A passage to Mars.

The mission uses a planar reference solar system with circular Earth and Mars orbits and a circular lunar orbit. The departure geometry is selected for this flight; it is not a prediction for a calendar launch date. All trajectory samples are embedded in this file. Playback interpolates the calculated states, rather than drawing a decorative curve between destinations.

Launch & Earth–Moon passage

Ascent is integrated under spherical Earth gravity, thrust, changing mass, drag, and a rotating exponential atmosphere. Two solid boosters burn for 120 seconds; core separation occurs at 300 seconds, upper-stage ignition at 310 seconds. Pitch guidance turns the thrust toward the horizon. An insertion trim and parking-orbit handoff are represented separately. From the 200 km reference parking orbit, a departure impulse sends the ship toward the Moon. Earth–Moon motion is numerically integrated with lunar gravity and the indirect term for the accelerating Earth-centered frame. The solar tide is omitted on this leg.

A 200 km lunar encounter changes the Earth-relative trajectory, then the ship returns near Earth for a powered departure. The flyby is not treated as an engine or an unlimited energy source. The displayed turning angle is the local two-body estimate; the surrounding path comes from the Earth–Moon integration.

Interplanetary transfer & arrival

The Earth departure velocity is solved by shooting the escape trajectory to an outer handoff at day 10. At that boundary, position and velocity match a Lambert transfer to the Mars arrival aim point. The Sun-centered coast uses inverse-square solar gravity. At the Mars sphere-of-influence handoff, the state is transformed into a Mars-centered hyperbolic approach. The arrival aim point is chosen for atmospheric interception, rather than aiming at the planet’s center.

Entry begins at 125 km. The planar entry model includes Mars gravity, an exponential atmosphere (surface density 0.020 kg/m³, scale height 11.1 km), ballistic coefficient 250 kg/m², lift-to-drag ratio 0.22, and a thrust-limited terminal descent controller. These are reference vehicle assumptions; heating, propellant reserves, terrain, winds, and structural loads are not solved. Arrival geometry and timing are computed; the vessel’s engineering is unspecified.

Body and spacecraft symbols are enlarged for identification. Distances follow the active tracking frame; the camera changes scale between local and interplanetary views. The spacecraft remains at the center. Habitat animation follows wall-clock time so the crew remains observable at high mission-clock rates. On a new departure the clock always starts at 1×; a saved passage resumes at its saved rate.

Flight reference library

NASA Glenn: Flight to Orbit · NASA: Trajectories · ESA: Gravity Assists · NASA: Earth–Moon Gravity Assists