Newtons thought experiment orbital velocity Surface escape velocities
Newton’s thought experiment: orbital velocity
Surface escape velocities Planet • Mercury • Venus • Earth • • Moon Mars Asteroid Eros Jupiter Vescape, ft/sec 13, 600 36, 700 7, 800 16, 700 ~50 197, 000
Rocket Equation delta V = g Isp ln (Mo/Mf) where: delta V = rocket velocity change (m/s) g = gravitational constant (9. 81 m/s 2) Isp = rocket specific impulse (s) Mo = initial rocket mass (kg) Mf = final rocket mass (kg) • Equation is for ideal conditions, with no strong gravity fields, as with near a planet. Corrections can be made by accounting for gravity “losses. ”
Rocket Equation, Mission Analysis and Performance Mo = Initial mass of vehicle (kg) Mf = Final mass of vehicle (kg) Mp = Propellant mass (kg) = Mo – Mf Mdry = Mf = Burnout mass Mdry = Payload mass + adapter mass + propulsion system dry mass + propellant residuals +. . .
Vehicle range ORBITING SATELLITES Burnout velocity (thousands of ft/sec)
STS launch
• Earth Orbit Definitions • Apogee: the farthest point from the Earth. • Perigee: the closest point to the Earth. Because of the Earth's atmosphere, this cannot be less than about 80 miles above the surface. • For circular orbits, the apogee and perigee are the same. • Period: the time it takes to go around the Earth once. (The apogee and perigee determine the period. ) • Inclination: the angle the orbital plane makes with the Earth's equatorial plane.
With advanced propulsion, one must always look to the past and look to the future.
- Slides: 56
