Orbital Spaceflight

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Orbital Spaceflight

• Thanasphere
• originally published in Colliers
• September 1950
• Christy L. Haynes

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Thanasphere Summary

• U.S. Air Force has sent manned spacecraft into
  orbit around the Earth
• Purpose of mission watch weather patterns and
  monitor military attacks
• Man in spacecraft realizes that space is filled
  with the dead and that the dead want to
  communicate
• To keep rocket and space dead secret, the
  spacecraft is forcibly returned to Earth

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Space Race Timeline

• 10/05/57 USSR launches Sputnik I
• 11/03/57 USSR launches first animal into
  orbit (a dog named Laika)
• 04/12/61 USSR puts 1st person in space
• 03/18/65 USSR has 1st space walk
• 07/20/69 US has 1st moon landing

http//en.wikipedia.org/wiki/Space_travel,
accessed 08/02/06
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What is space?

• Everything more than 100 km ( 62 miles) above
  the Earths surface

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Earths Atmosphere

• Layer of gases surrounding the Earth, retained by
  Earths gravity
• 78 Nitrogen
• 21 Oxygen
• traces of Water, Argon, Carbon Dioxide, Neon,
  Helium, Methane, Krypton, Hydrogen

• Atmosphere becomes thinner as one
• approaches outer space, no abrupt end

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What is orbital spaceflight?

• Full orbit of the Earth is completed before the
  object returns to Earth.
• A spacecraft must reach
• sufficient lateral velocity
• so that required centripetal force is
  equal to the Earths
• gravitational pull.

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What is gravitational force?
the attraction between the spacecraft and the
Earth along the line between the two objects
G gravitational constant m1 mass of
spacecraft m2 mass of Earth r distance
between objects
Physics, 2nd Edition Hans C. Ohanian, W. W.
Norton Company, Inc., New York, 1989.
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What is centripetal force?

• the force exerted by the Earth to move the
  spacecraft in a circular pattern instead of a
  straight path

m1 mass of spacecraft v velocity of
spacecraft r radius of path
Physics, 2nd Edition Hans C. Ohanian, W. W.
Norton Company, Inc., New York, 1989.
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What happens if

• Fg gt Fc
• Fg Fc
• Fg lt Fc

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How do we achieve orbital spaceflight?

• Requires launch with an acceleration of at least
  9 km/s (18,000 mph)

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How does the spacecraft accelerate so quickly?

• A solid rocket booster contains
• -ammonium perchlorate powder (NH4ClO4)
• -fine aluminum powder (Al)
• Ignite the booster to start a chemical reaction
• Al(s) NH4ClO4(s) Al2O3(s) AlCl3(s)
  H2O(g) N2(g)

• - exothermic reaction (5800 oF)
• gases expand rapidly to lift
• spacecraft

Chemistry 3rd Ed. M. Silberberg, McGraw Hill,
New York, 2003.
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How does the spacecraft accelerate so quickly?
H2(l) O2(l) H2O(g)

• - exothermic reaction (6000 oF)
• water vapor expands rapidly to
• provide remaining 29 of required
• thrust

solid rocket booster (71 of thrust)
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Returning to Earth

• Orient spacecraft to experience significant
  atmospheric drag.
• High temperatures are generated by friction.
• Cover spacecraft with thermal tiles
• - made of silica
• (SiO2), a good
• insulator
• - high porosity,
• lightweight

http//www.nasa.gov/mission_pages/shuttle/
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Thanasphere Discussion Questions

• What is the debatable thesis of this story?
• On the second page of the story, Vonnegut writes,
  He knew a great deal more than he was saying,
  but somewhat less than he himself thought. He
  did not believe in ghosts, for instance and had
  yet to learn of the Thanasphere. Why does
  Vonnegut reveal the secret of the story so early?
  How would the story proceed differently if this
  text was eliminated?
• What organizations/groups does each character
  represent? What statement is Vonnegut making
  about the relationship between these groups?
• How does Vonnegut use humor in Thanasphere?
• Is Dr. Groszinger a round or flat character?
  What does Vonneguts portrayal of Groszinger
  imply about scientists in general?

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Thanasphere Discussion Questions

• Does Vonnegut make a political or social
  statement through this work? Is this statement
  still relevant today?
• What would happen if historic leaders became
  involved in todays matters?
• How does the technical vocabulary/concept enhance
  or hinder the story?
• A protagonist is also characterized by his/her
  ability to change or evolve. Is there a
  protagonist in this work?
• An antagonist represents or creates obstacles
  that the protagonist must overcome. Is there an
  antagonist in this work?