Trajectory
The Mars gravity assist constrain the possible trajectories. The asteroid penetrator also imposes limits on the speed of the approach of the target asteroid (less than 4 km/s).
Nevertheless, 3 possible trajectories were designed, with two Mars gravity assists.
A single Mars swing-by is also possible, but the double gravity assist increases the mass budget of the spacecraft by 30%, at the cost of an additional 1.8 year in travel time to the asteroid belt. The following trajectories are for the 1994 launch window. The size and type of each asteroid is also shown here:
Trajectory 1:
- launch from Earth
- Mars gravity assist
- flyby of 2335 James (a 10 km X-type asteroid) (an Amor-asteroid)
- Mars gravity assist
- 109 Felicitas (C-type, 76 km)
- 739 Mandeville (EMP(?) type, 110 km)
- 4 Vesta (V-type, or Vestoid. Has a diameter of 570 km) flyby with 3.5 km/s. A penetrator is released.
Total delta-v: 450 m/s
Trajectory 2:
- launch from Earth
- Mars gravity assist
- flyby of the P/Tritton short period comet
- Mars gravity assist
- 2087 Kochera(30 km?)
- 1 Ceres (flyby & releasing a penetrator)
Total delta-v: 1150 m/s
Trajectory 3:
- launch from Earth
- Mars gravity assist
- 1204 Renzia (10 km?) (an Amor-asteroid)
- Mars gravity assist
- 435 Ella (U type, 30 km)
- 46 Hestia (F type, 165 km)
- 135 Hertha (M type, 80 km)
Total delta-v: 350 m/s
In other studies 11 Parthenope, 19 Fortuna and 20 Massalia were also considered.
Read more about this topic: Vesta Mission