Designing Interplanetary Launch Trajectories

Preliminary design and analysis of interplanetary launch trajectories.

This submission is a MATLAB script named launch1 that can be used for the preliminary design and analysis of launch trajectories for interplanetary spacecraft. Many of the algorithms implemented in this script are based on the classic technical reports, “Design of Lunar and Interplanetary Ascent Trajectories”, by Victor C. Clarke, Jr., JPL Technical Report No. 32-30, March 15, 1962, and “Interplanetary Mission Design Handbook, Volume 1, Part 2”, by A. Sergeyevsky, G. Snyder, and R. Cunniff, JPL Publication 82-43, September 15, 1983.

The Earth departure trajectory for interplanetary missions is usually defined by a “targeting specification” which consists of twice the specific (per unit mass) orbital energy (C3), and the right ascension (RLA) and declination (DLA) of the outgoing asymptote. The launch azimuth, park orbit altitude, and launch site geographic coordinates are also specified. This MATLAB script assumes that interplanetary injection originates from a circular Earth park orbit. The hyperbolic targets are specified in the true-of-date Earth-centered-inertial (ECI) coordinate system.

In order to estimate the park orbit coast duration, the user must also provide estimates of typical Earth central angles for launch-to-park-orbit-inject, and one or more propulsive and intermediate coasting maneuvers. The current version of this MATLAB script provides at most two injection propulsive maneuvers separated by a short coast. However, the software can be easily extended to include additional events.

This MATLAB script determines the launch universal time, orbital elements of the departure hyperbola, injection delta-v, and estimates park orbit coast times for both short and long coast injection opportunities. This information can be used to create initial guesses for other trajectory simulations.