Horsehead Nebula in Orion

UNIT 5 SPACE EXPLORATION

What technologies have been developed to observe objects in the sky, and what discoveries were made with them?

How has the development of these technologies contributed to the exploration, use, and understanding of space?

How have technologies designed for space science been applied to produce benefits on Earth?

Focussing Questions

Exploring

The first moon landing by Apollo 11 on July 20, 1969, would not have been possible without many prior technological advancements.

Increase in scientific knowledge gained by the moon missions promoted the development of new inventions on Earth for scientific and everyday use.

Exploring

Technology is a tool that helps solve a problem.

Science is one method of acquiring further knowledge.

Technology advances scientific knowledge, and science in turn develops new technology for solving new problems.

Topic 1 For Our Eyes Only

Ancient cultures used the regular cycles of the Sun, Moon, stars, constellations and visible planets to mark the passage of time.

Knowledge was passed on orally or in writing from generation to generation and culture to culture often in the form of legends and folklore.

Finding patterns in time was essential in predicting the changing of the seasons and marking important events in peoples’ lives.

The Big Dipper

What Our Ancestors Saw

Ancient peoples used their eyes, calendars and monuments to track important changes:

Examples– lunar cycles scraped on antler– Stonehenge - summer solstice– Chichen Itza - spring and fall equinoxes– Khufu Pyramid - Thuban (former North Star)– First Nations medicine circles in Alberta - rising of Sirius

Position of Objects in Space

Our reference point for measuring the position of objects in space is usually the Earth.

The two measurements required are:

1) compass direction (azimuth)

North = bearing 00

2) altitude above the horizon (max. = zenith)

horizon = 00

Models of Planetary Motion

The first calendars were lunar (Moon). They were accurate enough for nomadic hunters, gatherers and fisherman.

The settled societies that followed needed more precise solar (Sun) calendars to predict planting and harvest times.

Figuring out how the regular motions of the Sun and Moon fit in with the irregular wandering paths of the five known planets was a puzzle that took thousands of years to solve.

How the Earth fit into this puzzle was also a mystery.

The Geocentric Model

The Ancient Greek Ptolemy first proposed that the universe was Earth-centered. His conclusion made sense given the knowledge and technology of the time and the everyday experience of people.

Ptolemy thought the Sun and five known planets orbited the Earth, while the stars were fixed in place on a domed ceiling called the celestial sphere.

The Heliocentric Model

For thousands of years, math and geometry were the only tools available for studying the universe, but with the development of optical instruments, modern astronomers began to make discoveries that questioned the geocentric model.

In 1530, Nicholas Copernicus made observations that led him to conclude that the Sun was at the center of the universe while the Earth and other planets revolved around the Sun.

The Heliocentric Model

In 1610, Galileo Galilei provided evidence for Copernicus’s hypothesis using a telescope. Wandering planets made sense if they revolved around the Sun along with Earth. He was also able to observe lunar mountains, bumps on Saturn (rings), four moons orbiting Jupiter, sunspots and the phases of Venus.

Observations of planetary motion by Tycho Brahe and mathematical calculations by Johannes Kepler led Kepler to conclude that planetary orbits were elliptical instead of circular. The heliocentric model was now fully developed.

An ellipse is oval or egg-shaped.

The Sun is off center from a planet’s orbital path.

TOPIC 1 READING ASSIGNMENT For Our Eyes Only - Answers

If you look at the sky the sun and moon appear to move across the horizon. These objects rise in the east and set in the west. This motion is caused by the Earth’s rotation. However, as we look in the sky our common sense tells us that the Earth is not really moving. It seems that everything else is moving around our planet. When we make these observations it is because we are using the Earth as a fixed frame of reference.

If you are riding in a vehicle that is moving at a rate of 100Km per hour you feel stationary inside because you do not move relative to the vehicle. When you look out it feels as though the road is moving towards you at a rate of 100 km per hour. If you think this way you are using the vehicle as a frame of reference. A person standing next to the road would be using the Earth as their frame of reference. They would say that you and the vehicle were moving at 100km/h relative to the ground. Each frame of reference is neither correct nor incorrect. They are just two different reference frames – two different points of view.

What Our Ancestors Saw (short answer)

Describe 4 things that ancient peoples learned by watching the celestial bodies in the sky.

1.Stars make unchanging patterns in the sky – they looked like objects and were grouped and called constellations.

2. On successive days a star would rise and set 4 minutes earlier than the day before - different stars would be in the night sky over a period of months.

3. The sun rises and sets at a rate different than the stars The Moon also rises and sets at a rate different than the stars. The moon shows phases.

4. Five other solar bodies rise and set at rates different than the stars – Mercury, Venus, Mars, Jupiter, and Saturn. These special bodies were called planets.

The azimuth (first angle) is measured clockwise from the north. The next measurement taken is the altitude which is the celestial bodies angle (in degrees) above the horizon. The angles that are used to describe the co-ordinates are referred to as altitude-azimuth co-ordinates. These co-ordinates show the position of a celestial body relative to a fixed Earth (as if the bodies were revolving around the Earth). These measurements will change depending on the time of day that they are taken.

Accurate measurements of celestial and Earth objects depend on available technology. An astrolabe is a device that measures the altitude of an object. Te azimuth angle can be measured with a compass.

Sky Co-ordinates (paragraphs)Ancient peoples not only told stories about the celestial bodies in the sky, but they also made attempts to measure the celestial bodies locations in the sky. To do this they would give a celestial body two co-ordinates measured in degrees. In two or three paragraphs describe this process of measurement. Make sure to use the following terms in your description: azimuth, altitude, altitude-azimuth co-ordinates, astrolabe, and compass.

In actuality the stars do not revolve around the Earth. Although the model provided a means of predicting the dates and times when celestial bodies rose and set, it required up to 55 different inner spheres to account for the motions, which was cumbersome, and it was difficult to explain why Mars, Jupiter & Saturn sometimes reversed their direction (retrograde motion).

Models (Questions)1. Knowing what we know about the solar system now, what was the main problem with Aristotle’s earth-centered model.

2. Aristotle’s earth centered model was replaced with the heliocentric model. Why was this model better?

This model more accurately reflects what actually happens with the motion of stars, and our solar system.

Topic 2- Stronger Eyes and Better Numbers

Technology has been used for thousands of years to measure time. Examples include:– sundial– merkhet (Ancient Egyptians) to predict star motion– quadrant (also Egyptian) to measure star altitude– astrolabe (Arabs) to chart star positions– cross-staff (Gurson 1300s) to measure angle between

Moon and stars– first optical telescope (1500s)

Discovery Through Technology As lens grinding technology improved and telescopes became more

powerful, it became obvious that distance and size as we know them on Earth are minute compared to the scale of space and the objects in it.

Earth is a small planet orbiting an average star half- way out on one arm of the Milky Way galaxy. The Milky Way itself is but one galaxy in a local neighbourhood of 20 other galaxies surrounded by billions of others.

Distance & Time in Space

The kilometre is too small a unit to measure the vast distances in space. The two units commonly used are the:

– astronomical unit (AU) for local solar system distances 1 AU equals the average distance between the center of the Sun

and center of the Earth, and

– light-year for interstellar and intergalactic distances1 light-year is the distance light travels in one year

– because the speed of light is 300 000 km/s in a vacuum, a light year is about 9.5 trillion kilometres

Distance & Time in Space

Distance is not the only quantity that is immense in space. If light takes time to travel between two points, then we are actually looking back in time when observing distant objects in space. Given the small distances on Earth, light only appears to instantly move from place to place. In fact, it takes light:– 1 second to reach Earth from the Moon– 8 minutes to reach Earth from the Sun– 5 hours to reach Earth from Pluto– over 4 years to reach Earth from Proxima Centauri, the next

closest star– 25 000 years to reach Earth from the Milky Way’s center!

Birth of a Star

The life cycle of a star can be compared to the birth, growth and death of a living organism.– Gravity pulls gas and dust in a nebula together into a

rotating sphere.– The accumulation of more matter in the core causes the

temperature to rise and possibly start to glow (protostar).– Heating in the core to 10 000 000 0C will cause the fusion

of hydrogen into helium. A Star is born as huge amounts of radiation are given off.

Life & Death of a Star

A star continues to emit radiation for millions or even billions of years.

Depending on its mass, a star can be either:– Sun-like (main sequence in the H-R diagram), or– massive.

A star reaches the end of its life cycle when the supply of hydrogen fuel runs out.

Star Life Cycles

Sun-like Stars– become a red giant in their second stage as the outer layers expand

and cool– become a white dwarf in their third stage as fusion stops and the

remaining material collapses inward– further cooling may create a black dwarf

Massive Stars– become a red supergiant in their second stage– gravity causes them to collapse so rapidly in the third stage that an

outgoing shock wave makes the outer layers explode as a supernova

– supernova remnants form a neutron star or black hole

Star Definitions

red giant - a relatively cool, large-diameter stage of a Sun-like star

red supergiant - a larger-diameter red giant from an aging massive star

white dwarf - a low-pressure, fusion-less collapsed star with a small diameter

black dwarf - the death stage of a Sun-like star supernova - the explosion of a red supergiant following

collapse neutron star - a rapidly spinning star remnant black hole - a dense star remnant not allowing light to

escape

Topic 4 – Bigger and Smarter Telescopes

Adaptive Optics - Latest Advances

The latest advances in telescope design are adaptive optics and multiple mirror interferometry. Adaptive optics involves combining lasers with computers to sense the turbulence of the atmosphere. This information is relayed to machines under the telescope’s objective mirror that distort the mirror to cancel the effect of the atmosphere on the image.

Multiple Mirror Interferometry

This telescope advance combines the images from more than one mirror to create, in effect, a mirror the size of the distance between the mirrors.

TOPIC 5 NOTES

There are many types of radiation that come from stars. The type of radiation that we are most familiar with is light radiation. Other types are:

•radio waves• microwaves• infrared radiation• ultra violet radiation• x-rays •gamma rays

Astronomers use radio waves to tell them things about distant stars. Technology had provided science with radio telescopes – devices that can intercept and track radio wave emissions from far away stars. Radio telescopes gave scientists information about planets that they never had before.

As radio telescope technology improved, scientists were able to match radio signals to the optical telescopes that they had previously used. This resulted in much clearer images of distant stars. Taking this one step further, scientists started linking radio telescopes together. They then processed their images with computer technology in a process called interferometry. This is like seeing with many eyes instead of one.

Topic 6 – Above the Atmosphere and Under Control

Technologies for Space Transport

The greatest challenges in space travel have been:

– achieving escape velocity to break free of Earth’s gravitational force

– designing materials and equipment able to withstand the extreme environment of space

– transporting people out and back safely

Satellite technology is used for many Earth-based applications, including:

– telecommunications

– navigation

– remote sensing, and

– weather forecasting.

Satellites, unmanned space probes and manned

spacecraft need a velocity of about 28 000 km/h, or

11 km/s, to escape Earth’s gravity!

The Achievements of Rocket Science

Early experiments in rocket propulsion included:

- Archytas’s steam-powered pigeon (Ancient Greece)

- gunpowder arrows for warfare (China 1st C A.D.)

- Robert Goddard’s liquid fuel rockets (1920s)

- Wernher von Braun’s V2 rockets (1940s)

- Sputnik I, the first artificial satellite (October 4, 1957)

- Sputnik II, with Laika, the first space traveller (1957)

The father of modern rocketry is

considered to be Robert Goddard.

Along with Konstantin Tsiolkovsky of

Russia and Hermann Oberth of

Germany, Goddard envisioned the

exploration of space. Goddard was a

physicist with a unique genius for

invention.

By 1926, Goddard had

constructed and successfully tested

the first liquid-fuel rocket with a rocket

flight on March 16,1926, at Auburn,

Massachusetts.

Wernher von Braun was one of the first and foremost rocket engineers and a leading authority on space travel. His will to expand knowledge through the exploration of space led to the development of the Explorer satellites, the Saturn rockets, and Skylab, the world's first space station. In addition, his determination led to humans landing on the moon.

The V2 rocket was developed during World War II using a fuel of alcohol and oxygen.

The Apollo 17 capsule making a parachute landing in the ocean in December 1972

Rocket BasicsThree Parts

• mechanical elements (currently about 3% of mass)

- includes rocket, engines, storage tanks, fins

• payload (currently about 6% of mass)

- includes crew cabins, crew, food, water, air

• fuel (currently about 91% of mass)

What is currently the major challenge in rocket design?

TOPIC 6 READING ASSIGNMENT - Key Fill in the Blanks

Rockets were invented long ago and were used for fireworks as well as weapons. A rocket is a tube that contains _combustible_ material______ in one end. On the other end of the rocket is the _payload_____, which is what the rocket will transport. The principle that makes a rocket work is called the _action/reaction____________ principle.

Rockets must have some type of fuel to make them work. The escaping exhaust in the combustion reaction within the rocket is called the _exhaust____ _velocity____. This is one factor that determines how far the rocket will be able to go. The first scientist to launch a liquid fuel rocket in 1926 was _Robert_____ __Goddard___. He also realized that that a _staged________ ___rocket________ would be able to fly higher and faster.A _ballistic____ _missile_______ is a bomb that is powered by a rocket engine.

American and Russian scientists were able to calculate and control orbits by using _computers________. The early outer space flights were controlled by _computers__ on _the ground________________. Eventually technology improved to the point where the craft could be controlled from _within________.

Short AnswerRead the section on “Using Gravity” on page 402. Describe gravitational assist.This is a method of increasing acceleration by using the gravity of a planet. The spacecraft is sent around one planet. Its gravity attracts the craft causing it to speed up and change direction. The spacecraft slingshots away from the planet at a higher velocity.

Tell how the Hubble Space Telescope was put into outer space.The bus sized telescope was aboard the space shuttle Discovery, and was deployed by the astronauts aboard the craft.Describe how the world has become a “global village” of instant communications.With the deployment of satellites in a geosynchronous orbit, we are able to have improved radio and television signals.

ParagraphsRead about Global Positioning Systems on page 407. In a few paragraphs tell how GPS devices work and how they can be now used for non-military applications.Main points to mention:US military deployed many NAVSTAR (navigation satellite tracking and ranging) satellites 20 000 km above Earth.GPS satellites take about 12 hours to complete one orbit.Many satellites in orbit – always at least 3 above the horizonSatellites send out radio signals that tell the exact time and location.Hand-held GPS units use computer technology to calculate distances and locations on Earth.

Future Propulsion Technologies

Finding alternatives to liquid or gas burning fuels would

decrease our reliance on inefficient fossil fuels and the

mass problems associated with storing and transporting

all that fuel.

Possible alternatives for the future include:

1) ion drives (using electrically-charged xenon gas)

2) solar sails (using carbon-fibre sails to absorb photons)

Shuttles, Probes & Space Stations

The International Space Station (ISS) is a modularized

permanent laboratory that will also serve as a base for

building and launching rockets for interplanetary travel.

What are the advantages and disadvantages of building

and launching spacecraft from Earth orbit or the Moon?

The Voyager I and II space probes were launched in 1977

Sounds of Earth recording carried by

Voyager

Image of Saturn by

Voyager 2, 1981

International Space Station

Canadarm2

Living in Space The hazards of space consist of:

– no air (near vacuum) or air pressure– no water– cosmic rays– solar radiation (esp. solar flares)– debris and objects in space– temperature extremes– psychological stress due to confinement and isolation– physical stress due to lack of gravity and exercise

combined with extended time in space

Space Suit Technology Suits must be designed to mimic an Earth environment

capable of sustaining human life for periods long enough to work outside a spacecraft or space station.

What features must be built into a suit?– 1)– 2)– 3)– 4)– 5)– 6)

Space Station Technology Essential features include:

– clean water (electrolysis + recycling nearly 100%)

– breathable air (removing CO2, microorganisms, dust and moisture)

– suitable temperature and air pressure

– a source of power

Meeting Human Needs on Earth How do satellites transmit and receive information from the

ground? Data is relayed using radio waves.

Some satellites, such as those used in weather forecasting, are placed in geosynchronous orbit, which means the satellite moves so it is over the same location at all times.

Other satellites, such as RADARSAT and LANDSAT, monitor global activities such as shipping, soil, fires and potential resources. They are not placed in geosynchronous orbits for these reasons.

A sample satellite

Remote Sensing Satellites can monitor changes in:

– global temperature– soil and vegetation patterns– the atmosphere– industry and urbanization.

• In addition, remote sensing can locate mineral and fuel resources hidden undersea and underground.

Global Positioning Systems (GPS) Twenty-four satellites transmit location data back to Earth

from orbit. 1) What minimum number of satellites would it

take to pinpoint the compass position of an object on the

surface? 2) How many satellites would be needed to

establish the altitude at that same latitude and longitude on

Earth as in 1) above?

HINT: The navigating principle that is also used by GPS technology is called triangulation.

Space Age Systems & Materials Examples

– Computer: virtual reality software

– Consumer: improved bike helmets

– Medicine: digital imaging for detecting cancers

– Industrial: micro-lasers for cutting and melting

– Transportation: improved traction on winter tires

– Public Safety: emergency response robots

Topic 7 The Solar System Up Close

Planet Facts

• The inner planets are smaller and rocky (terrestrial)

Mercury, Venus, Earth, Mars

• The outer planets are larger and gaseous (Jovian)

Jupiter, Saturn, Uranus, Neptune, (Pluto)

Why do the inner and outer planets differ?

Topic 7 - Continued

Other Bodies

• asteroids - rocky, metallic bodies between Mars and Jupiter (Kuiper Belt)

• comets - dirty snowballs of dust and ice that orbit another body in the solar system such as the Sun (e.g. Halley’s comet)

• meteors & meteorites - rocky bodies that do (meteorite) or do not (shooting star = meteor) impact Earth’s surface

• meteoroids = meteors + meteorites

Asteroid Ida viewed by the space probe Galileo enroute to Jupiter.