Uranus, and Pluto were discovered (however Pluto
was discovered because of a calculation error).
18
Newtons mathematics also predicted the presence
of another planet called Vulcan. However, it was
later discovered by Einstein (1875-1955) that
Newtons laws were only approximately true if you
used masses large enough traveling fast enough.
Einstiens theory was called General Relativity.
Relativity is a difficult theory because in many
ways it is counter intuitive to how we think
about the world. If you try to find a simple
definition written in a language that is easily
understandable you will begin to appreciate how
difficult it must have been to develop General
Relativity theory. It was probably just as
difficult for Aristotle, Copernicus, Kepler,
Galileo and Newton.
19
Tools of Astronomy
We have already seen that the development of
astronomy has required the development of
technology so we can get more accurate
measurements of the night sky. One way we locate
objects is to use altitude-azimuth coordinates.
20
These were some of the first tools used by
astronomers to map the night sky. To measure the
altitude of a star or planet, either a cross
staff, astrolab, or quadrant were originally
used. A compass would be used to find the
azimuth. The astrolab could also be used to tell
time even at night.
Compass
Quadrant
Astrolab
Cross Staff
21
Without doubt, the invention of the telescope was
a major event in astronomy. Some people may
suggest that it was the defining moment between
ancient astronomy and modern astronomy. The
telescope was invented by a spectacle maker Hans
Lippershey in 1608.
22
This first telescope was basic in its design.
There was an objective lens and an ocular lens
that magnified the light.
Later, mirrors were used because they could be
made much larger than lenses and thus gather more
light.
23
Both designs combined make combination telescopes.
As well as magnifying light, telescope need to
also be able to distinguish objects that are
close together. The ability to distinguish two
close objects is called resolution. The size of
the objective lens or objective mirror defines
how much light can actually be captured by the
telescope. The bigger the lens the better the
resolution of the telescope. But large lenses
and mirrors are too heavy to stay intact.
24
The Keck I and Keck II telescopes in Mauna Kea in
Hawaii have several mirrors arranged in a
honeycomb to make 1 giant mirror 10m in diameter.
Both telescopes are controlled by computer and
can be combined to give an image that would be
produced with a single telescope with a mirror
with a diameter equal to the distance between
them.
25
Combining telescopes is called inferometry. The
combined power of the Keck telescopes can resolve
the headlights of a car from 800km away. They
were used to produce this image of Saturn where
the rings are clearly visible.
26
One of the main drawback to using optical
telescopes on earth is that the atmosphere
distorts some of the light images reaching us.
One answer to this problem was to launch a
telescope into space so that the images can be
taken without having to go through the
atmosphere. As well, the micro gravity allows
the use of larger lenses. The Hubble Space
Telescope is an orbiting telescope. Without
atmospheric interference, the ice caps on Mars
are clearly visible.
27
Another way to get around the atmospheric
interference is to look for radio waves instead
of visible light. Telephone calls used to be
transmitted by radio waves. Hiss and noise was
always on the line and worse at certain times.
In 1932 Karl Jansky was given the task of finding
out why telephone
calls had such interference. He made radio
receivers and found that objects in the sky
naturally emitted radio signals. In fact, he
could track them, day or night. Today, computers
are used to artificially assign colors to the
radio images (radio waves are not visible) based
on the strength of a radio signal.
28
An optical image is made only of the visible
light that reaches us. Dust can interrupt the
image. This is the galaxy NGC4261
A radio picture of the same galaxy can show us
and give information where visible light was
unable to penetrate.
29
We also use inferometry with radio telescope.
The VLA (Very Large Array) is a system of radio
dishes that act as a single radio telescope.
The VLBI (Very Long Baseline Inferometry) is a
network of radio dishes on different continents
that work together to produce a radio image.
30
Radio and light waves are just a part of the
spectrum of electromagnetic radiation that
reaches us. The visible light only makes a
fraction of the EM-spectrum. However, these
spectra (plural of spectrum) from visible light
can give us more information about the
composition of universe.
31
When light was passed through a prism a spectrum
is produced. But a single prism does not separate
light very well. A spectroscope uses many fine
prisms or even just fine slits to separate the
light. When many fine slits are used to produce
a spectrum we call the slits a diffraction
grating. The underside of a CD acts as a
diffraction grating.
32
When light from the sun was passed through a
diffraction grating, dark lines were noticed. At
the time nobody knew why the dark lines existed.
Gustav Kirchoff and Robert Bunsen began studying
spectra.
They found that if they heated a gas at low
pressure to incandescence (glowing) then looked
at the spectrum, bright lines were produced.
33
Every substance had its own set of spectral
lines. These were called bright line or emission
spectra.
34
They also found that if a solid, liquid, or gas
under high pressure was heated to incandescence
that a continuous spectrum was produced with no
lines.
35
Later it was found that if the light from a
glowing solid was passed through a low pressure
gas that a continuous spectrum would be produced
with dark lines through it. These were called
dark line or absorption spectra. More
interesting was the fact that the dark lines
corresponded to the bright lines from the
emission spectra of the gas.
36
This gave birth to spectral analysis where
scientists could use the dark line spectrum of
the sun to begin to understand what gasses would
exist in the suns atmosphere. We could even use
the same technology with a telescope to determine
the composition of distant stars. Just one more
problem exists with spectroscopy. Object
emitting light are not stationary. Since light
travels in waves it behaves in similar ways to
waves of any king (like sound waves). The
Doppler effect can alter the dark line spectra
that is seen from a start. Objects moving closer
to us will appear to have a shorter wavelength.
In the case of an ambulance siren, the pitch
appears to get higher as the ambulance
approaches. When the ambulance passes us the
pitch appears to get lower.
37
With light, objects moving away from us would
appear to have longer wavelengths which means the
lines would be red shifted. Objects moving
closer would be blue shifted. By measuring the
amount of shift a star displays we can determine
the speed and relative direction an object is
flying in space.
38
Close Objects in Space
When we look up into the sky we indeed see many
objects. One of the first problems we had in
understanding space was its enormous relative
size. A km is simply far too small a unit of
length to describe the distances in space. It is
similar to describing the size of the school in
mm.
The next largest unit we use is the astronomical
unit (AU). 1AU distance between the earth
sun. 1AU 150 million Km.
39
The next largest unit that we use is the light
year. 1 light year distance light travels in
one year. This is a very large unit since light
travels about 300 000 km every second. 1 light
year 63 240 AU 9.5 trillion km. The closest
start to us is Proxima Centauri which is about
4.28 light years away.
Proxima is a relatively small, dim, cool star in
the constellation centaurus.
40
How can we measure the distance of objects in
space when they are so far away? The principle
used is triangulation. If look at a distant
object from two locations, it will appear to be
at different angles.
The distance between the two points is called a
baseline. The baseline is measured as well as
the two angles.
68
57
Baseline 10m
41
A scale drawing is made and the height of the
triangle is measured. Then with the measured
numbers from the scale, the actual distance is
calculated. (Similar triangles have sides that
are proportional). The larger a baseline is, the
more accurate the calculation will be.
distance
68
57
Scale baseline 0.01m
42
To get the most accurate calculations, the
baseline length of the diameter of Earths orbit
(a known value) is used. Before telescopes no
parallax could be measured. Since the invention
of the telescopes we have used this triangulation
method to measure the distance to far away stars.
Earth in January
Orbital diameter
Earth in July
43
The closest objects to us are in our solar
system. Most of these objects are familiar to us
and we have been looking at them for thousands of
years. The sun is the largest body in our solar
system. Most of the pictures that we see of our
solar system give a very distorted view of the
scale. For example, if the sun were made only 1m
across, the earth would be less than a centimeter
in diameter and would be over 100m away. Pluto
would be over 4 km away from the earth at its
closest using this scale.
44
Our sun is the largest body in our solar system.
It is made mostly from hydrogen. The great mass
gives the sun intense gravity which fuels fusion
reactions where hydrogen is atomically combined
to give helium and energy. The sun is about 110
times the size of earth in diameter and about 1
million times the earth in volume.
Solar flares erupt from the surface of the sun
releasing charged particles outward. These
charged particles are called the solar wind.
Earths magnetic field protects us from the
harmful effects of the solar wind. The surface
temperature of the sun is about 5 500C and the
core temperature where the fusion reaction occurs
is around 15 000 000C.
45
Mercury is the closest planet to the sun. The
surface is similar to the moon. There is a very
thin atmosphere of sodium and phosphorus with a
silicate crust and an iron core. Surface
temperatures can reach around 400C and fall to
180C. Smooth regions suggest lava flows on the
surface.
46
Venus is similar to Earth in terms of size and
gravity. The surface is kept very hot due to
thick clouds of CO2(g) that intensify greenhouse
effects. The surface cannot be seen through the
clouds and temperatures can reach 450C. Radar
mappings of Venus show canyons and mountains.
47
Earth is mainly unique because of the large
presence of liquid water. The atmosphere is 78
nitrogen and 21 oxygen. Oxygen is only about 2
billion years old and is a result of early life.
The thin crust of rocks surround a liquid molten
mantle and a solid iron-nickel core.
48
Mars has been relatively well studied with 3
different missions. Iron oxides (rust) cover the
surface of mars leading to the name the red
planet. The atmosphere is mostly CO2(g). Polar
ice caps of frozen CO2(s) and H2O(s) can
sometimes be seen from Earth. Temperature are
cold.
49
Jupiter is the largest of the planets composed of
mostly hydrogen and helium. The giant red spot
is an enormous storm in the planets atmosphere.
Jupiter does have 3 very thin rings. There is a
solid core in Jupiter twice the size of Earth.
If Jupiter was larger, it may have formed into a
star.
50
Saturn is the second largest planet. The rings
of Saturn are composed of mostly ice and dust and
have been observed since Galileo in 1610. Saturn
also has a solid core with a mainly hydrogen
helium atmosphere. Saturns fast rotation makes
bands of clouds visible from Earth.
51
Uranus has a rotational axis that is tilted
severely from the plane of its rotation. It is
composed mainly of hydrogen and helium but
methane gives it its blue color. Voyager 2
visited Uranus sending back data before leaving
the solar system.
52
Neptune is similar in size and composition as
Uranus. The great black spot was seen by Voyager
2 and is a giant storm in the atmosphere.
Neptunes winds are very fast (2500km/h) and the
planet gives off a lot of energy. There is also
a faint ring system.
53
Little is known about Pluto. Its moon Charon is
almost as big as Pluto. The orbit is tilted 17
from the plane of the other orbits and it is very
elliptical. Between 1979 and 1999, Pluto was
closer to the sun than Neptune. There is some
debate over whether Pluto is even a planet or not.
54
The asteroid belt is a narrow region of floating
rocky pieces between Mars and Jupiter. They can
range in size from dust to the largest asteroid
Ceres which is 1000 km wide. Nobody knows where
the asteroid belt came from. One theory has it
that the belt used to be a planet that either
didnt form properly or that was torn apart by
the competing gravity of Jupiter.
55
The Moon is the only extraterrestrial body that
we have visited in person. The moon also rotates
as it orbits the Earth. It takes about 1 month
for the moon to orbit the Earth and it rotates in
about the same time. This means that the moon
always shows the Earth the same side.
The moon is about one sixth the size of Earth and
does not have an atmosphere. As a result, the
surface is full of craters from impacting space
debris.
56
A meteoroid is a floating bit of space rock.
They are usually relatively small. A meteor is
the name of this space rock if it is caught in
Earths gravity and pulled at great speed through
the atmosphere. The rock superheats from the
friction with the atmosphere that it begins to
burn up and make a bright streak across the sky
we call a shooting star. If a piece of the
meteor survives the atmosphere and lands on the
Earths surface, it is called a meteorite.
57
A comet is an orbiting ball of ice and dust that
have long visible tails when they get close to
the sun. Most of the time a comet circles slowly
in large orbits around the sun. Then when they
get closer, they speed up and their tails become
visible.
Halleys comet is visible every 76 years. The
last time it was seen was in 1986 and will return
in 2062.
58
Distant Objects in Space
The moon, sun, planets, asteroids, and even
comets are relatively close objects to us. Most
objects that we see are much further away. Their
distance means that we dont actually know much
about them. Most of what we have learned about
these objects has been discovered within the last
100 years. Much of this type of science is still
developing. As technology improves, astronomers
are becoming more and more interested in the
objects that lie outside our solar system.
Objects that lie outside our solar system are
very far away. Even light from these stars can
take many years to reach us. As a result when we
look up at the night sky, for the most part, we
are looking at ancient history.
59
Light from the sun takes about 8 minutes to reach
Earth. Light from Pluto takes about 5 hours to
reach us. Light from our closes star Proxima
Centauri takes 4.28 years to reach us. Light
from our galaxy center takes about 25 000 years
to reach us.
This galaxy, seen with the Hubble telescope, is
estimated to be 13 million light years away from
us. This means the images we see from it are 13
million years old.
60
Stars spend most of their lives in the main
sequence. Our own sun is a medium small star in
the main sequence. The main sequence is where a
star spends the majority of its life.
61
As dust collects and starts swirling around, a
protostar is formed when enough mass has gathered
to create enough gravity for the fusion of
hydrogen to helium.
As the fusion reaction continues, the star fuses
hydrogen to helium in the main sequence for 90
of its life. The size and heat of the star
depends on the mass. The larger the mass, the
brighter and hotter the star.
62
When most of the hydrogen has been transformed
into helium, the fusion reaction slows down. The
gravity then starts creating a lot of excess heat
and the outer layers of hydrogen the start fusing
around the helium core and rapidly expands in
size. How big the star expands depends on the
original size. Betelgeuse is a famous red
supergiant.
Our sun will become a red giant in about 5
billion years.
63
During the last stages of fusion of the red
giant, helium is further fused to make carbon and
oxygen. If the mass of the star is similar to
our own, a white dwarf is created. The white
dwarf is no larger than Earth but with about 10
million times the density. When all of the
energy is finally spent a black dwarf is created.
It is theorized that the universe is not old
enough for any black dwarfs to exist since they
would not have had sufficient time to cool.
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When larger red supergiants fuse their hydrogen
and helium, the intense gravity is able to
continue the reaction fusing oxygen and carbon
into neon, sulfur, silicon, and eventually iron.
The fusion of iron does not give off energy so
the reaction stops here. If enough iron is
produced in the core the gravitational pressure
fuses electrons with protons releasing a massive
amount of energy as well as sending a shockwave
outward. The supernova can release as much light
as several billion suns. The one seen on the
right shows the sky before a 1987 supernova and
after.
65
The Hubble telescope has been used to look at the
1987 supernova in 1994. The rings seen here
still puzzle astronomers.
Neutrons are made during the supernova and leave
behind a very dense very small neutron star.
Neutron stars can spin very quickly and emit
large amounts of radio waves and x-rays in
pulses. When they do, they are called pulsars.
This pulsar on the right is stealing material
from a nearby star. The actual neutron star is
at the very small center.
66
In 1054, a supernova occurred that was so bright
it could be seen during the day for months. The
crab nebula is the result of this supernova. The
large expanding cloud of dust is all that remains.
There is a pulsar in the center of the nebula
that rotates 30 times a second. The alternating
magnetic fields creates a huge electric current.
The neutron star itself is about the mass of the
sun but only 10 km across. The dust cloud has
also shown measurable expansion.
67
If the mass of the neutron star is great enough
that even a stable pulsar cannot be formed a
black hole is created. A black hole is not
actually very large.
In fact they are bodies with massive gravities
but extremely small surfaces. An imaginary ball
is defined around a black hole called the event
horizon. This is the boundary where only objects
traveling at the speed of light can escape the
gravitational pull. Provided you are outside the
black holes event horizon, gravity acts as it
normally would. We will never be able to see a
black hole since nothing can escape it but we can
detect them. If a star is orbiting an empty
space, we can assume it is orbiting a black hole.
X-rays from gasses near the event horizon are
emitted and can be detected here on earth.
68
One of the earliest and easiest ways we located
stars was to identify patterns in bright stars.
These patterns are called constellations.
Different cultures from around the world saw
different things in these patterns. Orion was a
great hunter and the three bright stars that make
his belt are easily recognized. There are 88
officially recognized constellations
69
Ursa major is an official constellation. The big
dipper is an unofficial asterism.
70
Galaxies are enormously far away. A spiral
galaxy are thin rotating disks of stars and dust.
Our own galaxy is a spiral galaxy. An
elliptical galaxy or globular cluster is a
massive ball of stars. Large globular clusters
can swallow other galaxies that come too close to
their massive gravitational pull. Irregular
galaxies has no normal shape and are usually
smaller with many older stars that spiral
galaxies.
71
Everything that we have talked about so far is
only a fraction of the matter in the universe.
Most of the matter is dark matter. Dark matter
is simply anything that doesnt emit some kind of
radiation that we can detect (whether it is
light, radio, x-ray or whatever). So, how can we
see dark matter? We infer that it must be
there. If we cannot see dark matter directly we
must look at the effects it has on the light
matter we can see. When calculating the
velocities of all of the bright luminous matter
we can calculate that there must be at least 65
to 99 of the universe made from dark matter.
This means that the majority of the universe we
know very little about. We are learning more and
more about dark matter all the time. We dont
know what the majority of it is yet but it is an
interesting question for the future.
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Exploring Space
Space exploration is an exciting branch of
science. In many ways, exploring space is very
new to us. Imagine people of the fifteenth
century looking out into the vast ocean and
wondering what must lay beyond the horizon.
Technology kept people from trying to cross the
ocean. Once they were capable, western culture
was changed in revolutionary ways. The new
horizon is the edge of the atmosphere.
Technology is developed every day to help us
explore and visit the new frontiers of space.
How it shapes our world and our culture is
unimaginable. Many other branches of science
have needed to come together to make space
exploration possible. Our first problem was
figuring out how to get there.
73
We would not have been able to reach space if it
were not for a rocket. A rocket is a device that
uses pressure and action-reaction principles to
fly. Rockets are as old as 400BC where steam
would be used to make a flying wooden pigeon.
Then, the Chinese experimented with using gun
powder and attaching rockets to arrows to make
them fly further. Later, refinements to gun
powder was used to make fireworks.
74
A basic rocket design looks something like this.
A payload is at the front of the rocket that
stays separate from everything else. The
oxidizer and liquid fuels are burned in the
combustion chamber creating pressure in the
rocket. The nozzle allows the the pressure to
escape out the bottom leaving an upward thrust,
pushing the rocket up.
Payload
Payload
Oxidizer
Liquid fuel
Combustion chamber
Nozzle
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A staged rocket uses a booster that burns its
fuel and is then dropped off to lighten the load
on a secondary (or tertiary) rocket. Staged
rockets are essentially rockets launching
rockets. These are more efficient and can reach
higher altitudes with the same fuel as a single
stage rocket.
Payload
Secondary stage
Primary stage
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In 1942, the first ballistic missile was
launched. The design was made by the German
scientist Werner von Braun. The missile could
deliver an explosive payload over 200 km away.
Many were launched at England during WWII.
Today ICBMs (Intercontinental ballistic
missiles) can travel long distances to hit
targets in different continents.
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Von Brauns design allowed us to achieve escape
velocity. Escape velocity is the speed that we
need to go to overcome the gravity of Earth. On
Earth the escape velocity is about 29000 km/h.
With this we were able to put objects into orbit
around Earth. These objects are artificial
satellites (natural satellites are moons). We
have launched many satellites for different
reasons. There are two main types of artificial
satellites.
Low Earth orbit satellites circle Earth very
quickly.
Geosynchronous satellites make one orbit every
Earth rotation.
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The GPS (global positioning satellites) are able
to locate you anywhere on Earth. Numerous
satellites between geosynchronous and low Earth
orbit circle Earth so that there is no one
location on the planet with fewer than 4
satellites over the horizon.
A small hand held device then communicates with
the satellites and determines your location using
triangulation. The system can be accurate to
within a meter. The system was originally
developed for the military but is now used by
sailors, hikers, and rescue people.
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The attempts to put men into were used as a
battle ground for the cold war called the space
race. The Soviet Union was the first to launch
an unmanned satellite (Sputnik I) into orbit in
1957. On April 12, 1961, the launched Cosmonaut
Yuri Gagarin into orbit and safely returned him
to Earth.
On May 5, 1961, during Project Mercury, Alan B.
Shepard became the first American in space.
Shepards flight was sub-orbital which means he
did not orbit the Earth.
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In 1962, John Glenn became the first American to
orbit the Earth. After project Mercury, and the
race to put a man in orbit, the next step was to
put a man on the moon. This project was called
Apollo.
The complete Apollo rocket was a three stage
rocket that housed a command and support module
(CSM) and a lunar module (LM).
LM
CSM
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The CSM had a crew of 3 people. Niel Armstrong,
Edwin Aldrin, and Michael Collins. Only the LM
would be used to land on the moon. Only
Armstrong and Aldrin would actually walk on the
moon, Collins would stay behind.
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In the summer of 1969, the Apollo 11 spacecraft
was launched. On July 20, 1969 Armstrong and
Aldrin stepped onto the moon. They were the
first humans to visit another world. This is
what the world looked like from their perspective.
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Humans are not adapted to living off of the
Earth. In orbit around Earth, there is almost
the same gravitational pull on the surface of the
Earth. The fact that an orbiting space craft is
constantly falling creates the micro gravity
environment.
Space suits need to be self contained
environments. They need to maintain atmospheric
pressure as well as protect against the enormous
heat and cold differences of space. A human
would not live long in space without a space suit.
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The voyager I and II space probes were sent out
to many of the outer planets. To get there, they
used the gravity of the planets they were
traveling past in a process called gravitational
assist. The slingshot effect greatly reduces the
necessary fuel.
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The space shuttle is a reusable spacecraft.
Booster rockets and a large fuel tank use liquid
hydrogen and oxygen to form water and blast the
shuttle to space. The have been 2 cases where
something has gone wrong with the space shuttle.
January 28, 1986, the Challenger shuttle was
destroyed seconds after launch. The Columbia
shuttle was destroyed on re-entry Feb 1, 2003.
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Canada has also contributed to the NASA space
shuttles with the Canadarm. The device is used
to help launch satellites and put them in orbit.
It can also be used to pull satellites into the
cargo bay for repair work.
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The international space station is a permanent
satellite that astronauts visit and maintain.
The space station is an international project
with 16 contributing nations.
More than an acre of solar panels seen here are
used to power the station.
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The environment inside the international space
station needs to be kept in balance. All water
needs to be recycled, including waste water. The
oxygen in the atmosphere needs to be replenished
and the CO2(g) released. Moisture needs to be
added to the air as well. When you are in the
space station, you are confined to a very small
space for long periods of time. You simply cant
go outside to stretch your legs. Canada is
contributing a robotic arm to the station called
Canadarm II. The new gripping device has been
called the Canadhand and will be needed to make
repairs on the station as well as aid with the
docking of future space vessels.