Announcements

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Announcements

• Pick up graded homework.
• Pick up handout (The Virtual Astronaut) and
  read over the weekend.
• First project due today by 500 p.m.

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Space Exploration

• 13 October 2006

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Today

• History of space exploration
• Cost of the space program
• Why its difficult, expensive, and dangerous
• WARNING Todays lecture will contain OPINIONS!

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History

• 1957 Sputnik 1, first artificial satellite
• 1958 Explorer III, first US satellite,
  discovered radiation belts
• 1959 Lunar flyby, landing
• 1960 Weather satellite
• 1961 Humans in space
• 1962 Venus flyby
• 1965 Mars flyby
• 1969-72 Apollo moon landings
• 1973 Jupiter flyby
• 1979-89 Voyager flybys of Jupiter, Saturn,
  Uranus, Neptune
• 1982-2010 Space shuttle program
• 1990 Hubble Space Telescope deployed
• 2000-? International space station

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Apollo Moon Landings
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NASA budget
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NASA budget
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Physics of Space Flight

• Low earth orbit 200 miles high
• Gravitational energy is about 3.1 megajoules per
  kilogram
• Required speed 7.9 km/s (!)
• Kinetic energy is 31 MJ/kg
• (For comparison, boiling water into steam
  requires about 2.5 MJ/kg)

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Physics of Space Flight

• Rocket propulsion is inefficient!

Cost of shuttle program 1.3 billion per launch
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Humans vs. Robots

• NASA annual budget is about 16 billion
• Of this, about half is for human space flight
  (shuttle, space station) other half is for
  robotic missions, space telescopes

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Why havent we gone to Mars?

• 140 times farther than the moon (at best)
• Months of weightlessness is crippling
• Serious radiation hazards
• Would have to carry food, fuel, oxygen to last
  years
• Taking earth life to Mars could confuse search
  for native Martian life
• So much to learn from unmanned exploration!

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The Outer Solar System
Neptune
On this scale 1 A.U. 7 pixels Orbital
radii Jupiter 5.2 A.U. Saturn 9.5
A.U. Uranus 19 A.U. Neptune 30 A.U.
Uranus
Saturn
Jupiter
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The Inner Solar System
Mars
Earth
On this scale 1 A.U. 120 pixels Diam. of Sun
1 pixel Diam. of moons orbit 1/2 pixel Diam.
of earth 1/100 pixel
Venus
Mercury
Sun
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Earth and Moon to scale
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Low-Earth orbit
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Low-Earth orbit
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NASAs future plans