Untitled Flashcards Set

Our Universe

Models of Planetary Motion

Religions, traditions, myths, and rituals of ancient cultures all reveal different interpretations of how the

universe works. Seen from Earth, everything in the sky appears to be in motion: the Sun rises and sets, the

Moon changing phases and traveling across the sky, planets shift against a background of stars, and even

constellations appear to change position in the sky throughout the year. Our ancestors had to make sense of

this constant pattern of change by using the science and technology that was available to them at that time. As

science and technology advanced, so did our understandings of space

GEOCENTRIC MODEL

Geocentric Model: Earth-centered model of the universe.

About 2000 years ago, the Greek philosopher Aristotle proposed a geocentric, or

Earth-centered model to explain planetary motion. In the model, he showed Earth

at the center, surrounded by a series of concentric spheres that represented the

paths of the Sun, Moon, and five planets known at the time. To explain why the

distant stars did not move, Aristotle hypothesized that they were attached firmly to

the outermost sphere (what he called the "celestial sphere") where they stayed put

as though glued to an immovable ceiling.

Little optical technology is believed to have existed in Greece during the time Aristotle was making his

observations about the cosmos. However, he was aided by the mathematics and geometry of Pythagoras and

Euclid (two mathematicians), which he used to calculate the size and shape of the spheres.

The geocentric model allowed early astronomers to forecast such events as the phases of the Moon, but it still

could not explain many other observations.

HELIOCENTRIC MODEL

Heliocentric Model: Sun-centered model of the universe.

The Earth-centered model of our solar system lasted for almost two thousand years.

Then, in 1530, Polish astronomer Nicholas Copernicus proposed a dramatically

different model, where the Sun was at the center of the universe, called the

heliocentric model. It correctly stated that all the planets revolve around the sun. It

also correctly stated that the moon revolved around the Earth.

This model is closer to being correct than the geocentric model, however, we know

today the sun is not the center of the universe; it is only the center of our solar

system. We also know today that stars are spread out through the entire universe and are not located on a

single sphere. Despite the inaccuracies, the heliocentric model was a huge leap forward in human

understanding of space.

In the 1600s, using a telescope not much stronger than today’s standard binoculars, the renowned scientist

Galileo Galilei (Italy) was the first person to view mountains on the Moon, a "bump" on either side of Saturn

(later found to be the outer edges of the planet's rings), spots on the Sun, moons orbiting Jupiter, and was able

to provided evidence for Copernicus’s heliocentric theory.

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The Solar System

The celestial bodies of our solar system were created from an accumulation of gas and dust called a nebula. Before

our sun and planets formed, this gas and dust swirled around. Most (more than 90%) accumulated in the center

and formed our sun. The remaining material accumulated in smaller clumps, circling the center, and formed the

planets and asteroids.

THE SUN (OUR STAR)

At the center of our solar neighborhood sits the sun. Like all other stars, it is made up of mostly hydrogen and

helium. For thousands of years, we learned all we knew about the Sun from looking at it, and that wasn't easy

to do. After telescopes were invented it wasn't long before filters were designed to allow observers to gaze

directly at the Sun. Satellites have offered an even closer look. The Sun is almost 110 times wider than Earth. If

the Sun were a hollow ball, almost a million Earths would be required to fill it.

The temperature at the surface of the Sun, which is constantly bubbling and boiling, is about 5500°C, while the

core is close to 15,000,000°C. The Sun releases charged particles that flow out in every direction. This solar

wind travels at a speed of 400 km/s. Earth is protected from the solar wind by its magnetic field.

THE PLANETS

All the planets in our solar system orbit the sun and receive heat and energy from the solar wind lea ving the

sun. Every planet has its own unique features and characteristics. The solar system can be divided into two

distinct planetary groups: the inner (terrestrial) planets and the outer (Jovian) planets.

Terrestrial Planets: Smaller, rockier, more dense, warmer, and closer to the sun.

Jovian Planets: Larger, have a greater mass, more gaseous, less dense, colder, and are located greater

distances from the sun.

Technology has enabled us to learn a lot about our nearest neighbors in space. All the planets have been visited

by orbiting space probes. Mars and Venus have had robots land on their surface.

ASTEROIDS, COMETS, AND METEOROIDS

Asteroids: Small, rocky or metallic bodies, which revolve around the sun in a regular pattern, just like

our planets.

Asteroids orbit between Mars and Jupiter in a form referred to as the asteroid belt. They can range in size from

a few meters to several hundred kilometers across. The largest asteroid, called Ceres, is over 1000 km wide.

Scientists aren't certain where the asteroids came from.

Comets: Objects made up of dust and ice that travel through space in a particular path around a star.

When comets get close to the Sun, it heats the materials on the comet, causing gases to be released, which

appears as a long, bright tail, which can be millions of kilometers long.

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Meteoroids Small pieces of rocks flying through space with no particular path.

Meteoroids can be as small as a grain of sand or as large as a car. They are invisible to most telescopes, so we

are usually only aware of them when one gets pulled into the atmosphere by Earth's gravity. When this happens

the heat of atmospheric friction causes it to give off light, and most of the time, burns it up before it hits Earth.

Ones which do not burnt can caused great destruction.

Distribution of Matter

Away from the light pollution of the city the night sky appears to be completely full of stars. All of those bright

points of light in space are separated by unimaginably large distances. The closest star to our Sun is 39 trillion

kilometers away. Even with the fastest spacecraft we have, which can go 241,000 km/hr, it would take 19,000

years for us to reach this star. The farthest star would take trillions of years to reach at this speed.

STARS

A star is a hot, glowing ball of gas (mainly hydrogen) that gives off tremendous light energy as the hydrogen

atoms squish together into helium atoms. Stars vary greatly in their characteristics. Our Sun has a mass 300 000

times greater than Earth, with an average density of 1.4 times that of water. In diameter, the sun Betelgeuse is

670 times larger than our Sun, but only 1/10-millionth as dense.

Star Lifecycle

Stars form in regions of space where there are huge accumulations of gas and dust called nebulae. Each nebula

is composed of about 75% hydrogen and 23% helium, and 2% of other gases (oxygen, nitrogen, carbon, and

silicate dust). A small nebula may only create 1 star while a larger nebula may create millions of stars as well as

millions of planets. The attraction of gravity acting between the atoms of gas and grains of dust can cause the

nebula (or a part of the nebula) to start collapsing into a smaller rotating cloud of gas and dust. Most of the gas

and dust will be drawn to the center to make the star at the center, while some of the other gas and dust will

make up planets and asteroids that will circle the star. When the gas and dust at the center reaches a certain

mass, hydrogen starts to change to helium. This process, known as fusion, releases great quantities of light and

heat energy and a star is now born.

While stars are burning their hydrogen they are considered to be in their main sequence (which is about 10

billion years for a star the size of the sun). When most of the hydrogen is gone stars about the size of our sun

will expand into a red giant and then after millions of years will shrink down to a small dense star called a white

dwarf.

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Stars that are much larger than our sun will expand into a red supergiant and will then shrink with such a force

that it will explode outward in an event called a supernova. Most of the time after a supernova occurs a small

dense neutron star is left over but if the red supergiant was large enough a black hole will form, which is a

point in space that is smaller than a single atom, but that due to its huge mass (trillions of times greater than

our sun) it “sucks” in all objects or light that come near it and crushes it down to a single point.

SOLAR SYSTEM

Our solar system is composed of our star (the sun) and all the planets that revolve around it. But our sun is just

one of trillions of stars in the universe, and most of those stars will also have their own planets revolving around

them.

STAR SYSTEMS

A star system is a small number of stars which are fairly close together and orbit each other, bound by

gravitational attraction. Most star systems are composed of only 2 or 3 stars which circle each other, but a few

star systems of 6 stars are known to exist.

GALAXIES

A galaxy is a grouping of millions or billions of stars. There will be billions of objects in galaxies, such as planets,

asteroids, and comets along with areas of gas and dust that may form even more stars and planets. Galaxies

were formed from huge nebulae. Smaller nebulae are still found within galaxies so new stars are always being

created.

The galaxy we live in is a spiral galaxy called the Milky Way. It is shaped like a flattened pinwheel, with arms

spiraling out from the center. Viewed from the side, a spiral galaxy looks a little like a compact disc with a

marble in the middle sticking out evenly on either side. Our galaxy is believed to contain 300 billion stars.

Astronomers have estimated there are trillions of galaxies in the universe. Each of these galaxies will contain

billions of stars.

A galaxy contains billions of stars but the distances between stars are still huge. If you were to travel from one

side of our galaxy (the Milky Way) to the other side of it at the speed of light (300,000 kilometers every second),

it would take you 100,000 years. If you were to travel from the edge of the Milky Way, through empty space to

the edge of the next nearest galaxy at the speed of light it would take you 2.5 million years. The farthest known

galaxy would take you 13.23 billion years to reach at the speed of light.

Location & Movement of Objects in Space

As telescope size increases, it enables astronomers to see more distant stars, but this posed new questions. Where

are these stars? How far away are they from Earth? How big is the universe? To find answers to some of these

questions, astronomers developed methods to measure the distances to the stars.

Triangulation

You and a friend are standing beside a lake, looking out at an island. You are thinking of rowing out to the

island, but you do not know how far away it is. Because you do not have a map of the lake and there is no

bridge to the island, you have no means of measuring the distance directly. Is there some other way you can

estimate it?

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By using a distance you know, you can calculate an unknown distance indirectly. One of the most common ways of

doing this is called triangulation. Triangulation is a method of measuring distance indirectly by creating an imaginary

triangle between an observer and an object whose distance is to be estimated. It is the same method that astronomers

use to measure distances to celestial objects.

It is important to remember, when measuring distances with triangulation, that the longer the baseline, the

more accurate the results.

Steps in Finding Triangulation:

1. Create a baseline, using an easy measurement (like 100m). Then measure the angles the baseline forms to the

object.

2. Draw a similar triangle on paper, using an easy baseline measure (like 10cm), using the same angles.

3. Measure the distance from the baseline to the point of your drawn triangle. This will be the same ratio as the

real object is from the real baseline.

4. Using ratios, and cross-multiplication, calculate the actual distance to the object.

Parallax

Parallax is the apparent shift in position of a nearby object when the object is viewed from two different

positions. If you hold out your arm, stick up your thumb, close your right eye and move your thumb so that an

object on the far wall is behind it. If you open your right eye, and close your left, you will notice that your

thumb appears to have shifted in relation to the object on the wall. This is because you are viewing it from two

different positions (from your left eye only and then from your right eye only).

Because we don’t notice our movement around the sun here on Earth, it will appear that the stars in the sky

have moved. Stars often appear to have moved because the stars in the background are different. This is an

example of parallax.

Using parallax, astronomers are able to use much bigger baseline, one that is much bigger than the entire Earth,

when doing triangulation calculations. Astronomers use a star's parallax to determine what angles to use when

they triangulate the star's distance from Earth. The longest baseline we can use from Earth is the diameter of

Earth's orbit. This means that measurements must be taken six months apart to achieve the maximum baseline

length.

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Azimuth, Altitude & Zenith

To find the co-ordinates of an object in space, two questions must be answered: "In which direction is it"? and

"How high in the sky is it"?

The first is the compass direction, called the azimuth. With due north as 0°, and moving clockwise, the azimuth

will tell you which direction to point. For example, 90o from North would have you pointing East; 180° would

have you pointing due south; 270o would have you pointing west.

The second measurement shows how high the object is in the sky, which is called altitude. The altitude ranges

from 0° at the horizon to 90° straight up. Zenith refers to the highest point directly overhead (90o would be the

Zenith, as 90o is straight up).

With these two measurements, stargazers can accurately locate celestial objects in space.

Movement

THE PLANETS

Copernicus was correct when he stated that the Earth revolved around the Sun, but people still struggled to

predict planetary motion. It had been assumed that the planets revolved around the Sun in a circular motion,

but in 1609, Johannes Kepler, a German mathematician, combined mathematics with observation of the

planets’ motions to determine that the planets move in an ellipse, rather than a circle. An ellipse is a figure that

looks like a squashed circle (an oval). Kepler not only found the shapes of the orbits, but also figured out the

shape and scale of the entire known solar system.

THE EARTH

The movement of an object around the sun is called its revolution. The Earth revolves around the sun in an

elliptical pattern (as mentioned above) and takes 365.25 days to make one complete revolution, equal to one

year. As planets and other objects get farther away from the sun their orbits get larger, resulting in a longer

time to revolve around the sun.

The setting and rising of the sun is due to Earth’s rotation (spinning) on its axis. Earth spins on an imaginary

axis, just as if there were a large pin sticking through it. The rotation of Earth takes 24 hours and is responsible

for our days and nights. The Earth will rotate (spin) 365.25 times for every time it revolves around the sun.

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OUR MOON

Just as we revolve around the sun, the moon revolves around the Earth. Because of this, there are two unique

situations that can occur; the moon can come directly between the Earth and sun causing a solar eclipse; or the

Earth can be between the moon and sun causing a lunar eclipse.

During a solar eclipse, when the moon is in between the Earth and the sun, the moon blocks out the sun and

casts a shadow on part of the Earth. If you were on this part of Earth, it could be a perfectly sunny day, and all

of a sudden the moon will block the sun out and it would turn dark all around you. Minutes later, as the moon

moves out of the way, it would return to being sunny.

The moon does not produce light. We can see it because the sun shines on the moon, and that light is reflected

off the moon towards Earth. During a lunar eclipse, the Earth moves between the sun and moon, blocking the

light from getting to the moon. The Earth’s shadow will fall on the moon, putting it in total darkness, and

preventing us from seeing it.

STARS

Many ancient civilizations, such as the ancient Greeks, Babylonians, Hindus, and Egyptians built up a body of

knowledge about the stars, as started to see patterns among them. These patterns of stars seemed to look like

objects, which people grouped and named. These groupings are called constellations.

On each successive day, a given star rises and sets four minutes earlier than the day before. This means that

over a period of months, different stars are in the night sky. Since each month has its own set of stars in the

night sky, people developed the ability to predict the changing of the seasons. This helped lead to the creation

of calendars. This means that stars appear to move slowly across the sky as the days and months pass on. The

exception to stars appearing to move across the night sky is the North Star, which aligns with the axis of

rotation, and therefore appears to be fixed in one spot.

Because the Earth rotates so slowly, you don’t actually see the stars moving as you look at them. In reality, it is

only after several days that you may notice the stars have moved slightly and you may see new stars appear on

the horizon.

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Space Exploration

Technologies

ROCKETS

Today, hundreds of satellites circle Earth. They transmit non-stop information for use in communications,

navigation, research, and weather forecasting. Robotic space probes have investigated all the planets of our

solar system except Pluto. As well, manned spacecraft—notably the Russian Mir space station, the American

space shuttle, and the International Space Station—have conducted studies while in Earth's orbit.

On October 4, 1957, the Soviet Union became the first country in the world to launch an artificial satellite. It

was called Sputnik, the Russian word for satellite. A month after Sputnik was put into orbit around Earth, the

Soviet Union launched a second space capsule. This one carried an occupant, a small dog named Laika, who

survived for seven days as the capsule orbited Earth. The event marked the first time any living creature had

been sent into space. The valuable information gained from that mission set the path for human space travel.

Rocketry relies on a fundamental law of physics: for every action, there is an equal and opposite reaction. An

inflated balloon is similar to a simple rocket. A balloon filled with air is confining gas under pressure. Release

the mouth of the balloon and it will be propelled in a direction opposite to the path of the escaping gas. Rockets

also use gas under pressure confined in a chamber or tank. An opening in the chamber allows the gas to be

released, producing thrust (push) and causing the rocket to be propelled in the opposite direction.

The 3 basic parts of a space vessel going into space

1) The structural and mechanical elements are everything from the parts of the rocket itself to engines,

storage tanks, bolts, wires, and the fins on the outside

2) The fuel can be any number of propellants (a propellant is any chemical substance that can produce a

pressurized gas). The fuel propellant is found inside the rockets where it will burn and propel the rockets

as well as the space shuttle up into space. The force acting on an object causing it to move is called

propulsion.

3) The payload refers to the passengers and the materials needed for those passengers, including crew

cabins, food, water, and air (oxygen) supplies. It also includes anything being transported to space, such

as parts for a space station.

Multi-Stage Rockets

A multi-stage rocket is a rocket that uses two or more stages, each of which contains its own engines and

propellant. A stacked stage is mounted on top of another stage. The result is effectively two or more rockets

stacked on top of each other. Two stage rockets are quite common, but rockets with as many as five separate

stages have been successfully launched.

The advantage of this is that once the fuel from one stage is used up, the empty fuel tank is released from the

rest of the rocket. This decreases the weight of the rocket. The empty fuel tank falls back to Earth. Multistage

rockets make it easier for space shuttles to escape Earth’s gravity and saves on the cost of fuel as well.

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SHUTTLES AND SPACE STATIONS

Space shuttles Transport personnel and equipment to space and to orbiting spacecrafts using the technology

of rocketry. They are designed to re-enter Earth, bringing astronauts back.

Space stations They are orbiting spacecraft that have living quarters, work areas, and the support systems

needed to allow people to live and work in space for extended periods. Designed for humans

to live in space, and not ever meant to re-enter Earth’s atmosphere. Space stations have

more technology that allows them to be more self-sufficient, including solar panels and

systems to recycle water.

Living in Space

HAZARDS IN SPACE

Environmental Hazards

Only a thin atmosphere encircling our planet holds all we need for life on Earth. Outside that bubble is the “cold

vacuum of space” which contains none of the gases (like oxygen), the atmospheric pressure, water and

nutrients, or temperatures that we need to survive. It also contains many hazards for the spacecraft and its

occupants, including the damaging effects of UV radiation from the Sun, micro-meteors and space junk.

Space junk: Material not used anymore that is left in orbit by astronauts.

Humans require a specific atmospheric pressure, which is in part caused by Earth’s gravity and not found in

space. The atmosphere on Earth regulates temperatures, preventing Earth from getting too hot by reflecting

some of the sun’s rays and prevents Earth from getting too cold by trapping heat, and filters out UV radiation

from the sun.

Since the atmosphere is not present in space, space environments get extremely hot when in the sun, and

extremely cold when in the shade. Technology must protect the astronauts from -2000 to +2000 Celsius

temperatures. Addition protection from other forms of radiation comes from the Earth’s magnetic field. This

field extends far beyond the Earth and shields us from radiation that would kill us and fry our technology.

Effects of microgravity

Gravity: The force of attraction between masses. On Earth, gravity gives us our feeling of weight.

Microgravity: A condition in which the gravitational forces that act on mass are greatly reduced.

A person would weigh only one-third on Mars of what he or she would weigh on Earth, because on Mars the

force of gravity is weaker (only one-third) than on Earth. In space, that person is almost completely weightless,

as are the spacecraft and all of its contents.

In conditions of weightlessness, bones have much less pressure on them than normal and so they expand. The

heart does not have to pump as hard to circulate blood, and so it weakens. Muscles used for walking and lifting

do not get used as much, and therefore they too weaken. Even a person's visual depth perception is affected.

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TECHNOLOGIES

The Spacesuit

Once astronauts leave their spacecraft, everything they need to survive must be brought with them. The space

suit must provide all the conditions needed for survival which include:

1. Pressurized atmosphere: The suit must be pressurized as there is no atmosphere in space to provide the

air pressure our bodies need. Without this pressure, our body fluids would begin to bubble.

2. Provide oxygen: Space suits must have an oxygen supply, either a tank, or a supply through a cord coming

from a shuttle or space station

3. Regulating temperature: To cope with the extremes of space, space suits are heavily insulated with layers

of fabric and covered with reflective outer layers. The side of an astronaut that is facing the

sun would reach temperatures of +120oC while the side facing away from the sun would

reach temperatures of -100oC. Therefore, heating and cooling systems are both needed in a

space suit.

4. Protecting from radiation: The space suit must be able to provide some protection from UV radiation

from the sun. The helmets have a tinted “window” in the front that blocks some of this UV

radiation. Without this protection, astronauts would almost immediately go blind.

5. Flexibility: The suit must be flexible enough to allow the astronaut to grasp a wrench or twist a bolt. Each

space suit is custom-designed for the man or woman who will wear it, from the size of the

shoes to the size of the gloves.

6. Waste receptacle: The space suit even has a portable toilet (which is really just a super absorbent

material, much like a diaper).

Space Stations: A Home in Space

If people are planning to move out to space colonies in the coming years, their space station homes will have to

come with several important features. First, clean water, breathable air, and comfortable temperatures and air

pressure must be provided. As well, the station must carry its own source of power to provide the energy

necessary to run the life-support systems and other equipment at all times.

Recycling Water and Air

Recycling is essential in the day-to-day life in a space station because there is so little room for storage. Each

liter of water taken into space cost approximately $15 000 dollars worth of fuel. The good news is that

researchers have developed the technology to filter, purify, and recycle the same water again and again on long

space flights. This includes the water used for washing, the moisture astronauts breathe out, as well as the

water in urine and sweat.

Air must also be recycled on a space station, and there are technologies in space stations that do this. Humans

breathe out carbon dioxide as a waste product. This carbon dioxide is combined with hydrogen, which will

produce water. This water can be drank, or can be split to produce hydrogen and oxygen, which can be used

once again for breathing.

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Powering the International Space Station

The international space station needs power to run all of the machinery needed to recycle water, filter the air,

and do all of the other things needed for humans to survive. This cannot be achieved through batteries brought

up from Earth since the batteries would be too heavy to transport and a constant supply of batteries from Earth

would be needed. Using solar panels fixes this problem. Once they are transported to and set up on the space

station, they can supply the energy needed as the sun provides all of this energy.

SATELLITES

Satellites: ("Artificial Satellites”) Objects using electronic equipment, digital imaging apparatus, and

other instrumentation, that are built by humans and sent into either low-Earth orbit or

geosynchronous orbit.

"Natural Satellite”: A small body that orbits a larger body, such as a moon orbiting a planet.

Low Earth Orbit: 300-2,000km above Earth’s surface and revolves around the Earth faster than Earth is

rotating, moving across the sky in a matter of minutes. These satellites are good at

transmitting signals quickly to the Earth and back but have the disadvantage of not being able

to send signals over a large area of Earth.

Geosynchronous Orbit: 35,786 km above Earth and revolve around the Earth at the same rate that Earth rotates

(once every 24 hours), appearing motionless and in constant view overhead. They can “see” a

much larger part of Earth and can send signals over a large area of Earth, but take longer to

send or receive signals.

Communication Satellites: Some communications satellites are placed in low Earth orbit, while others are placed

in geosynchronous orbit. Radio and television satellites are usually placed in geosynchronous

orbit. Telephone communication uses low-Earth orbit satellites to reduce lag-time (delay)

during telephone conversations, but many satellites are needed to completely cover the

Earth and communicate with each other.

Observation (remote sensing) satellites: A low Earth orbit satellite to observe Earth’s surface, using a process

called “remote sensing”. Images can be photographs taken by cameras or data collected from

the sensing of heat and other invisible energy waves, providing information on the condition

of the environment on Earth, natural resources, and effects of urbanization.

Navigation/Positioning Satellites: Global Positioning System (GPS): Technology designed to provide a ground location at any

time. Twenty-four GPS satellites are in orbit around Earth. These satellites are placed in a low

Earth orbit so that signals can be sent quickly from the Earth and back. At least 3 are above

any given spot on Earth at all times.

GPS Triangulation

Three satellites are needed to triangulate an object or person. If there are less than 3 satellites above a spot on

Earth, accurate positioning of a person or object would not be possible.

Diagram 1 below shows a 2-D version of how the satellites above locate the position of an object. The satellites

would be above the circles shown below. The spot where all 3 triangles intersect shows the location of the

object.

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Very accurate GPS receivers would have a very small space in the middle which more accurately locates an

object (see diagram 2 below). A less accurate receiver would give a larger area that the object could potentially

be in (see diagram 3 below). U.S. military GPS technology can locate an object to within inches.

“SPACE AGE INSPIRED MATERIALS”

Many items, materials, and systems originally designed for a space application have been put to practical use on

Earth. Innovations to help us study our universe, travel out into it, or exist in the space environment can be

found today in just about every aspect of our lives. The table below lists some of the “ spin-off” applications of

space technology.

Field Space Use Earth Use

Computer

technology

•Monitoring of air quality aboard spacecraft •Monitoring of smokestack emissions by factories

• Software designed to simulate space

environment for training of astronauts

•Development of virtual reality software

Consumer

technology

•Design of space food for astronauts flights. •Manufacture of freeze-dried foods.

• Study of aerodynamics for shuttle launch

and re-entry

•Design and manufacture of improved bike

helmets, golf balls, running shoes, and ski goggles

Medical and

health

technology

•Development of communications to control

robotic systems

•Development of voice-controlled wheelchairs

•Development of lasers to measure

gravitational waves

•Development of a “cool” laser that does not

damage blood vessels to be used in heart surgery

Transportation •Viking lander parachute material developed

to be super strong

• This material was adapted to make better winter

tires. The chainlike molecules have a structure

that allows them to be 5 times stronger than steel

Public safety

technology

•Development of computer robotics •Design of emergency response robots for use in

situations too dangerous for humans (ex: to

inspect explosive devices)

The Risks of Space Travel

Accidents that may result in loss of life as well as economic setbacks are a couple of risks we take when trying to

explore space. There are tragedies that bring to light the true dangers of space travel. Below are some examples

of things that have gone wrong:

 1967 3 astronauts of Apollo 1 died during a training exercise when a fire broke out in the cockpit

 1986 7 astronauts died when the Space Shuttle Challenger exploded shortly after launch

 2003 7 astronauts died when the Space Shuttle Columbia broke apart during re-entry

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Other accidents or lost missions have occurred that have cost many millions of dollars and thousands of hours

of work, including most recently, the European Rover “Beagle” on Mars, which did not return any data, or signal

after it landed.

LAUNCHING AND THE SPACE ENVIRONMENT

A launch can be affected by many dangers, including highly explosive fuel, poor weather, malfunctioning

equipment, human error and even birds. Once in space, the spacecraft can be affected by floating debris,

meteoroids and electromagnetic radiation from coronal mass ejections (solar flares). People and machines are

protected from solar radiation by the Earth’s atmosphere and magnetic field, but these are not present in

space.

Solar Flares: Violent explosions in the Sun’s atmosphere which releases huge amounts of energy and

radiation. The radiation can be harmful to humans and can fry the electrical equipment on

space shuttles and space stations.

RE-ENTRY

Re-entering Earth’s atmosphere also has it dangers (as proven by the Colombia disaster). The re-entry path the

spacecraft takes must be at a precise angle. If it is too shallow it will bounce off the atmosphere and drift off

into space. If it is too steep it will burn-up due to friction caused by the Earth’s atmosphere.

SPACE JUNK

Space junk refers to all the pieces of debris that have fallen off rockets, satellites, space shuttles and space

stations that remain in space. This can include specks of paint, screws, bolts, nonworking satellites, antennas,

tools and equipment that is discarded or lost. Even small flecks of paint can cause a large amount of damage

because things travel at such a high velocity in space.

HAZARDS ON EARTH

Some debris in space will enter the atmosphere and will not totally burn up; landing in populated areas can

cause loss of life or damage to property. Some satellites, or decommissioned space stations, that re-enter the

atmosphere have radioactive parts and can contaminate a very large area, costing a lot of money and hours to

clean it up.

On January 1978 a nuclear-powered Soviet satellite crashed into the Great Slave Lake area of the Northwest

Territories. On re-entry to Earth’s atmosphere, the satellite disintegrated, showering radioactive debris over

124 000 km2

. No lives were lost, but clean up by Canadian and U.S. military personnel took almost eight months

and cost $15 million dollars.

Canadian Contributions

Despite the many risks of space, Canada has had a proud involvement in the development of technology for

space exploration and observation. Many Canadian made technologies have been used on space missions, but

one of its most famous contributions is the robotic arm, the "Canadarm". Since its debut in 1981 on the U.S.

space shuttle Columbia, the Canadarm has proven to be one of the most versatile pieces of technology ever

designed for the space shuttle program. Manipulated by remote control, the Canadarm has helped fix optical

apparatus on the Hubble Space Telescope, and put together modules of the International Space Station.

Without it, more astronauts would have to risk their lives doing the various tasks that the Canadarm was

designed to do.

14 Space Exploration

Space Exploration Issues



ARGUMENTS FOR

Firstly, the resources space has to offer may be able to satusfy our energy needs on Earth for a long time.

Scientists are looking for ways to capture solar energy in space and beam it to Earth. Space is also a boundless

source of mineral resources. The asteroid belt that lies between Mars and Jupiter, for instance, contains

hundreds of thousands of asteroids, which have been found to contain iron, nickel, magnesium, as well as gold

and platinum metals. A single average sized asteroid may contain more than $350 billion worth of mineral

resources.

Second, the cost of space travel could be cut substantially. It costs a great deal of money to transport fuel and

materials from Earth into space. If materials for the construction of space vehicles, supplies, and fuel can be

found where they are to be located in space, costs would be reduced.

Both hydrogen and oxygen can be easily processed from Moon rocks. The hydrogen may be used as fuel for

lunar bases and space travel. The oxygen could be used for breathing. Combine the two and you have a readily

available supply of water. Our Moon is not the only source of material. Phobos and Deimos, the moons of Mars,

could be used to supply shuttles to that planet.

Additionally, discoveries that we have made by exploring space have help us find ways of improving life on

Earth. As discussed earlier, many technologies originally designed for space have been adapted to help the

general public.

ARGUMENTS AGAINST

Debate rages today over the huge amounts of money, time, and resources that are being expended on sending

equipment and people into space. In the United States and Canada alone, the space program costs b i l l i o n s of

dollars every year.

Some people argue that, because there are so many problems on Earth to be solved (such as poverty, hunger,

pollution, and disease epidemics), countries should not be spending huge sums of money to explore new

regions. Instead, that money should go to relieving the suffering of citizens on our own planet.

Political questions center around which country (or countries) would get to be responsible for making decisions

regarding space. Ethical questions center around what is right and wrong when it comes to space exploration.

Environmental questions center around the impacts humans will have on the space environment. The table

below looks at the issues from 3 different points of view (political, ethical, environmental).

Political Ethical Environmental

Who should own space or the different

parts of space? Should it be the most

powerful counties, the countries with the

most people, the countries who have put

the most money into the space program?

Is it right to spend so much on space,

instead of fixing Earth’s problems?

Who is responsible for protecting space

environments from alteration?

Who can use the resources (ex: minerals)

brought back from space? Should the

countries who bring the resources back be

forced to share it or should they keep it

for themselves?

How can we ensure that space resources

will be used for the good of humans and

not to further the interests of only one

nation or group

Who is responsible for cleaning up space

junk and who should pay for doing it?

Who will determine what goes on in

space?

Do we have a right to alter materials in

space to meet our needs?

15 Space Exploration

Data Collection

Optical Telescopes

Look up at a clear, cloudless night sky and you can see a few thousand stars. With binoculars, you would see

thousands more. Use a telescope and millions of stars will be revealed. Use one of the most powerful telescopes

available and billions of stars come into view. Telescopes allow us to see fainter and more distant objects in

detail that cannot be detected by the unaided eye. Two types of telescopes are described in this section. Both

provide us with a variety of information about the objects that make up our universe. Optical telescopes have

been in use for the past 400 years, and CANNOT be used during the day, as the light in the atmosphere is

brighter than the light from the stars.

Optical Telescope: A series of lenses and mirrors which gather and focus the light from stars. The larger the area

of the lenses or mirrors, the greater the ability of the telescope to see the faint light of

objects that are very distant.

REFRACTING TELESCOPES

The first telescope ever designed was a simple refracting telescope.

Refracting telescopes use two lenses to gather and focus starlight. The

lens that light goes through first is called the primary (objective) lens.

There is a limit to how large the lens in a refracting telescope can be. Any

diameter over 1 m causes the glass in the lens to warp under its own

weight, distorting the image

REFLECTING TELESCOPES

Reflecting telescopes use mirrors instead of lenses to gather and focus

the light from stars. At one end of a reflecting telescope is a large

concave mirror (called the primary, or objective mirror), which is

made from glass-like material that is coated with a thin layer of metal.

The metal, such as aluminum, is polished to a shiny finish so that it

can reflect the light it receives. Mirrors can be made much larger than

lenses, which is why reflecting telescopes can be made to see farther

into space than refracting telescopes. In addition, many mirrors can

be put together to form one huge primary (objective) mirror. The largest mirror used in a reflecting telescope is

over 12 meters large.

Although remote mountains make excellent sites for building and operating telescopes away from light

pollution and air pollution, astronomers are still at the mercy of the weather. Clouds, humidity (moisture in the

air), and even high winds can interfere with star-gazing.

Launched in 1990, the Hubble Space Telescope, another type of reflecting telescope, offers a solution to these

problems. Orbiting about 600 km above Earth, it uses a series of mirrors to focus light from extremely distant

objects. The Hubble is cylinder-shaped, just over 13 m in length and 4.3 m in diameter at its widest point, and

orbits the Earth in about 95 min. Even though the primary mirror of the Keck telescope in Hawaii is larger,

Hubble can see farther and clearer than Keck or any other Earth based telescope because the atmosphere

doesn’t disturb the light reaching Hubble in any way.

16 Space Exploration

Star Composition

Isaac Newton passed a beam of light through a prism to produce a spectrum of colors. If you pass the light

through a narrow slit before sending it through a prism (which is found inside spectroscopes), the resulting

spectrum will contain all the colors.

The light from any light source can be split so the colors within that light source can be seen individually.

Scientists used spectroscopes to observe the spectrum produced by the Sun, but noticed dark lines in the

spectrums of light throughout the solar system, called spectral lines. Each particular element has its own unique

spectral lines and will absorb certain parts of the color spectrum if light passes through them.

With this technology and information, the composition of stars, millions of light years away, can be determined.

Stars emit light and the light passes through the star’s own atmosphere, which is made up of various gases.

Certain parts of the light spectrum will be filtered out as the gases in that stars atmosphere absorb those parts

of the spectrum.

Because we know which elements will filter out specific parts of the spectrum, we can determine stars’

compositions by analyzing the black-line fingerprints of the spectrum. We know that hydrogen is the main

component of all stars with helium being the second main component, so the spectrum from all stars will have

the black-line fingerprints of hydrogen and helium. Other elements can be found in some stars but not others,

which has been identified using the black-line fingerprints. The diagram to the right shows how to determine a

star’s composition based on the known black-line fingerprints of the elements.

Star Motion

Johann Doppler is famous for discovering what

became known as the Doppler Effect. When a train

blowing it’s whistle while it is motionless (diagram

1), a person behind it and a person in front of it will

hear the same sound, but if the train is moving

forward (diagram 2) it compresses the sound waves

emitted in front and stretches the ones behind it.

The same thing happens with light (which also travels in waves). Each color has a different wavelength, with the

blue end having higher frequency waves, and the red end having lower frequency waves. When a light emitting

source, like a star, is moving away from us the light waves are lengthened and the light looks more red (called

red shifting). When a star is moving toward Earth, the light waves are shortened and looks more blue (called

blue shifting). We can measure red shift and blue shift by observing the spectral lines of the light from stars.

In the diagram to the right star “x” is motionless when compared to

to Earth. Star “y” is moving away from Earth, as the spectral lines

are shifted towards the red end. Star “z” is moving towards Earth, as

the spectral lines are shifted towards the blue end. The greater shift

you see of the spectral lines, the faster the star is moving either

toward or away from Earth.

Radio Telescopes

Light isn’t the only kind of radiation coming from the stars. Other forms include radio waves, infrared waves

(heat), ultraviolet waves, X-ray waves, and gamma ray waves. Light waves (which can be seen with optical

telescopes) occupy only a small portion of the spectrum (the entire spectrum is seen below). Celestial objects

such as stars emit many types of radiation, including radio waves.

17 Space Exploration

Radio waves are received from stars, galaxies, nebulae, black holes, and even some planets—both in our own

solar system and in others and provide data that is not available from the visible spectrum. These signals are

mapped through the use of sophisticated electronics and computers.

ADVANTAGES

Radio waves, and therefore radio telescopes, are not affected by weather and can be detected during the day

and at night. They are also not distorted by clouds, pollution, or the atmosphere as are light waves.

Furthermore, by focusing their radio telescopes on certain areas of space that appear empty, astronomers have

discovered additional information about the composition and distribution of matter in space—information that

cannot be detected by optical equipment. Using radio telescopes, astronomers have been able to map the

distribution of hydrogen in the Milky Way galaxy. This is how they learned that the shape of our galaxy is a

spiral.

Radio waves have wavelengths that are millions of times longer than light waves, meaning that these waves

give less resolution, but can penetrate dust clouds in the galaxy, where light waves cannot. They can also go

right through clouds not to mention materials like wood, brick and cement (this is why you can get radio

reception almost anywhere). Radio waves can also be picked up during the day so scientists can work at any

time (optical telescopes can only be used at night.)

Having such large waves requires a large object to read these waves. To the right is a radio telescope found in

Arecibo, Puerto Rico that has a diameter of more than 300 meters. Radio telescopes are typically made of metal

mesh and resemble a satellite dish.

Radio waves are not in the visible light spectrum so there is nothing to see. Today, computers can provide an

artificial image which uses color codes for the strength of radio waves.

Space probes

Telescopes, optical or radio, cannot provide answers to all the questions we have about our solar system. Often

it is necessary to send the observation equipment right to the object so that tests not possible to conduct by

telescope can be done. In the past several decades, astronomers have done just that, sending numerous space

probes to explore distant areas of our planetary neighborhood.

Space Probes: Unmanned devices sent to planets or other celestial objects to make observations and

collect data.

When a device takes observations of Earth we call the device a satellite. When a device takes observations of

other planets, asteroids or other celestial bodies we call the device a space probe. Some probes fly by celestial

bodies and take pictures, some will be put in an orbit of celestial bodies and become a satellite for them, while

others actually land on celestial bodies and make observations such as analyzing the soil. All probes are

unmanned.