Orbital Mechanics

One of the most important steps in designing any space mission is precisely determining the trajectory that the spacecraft will follow en route to its final destination. It is obvious to say that the success and even the feasibility of any mission depends primarily on a good design of its trajectory.

Two essential design parameters will result from the adoption of a certain class or trajectory for a mission : the overall time of the mission, including transit and eventual stays or orbits and the propulsion requirements to achieve the desired trajectories and orbits.

These two parameters are absolutely critical in the design of any mission, for they affect the human factors (medical, supplies, psychology) and the hardware requirements (propulsion, engines, systems, etc.) of the mission.

• Newton's Law of Gravitation
• General considerations for a Mars mission
• Orbits
• From Earth to Mars
• Getting to Low Earth Orbit
• From Low Earth Orbit to Mars
• The Launch Opportunity
• Calculating the velocity needed to enter the transfer orbit
• Velocity at any point in the orbit
• Velocity at perihelion
• Time needed to effect the transfer
• Determining the initial angle between planets
• Calculating the launch date
• The arrival date
• The Return Trip
• Martian orbit
• Calculation of change in velocity required to enter the transfer orbit
• Time for the return journey
• Aligning the planets for the comeback.
• Determination of return date
• Back to Earth
• Mission timeline
  

Orbital Mechanics Links

• Hohmann Transfer Orbits
• Interplanetary Trajectories
• Planetary Orbits
• Orbits, Orbits Everywhere
• A Lesson in Orbital Mechanics
• Headquarters for the Mars Direct Manned Mars Mission by Dr. Robert Zubrin
• Orbital Mechanics at Liftoff! from NASA MSFC
• Trajectories and Orbital Mechanics
• Orbital Mechanics Lectures at SEDS
• Kepler's Laws applied to Mars
• Mars Mission Research Center