I think, similar to the achievements, there should be an area with specific goals, US doesn't have to know if you made it. Just a preset system, and a goal, and maybe you could even find a different mission.
My Ideas for this:
Real Missions, Realistic (never occured, but are in real systems), and Fake (everything is fake)
REALISTIC
1. Lunar Orbiter
Briefing: Get the probe in low-earth orbit, to orbit the moon.
Vehicle Location: Low-Earth Orbit
Destination: Moon
Bonuses (this part would need to be noticed by US to be really a good addition): Have <0.1 eccentricity, >500000 km semi-major axis.
2. Mars orbiter
Briefing: Take the Lunar Orbiter, out to Mars, and orbit.
Vehicle Location: Lunar orbit
Destination: Mars
Bonuses: <0.2 eccentricity, >5,000,000 km sma
FAKE
1. Two moons
Briefing: Take both objects in low-Earth orbit (at any time, you can do it one at a time if needed) and get them to orbit both moons.
Vehicle Location: Low-Earth Orbit
Destination: both moons
Bonuses: If the vehicle going to the outer moon has a flyby of the inner moon