1. Orbital Mechanics & Other Fun Stuff Part I Basic Orbital Mechanics Tom Rudman Thursday Morning Space Odyssey Crew

2. Discussion Topics Basic Earth Orbits (Part I) Traveling to Mars (Part I) Going Beyond Mars (Part II) Relativity Effects (Part II) Earth and Moon as Seen from Mars by MRO HiRISE camera Image Credit: NASA/JPL-Caltech/University of Arizona

3. How do Rockets Get into Space? Isaac Newton showed if you can achieve a sufficient velocity you will go into orbit around Earth –The orbital velocity balances the acceleration due to gravity –It is all about Velocity The velocity comes from the rocket engine firing –Earth Orbit, 18,000 mph –Escape Earth, 25,000 mph Earth orbit is not “Zero-Gravity ” you are in FREE-FALL –There is gravity in orbit - it is what is holding you in Orbit –You are always being pulled towards the Earth Isaac Newton’s Cannon PERIAPSIS APOAPSIS Pictures NASA JPL Ballistic

4. Geosynchronous Equatorial Orbit, (GEO) Most Popular Orbit for Satellites –Inclination is 0º or around the equator –Launch site latitude determines orbit plane change –Kennedy Space Center is at 28º –Baikonur (Russia ) is at 60º –Ariane launch site in French Guiana is near the equator The spacecraft stays over the same spot on earth –If you have satellite TV, that is where the satellite is located. –Weather Satellites are sometimes in this orbit (GOES), –All types of communications, broad band, pagers, etc Proposed by Arthur C. Clark for communications, 1945 –1 st Described in 1928, “The Problem of Space Travel - The Rocket Motor”, Dr. Herman Potočnik (Austrian Rocket Engineer) for a Space Station Source: Wikipedia.org Super Dish 121 Arthur C. Clark Dr. Herman Potočnik

5. Other Earth Orbits GPS orbit 12,550 mi (20,200 km),12 hr circular, 24 satellites (USAF) Sun Synchronous (polar) Orbit –Earth weather & resources satellites - constant solar conditions –Altitude typically 600 - 1000 km, ~98 deg –NOAA weather satellites use this orbit GPS block II, NASA & USAF GPS block I No longer used Source: wikipedia.org

6. Earth-Mars Transfer Mars at Spacecraft Arrival Mars at Spacecraft Departure A (nearly) Hohmann transfer to Mars “To Orbit and Spacecraft Systems Engineering” Scott Schoneman Arizona State University Nov 2003 Phoenix Viking Mars 3 Orbiter Mars Curiosity Phobos NASA Photo Spacecraft Transfer Orbit