Types of Radiation from Space

(Physics)

Dynamics and Space

1.3 Space

Name_______________ Class ____

SCN 4-06a

By researching developments used to observe or explore space, I can illustrate how our knowledge of the universe has evolved over time.

SCN 4-16a

I have carried out research into novel materials and can begin to explain the scientific basis of their properties and discuss the possible impacts they may have on society.

SCN 4-20a

I have researched new developments in science and can explain how their current or future applications might impact on modern life.

SCN 4-20b

Having selected scientific themes of topical interest, I can critically analyse the issues, and use relevant information to develop an informed argument.

Content National 4

Satellites

· The range of heights and functions of satellites in orbit around the earth, including geostationary and natural satellites.

· The dependence of period of orbit on height.

· The use of parabolic reflectors to send and receive signals.

· Use of the relationship between distance, speed and time applied to satellite communication.

· Range of applications of satellite including telecommunications; weather monitoring; the use of satellites in environmental monitoring.

· The use of satellites in developing our understanding of the global impact of mankind’s actions.

Cosmology

· Description of planet, moon, star, solar systems, exo-planet, galaxy and universe.

· Scale of the solar system and universe measured in light years.

· Space exploration and its impact on our understanding of the universe and planet Earth.

· Conditions required for an exo-planet to sustain life.

Content Level 4

Dynamics and Space 52 Content Statements

Space exploration

· Evidence to support current understanding of the universe from telescopes and space exploration.

· Impact of space exploration on our understanding of planet Earth, including use of satellites.

· The potential benefits of space exploration including associated technologies and the impact on everyday life.

· Risks and benefits associated with space exploration, including challenges of re-entry to a planet’s atmosphere.

Cosmology

· Use of the term ‘light year’ and conversion between light years and metres.

· Observable universe — description, origin and age of universe.

· The use of different parts of the electromagnetic spectrum in obtaining information about astronomical objects.

· Identification of continuous and line spectra.

· Use of spectral data for known elements, to identify the elements present in stars.

Content National 5

.

Dynamics and Space 53 Content statements

At National 4 level, by the end of this section you should be able to:

Cosmology

1.List the risks and benefits associated with space exploration and challenges of re-entry to a planet’s atmosphere.

2.Describe the use of thermal protection systems to protect spacecraft on re-entry.

3.Provide descriptions of the following; planet, moon, star, solar systems, exo-planet, galaxy and universe.

4.State the scale of the solar system and universe measured in light years.

5.Describe the impact of space exploration on our understanding of the universe and planet Earth.

· Research developments used to observe or explore space and illustrate how our knowledge of the universe has evolved over time.

6.Describe the conditions required for an exoplanet to sustain life.

Additionally, at National 5 level:

7.Describe the term ‘light year’ and use the conversion between light years and meters.

8.Provide a description of the observable universe and know the origin and age of the universe.

9.Describe the use of different parts of the electromagnetic spectrum in obtaining information about astronomical objects.

10.Identify continuous and line spectra.

11.Identify elements present in stars from the use of spectral data for known elements.

Learning Outcomes - Cosmology

Dynamics and Space 4/54 Learning outcomes- Cosmology

(Planet and moons do not make their own light, they reflect light from the sun.planets orbit the Sun.planets are roughly spherical/ball shaped.moons come in many sizes, but always orbit a planet.planets and moons produce their own gravitational field)

Stars – what are they? (s)

(Stars produce visible light (plus every other type of electromagnetic radiation) by nuclear fusion reactions.they are large, massive, balls of gas, mostly made of hydrogen and helium.)

Planets and Moons

Dynamics and Space 46 Cosmology

Our Solar System (Our solar system consists of our star (“Sol”, the Sun) plus the 8 planets, lots of moons, comets and asteriods.In order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.Mercury and Venus have no moons. Earth has one. The others have many moons.The four “inner planets” are rocky and dense. Planets nearest the sun are warmer.The four “outer planets” are gas giants, with cooler atmospheres.All these planets have atmospheres except for Mercury.) (It is the distance travelled by light in one whole year.1 light-year is usually written as 1ly for short.The nearest star to the Sun is 4.2ly away (Proxima Centauri).)

Light year Equivalent in Metres

(Calculate the distance in metres, that light travels in one year. The speed of light in vacuum is 300 000 000m/s..Distance = speed x time = 300,000,000 x 365 x 24 x 60 x 60 = 9,460,800,000,000,000= 9.46 x 1015m)

Distances in Space

Time for light to travel from the sun to Earth – 8 minutes

Time for light to travel to Proxima Centuri - 4.22 years

(nearest star to Earth other than the sun)

Time for light to travel to the edge of the Galaxy – 100,000 years

Definition of a light year

(Booklet 3 – P 10 Q 1 – 10, P 12 Q 1 - 8)Dynamics and Space 47 Cosmology

(This graphic shows our galaxy, the Milky Way. It is roughly 100,000 ly across.Our galaxy has a spiral shape with a bar at the center.Others shapes like rugby balls also exist.Galaxies typically contain about 100 billion stars each.Galaxies are held together by their own gravity)

Exoplanets and Life Beyond Our Solar System (An exo-planet is a planet orbiting around another star (not our Sun). To support life-as-we-know-it, an exoplanet must be not too hot or too coldhave liquid waterhave air with oxygen in itbe rocky (not a gas giant))

The Age of the UniverseOur Milky Way and other Galaxies

(Cosmologists estimate the age of the universe to be around 14 billion years, since the “Big Bang”.The idea of the Big Bang is that there was a hypothetical violent explosion that created the universe. The theory states that all the matter and energy of the universe was once an unimaginably dense mass and that the universe has been expanding from the explosion of this mass ever since.Evidence for the Big Bang is that we can see that the universe is still expanding as stars get further apart.)

(Booklet 3 – P 7 Q 1 – 20, P 9 Q 1 - 18)Dynamics and Space 49 Cosmology

(Simply, this is the part of the universe that we can see now, from Earth.)

How do we Explore Space?

(There are 3 main ways to explore space:By observing. This is astronomy.Sending humans on rockets. We have visited near Earth orbit and the Moon only.Sending robotic probes. Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune have all been visited by robotic probes. )

(When a spacecraft re-enters the atmosphereit slows down due to friction with the atmosphere.The friction also causes it to heat up.This is potentially a very dangerous part of a space mission.)Re-entry to atmosphere

The Observable Universe

Satellites

1.Describe the range of heights and functions of satellites in orbit around the earth, including geostationary and natural satellites.

2.Describe the dependence of period of orbit on height.

3.Describe the use of parabolic reflectors to send and receive signals.

4.Carry out calculations involving the relationship between distance, speed and time applied to satellite communication.

5.Describe the range of applications of satellites including telecommunications; weather monitoring; the use of satellites in environmental monitoring.

6.Describe the use of satellites in developing our understanding of the global impact of mankind’s actions.

Learning Outcomes - Satellites

Dynamics and Space 410 Learning Outcomes -Satellites

(Any projectile follows a curved path.)

(If you fire a projectile with greater velocity it will travel further.)

(Newton’s Thought ExperimentNewton thought that if it were possible to fire an object from a very large cannon with enough velocity it would fall towards Earth at the same rate as the Earth falls away.The object will orbit Earth.This is how satellites work.)

Newton’s Thought Experiment

Dynamics and Space 413 Satellites

( A satellite is an object which orbits a planet. The Moon is an natural satellite. )

(Communications – used to transmit radio and tv signals as well as mobile phone signals across the world.Weather forecasting – Used to track the progress of weather fronts round the globe. Can predict where hurricanes may make landfall.GPS/ Navigation – Used to locate the position of cars, boats and planes. This can be useful in locating good fishing areas. A satellite navigation system receives radio signals transmitted by satellites in orbit around the Earth. The satellite navigation system finds it location by calculating the distance the transmitted signals travel.Security/Spying – Used to watch for potential hazardous situations arising.Monitoring changes – Ice Floes/COs/ Ozone Layer - used to monitor the changes over time caused by the changes in the environment.)Uses of Satellites

Satellites

(The time it takes a satellite to make one complete orbit of Earth.The higher the satellite orbit the longer it takes for one complete orbit)

Geostationary Satellite

(A satellite which appears to stay in the same place, relative to Earth, all the time.Period = 24hours)

Satellite Transmitter

(Signals sent out from central transmitter hit the dish and bounce back in a parallel beam so that they can be aimed at the satellite.)

Satellite Receiver

Period of a Satellite

(Weak signals are collected over a large area, then reflected to a central point. This makes the received signal stronger.)

(Example 51A satellite is at a height of 150km. If the signal travels at 300,000,000m/s, how long will it take for the signal to travel from one ground station to the other?Total distance travelled = 2 x 150,000 = 300,000 mTime = distance/speed = 300,000/300,000,000 = 0.001s) (Example 50In addition to the speed of the signals, what other quantity must be known to calculate distance? Time) (B) (A)

Signals are sent from ground station A to the satellite.

The satellite receives, then retransmits the signal.

Ground station B receives the station.

Signals can travel in either direction.

If the satellite is geostationary the communication link is available 24 hours a day.

If the satellite is in a lower orbit it will be visible less often because it is not always over the same part of the Earth the whole time.

Intercontinental Communication Using Satellites

(Booklet 3 – P 28 Q 1 - 15)Dynamics and Space 414 Satellites

(Weight is a force which pulls us down towards the ground – we are aware of our weight because of the ground pushing back on our feet.If the ground falls away from you at the same rate as you fall towards the ground you experience weightlessness.If you are a long way away from a planet the gravitational force of the planet would be so small that you feel weightless.In the Space Station astronauts are weightless because they fall at the same rate as the Space Station falls round Earth.)

(Example 52On Earth an astronaut has a weight of 550N. What is her weight in the Space Station?0N) (Example 53On Earth an astronaut has a weight of 550N. What is her mass in the Space Station?W = mg => m = 550/10 = 55kg)

Freefall and Weightlessness

Dynamics and Space 515 Newton’s Laws

Space Exploration

1.List evidence that supports our current understanding of the universe from telescopes and space exploration.

2.Describe the impact of space exploration on our understanding of planet Earth, including the use of satellites.

3.Describe the potential benefits of space exploration including associated technologies and the impact on everyday life.

4.Describe the risks and benefits associated with space exploration, including challenges of re-entry to a planet’s atmosphere.

Learning Outcomes - Space Exploration

Dynamics and Space 5 16Learning Outcomes - Space Exploration

(Space Exploration has risks – so far 18 people have lost their lives during spaceflight missions. A further 11 people have died during training.In comparison over 200 people were killed in road traffic accidents in Scotland in 2010. Although Space Exploration is dangerous astronauts go through extensive training to help them deal with whatever situations they find themselves in. The benefits to society includeIncreased aviation safetyKnowledge about the moon Increased knowledge about how Earth was formedNew materialsNovel uses of existing materialsNew technologyAn opportunity to try experiments in zero gravity)

(One of the most dangerous aspects of space flight is getting back to Earth.When a spacecraft comes back into the atmosphere it slows down due to friction between the spacecraft and the air particles in the atmosphere.The work done by friction is converted to heat energy, which causes the spacecraft to heat up. This can be as much as 1300⁰C.To protect the astronauts special materials are used which prevent heat transfer into the spacecraft.)Re-entry to atmosphere

Risks and Benefits of Space Exploration

(Booklet 3 – P 13 Q 1 – 3, P 14 Q 1 - 5)Dynamics and Space 5 17Space Exploration

(When a parachutist (or other object) falls they accelerate because gravity pulls them downwards.As they get faster the air resistance increases until the forces are balanced.When the forces are balanced they travel at constant speed. This is called their terminal velocity.) (Air resistance)/kg⁰)

(Air Resistance)

(Weight)

Terminal Velocity (Speed) (Weight) (time) (0) (When a parachute is opened there is a greater air resistance, so the person slows down.Eventually the force acting on the person are balanced.When the two forces are balanced they again travel at constant speed. This is their new terminal velocity.)

Dynamics and Space 5 18Space Exploration

(All parts of the electromagnetic spectrum can be used in astronomy.Remember, starting with the lowest frequency, the components of the spectrum are:Radio, Microwaves, Infrared, ROYGBIV, Ultraviolet, X-Rays, Gamma.As the frequency increases, the energy of the radiation also increases.This means that gamma ray telescopes (for example) pick up more astronomically violent events (like supernova explosions).Because the Earth's atmosphere protects us from dangerous UV, X-ray and gamma radiation, we have to observe these frequencies from Earth orbit.)

(All electromagnetic waves (in a vacuum) travel at 3 x 108 m/s (speed of light))

The Electromagnetic Spectrum in Astronomy

Dynamics and Space 5 20Space Exploration

When white light is passed through a prism it forms a spectral pattern

(R – RedO - OrangeY - YellowG - GreenB – BlueI - IndigoV - Violet)

(White light)

When white light is passed through a prism it forms a spectral pattern

(Objective Lens - Large to allow lots of light to enter the tube.Eyepiece Lens – allows the observer to focus on the image produced by the Objective LensLight tight tube – keeps out light from surroundings.)TelescopesWhite light

(Objective lensEyepiece LensLight tight tube)

(Radio telescopes tune into radio waves from space. Signals detected are turned into images using a computer. To produce a sharper, more detailed, image a number of smaller telescopes can be joined together to make a ‘Very Large Array’ (VLA).Radio astronomy has led to the discovery of new types of star such as Quasars in the 1950’s and Pulsars in 1967.)

(Parkes Observatory, NSW, Australia)

(Very Large Array, New Mexico, USA)

Radio Telescopes

(A line spectrum consists of a complete (continuous) spectrum with certain colours missing which appear as black line in the spectrum.Every element produces a unique line spectrum. Studying line spectra allows theelements present in a light source (e.g. a star) to be identified (this can allow the type, distance, age or speed of a star to be identified))Radiations from Space

Dynamics and Space 5 21Cosmology

(Example 54Some spectral lines of radiation from a distant star are shown below. The spectral lines of a number of elements are also shown. Use the spectral lines of the elements shown to identify which of these elements are present in the distant star.Cadnium and Mercury, Triple group at right are missing for CalciumSecond double group for Krypton are missing – just!)

Radiation from Space

(Booklet 3 – P 35 - 37)Dynamics and Space 5 22Cosmology

(The Earth’s atmosphere and magnetic field protect us from most harmful radiation from space.The Sun, other stars, supernovae explosions are all producing high energy radiation.Gamma rays are the most energetic, high frequency parts of the electromagnetic spectrumCosmic rays are fast moving particles, mostly protons and electrons, but some antimatter too. Cosmic rays are NOT part of the electromagnetic spectrumNeutrinos are particles having no electrical charge and almost no mass. They are produced in vast numbers by the nuclear fusion reactions in the Sun’s core. They mostly pass straight through our entire planet (and us).)

(Booklet 3 – Revision P 37 Q 1 - 6)Dynamics and Space 5 23Cosmology

high frequencylow frequency

gamma

rays

X-rays

ultra-violet

rays

infrared

rays

micro-

waves

TV & radio

waves

visible

useful in communication and

heating

useful in medicine and

industry

invisibleinvisible

long wavelengthshort wavelength