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					Space Technology & Engineering

     Chapter 9: Space Exploration
     SECTION 1
Introduction to Astronomy
        General questions for any trip
•   Where do I want to go?
•   What route will I take to get there?
•   How far is it?
•   How do I know if I’m going the right way?
•   How am I going to get there?
•   What do I need to take with me?
•   What am I going to do when I get there?
         “Do you see what I see?”
• Most of what we know about the Universe comes
  from use of ___________________

• Further knowledge comes from the use of robot
  explorers

• At present, only a small amount of knowledge has
  been gained by humans in space
         Through the looking glass

• To learn about the universe through a telescope,
  you must understand the following concepts:
• Nature of light
• Electromagentic spectrum
• Absorption of light and resultant Spectra
• Doppler effect
               Two sides of a coin
• Light has both a particle and wave nature
  – Under certain circumstances, it behaves as a particle
  – Under certain circumstances, it behaves as a wave


• For this chapter, only the _________ nature will be
  covered
                 Types of Waves
• A wave is the manner through which energy moves
  through matter and space
• Mechanical waves
  – Particles relay energy from one to the other
  – Must have __________ present
• Electromagnetic waves
  – Energy moves through interactions of _____________
    and __________________ fields
  – Does not need __________ present
   “What’s the frequency, Kenneth?”
• One characteristic of light is its frequency

• Frequency is how many waves go be each second
  – The unit of frequency is the Hertz (Hz)
                2 waves per second = 2 Hz




1s    2s




                1 waves per second = 1 Hz


           2s
1s




                ½ wave per second = .5 Hz


 1s    2s
              “Let there be light”

• An electromagnetic wave is called light

• Light can have many frequencies

• All of light’s frequencies together are called the
  __________________________________
  – Includes visible light and invisible light
                       Electromagnetic Spectrum
                                       GAMMA RAYS
                                       X-RAYS
Frequency Increasing




                                       ULTRAVIOLET
                       VISIBLE LIGHT

                                       INFRARED
                                       MICROWAVE
                                       RADIO WAVE
          “I spy with my little eye”
• By using all of the wavelengths of light, we can see
  things in space that we might not be able to see
  normally
                “Fade to Black”
• Many objects in space emit light

• However, many of these objects do not emit light in
  visible light wavelengths

• As they can’t be seen with the human eye, they are
  invisible in the blackness of space

• These objects are called ____________ radiators
VISIBLE LIGHT   INFRARED LIGHT
               Looking for prints
• When light hits matter, some of the light is
  temporarily absorbed and the rest is reflected
• Every substance absorbs and reflects differently
• So, every substance gives off its specific light
  “fingerprint” – called _______________
• By studying the _____________ of the light given
  off by planets and stars, we can estimate what their
  ______________________ are
Example of a spectra “fingerprint”
                Doppler effect
• When the source of the wave moves, it changes the
  wave
• The wave in front of the source will bunch up
  increasing the frequency
• The wave behind the source will spread out
  decreasing the frequency
      When car is stopped, the waves are evenly spaced

Lower frequency
                                                     Higher frequency




When car is moving, the waves more frequent in front of the car than
behind
              Red and Blue states
• Everything in space is moving

• If something is moving towards us, the frequency of
  its light hitting us increases
  – So the frequency of light increases – called a
    “__________ shift”
• If something is moving away from us, the frequency
  of its light hitting us decreases
  – So, the frequency of light decreases – called a
    “____________ shift”
                       Practice
 What do mechanical waves require that electromagnetic
  waves don’t?
 What is a Hz?
 List the parts of the electromagnetic spectrum from
  lowest to highest frequency
 What is a blackbody radiator?
 What is a spectra?
 You are approaching an object, explain what is happening
  to your radar signal

 All practice questions are due at the end of the chapter
        SECTION 2
Astronomical Coordinate Systems
              Where’s Waldo?
• To plan a route, you must know where you are
• It is also helpful to have a map
• On Earth, your location is given by latitude and
  longitude
• _____________ – the number of degrees from the
  equator you are
• ______________ – the number of degrees from the
  Prim Meridian
LONGITUDE   LATITUDE
“…as long as you know where you’ve been”
• All stars and planets also have coordinates

• These coordinates use the Earth as the reference
  point

• Unlike coordinates on the Earth, coordinates in
  space constantly change as everything is moving
              Dividing up the sky
• On the Earth, we use the equator and the Prime
  Meridian to divide the Earth up into hemispheres

• Space coordinates also use the equator and the
  poles to divide up the sky into hemispheres
  – The _______________ equator is right above our
    equator
  – The ________________ poles are right above our north
    and south poles
              “If I’m so inclined”
• To determine how far away from the celestial
  equator an object is, an angle called
  __________________ is used

• Going up from the equator gives a positive angle
  (from 0° to 90° )

• Going down from the equator gives a negative
  angle (from 0° to -90° )
            Around the world in…

• The equivalent of longitude is called right
  ___________________ (RA)

• The ordinate can be given as degrees

• It is most often given in hours, minutes, and
  seconds due to the Earth’s rotation
  – One hour equals _________
                       Ecliptic
• We also use the equator of the Sun
• An imaginary line above the Sun’s equator is called
  the ecliptic

• Since the Earth is tilted compared to the ecliptic,
  there is an angle between the ecliptic and the
  celestial equator
      “Round and round she goes..”

• Earth rotates around the Sun

• Earth revolves around its axis

• Earth’s axis also moves – similar to a top
  – This movement is called _________________
  – It normally takes _____________ Earth years to make
    one full precession
  – Currently the “north star” is the star ____________
   “Where in the solar system is Carmen
               Sandiego?”
• As each planet takes different amounts of time to
  orbit the Sun, then the distance between them
  changes
  – ________________– a point on the line from the Earth
    toward the Sun
  – ________________– a point on the line from Earth away
    from the Sun
  – ______________position – an orbit farther from the Sun
    than Earth
  – ______________position - an orbit closer to the Sun
    than Earth
                        Practice
 Define longitude and latitude
 Define celestial equator, celestial north pole, and ecliptic
 An object has a declination of 15 degrees and right
  ascension of 30 degrees. About where in the world is it
  overhead?
 Define precession
 A planet is in superior opposition. Where is it in relation
  to the Earth?

 All practice questions are due at the end of the chapter
SECTION 3
  Orbits
                    “Blast off”

• Before you get to space, you have to get to orbit

• To reach orbit, you must travel _____________
  km/h (about 17,000 mph)

• To escape Earth’s orbit to go into space, you must
  travel _______________ km/h (about 25,000 mph)
 “It’s not flying, it’s falling…with style”
• When a rocket launches, the Earth’s gravity is trying
  to pull it back
• If the rocket launches at an angle, the Earth will pull
  it back a distance away from the start point
• With enough speed, the rocket can make it all the
  way around
• Once this happens, it has reached a balance
  between speed and gravity…orbit
                 Types of Orbits
 Geostationary
 Geosynchronous
 Polar
 Solar Synchronous
 Molniya
 Hohmann transfer

 Direction of orbit
   A _______________ orbit means travelling in the same
    direction as the planet’s rotation
   A ________________orbit means travelling in the opposite
    direction as the planet’s rotation
       Geosynchronous Orbit (GEO)
• A prograde, circular, low inclination orbit about
  Earth lasting one day.

• A spacecraft in geosynchronous orbit appears to
  remain above Earth at a constant ____________,
  although it may seem to wander north and south.
             Geostationary Orbit

• A geosynchronous orbit is with an inclination of
  either zero, right on the equator, or else low enough
  that the spacecraft can use propulsive means to
  constrain
• the spacecraft's apparent position is that it hangs
  motionless above a point on Earth.
• This orbit is ideal for certain kinds of
  communication satellites or meteorological
  satellites.
                     Polar Orbits
 90-degree inclination orbits, useful for spacecraft that
  carry out mapping or surveillance operations.
   The planet rotates below a polar orbit, allowing the
    spacecraft low-altitude access to virtually every point on the
    surface.
 To achieve a polar orbit at Earth requires more energy,
  thus more propellant, than does a regular orbit of low
  inclination.
   For a regular orbit, launch is normally accomplished near
    the equator, where the rotational speed of the surface
    contributes a significant part of the final speed required for
    orbit.
   A polar orbit will not be able to take advantage of the "free
    ride" provided by Earth's rotation, and thus the launch
    vehicle must provide all of the energy for attaining orbital
    speed.
       Sun synchronous orbits (SSO)
• Walking orbits whose orbital plane precesses with
  the same period as the planet's solar orbit period.

• In other words, an orbit can be established so that a
  spacecraft can either face the day side or the night
  side of a planet
                  Molniya orbits
• Highly eccentric Earth orbits with periods of
  approximately 12 hours (2 revolutions per day).

• The orbital inclination is chosen so the rate of
  change of perigee is zero, thus both apogee and
  perigee can be maintained over fixed latitudes.
  – This condition occurs at inclinations of 63.4 degrees and
    116.6 degrees.

• This orientation can provide good ground coverage
  at high northern latitudes.
       Now I’m getting… perturbed?
• There are other forces acting on a satellite that
  perturb it away from the nominal orbit.

• These forces result in ____________________, or
  variations in the orbital elements

• Precise orbit determination requires that the
  periodic variations be included as well.
           Third-Body Perturbations
• The gravitational forces of the other objects can
  cause periodic variations in all of the orbital
  elements

• The two primary objects with this effect in Earth
  orbit:
  – Sun
  – Moon
Perturbations due to Non-spherical Earth
 When developing the two-body equations of motion,
  we assumed the Earth was a spherically symmetrical,
  homogeneous mass.

 In fact, the Earth is neither homogeneous nor
  spherical.

 The most dominant features are
   a bulge at the equator
   a slight pear shape
   flattening at the poles
    Perturbations from Atmospheric Drag
• A spacecraft is subjected to drag forces when moving
  through a planet's atmosphere.

• This drag is greatest during launch and reentry,
  however, even a space vehicle in low Earth orbit
  experiences some drag as it moves through the Earth's
  thin upper atmosphere.

• In time, the action of drag on a space vehicle will cause
  it to spiral back into the atmosphere, eventually to
  disintegrate or burn up.
                 Hitting the brakes

• For space vehicles within 120 to 160 km of the Earth's
  surface, atmospheric drag will bring it down in a few
  days, with final disintegration occurring at an altitude
  of about 80 km.

• Above approximately 600 km, drag is so weak that
  orbits usually last more than 10 years - beyond a
  satellite's operational lifetime.

• The deterioration of a spacecraft's orbit due to drag is
  called _______________.
   Perturbations from Solar Radiation
• Solar activity also has a significant affect on
  atmospheric density, with high solar activity resulting in
  high density.
   – Below about 150 km the density is not strongly affected by
     solar activity
   – At satellite altitudes in the range of 500 to 800 km, the
     density variations between solar maximum and solar
     minimum are approximately two orders of magnitude.


• The large variations imply that satellites will decay
  more rapidly during periods of solar ___________and
  much more slowly during solar _____________.
            Hohmann Transfer Orbit
• What happens if you want to go from one orbit to
  another?
   – You can’t just point upwards and fire your engines

• Instead, you change how fast you are travelling
   – Increased speed will push you into a higher orbit
   – Decreasing speed drops you to a lower orbit


• You are still orbiting but your new orbit is a temporary
  one that will intersect with the new orbit
   – Hohmann Transfer orbits are temporary
     Hohman Transfer Orbit


            ORIGINAL
                        HOHMAN




NEW ORBIT
                       Practice
 What speed must you reach to get to orbit? To escape
  orbit?
 Briefly explain how something gets into orbit
 Explain the advantages and disadvantages of a polar orbit
 A sun synchronous orbit could be said to be a special kind
  of what orbit?
 A ship goes into a retrograde orbit. What does that mean?
 Describe factors that can affect an orbit

 All practice questions are due at the end of the chapter
  SECTION 4
Celestial Mechanics
                 Moving on up..
• After reaching orbit, you must determine the path
  that you must take to get to your destination

• If you aim the spacecraft where a planet is, it will
  never get there…..that planet is moving
  – You must aim to where the planet will be

• So, that means you must know how planets move
  through the solar system
             Good job, Johannes
• Johannes ____________ was an astronomer who
  developed rules for how planets orbit the sun

• These came to be known as:
  – Law of Ellipses – the ___________ of orbits
  – Law of Equal Areas – the ___________traveled in an
    orbit
  – Law of Periods – the __________ required to make an
    orbit
            Keplar’s Law of Ellipses
• All planets orbit in an ellipse

• The combined distance from the two foci to any
  point on the ellipse always stays the same
             An eccentric old man
• Eccentricity – means how round an ellipse is
  – Related to how far apart the foci are
• Eccentricity of ______ means a perfect circle
• Eccentricity of ________ means a straight line


                                            NOTICE THAT THE
                                            RINGS OR SATURN
                                            FORM AN ELLIPSE, NOT
                                            A CIRCLE
        Kelpler’s Law of Equal Areas
• Objects in an elliptical orbit cover the same amount
  of area in a given time period throughout the orbit

• Elliptical orbits then mean that objects speed up
  when they are close to the Sun (or whatever they
  are orbiting around) and slow down when they are
  farther away
            Kepler’s Law of Periods
• Orbital speed depends on distance from the sun
  – Predicts the distance each planet would be from the sun
    (confirmed by spacecraft and other devices)
• A planet’s speed of its orbit decreases the farther
  from the Sun it is
• The period (or how long it takes) of a planet’s orbit
  increases the farther from the sun it is

• P2 = R3
  – P = time of orbit (in years)
NAME          AVG      APPROX.       TIME OF     APPROX.
           DISTANCE    DISTANCE        ORBIT      ORBIT
          FROM SUN    OF ORBIT (in   (in Earth   SPEED (in
             (AU)         AU)          Years)    AU/year)

Mercury    .39 AU        2.45          .24         10.2
 Venus     .72 AU        4.52          .62          7.3
 Earth        1          6.28           1           6.3
 Mars      1.52 AU       9.55          1.88         5.1
Jupiter    5.2 AU        32.67        11.86         2.8
Saturn     9.5 AU        59.69        29.46         2.0
Uranus     19.2 AU      120.64        84.01         1.4
Neptune    30.1 AU      189.13       164.79         1.1
 Pluto      39.5        248.19       248.54         1
    “Which came first, the chicken..”

• Most of Kepler’s Laws seem pretty much like
  common sense today

• You may ask, “Didn’t Newton predict the second
  law would happen because of gravity?”
• Yes. But Kepler came up with his laws before
  Newton was alive – he knew what was happening
  without knowing the why
• Newton’s Law of Gravity explained the “why”
                 Plotting a course
• To get from Earth to another planet, you must use a
  _____________________________ orbit
  – This time, the transfer orbit will be an orbit around the
    Sun instead of around the Earth


• To launch a spacecraft from Earth to an outer planet
  such as Mars using the least propellant possible,
  first consider that the spacecraft is already in solar
  orbit as it sits on the launch pad.
     Going round and round in circles
• This existing solar orbit must be adjusted to cause it
  to take the spacecraft to Mars:

• The orbit's _______________(closest approach to
  the sun) will be at the distance of Earth's orbit, and
  the ________________(farthest distance from the
  sun) will be at the distance of Mars' orbit.

• The portion of the solar orbit that takes the
  spacecraft from Earth to Mars is called its
  _____________.
   “..good timing brought me to you”
• Getting to the planet Mars, rather than just to its
  orbit, requires that the spacecraft be inserted into
  its interplanetary trajectory at the correct time so it
  will arrive at the Martian orbit when Mars will be
  there.

• The opportunity to launch a spacecraft on a transfer
  orbit to Mars occurs about every _______ months.
               A Martian captive
• To be captured into a Martian orbit, the spacecraft
  must then decelerate relative to Mars using a
  ______________rocket burn or some other means.

• Since Mars has an atmosphere, final deceleration
  may also be performed by aerodynamic braking
  direct from the interplanetary trajectory, and/or a
  parachute, and/or further retrograde burns.
  – _____________________________ – using the
    atmosphere to slowdown
               The evening “star”
• To go from Earth to an inner planet such as Venus
  using least propellant, a different transfer orbit
  must be used.

• To achieve this, the spacecraft lifts uses its rocket to
  accelerate opposite the direction of Earth's
  revolution around the sun, thereby decreasing its
  orbital energy to the extent that its new orbit will
  have a perihelion equal to the distance of Venus's
  orbit.
           The right time and place
• The spacecraft will continue going in the same
  direction as Earth orbits the sun, but a little slower
  now.

• To get to Venus, rather than just to its orbit, again
  requires that the spacecraft be inserted into its
  interplanetary trajectory at the correct time so it
  will arrive at the Venusian orbit when Venus is
  there.

• Venus launch opportunities occur about every 19
                “Slingshot effect”
• Spacecraft can use the planets to speed up
• If a spacecraft approaches close enough to a planet,
  its path will curve

• The planet is travelling much faster around the Sun
  than the spacecraft
  – If the spacecraft is heading in the same direction, then it
    will speed up due to gravity attraction (the planet slows
    down very slightly…to maintain balance)
  – When the curved path arcs away from the planet, the
    spaceship will have a higher speed
                  Hitting the gas

• In a gravity-assist trajectory, angular momentum is
  transferred from the orbiting planet to a spacecraft
  approaching from behind the planet in its progress
  about the sun.

• Gravity assists can be also used to slow down a
  spacecraft, by flying in front of a body in its orbit,
  donating some of the spacecraft's angular
  momentum to the body.
                       Practice
 Explain each of Kepler’s 3 Laws
 A planet has an eccentricity of .001. What does this
  mean?
 A baby is born on Mars. When it celebrates its 3rd
  Martian birthday, how old would it be on Earth?
 A ship leaves an asteroid near Jupiter to bring its cargo
  back to Earth. Explain how it would proceed?
 How can a spacecraft get a speed boost from a
  planet?

 All practice questions are due at the end of the
  chapter
SECTION 5
 Distances
         How to measure distances

• Once you know where you are going, you next need
  to determine how far away it is

• For “short distances” (less than __________ light
  years) you would use a method called ___________

• For “long distances” you would a variety of
  methods can be used
                 A shifty character

• If you hold your finger in front of your face and
  close one eye and look with the other, then switch
  eyes, you'll see your finger seem to "shift " with
  respect to more distant objects behind it.
  – The effect is called parallax.


• Astronomers can measure parallax by measuring
  the position of a nearby star very carefully with
  respect to more distant stars behind it
                       Parallax
• A ground station measures the angle to an object in
  January
• It measures again in July (when it is on the other
  side of the Sun)
• The angles form an arc
• The angle to the bisector is called the parallax
  – There are ______ arc minutes in a degree
  – There are _______ arc seconds in a arc minute
  – Each arc second in the parallax equals 1 __________
    (3.26 light years)
           “This little light of mine”
• Most energy in the universe follow the
  ___________________Law

• As energy moves from its source it spreads out

• This means that there is less energy per square
  meter

• A simplified version of this is: E/r2
   – So, if you double the distance, energy is divided by four
   – If you triple the distance, energy is divided by nine
        Tripping the lights fantastic

• We can measure the amount of light reaching the
  Earth from the Sun and other known stars

• We can then measure the light from stars far away
  to determine the distance

• Before we can finish, we must know how much light
  it started with
               You get a gold star
 By looking at the spectra of a star, we can tell what
  color it is, what it’s made of, and how hot it is
   We compare this information to known stars to determine
    how old it is

 We then compare it to how large the star is
  (determined by other methods)

 With the age and size of the star, we can determine
  how much light the star is emitting

 Using the Inverse Square Law, we can then tell how far
  away it is
              “A.U., …over there!”
• Space is so large that new units were made

• The Earth has an average distance of 93,000,000
  miles from the Sun (150,000,000 km)
  – This distance is used to determine the new unit –
    ____________________________ (A.U.)
  – Ex. Jupiter is about 5 AU from the sun


• Astronomical units are only good for star systems
NAME         AVERAGE         AVERAGE
          DISTANCE FROM   DISTANCE FROM
               SUN            EARTH
Mercury       .39 AU          .61 AU
 Venus        .72 AU          .28 AU
 Mars        1.52 AU          .52 AU
Jupiter       5.2 AU          4.2AU
Saturn        9.5 AU          8.5 AU
 Uranus      19.2 AU         18.2 AU
Neptune      30.1 AU         29.1 AU
             “E.T. phone home”
• Because of the distances involved, all spacecraft
  and settlements will experience a time delay when
  communicating with Earth

• Sending information or having conversations would
  take far longer

• This forces both humans and robots to be more
  independent
    NAME      TIME DELAY       MIN. TIME FOR
                                  RESPONSE
MERCURY    5.1 minutes       10.2 minutes
VENUS      2.3 minutes       4.6 minutes
Moon       1 second          2 seconds
MARS       4.3 minutes       8.6 minutes
JUPITER    35 minutes        1 hr 10 minutes
SATURN     1 hr 11 minutes   2 hrs 22 minutes
URANUS     2.5 hours         5 hours
NEPTUNE    4 hours           8 hours
           In a galaxy far, far away
• Stars produce light throughout the universe

• Light is the ________________ thing in the universe
  – It travels 300,000 km (186,000 miles) PER SECOND


• So, the distance light travels in one Earth year is one
  light-year
  – Equal to 9.46 x 1012 km (5.87 x 1012 miles)
  – Equal to ___________________ AU
                       Practice
 Explain how the distance to nearby objects are
  determined
 Explain how the distance to objects far away are
  determined
 What is a parsec?
 What can the spectra of a star tell us?
 How much light gets to Jupiter compared to Earth?
 An object is approximately 100 AU from the Sun. About
  how many miles is that?

 All practice questions are due at the end of the chapter
                             Practice
 The closest star to Earth is Proxima Centauri, 4.2 light
  years away. How many AU is that? How many miles (in
  scientific notation)?
 A conversation between Mars and Earth:
       Mars: “Can’t wait to see you”
       Earth: “See you soon”
       Mars: “Bye”
       Earth” “Bye”
How long will it take from the beginning of the conversation
until the last message is heard on Mars?

 All practice questions are due at the end of the
  chapter
SECTION 6
 Propulsion
   “Got a long way to go and a short time
                to get there”
• Due to the distances involved, space travel outside
  of Earth orbit takes an long time

• Time involved depends on speed of rocket as well
  as path you will take to get where you are going
  • A straight flight to Mars at its closest point to Earth with
    a rocket travelling 40,000 km/h would take 60 days to
    reach
• NOTE – This is based on the planets not moving
              Spacecraft Propulsion
•   Chemical rockets
•   Ion engines/Solar-electric engines
•   Solar sails
•   Nuclear powered engines
•   Antimatter engines
      Current and Near-term engines
• Chemical rockets
   – What is mostly used today (called
     “_________________rockets”
   – Use fuel quickly and most of spacecraft is propellant
• Ion/solar-electric
   – Sends a stream of accelerated charged particles
   – Provides a very _________ acceleration that will
     continuously build speed
   – EX. An acceleration of .01m/s2 will only be at 36km/h in
     the first hour, 864 km/h at the end of a day, 6048 km/h
     at the end of a week, 24192 km/h at the end of a month,
     and 315000 km/h at the end of a year (8 times current
     chemical rockets)
                “I’m sailing away”
• Solar sail - large sail attached to a spaceship that
  catches the “solar wind” and light for propulsion
  – Solar wind – charged particles (ie electrons, protons, etc)
    ejected from the Sun
• Must be very large to have enough force applied
• Must be very thin and durable to limit weight and
  vulnerability to space conditions

• Advantage – propellant is __________
• Disadvantage – acceleration is low and becomes
  less the farther away from the Sun
SHIP
               Future Propulsion
• Nuclear engines
  – Use nuclear reactions or explosions to create thrust
  – Current issues with international treaty
  – Radiation factors a concern for crew and electronics
• Antimatter
  – Create more energy per mass than any other type (about
    100 times more than nuclear)
  – Only small amounts of antimatter have been created at
    high monetary and energy costs ($62.5 ___________per
    gram)
  – May be able to capture naturally occurring antimatter in
    Van Allen Belt or around Jupiter
“Time keeps on slipping….into the future”
• According to the Theory of ____________Relativity,
  time also depends on your frame of reference
• The faster you go, the more time slows down for
  you compared to the outside
• Additionally, the more gravity there is, the more
  time slows down for you
• Satellites orbiting the Earth must have their clocks
  updated to adjust for this effect
• Time adjustments are currently small but will
  increase with velocities
                “What time is it?”
• The difference in time is known as time dilation
• The formula for time dilation is:



•   v - the speed
•   c - the speed of light
•   t’ - time experienced on the outside
•   t - time experienced by the traveler
                             “Tik Tok”
• As people expand into space, a new timekeeping
  system might need to be created
• Example: two ships leave the Earth on January 1,
  2020. One travels the .5C ( ½ speed of light) and
  the other travels .75C ( ¾ speed of light). They
  travel to a star 4 light years away.
  – When they arrive, the calendars would show:
     • 1st ship:
         – Calendar on Earth – January 1, 2028
         – Calendar on the ship – December 2, 2026
     • 2nd ship:
         – Calendar on Earth – May 2, 2025
         – Calendar on the ship – July 9, 2023
                    Heavy load
• The faster you go, the more and more difficult it is
  to ___________________
• An effect of Special Relativity is that explains that
  ______________ is related to speed
• A formula similar to time dilation is used. Instead of
  time, mass is substituted
• For the near future, this effect is minimal (like time
  dilation)
  – EX. the New Horizons space probe has a mass increase
    of 3 x10 -7 percent
                        Practice
 A spacecraft is travelling at 50,000 km/h. Assuming
  neither planet moved, how long would it take to travel
  from Earth to Neptune?

 Describe each type of current and future propulsion
  discussed.

 A spacecraft is able to travel at .99C (99% speed of light).
  If it leaves Earth orbit on January 1st, 2012 and travels to
  Proxima Centauri, what will the calendars on Earth and
  the spacecraft say when the destination is reached?

 All practice questions are due at the end of the chapter
   SECTION 7
Supply Requirements
             Packing for the trip

• Everything an astronaut needs to survive must be
  taken or recycled on the trip
• Water
• Food
• Air
• Energy
         “That’s high quality H2O”
• Current NASA data indicates that at a minimum, the
  average astronaut needs about _______ kg of water
  per day
• A 6-month journey to Mars would require nearly
  2000 kg of water (about 4500 pounds)… each way
  per astronaut
• As the cost and storage for this amount is
  prohibitive, astronauts must conserve water as well
  as recycle it
                  CO2 cartridge
• When a person exhales, that person breathes out
  carbon dioxide

• If not controlled, the percentage of carbon dioxide
  to oxygen will increase until the air is poisonous

• ________________ must be used, maintained, and
  replaced to keep astronauts alive
            “Sit on it and rotate”
 One possible strategy to reduce effects of zero gravity
  on astronauts is to have a part of the spacecraft spin

 Since changing direction in a spin makes an
  acceleration, then a slow spin can induce partial
  gravity

 The mechanism would be complex, heavy, and
  expensive

 Spinning sections would have gravity but the rest of
  the ship would not
ROTATING
SECTION
     “Green acres is the place to be”
• Food is another concern due to weight and storage
• One possibility is to grow food
• However, soil cannot be used due to free-floating
  dirt and dust

• Further requirements:
  – Plants need light for ______________________
  – Plants need __________________
  – Plants may be able to act as air filters
  – Plants need water also, which places further strain on
    water supplies and also could increase humidity
                  Veggie tales?
• Plants selected should:
  – Be easy to ____________________
  – Have short life cycles
  – Have seeds that are easy to collect
  – Be ______________________
  – Have a high food value and a wide range of amino acids


• Animals could also be brought or grown
  – Increased water and food demands
                         Energy

 Energy is just as important to the survival of
  astronauts as food, water, and air are
 Currently, the two types of energy production are:

 Solar
   The solar panels on the space station generate .25V (volts)
    per 6 cm diameter solar panel

 Nuclear
   Radioisotope thermoelectric generators use a radioactive
    substance
   As it decays, electrons are given off….so, _______________
  “..Mr. Golden Sun, please shine down on
                    me”
 Solar cells are also called ________________cells
 photo means light
    Voltaic deals with electricity
    Literally electricity from sunlight
• The upside of solar energy is that sunlight is free
 The downside is that a large area is required to
  generate increased power
 The amount of sunlight decreases with distance
  from the sun
 The atmosphere of a planet can further change
  the amount of sunlight
                  Atom Smasher
• ________________reactors – create energy by
  splitting the nuclei of atoms
  – Current technology
  – Produces radioactive material that must be stored


• __________________reactors – create energy by
  merging nuclei of atoms
  – Energy is several times greater than fission for the same
    mass
  – Not developed yet
                       Practice
• About how much water would be needed for a 6
  person crew to Mars (assuming a 12 month round
  trip)?
• Explain the need for and the difficulties in growing food
  in space
• Describe the advantages and disadvantages of each
  power supply system described.

• All practice questions are due at the end of the chapter
  SECTION 8

Course Corrections
                    Mapquest
• How do you know if you are heading in the right
  direction, how fast you are going, or where you are
  along your trip?

• On Earth, you can use a map or a digital device tied
  in with GPS
• For speed, you can use a speedometer

• In space, you won’t have any of these things
             How far have I gone?
• NASA currently sends out a constant signal called a
  ________________________

• Using the time it takes to return (minus the time for
  spacecraft to process and return the signal), the
  distance to the spacecraft can be determined
  – Time is divided by 2 to get time one-way
  – Time is multiplied by the speed of light
            How Fast Am I Going?
• Using signals from Earth, the speed of a spacecraft
  can be determined

• The Doppler shift of the frequency is used to
  determine the velocity either towards or away from
  Earth
                 Where am I?
• Ground stations on Earth observe the spacecraft
  and determine the angle of observation

• The angles from the ground stations are used to
  determine the coordinates with reference to Earth

• These coordinates and the distance is used to
  determine where the spacecraft is relative to Earth
            Where Am I Heading?
• While travelling, all celestial bodies appear as stars
  until a spacecraft gets closer

• NASA uses known star fields

• Spacecraft can compare the star fields to the way
  that stars look around them to determine which
  way they are headed
             “Twinkle, twinkle,…”
• Star fields are based around _______ stars as
  reference points
• Many of these stars are in ________________
• However, the appearance of stars can change as
  you move through space
• Besides these reference points, it is important to
  know where the Earth and the Sun is
Star field used by NASA Kepler mission
                  Lost in Space
• If signal is lost from Earth, it becomes very difficult
  to know how far you’ve travelled, where you are, or
  how fast you are going

• If it also becomes difficult to determine location or
  heading using star fields, then it may be impossible
  to get to where you are going or to get back

• Over the years, various robotic spacecraft have
  been lost due to these sorts of problems
                      Practice
 Explain how a spacecraft knows how far it has
  travelled from Earth
 Explain how a spacecraft knows how fast it is
  travelling
 Explain how observers on Earth can tell where the
  spacecraft is in comparison to the Earth
 Explain how a spacecraft can tell where it is and
  where its heading

 All practice questions are due at the end of the
  chapter
      SECTION 9

Introduction to Solar System
            A need to know basis
• When deciding where to go, there are 3 factors to
  consider
• The amount of gravity that is there
• How it compares to Earth
• Whether life might have developed there
    “He ain’t heavy, he’s my brother”
• To determine how much force gravity will enact,
  you need to know the mass of both objects and
  how far away they are from each other

• On a planetary body, the distance is the radius from
  the center to where the other object is
          Law of Universal Gravitation
• To determine weight, you must first calculate
  acceleration of gravity
• The formula is:




•   m1 = one mass (in kg)
•   m2 = the other mass (in kg)
•   r = the distance between them (in meters)
•   G = 6.674×10−11 N m2 kg−2
     “Have you been losing weight?”
• On Earth, the average acceleration of gravity is 9.8
  m/s2

• Mars has a mass that is only__________ of Earth
  – Since the radius is about _________of Earth, the overall
    gravity is about ___________of Earth
             Mass (kg)      Radius       Orbital          Orbital
                              (km)     Radius (m)         Period
Mercury       3.30  1023     2439     5.79  1010       88.0 days
Venus         4.87  1024     6052     1.082  1011     224.7 days
Earth        5.974  1024     6378     1.496  1011    365.25 days
    Moon      7.35  1022     1738      3.84  108       27.3 days
Mars          6.42  1023     3394     2.279  1011     686.9 days
   Phobos      9.6  1015   10 to 14   9.378  106     7 hrs 39 min
  Deimos       2.0  1015    5 to 8    2.346  107    30 hrs 18 min
Jupiter      1.899  1027    71,492    7.784  1011    11.86 years
        Io    8.97  1022     1820      4.22  108       1.77 days
   Europa      4.8  1022     1570      6.71  108       3.55 days
Ganymede      1.48  1023     2640      1.07  109       7.15 days

  Callisto   1.07  1023     2400       1.88  109      16.7 days
Saturn       5.68  1026    60,268     1.427  1012    29.42 years
     Titan   1.34  1023     2570      1.222  109      16.0 days
Uranus       8.69  1025    25,559     2.871  1012    83.75 years
                      26                         12
            Solar System Overview
• Inner Planets – rocky with limited gas atmosphere
  –   Mercury
  –   Venus
  –   Earth
  –   Mars

• Outer Planets – very small rocky cores with immense
  gas atmospheres
  –   Jupiter
  –   Saturn
  –   Uranus
  –   Neptune
                     MERCURY
•   Length of Day: 58 Earth days
•   Length of Year: 88 Earth days
•   Average high temperature: 350° C (662° F)
•   Average low temperature: -170° C (-274° F)
•   Gravity: 38% of Earth
•   # Moons: 0
•   NO LIFE EXPECTED
                       VENUS
•   Length of Day: 243 Earth Days
•   Length of Year: 225 Earth Days
•   Average temperature: 480° C (900° F)
•   Gravity: 90% of Earth
•   Number of moons: 0
•   NO LIFE EXPECTED
             “Birds of a feather,..”
• Venus’s atmosphere is made of nearly completely
  carbon dioxide
• It is the hottest planet in the solar system due to a
  runaway greenhouse effect
• Studying Venus may help understand global
  warming on Earth



          Radar map of surface
            Not quite Hell on Earth
 Cloud cover is approximately 100%
   Clouds are made of _______________________
   They reflect nearly all sunlight making it the brightest “star”
    in the night sky

 May be seismically and volcanically active

 Dense atmosphere makes pressure on surface ______
  times that of Earth

 Hottest planet in the Solar system (hot enough to melt
  _____________)
                           3D view of Maat Mons with lava
                                       plain




Impact craters with lava
Projected Near Term Destinations of US
           Space Program*




*As per US Human Spaceflight Plans Committee, 2009
                        MOON
• No atmosphere (so little not even to count)
• Soil is a ___________and is very abrasive
  – Contains helium-3, which could be extracted for future
    fusion reactors
• Has an extremely weak magnetic field
• Gravity is only _____________of Earth
• Is moving away from the Earth _______ mm per
  year
• Water ice has been detected on the surface
• Moonquakes up to ________ on Richter scale have
  been recorded
                  “Moon First”
• The previous plan for the American space program
  was to establish an outpost on the moon
  – Could try out technologies and building techniques
    before going to Mars
  – Much closer (about 1/220th distance to Mars), so much
    easier to provide help in emergencies
  – Much cheaper to get to and much easier to launch from
    (low gravity and no atmosphere)


• Observatories on the dark side of the moon would
  give far better results than here on Earth
                  Seeking asylum
• One of the tenants of the 1963 Outer Space Treaty is
  that no country can claim any part of space or any
  celestial body

• However, all spacecraft, space stations, or colonies
  belong to the nation that created them
   – Similar to the way embassies are treated – they are
     treated as part of the country that they represent even
     though they are physically in another country


• Future law may be similar to the __________________
  relating to outposts of multiple countries
         Location, location, location
• Under the Outer Space Treaty, space and everything
  in it is considered the __________________of Man
   – Meaning it is to be shared for all mankind
   – One meaning is that nothing in space can be owned by
     an individual, group, or business (no private property)


• Space treaties only currently are related to countries

• Nothing has been specifically written about private or
  business related space activities except regulating
  ___________________
The International Space Station
              LAGRANGE POINTS
• These points are locations that are equally affected
  by two opposing bodies

• The gravitational pull is cancelled out, so these
  points have true ____________________ (except
  for inside a spacecraft)

• Space stations in these locations would remain
  there permanently without being slowly pulled in a
  particular direction
Orbiting Pit Stops?
                       Practice
 Determine the gravity on Europa compared to the Earth
 Compare the inner planets to the outer planets of the
  solar system
 Explain the factors of Venus that make life there unlikely
 List characteristics of the moon that might be experienced
  by visitors
 Explain the reasons behind the Moon First approach of
  space exploration?
 What is a Lagrange point?

 All practice questions are due at the end of the chapter
                       MARS

•   Length of Day: 1 Earth day
•   Length of Year: 687 Earth days
•   Max temperature: 20° C (68° F)
•   Min temperature: -140° C (-220° C)
•   Gravity: 38% of Earth
•   Number of moons: 2 (small captured asteroids)
•   Life possible
Previous landing sites
              Mars Characteristics
• Coordinate system similar to Earth
  – Instead of the Prime Meridian, there is the
    _________________Meridian


• Has seasons similar to Earth due to similar tilt of
  axis

• Little to no magnetic field

• ______________________are possible
               Little Green Men

• Life may have existed there
• Life may still exist there




• Most plans call for Mars to be the main destination
  for manned space flight this century
           MARTIAN ATMOSPHERE
• Atmosphere is 95% carbon dioxide
  – Relatively no greenhouse effect due to ________air
    density


• Atmospheric pressure too low to exist outside of a
  pressurized environment (about 1% of Earth)
  – Wind blows with ___________ the force on Earth
  – Sounds are not as loud


• Clouds are made of mostly carbon dioxide crystals
  – It may snow dry ice (frozen carbon dioxide) at the poles
    in the winter time
            “Catchin’ some rays”
 Atmosphere is much thinner than Earth making
  meteorite impacts more common

 Receives about __________of sunlight of Earth due to
  distance

 Surface receives more _________rays than on Earth
  due to differences in atmospheric absorption

 Weak tornados have been recorded by the Spirit Mars
  rover
             ATMOSPHERE




DUST STORM
               MARTIAN SURFACE
 Red tint of soil is due to high iron content (iron (III)
  oxide)
    Could be used to extract iron and oxygen for settlements

 Soil has a pH of _______________

 Large, frequent dust storms

 Land area the same as the dry land area on Earth
    Largest volcano in the solar system – Olympus Mons
    Largest canyon system in the solar system – Valles Marineris
                  Olympus Mons
• Means “Mount Olympus”

• Height 25 km
  – Three times as tall as Mount Everest
  – Twice as tall as Mauna Kea (if measured from the sea floor)
• Diameter: approximately 600 km
  – Would cover the state of ________________

• Is so much bigger than Earth mountains because
  weaker gravity doesn’t make it sink back into the
  ground

• Not thought to be active
                 Valles Marineris
• Dimensions:
  – Length: 4000 km
  – Width: 200 km
  – Depth: up to 7km


• Grand canyon
  – Length: 446 km
  – Width: 29 km
  – Depth: 1.6 km
Valles Marineris




                   3-D false color image
       SUNSET…sky is blue




VICTORIA CRATER at CAPE VERDE, MARS
        (near Sinus Meridian)
“Water, water, everywhere, and not a drop
                 to drink”
• Liquid water cannot currently exist on Mars
• Low atmospheric pressure would cause it to boil off
  as per Gay-Lussac’s Law

• Majority of frozen water is at the __________
• The amount of water in the south pole of Mars
  contains enough water to cover the entire planet 11
  m (36 feet) deep.
• _____________(frozen water trapped in soil) exists
  to 60 latitude
Areas of detected water ice
                      Mars First
• An alternate plan for American spaceflight is to skip
  the Moon and go straight to Mars
• More public interest in Mars
• Money going to the moon could be saved and put
  to the Mars mission(s)
• Unmanned rockets and robots would be launched
  first
  – Supplies
  – Robots could build or partially build outpost
• People would be launched second
                   Terraforming
• One idea is to change Mars to be more Earth-like –
  known as terra forming
• Most ideas would take decades to centuries and
  would be the largest engineering project in the history
  of man

• Ideas include:
  – Covering Mars with microbes or plants that would convert
    atmosphere to have oxygen
  – Using impacts or other nuclear devices to cause greenhouse
    effect
  – Heating Mars with space mirrors/lasers to release oxygen
    from permafrost
  – Spreading a dark dust over surface to increase amount of
    sunlight absorbed
                      Practice
 What characteristics of the Martian atmosphere make
  wind power unrealistic?
 Compare Olympus Mons to mountains on Earth and
  explain how it became so large
 A person falls off a cliff at the top of the Valles
  Marineris. How long would it take to hit the bottom
  (neglect air resistance)? Compare to the time
  required to reach the bottom of the Grand Canyon.

 All practice questions are due at the end of the
  chapter
                      Practice
• If Mars formerly held life that required water, where
  should astronauts look for evidence?
• Explain the reasons behind the Mars first approach
  to space exploration?
• Define terraforming

• All Practice questions will be collected at the end of
  the chapter
                    ASTEROIDS
• Rubble of destroyed protoplanets from the early
  Solar system
• Many exist between the orbits of Mars and Jupiter
  in the main asteroid belt
• ______________asteroids – share Jupiter’s orbit
  around the Sun
• Can be solid or a group of rocks travelling together
• A large enough spaceship would attract small
  asteroids towards itself due to gravity
                    “Cha-ching”
• Asteroids can be a range of sizes
• The largest asteroid was reclassified as a “dwarf
  planet” called Ceres
• Asteroids could be used as staging areas to the outer
  planets
• Asteroids could also be mined for minerals
  – Asteroid 16 Psyche alone could supply _____________ of
    years worth of iron and nickel (at 2004 rates)
  – Estimates are that a 1 mile diameter asteroid may have up
    to $20 _________________ of metals
• Some asteroids may contain or be made up of frozen
  water
VESTA
        CERES
                  Mobile home
• One idea for space station construction is to use
  Near Earth Asteroids (NEA’s)

• These would be excavated and a the space station
  built from the materials
                       JUPITER
•   Length of Day: 10 hours
•   Length of Year: 11.86 years
•   Average cloudtop temperature: -110° C (-164° F)
•   Gravity: 2.5 times Earth
•   Number of moons: 50
•   No life expected
                     EUROPA
• One of the Galilean moons – large moons around
  Jupiter discovered by Galileo

• Icy surface (10-30 km thick)

• Expected liquid water below surface
  – Approximately 100 km deep
  – _________________the liquid water as Earth
  – May have organisms living in these oceans
                       SATURN
•   Length of Day: 10 hours
•   Length of Year: 29.4 Earth years
•   Average cloudtop temperature: -180° C (-292° F)
•   Gravity: 1.07 times Earth
•   Number of moons: 53
•   No life expected
                        TITAN
• Largest moon of Saturn
• Has surfaces features similar to Earth

• Instead of water, it has lakes, rivers, and oceans of
  methane (it even rains methane)
  – Methane based oceans could sustain some types of life
  – Could be a future fuel supply (maybe the Saudia Arabia
    of space?)
                 ENCELADUS
• A frozen moon of Saturn
• Shown to have __________________– volcanoes
  that erupt steam instead of lava
• Having warmth and water may be able to support
  life
• __________________ has been detected – a
  compound that can be given off by living things
                      URANUS
•   Length of Day: 17 hours
•   Length of Year: 84 Earth years
•   Average cloudtop temperature: -216° C (-357° F)
•   Gravity: .92 times Earth
•   Number of moons: 27
•   No life expected
                     NEPTUNE
•   Length of Day: 16.1 hours
•   Length of Year: 164.8 Earth years
•   Average cloudtop temperature: -216° C (-357° F)
•   Gravity: 1.12 times Earth
•   Number of moons: 13
•   No life expected
                     TRITON
• Largest moon of Neptune

• Predicted to have large underground oceans of
  water (like Europa) with cryovolcanoes like
  Enceladus
                  Dwarf Planets
• Objects not meeting a requirement to become a
  planet
  – Must not orbit another planet
  – Must be large enough to be close to spherical-shaped
  – Must have cleared their orbits around the sun


• Examples:
  – Pluto
  – Eris
  – Ceres
ERIS




               CERES




       PLUTO
                       Charon
“Plutoids”
                      Practice
• What are two possible uses for asteroids?
• Explain why the moons Europa, Titan, Enceladus,
  and Triton have special significance in studying the
  solar system?
• Define dwarf planet

• All practice questions will be collected at the end of
  the chapter
          Warped sense of humor

• By the Theory of Relativity, gravity warps space
  – This makes the path of even _____________ curve


• Recently, astronomers have detected planets
  around stars by noticing a “____________” of their
  starlight caused by planets passing nearby
  – At present (April 2011), astronomers have detected
    __________planets in ____________star systems
          “Who ate my porridge?”
• For life as we know it, a planet must be an area
  around their star that is habitable
  – Cannot be too cold
  – Cannot be too hot


• Known as the “____________________zone”
Exoplanets?
                       Practice
• What effect does gravity have on light?
• How did astronomers detect planets outside of the
  solar system?
• Define the Goldilocks zone

• All practice questions are due at the end of the chapter
                  REFERENCES
• Basics of Spaceflight, NASA,
  http://www2.jpl.nasa.gov/basics/index.php
• Destiny in Space, National Air and Space Museum,
  Smithsonian Institution, 1994
• The Hazards of Space Travel: A Tourist’s Guide, Neil
  J. Comins, PhD Villano Books 2007
• Review of U.S. Human Spaceflight Plans Committee
  Final Report: Seeking a Human Spaceflight Program
  Worthy of a Great Nation, 2009
• http://solarsystem.nasa.gov
                REFERENCES
• http://www.braeunig.us/space/orbmech.htm
• http://planetquest.jpl.nasa.gov/
• http://www.nasa.gov/pdf/412508main_What.Is.a.P
  lanet.Lithograph.pdf
• Explorations: An Introduction to Astronomy, 6th
  edition, Thomas Arny and Stephen Schneider,
  McGraw Hill, 2010

				
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