Transfer Orbits

Direct Flight Minimum Energy Orbits

The Minimum Energy Orbits to travel to Jupiter and Neptune are shown in the diagram below.

Energy and Velocity Changes for Orbit Transitions

Transistion	Velocity Change km/s	Energy Change MJ/kg
Earth orbit to Jupiter Transfer Orbit	8.7	297
Jupiter Transfer orbit to Jupiter orbit	5.6	57.8
Earth orbit to Neptune Transfer Orbit	11.5	409
Transfer orbit to Neptune orbit	4.1	13.8
Earth Orbit to Jupiter Orbit	-	355
Earth orbit to Neptune Orbit	-	423

Orbits using Gravitational Assist from Jupiter

Parameters of Orbit #1

a = 3.50 AU
P = 6.548 yrs
e = 0.714
E = -126.7 MJ/kg
v_peri = 39.0 km/s
t_Transit= 1.674 yrs
Angle from Perihelion = θ = 160°

Parameters of Orbit #2

a = 18.0 AU
e = 0.776 (from Tisserand Relation)
E = -24.6 MJ/kg
P = 76.368 yrs
r_peri = 4.025
t_Transit= 25.37 yrs
v(at Neptune) = 3.14 km/s

Parameters of the Jupiter Flyby

v_ingress = 10.25 km/s
v_egress = 16.46 km/s
ΔE = -24.6 - (126.7) = 102.1 MJ/kg
t_flyby = 0.37 yrs

Transition	Velocity Change (km/s)	Energy MJ/kg
Earth Orbit to Orbit #1	9.2	316.5
Orbit #2 to Neptune Orbit	2.30	9.9
Total Energy	-	326
Jupiter Flyby	6.2	83

So the use of Jupiter's Gravitational Assist saves (423 - 326) = 97 MJ/kg. Another benefit is a reduction of the velocity change needed at Neptunes orbit with there is less fuel available.

Created by L.Bogan - June 07, 2005