James Michael Longuski (born 1951) is an American scientist, inventor, writer, and educator known for his contributions to astrodynamics and space mission design.

[1][3][4] In the late 1990s together with Nathan Strange of JPL, he developed the method and coined the term, the “Tisserand graph,”[5] widely used for gravity-assist spacecraft trajectory design (a concept independently introduced by Labunsky et al.[6]).

The concept involves placing a large spacecraft (or astronaut hotel) in orbit around the Sun that continually flies by Mars and Earth, providing a permanent human transportation system between those planets.

[8] In 2001, Longuski with Ephraim Fischbach and Daniel Scheeres proposed a test of Albert Einstein's General Theory of Relativity based on spacecraft trajectories.

[9] Longuski is co-inventor with Dan Javorsek of a Method of Velocity Precision Pointing in Spin-Stabilized Spacecraft or Rockets.