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Mars Help - the numbers



The data edit forms are a convenient way to study the actual numbers generated when integrating the orbits. There are several things you should notice. The time step decreases as the gravitational forces on the spacecraft become greater. Look at the range too, to be sure the trajectory does not crash into the planet. If you select a gravity assist or low flyby parameter, see how closely the computer can find a trajectory that takes advantage of these parameters.

Following are some useful statistics that will help in evaluating this output.

Earth

planet radius - 6378.1363 km
sphere of influence - 924647 km
orbit radius - 149598023 km
orbital velocity - 29.7846753 km/sec (circular orbit)


Mars

planet radius - 3397.2 km
sphere of influence - 577213 km
orbit radius - 227939186 km
orbital velocity - 24.1293877 km/sec (circular orbit)


Some numbers for the two-body Hohmann transfer are also interesting, for comparison with the integrated orbits.

Hohmann Transfer

semi major axis - 188768605 km
eccentricity - .2075058064
time of flight - 260 days


EARTH ESCAPE (geocentric hyperbola)

radius at periapse - 6378.. + 200 km
velocity at periapse - 11.3958 km/sec
thrust to escape - 3.6114 km/sec


HELIOCENTRIC PERIAPSE

velocity - 32.7293578 km/sec
escape thrust - 2.944683 km/sec


HELIOCENTRIC APOAPSE

velocity at apoapse - 21.480498 km/sec
capture thrust - 2.648890 km/sec (slowing down)


MARS CAPTURE (mars centered hyperbola)

radius at periapse - 3397.2 + 100 Km
velocity at periapse - 5.6233 km/sec
capture thrust - 2.116 km/sec

© 2003 by will h. clark ii
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