Orbital Mechanics

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# Orbital Mechanics - PowerPoint PPT Presentation

Orbital Mechanics. Orbital Mechanics refers to the general description of how bodies move in force fields (such as gravity) given that energy and momentum are conserved.

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## Orbital Mechanics

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Presentation Transcript
Orbital Mechanics
• Orbital Mechanics refers to the general description of how bodies move in force fields (such as gravity) given that energy and momentum are conserved.
• For two spherical objects in which gravity is the only force, this problem is analytic, and both bodies execute elliptical orbits (i.e., they obey Kepler’s laws).
Vis-Viva Equation
• Gravity is an attractive force. As you fall toward a body of mass, you speed up; as you move away, you slow down.
• The Vis-Viva equation is a simple and useful relation describing this interrelation between total orbital speed and proximity to the dominant massive body.
Being a Rocket Scientist!
• Spaceflight is expensive. Energy is required to lift mass away from the Earth into space (\$thousands per kilogram).
• Question: What is the minimum energy orbit transfer, requiring the minimum fuel to move from one planet to another?
• Ans: Hohmann orbit transfers.
• In part, want to take advantage of the fact that the Earth is already moving at about 30 km/sec.
Issues for Colonizing Other Worlds
• TRAVEL - Getting there and back (cost and time).
• POLITICS - Who is in charge? Who reaps the benefits? Who “owns”?
• GRAVITY - What happens anatomically, physiologically, psychologically, and sociologically in terms of future generations born in different gravity (lower g) environs?
• WATER - Finding, bringing, controlling.
• ATMOSPHERE - Atmospheres moderate day/night temperature extremes. Also need breathable air. Terra-forming versus building and maintaining specialized habitations.
• RADIATION/SOLAR WIND/COSMIC RAYS - What if no ozone? What if no magnetosphere? Might have to live underground.