[Little Pig]

Only one rocket available for this mission, so only one project gets the nod.

[Red Badger]

A comet mission should be an international cooperation, pool their resources and get ‘er done!.............

[Moonman62]

Only one rocket available for this mission, so only one project gets the nod.

...

I wonder if a successful Falcon Heavy launcher would change that.

[Moonman62]

Actually rocket cost is only a fraction of the total cost:

Mission cost is capped at $850 million; launch cost runs about $150 million.