more about orbits
DESCRIPTION
More About Orbits. Orbits can be ellipses, parabolas or hyperbolas. All Orbit Shapes are Conic Sections. Why Do We Call it a “Focus?”. Escape Velocity. Every object has an escape velocity Anything launched with less than escape velocity will fall back - PowerPoint PPT PresentationTRANSCRIPT
More About Orbits
Orbits can be ellipses, parabolas or hyperbolas
All Orbit Shapes are Conic Sections
Why Do We Call it a “Focus?”
Escape Velocity• Every object has an escape velocity• Anything launched with less than escape
velocity will fall back• Anything launched with greater than escape
velocity will keep going and never return• Escape velocity from Earth’s surface is 11
km/sec or 25,000 miles per hour.• For anything in a circular orbit, escape
velocity is 1.4 times its orbital velocity.
Orbits and Escape Velocity
• Anything moving with less than escape velocity will travel in an elliptical orbit
• Anything moving exactly with escape velocity will travel in a parabolic orbit (Think of it as an infinitely long ellipse)
• Anything moving with more than escape velocity will travel in a hyperbolic orbit
Orbits and Escape Velocity
What About Three Objects?
• Kepler and Newton solved the problem of one object orbiting about another
• Are there formulas for three interacting bodies?
• Bottom Line: No (After much effort)• Except for a few special cases...
The Lagrangian
Points
Gravity Assist• Gravity assist happens naturally. It can
capture comets into short-period orbits or expel them from the Solar System
• We use gravity assist to speed up, slow down, or redirect spacecraft
• The Cassini mission to Saturn was launched with only one-fifth the energy needed to reach Saturn
We’re Pretty Good At It
In Gravity Assist, a Massive Object Causes a less Massive One to
Speed Up or Slow Down
Gravity Assist Can Speed Objects Up
Gravity Assist Can Slow Things Down