[RockyTx]

why is the West coast being used,
instead of the Cape?

surely, an escape trajectory does not
need a polar orbit.

is the Atlas booster
specific to Vandenberg?

[Textide]

Saw this in the Press Kit for the mission:

"For InSight, the Atlas V 401 offers enough performance to enable launching a Mars mission southward from Vandenberg, mitigating a more-crowded launch schedule in Florida."