Adam Hibberd
I’ve been investigating the Double Jupiter Gravitational Assist (DJGA) and comparing it with the ordinary Single Jupiter Gravitational Assist (SJGA) which we know well and is propounded in the Interstellar Probe Concept Report. For context, refer to my poster:
I seems that at DJGA (which I invented) is not all that it was cracked up to be.
For your information, please find in the attached plots below:
(a) a passive DJGA (at both encounters) – compared with a passive SJGA.
(b) a passive DJGA at the first encounter followed by a DeltaV=3km/s at the second encounter – compared with an SJGA with DeltaV=3km/s at the only Jupiter encounter.
(c) a passive DJGA at the first encounter followed by a DeltaV=9km/s at the second encounter – compared with an SJGA with DeltaV=9km/s at the only Jupiter encounter.
For further explanation (b) & (c) represent the hyperbolic excess speed w.r.t. the sun achieved by the respective trajectories against the latitude of the escape asymptote out of the solar system. We find in (b) & (c) above that the SJGA out-performs the DJGA.
(a) represents the achieved hyperbolic excess speed w.r.t. the sun against the characteristic energy C3 at Earth Launch (optimal escape asymptote latitude is assumed). We find in (a), there is only a marginal superiority of the DJGA compared with the SJGA, especially at C3>115km2/s2.
In summary I would say there is no appreciable gain in using a more complicated DJGA, particularly when the SJGA out-performs it in most circumstances.
I am still trying to reconcile the above findings with the efficacy of this trajectory when I studied missions to ‘Oumuamua and Borisov. I may be missing something here!
