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Interplanetary, patched-conic gravity assist - OTB version

version 1.0.1 (834 KB) by David Eagle
A MATLAB Script for Interplanetary Patched-Conic, Single Gravity-Assist Trajectory Design, Analysis and Optimization


Updated 01 Jan 2020

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PDF document and a MATLAB script called flyby_matlab that can be used to design and optimize interplanetary trajectories that include a single gravity assist maneuver. The user specifies the launch, flyby and destination planets, and the desired flyby altitude. The algorithm also requires initial guesses for the launch, flyby and arrival calendar dates. This script searches for a patched-conic gravity-assist trajectory that satisfies the flyby mission constraints (V-infinity matching and user-defined flyby altitude) and minimizes the launch, arrival or total impulsive delta-v for the mission. The type of delta-v optimization is specified by the user.

Cite As

David Eagle (2021). Interplanetary, patched-conic gravity assist - OTB version (, MATLAB Central File Exchange. Retrieved .

Comments and Ratings (2)

David Eagle

Download the DE424.bin ephemeris file from

Place the file in the same directory as the IPTO MATLAB scripts.

Log into that directory from within MATLAB. Run the script

Miro Patrese Amoyan

Error using fread
Invalid file identifier. Use fopen to generate a valid file identifier.

Error in jplephem (line 71)
ttl = fread(fid, 252);

Error in p2000_ecl (line 95)
result = jplephem (jdtdb, ntarg, ncent);

Error in flyby_objective (line 44)
[rplanet1, vplanet1] = p2000_ecl(ip1, jdtdb1);

Error in fmincon (line 546)
initVals.f = feval(funfcn{3},X,varargin{:});
Im getting the error:

Error in flyby_matlab_otb (line 159)
[x, fval] = fmincon('flyby_objective', xg, [], [], [], [], xlwr, xupr, 'flyby_constraints', options);

Caused by:
Failure in initial objective function evaluation. FMINCON cannot continue.

MATLAB Release Compatibility
Created with R2019b
Compatible with any release
Platform Compatibility
Windows macOS Linux

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