Newton’s thought experiment: orbital velocity

Surface escape velocities Planet V escape, ft/sec Mercury13,600 Venus33,600 Earth36,700 Moon7,800 Mars16,700 Asteroid Eros ~50 Jupiter197,000

Rocket Equation delta V = g I sp ln (M o /M f ) where: delta V = rocket velocity change (m/s) g = gravitational constant (9.81 m/s 2 ) I sp = rocket specific impulse (s) M o = initial rocket mass (kg) M f = 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 M o =Initial mass of vehicle (kg) M f = Final mass of vehicle (kg) M p =Propellant mass (kg) = M o – M f M dry = M f =Burnout mass M dry = Payload mass + adapter mass + propulsion system dry mass + propellant residuals +...

ORBITING SATELLITES Burnout velocity (thousands of ft/sec) Vehicle range

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.