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SPU 30 - Midterm
Aerospace Engineering

Additional Aerospace Engineering Flashcards




How is an element defined?

By the number of protons in atom.


(there are 90 stable elements)

How is an isotope defined?

By the number of neutrons in the atom


(there are 266 stable isotopes)

Give the definiton of the periodic table
"Analytical description of all species of mineral or biological origin."

What are the 2 main sources of the origins of elements?


Which elements did each one produce?


(how long ago?)

  1. The Big Bang
    • 13.7 ga = 13.7 billion years ago
    • Produced Hydrogen (H), Helium (He) and a tiny amount of Lithium (Li)
    • "H, He & Li were synthesized ~ 13.7 Ga ago"
  2. Stellar cooking
    • Stars transform hydrogen and helium (H & He) into everything else
    • Each generation of star forms more elements
    • The more elements you have the more likely life is
    • When the stars explode, elements are thrown around the universe
What are Kepler's 3 laws?
  1. Planets move in elipses 
  2. Planets must move over equal area for equal time:
  • Planets in orbit have to carry the same amount of area in the same amount of time
  • Which means the planet is moving  fastest when it is closest to the star on the ellipse
3. p^2 is proportional to a^3 but only if p is in years, and a is in AUs
  • p = the period it takes for the planet complete one orbit (measured in years)
  • a = the distance of the semi-major axis (that is, half of the major axis) - MEASURED IN AUs
What are Newton's 3 Laws?
  1. An object in motion tends to stay in motion; an object at rest tends to stay at rest – (momentum)
  2. Force = Mass x Acceleration
    • F = ma
  3. Every action has an equal and opposite reaction, meaning that when you apply a force, an opposite force is also applied
    • If you push against a wall then the wall there is an equal and opposite force pushing back

What is the law of universal gravitation?


When the distances between the 2 masses increases, what happens to  gravity?


F = force (which in this case, is GRAVITY)

M = mass

d = distance between them

G = Gravitational Constant


"The force of gravity is equal to the gravitational constant, G, multiplied by the product of the 2 masses involved e.g. 2 planets (M1 x M2) divided by the distance between those 2 masses"


When the 2 masses are FAR APART (i.e. distance increases) the force of gravity is lower

How does the sun (in fact, all stars?) form?
  • The sun (and all stars) form from gas "clouds" that collapse under their own gravity

How did the earth (and all planents) form?



The earth (and all planets) form from leftover gas and dust orbiting a newly-formed star in a flattened disk


A planet can only form from a destroyed star


The flattened disk is called a "proto-plantary disk"


What is a proto-planetary disk


Why is it important?


The flattened disk made up of:newly formed planets, dust and gas, that orbit a newly-formed star

  • So remember:
    • It's a disk
    • It's made up of newly-formed planets
    • It orbits a newly-formed star


Proto-planetary disks are important becasue they illustrate the Conservation of Angular Momentum:



DEFINE: Conservation of Angular Momentum


What phenomenon does conservation of angular momentum help explain?

  • Conservation of Angular Momentum:
  • Explains how planets act in orbit around star
  • Angular momentum is conserved (like all momentum – remember Newton's law 2) unless acted upon by an outside force
  • Therefore, when the radius gets smaller, momentum speeds up
What the 3 conditions under which the Kepler's law applies?
  1. P must be in years
  2. A must be in AU
  3. The objects in question must be orbiting OUR SUN

Newton's form of Kelper's 3rd Law


Why is Newton's version more useful?

  • Kepler's has very specific conditions (years, AU, sun)
  • Newton's is more general
  • Newton's is more precise
  • Includes a dependence on mass that Kepler's does not
  • As such, Newton's version can be used to calculate the masses of objects orbiting other stars (so not just our solar system)
  • Why are meteorites considered useful (in the context of SPU-30?)
  • Meteorites preserve evidence of the early events in the formation of the planets

When the earth did the form?


How many years after the sun was this?

  • The earth formed about 4,530 million years ago
  • This was ~30 million years after the Sun

Radioactive Decay...

Explain in one sentence why it's important


"Radioactive decay is a reliable chronometer"



What's the word to describe earth's interior?



Describe the earth's differentiated interior


(4 parts)

  • 1) Solid iron core
  • 2) Covered by a liquid iron core shell
  • This whole core (i.e. both the solid and the liquid part = the core) is half of the earth's radius
  • 3) Above the core is the mantle, which is defined by slow, convected currents
  • 4) Above the mantle is the solid crust (thin)
What do Earthquakes and Seismic Waves allow us to do?
  • Earthquakes and Seismic Waves allow us to map the interior of the earth (i.e. see the different layers - core, core shell, mantle, crust)
Explain plate tectonics (2 steps)
  1. The crust is broken up into several plates
  2. The mantle convective currents cause these plates to move:
  • Rub against each other
  • Collide
  • And subduct under each other



How many types of atmosphere did the earth once have?


What is the composition of today's atmosphere? (%)

  • Earth had 3 types of atmosphere
  • Today's composition: 
    • Nitrogen, N2 (78%)
    • Oxygen, O2 (21%)

Formation of the solar system


(3 steps)

  1. The sun formed first
  2. Flattened debris disk (proto-planetary disk) circled the sun 10 million years ago
  3. Small clumps of debris coagulated to form planets 

Formation of the earth


How many years ago did it happen?


Which event marked its completion?

  • The earth formed 4.53 ga (billion years ago)
  • It was formed by the agglomeration of solid materials (random space dust shit)
  • It was completed with the formation of the moon, after a mars sized planet impacted the proto-earth
Define: Habitable Zone
  • A region where planets have the right amount of sunlight for liquid water on their surface
  • Earth is in the middle of this region

The Frost Line


Where does it start?

What characterizes the Frost Line?

Which compounds freeze?

  • Frost line conists from Jupiter on out
    • ~2.6 AU from the sun
  • At this distance from the sun, the compounds H2O, CO2, methane (CH4) and ammonia (NH3) begin to freeze so there
  • Defining characteristic: is high ice content compared to the region closer to the sun

Gas Giants

  • What is the name of the process that forms gas giants?
  • What about the gas giants' location allows them to grow?
  • What allows them to continue growing?
  • Gas giants are formed by a process called runaway growth
  • Because Gas Giants form outside the frostline – where there a lot of frozen H2O CO2 CH4, NH3, the giants "gain ices"
  • This additional mass means the Gas Giants have enough gravity to then hold onto abundent H + He.
    • So, they gather all the H and He and grow even bigger

Define: Tidal Heat


Explain process


Why is important (in relation to the course)



  1. When two bodies circle each other, the gravity can generate a "tidal bulge":
    • E.g. earth and the moon – the earth has water but the moon does not. So the effect is only on the earth
  2. The "tidal bulge" repeatedly deforms the object (e.g. earth)
  3. This generates heat by friction
  4. This heat can create pockets of warmth for life  which are outside of the habitable zone
What are the 3 possible ways that there will exist in the solar system enough heat for life to exist?
  1. Radiant heat from the parent star – which creates the habitle zone (i.e. the earth's proximity to the sun means there is enough heat)
  2. Planetary interiors: radiactive & core heat from within the planet
  3. Tidal heating – friction creates "pockets of warmth" in which the life can exist



What dat?


Why's it important




  • A moon of jupiter
    • with rocky core
    • ice mantle
  • But, because of tidal heat, is expected to have a large liquid water ocean between the ice and the rock
  • Europe is important because its outside of the Frost Line but because of tidal heat it has the potential for water – potential for life?



  1. What is it?
  2. What's significant about it?
  3. Which mission discovered this?
  • A moon of Saturn
  • Tidally driven geysers of water vapor at its south pole
    • A geyser means that water vapor is being pushed up from within the moon
    • Which means that there is water beneath the surface
    • The presence of water is again the result of tiding heating
  • Discovered by the Cassini Mission





What is it?

Which mission explored it?


Why significant?


Which two compunds is the atmosphere compsed of?


What is Titan "abundant in"




  • Largest moon of Saturn
  • Also studied by the Cassini mission / Huygens lander
  • Liquid methane (CH4) and rain, lakes, river channels:
    • Evidence of atmosphere convection
    • Atmosphere is made up of nitrogen (N2) and methane (CH4)
  • Titan is abundant in organic material

Using the relative dating by saying which layers of sedimantary rocks were put down first


Which were put down first?

Using the relative position of these rocks


Carbon dating on those rocks

How old are the earliest earth rocks?
3.5 billion years old

Geological evidence of life



  1. Microfossils – preserved remains of single-celled organisms (different from a macrofossil e.g. dinosaur)
  2. Molecular fossils –preserved remains of molecules (mainly lipids, because lipids degrade much more slowly than DNA, or proteins)
  3. Stro-mat-o-litesmats of microbes in shallow seas which form small towers of hardened material
  4. C and S isotopic signatures
    • An element can have multiple stable isotopes
    • So if you have 2 stable isotopes there is  a slight mass difference
    • Because of the difference in mass, living matter incorporates the 2 at slightly different rates
    • This can lead to preserved isotopic evidence in rocks, which can tell you if life existed
3 ways in which Mars is different from Earth
  1. Smaller
  2. Thinner atmosphere
  3. Further away from the sun

This means that it cools quickly, so any water would be frozen. It's not warm in the middle.


Evidence for water in the past on Mars:



  1. Dry River Channels (self-explanatory)
  2. Hematite – a mineral that forms mainly in the presence of liquid water, which is in the shape of...
  3. "Blueberries" – technically known as Concretions, which also only form via liquid water (as they do on Earth)
  4. Jarosite – another mineral that forms only with liquid water
  5. Sandstones – which contain evidence of water erosion, as opposed to wind
  6. Wave ripples – sedimentary patterns that indicate that they were created as sand ripples under liquid water
Space missions to Mars
  • Viking landers in the 1970s
  • Pathfinder was the first
  • Currently: Mars exploration Rovers:
    • "Spirit" and "Opportunity"
What is the universe made of? (%)
  • 73 % dark energy
  • 23% dark matter
  • 4% atoms

Remember 4% then subtract 2 from both parts of the 25/75 split

What is the difference between dark energy and dark matter?
  • Dark matter is what the universe is filled with
  • Dark energy is the mysterious force that is causing the universe to expand
    • Energy = expansion
Which part of the periodic table determines how an element bonds, reacts and behaves?

The column

which is also known as the "group"

What is an ion?

An ion is an atom with a net charge


in other words, an atom that has more or less electrons than protons

Periodic Table
  • Elements are listed by number of protons
  • The column or "group" determines how an element bonds, reacts & behaves
The notation for atoms

1s2, 2s2,


  • In terms of notation:
    • the first number is determined by which ROW it is in
    • the letter by its column (first 2 columns = S)
    • and second number by which column its in (i.e. how many electrons in the outershell)
  • The first number: the first shell -- known as the "energy level"
  • Letter:"orbital"
    • The first 2 columns are S, after that it's P
  • Second number: number of electrons

Preferred Ionic State



  • Atoms "want" to have 8 valence electrons
  • In other words, they want to have 8 electrons in their outer shell:
  • In order to do this, they can either:
    • gain electrons to go up to 8
    • lose electrons to go down to 8
  • Elements with 8 electrons in the outershell are found in the the "noble gas" column of the table
  • Atoms want to shit into this column

3 Types of Star


What color is each?

Which category does our sun fall into?

How does each one end?

  • M: Small, red, cooler, very numerous
  • G: Medium, yellow, like our sun – end in a modest "regular nova"
  • O: Supergiants, red, extremely massive, rare, end in supernovae

The first 18 elements


Which direction do you read these?


Harry, He Likes Beer, But Cold, Not Over Frosty.

Ned's Natty Mg, Always Silences People's Social Clamour, Around.


Hydrogen, Helium, Lethium, Berilium, Boron, Carbon, Nitrogen, Oxygen, Florine, Neon, Sodium, Magnesium, Aluminum, Silicon, Phospherus, Sulphur, Chlorine, Argon


These read ACROSS the periodic table from right to left

Covalent Bonds
  • Covalent bonds:
  • Refers to atoms which share electrons with one other
  • Important because, almost all organic material is made from covalent bonds:  cells, proteins, DNA, the air we breathe - etc. are made up of covalent bonds
The noble gases

Noble gases

  • Noble gases have a filled valence shell8 electrons in the outer shell – and so they are very stable and do not react
  • The elements in the 2 columns nearest to the noble gas common – just before it, or just after it –  are the most reactive, because they just need to gain 1 electron or lose 1 electron







  • Meteorites from Mars which are found on earth
  • They suggest that life can move between planets
    • Why? Because we can still find evidence of living things that once existed on these meteorites
Radiometric dating

A way to measure the age of geological artifacts


  • Radioactive isotopes decay expontentially over time – a constant rate of decay
  • We can measure how much of a particular radioactive isotope is left in a geological sample
  • We know the half-lives of particular isotopes, therefore by figuring out how much is left, we can figure out how long the isotope has been decaying
Ionic bonds

Remember ions? Ions are charged atoms (they have more electrons than protons, or vice versa). They are either positively or negatively charged

  • Proton = positive
  • Electron = negative
  • Ions of opposite charges, such as Na+ and Cl-, are electrically attracted to each other
  • Na+ plus Cl- = NaCl
Radioactive isotope
  • An element defined by the number of protons it has
  • An isotope is the same element – so it has the same number of protons – but a different of neutrons in its nucleus
  • Radioactive isotopes are unstable and decay exponentially, which makes them useful for dating
What is the difference between mass and weight?

Cosmic Microwave Background




Radiation leftover from the big bang.

  • The CMB
  • motion of galaxies away from us
  • and relative abundance of H and He, are each evidence of the Big Bang
Major steps of universe evolution
  1. Big Bang > H, He, Li
    • Evidence?
      • Cosmic Microwave Background (CMB)
      • The motions of galaxy moving away for us
      • Relative abundance H and He
  2. Creation of 1st generation stars: 
    • Big cloud of gas and dust starts contracting under the weight of its own gravity
    • Conservation of angular momentum flattens the gas into a disk – protplanetary disk
    • Early star at the center
    NO PLANETS YET – the elements of which they are made have not yet been made
    • Stars transform H + He via fusion – also known as stellar cooking, to create all the elements up to iron. 
  3.   As time goes on (millions of years), the elements within the start to stratify:
    • iron at the core, shells of different materials around that --
    • hydrogen on the outside
  4. When the star gets really old, the Fe core gets to be a significant size -- it gets cold because there’s no energy, and that creates pressure and a collapse - star explodes!

    o      Then the outer layer of the star ends up flying out

    o      What we see is a giant explosion

    o      The debris goes flying into space - carbon, oxygen etc.


  5. 2nd generation stars – same deal
  6. 3rd generation stars – like our sun: 
    • Same process: conservation of angular flattens the gas and dust into a disk with a proto star in the middle
    • Solar system: 4.55ga years ago
    • The dust in the disk starts colliding and agglomerating into larger particles
    • Grows into embryos
  7. The formation of earth:
    • Mars-sized body crashed into the earth, forming the Moon.
    • 30ma after the creation of the sun
Planetary Differentation

Differing size

Smaller = colder interiors

Distance from the sun also


Evidence for universe formation / solar system formation


(Observational evidence)

  1. Cosmic Microwave Background radiation:
    • leftover radiation from the big bang
  2. Direct astronomical observation which show current protoplanetary disks around young stars
    • Same process, happening still
  3. Analysis of Meteorites – were formed in the early "agglomeration" process and are still around
    • They can be radiometrically dated
    • The dates of these meterorites is consistent with the story of the solar system

Characteristics of young Earth


Also known as "Hadean Earth"

  1. Surface – molten surface with no crust because it was still hot
  2. Continents were arranged differently because plate tectonics
  3. Atmosphere was different – much less oxygen
Mantle and convective currents
  • The mantle the is one level down from the crust
  • The mantle is characterized by its convective currents
  • The crust is broken up into several plates
  • These convective currents cause the plates to move, rub against each other, collide etc.
Evidence for water on Mars

Remember there are two types of evidence:

  1. Present frozen: Mars has significant amounts of H2O at or near its surface
    • In its ice caps
    • Below the surface as permafrost
  2. Past liquid: (for which there is evidence)
    • Dry river channels
    • Hematitemineral that forms in the presence of liquid water
    • Concretions i.e "Blueberries" – only form via liquid water. Concretions are a type of hematite
    • Jarosite – another mineral that only forms with liquid water
    • Sandstones – the grain sizes suggest water erosion, rather than wind
    • Wave ripples – sedimentary patterns suggest that they were created as sand ripples under liquid water that was a few metres deep
Evidence of early life on earth:
  1. Microfossils: preserved single-celled organisms
  2. Molecular fossils: Lipids that degrade slowly (billions of years)
    • STRE/STER- EXAMPLE = streols degrade into steranes, which are found in rock layers
    • -ols into -anes
  3. Strom-at-o-lites: mats of microbes can be found today in:
    • they form small towers of hard material
    • ancient rocks
  4. C+S fractionation: Elements can also have multiple stable isotopes e.g. Carbon 12C (stable) vs. 13C (stable) vs. 14C (radioactive):
    • Living matter incorprates the two at slightly different rates
    • Therefore there is isotopic evidence in rocks that can tell you whether life existed when the rocks formed
Kuiper Belt and Oort Cloud

Beyond the frostline (beyond Jupiter)


Contains small icy bodies, condensing

Which elements do supernovae create?
  • Everything up to uranium
  • So importantly, supernovae are the only way to create Iron to Uranium
  1. Smaller size:
    • Colder core
    • Heat can escape more easily
  2. Colder core means that a planet's core will be undifferentiated
  3. Distance from the star:
    • Further = colder > not in the Habitable Zone so there is not enough sunlight for liquid water on the surface
    • Further = loses its atmosphere (weaker gravity)
  4. Past the frost line:
    • If they are past the frost line, they can accumulate large mass through runaway growth – i.e. The Gas Giants

Basic atmospheric compositions of:

  • Early Earth (Hadean Earth)
  • Modern Earth
  • Mars
  • Titan
  • Early Earth (Hadeon Earth)
    • CO2, H2O, SO2, N2
    • Carbon dioxide, water vapor, sulphur dioxide, nitrogen
    • Remember the two "dioxides"; the other 2 are obvious
  • Modern Earth:
    • 78% nitrogen (N2)
    • 21% oxygen (O2)
  • Mars:
    • CO2

    • Traces of noble gases

  • Titan (Saturn moon):
    • Nitrogen (N2)
    • Methane (CH4) -- has liquid methane rain, lakes and river channels

Hadean Earth


How many years ago?


Characterized by what?


What was its atmosphere?

  • 4, 430 – 4,000 million years ago
  • Heavy bombardment epoch
  • Outgassing: as a result of the young earth being really hot, made up of molten rock
  • Oceans


  • CO2, H2O, SO2, N2

Radionuclide systems



Parent/daughter/half life etc.


Used in radiometric dating


Half-life: The time taken for a given amount of a radioactive substance to decay to half of its initial value


The half-life for each radionuclide system will always be the same because the rate of decay is constant


Radioactive decay (gamma): each rate of decay has a specific constant.

  • The "parent" decays
  • The "daughter" is produced

The graph: y-axis is goes from 0.0 to 1.0 representing the sample. The x-axis is time. 


For the parent (which decays): the curve goes left to right, top to bottom.

  1. 1.0 > 0.5
  2. 0.5 > 0.25
  3. 0.25 > 0.125
  4. 0.125 > 0.0625

For the daughter (which develops): the curve from left to right, bottom to top


The order of the planets (starting with closest to the sun)

My Very Extravagant Mother Just Sent Us Nachos
Radionuclide systems: what each is most useful for
  • Carbon dating for organic material
    • Lots of C14 in the atmosphere because of cosmic rays
  • Uranium 238

Main point is that "radioactive decay is a reliable chronometer"

Considerations for radiometric dating
  1. anticipated age of speciment similar (but not less than) the half life
  2. is there parent nuclide in the sample?
  3. radiometric clock starts running when rocks solidfy and tissue dies
  4. Re-melting of rock will reset its clock:
    • Zircons are the exception: they retain their clock age after heating
Layout of our solar system
  2. Frost Line – Jupiter and beyond
  3. Habitable zone – essentially just earth

Facts about the solar system (which Kant saw as a clue to the origin of the solar system):

  1. All planet's orbits are in the same plane
  2. All planet's orbits are almost circular
  3. All planets move in the same direction
    • And so does the sun
which formula would you use to calculate the a planet's average distance from its parent star?

start with Newton's version of Kepler's 3rd law

  • p must be in years
  • a must be in AU
  • And also mass 1 is much larger than mass 2:
    • M1 >> M2

  • Then use the momentum formula
Calculate density of a planet

Density = Mass / Volume


You are likely to have to calculate the mass using Newton's version of Kepler's, so that calculation would come first






What are the units required for Newton's-Kelper's-3rd for:

p =

a =

M =


Match the units to those used in the Gravitational constant equation:


p = seconds

a = metres

M = kg


It is very likely that you will have to convert the given information into the appropriate units


a) How do you convert from minutes to seconds?


b) How do you convert from hours to seconds?


b) How do you convert from days to seconds?


c) How do you convert from years to seconds?




a) N minutes x (60 / 1 minute)


b) N hours x (3600 secs / 1 hour)


c) N days x (86,400) / 1 day


d) N years x (31,536,000) / 1 year


In each case the years cancel, leaving a figure in seconds.


a) How do you covert from grams to kg?



a) N g / 1000


or put another way: N g x 0.001 / 1000g

a) How do you convert from metres to km?

a) N m / 1000m


or N m x 0.001 / 1000m

How do you convert from AU to metres?
  • 1 AU = 93 million miles = 1.496 x 10^11 metres
  • n AU x (1.496 x 10^11 / 1 AU)
You find an object and you measure that element A is three times as abundance as element B. A decays to B with half life of 400Myrs. How old is the object?

Momentum Equation


And why would you really use it?




M = mass

V = velocity


S = star

P = planet


Rearranged to find the volume of the planet (to then find density later)

  • VP = (2πa / P)
  • MSVS = MP x (2πa/P)
  • So: MS = (MS x VS x P / 2πa)

Standard Deviation


Multiplying and Dividing


When you multiply, you add the powers


When you divide, you subtract the powers



a) Surface area of a sphere


b) Volume of a sphere


a) Surface area = 4πr2 = 4 x π x r2

Units in m2


b) Volume of a sphere = 4/3 x π x r3

Units in m3

What is ceres?

A dwarf planet, found in the asteroid belt, which is between Mars and Jupiter


Monster & Jumper

Kepler's 3rd law – in words

P^2 = a^3

In other words, the square of the orbital period ( in years) is proportional to the cube of the farthest distance from the sun (in Astronomical Units).


Only around our Sun (not other stars)


Circumference of a circle


Area of a circle


Circumference = 2πr


Area = πr2





 Planet P orbiting Star S.


What is another way to describe the semi-major axis of P's orbit?

 the average distance of Planet from Star
Newton's version of Kepler's 3rd – rearranged to find the mass


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Units for density?

The standard is kg/m3


But it is just a ratio


Approximate densities of:


Air/Gas, Water, Rock, Iron, Bulk Earth, Bulk Sun


Air/Gas ~ 1 kg/m^3

Water ~ 1000 kg/m^3

Rock ~ 3000 kg/m^3

Iron ~ 7000 kg/m^3

Bulk Earth ~ 5000 kg/m^3 –– earth is made up of rock and iron?

Bulk Sun ~ 1000 kg/m^3 (MUCH LESS THAN EARTHour sun is like a giant sphere of water!)

How long ago was the universe/sun/earth created
  • Big Bang - 13.7bn
  • Formation of 1st stars: 13-12bn
  • Sun - 4.56bn (i.e. the solar system)
  • Earth - 4.53bn
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