Page:Project Longshot - Advanced Design Program Project Report.pdf/28

Rh declination of −61 degrees relative to the ecliptic of our solar system. At the optimum launch position, the obliquity (23.5 degrees from the ecliptic) will sum with the inclination angle of the spacecraft's orbit (28.5 degrees from the equator). This will make the probe's orbit 52 degrees from the ecliptic. Thus, a 9 degree plane change is required to put the probe into a 61 degree orbit around the earth (relative to the ecliptic). From this orbit, another velocity change is necessary to escape the earth's gravity and inject the probe into a circular orbit about the sun at 1 AU and a 61 degree inclination. At this point, there are two options to be considered, depending on the fuel source, Earth or Jupiter. For the first option, the probe will leave from this orbit directly for Alpha Centauri, in which case it will change velocity at the perihelion of the transfer orbit between our solar system and Alpha Centauri. For the second option the spacecraft will transfer to a Jupiter-distanced heliocentric orbit, using a velocity change at the perihelion of the Earth to Jupiter transfer orbit, and inject into an orbit around Jupiter at a 61 degree inclination (to take on fuel). The probe will then escape back into a Jupiter-distanced heliocentric orbit at 61 degrees relative to the ecliptic. Finally, it will escape the solar system and head for Alpha Centauri, with a burn at perihelion of the Sol-Centauri transfer orbit.

(see appendix for actual number calculations)