Very interesting report on outer solar system Discovery class medium priced ($400M-$600M) missions. One thread that runs thru all the scenarios is lack of adequate propulsion and consequently payload limitations requiring high cost R&D of exotic ultra low weight payloads. I think the best shot is the 10-20 KW large solar array powering a VASIMR engine. Instead of limping along and waiting years and years for gravity assist missions to arrive and instead of spending fortunes creating one-of-a-kind ultralightweight probes, bite the bullet and engineer a deep space propusion bus as I proposed. Then use it time and again to haul heavier, easier engineered payloads to the asteroids, comets, Europa, Jupiter entry and Titan rover. These missions will arrive on site before the lomo gravity assist missions.

The other issue was only if NASA had $1B/year for non-Mars solar system missions instead of roughly half that amound which it does have. We spend $14B/yr on NASA. Tell me again why $0.5B could not be re-allocated. Oh wait, the flying albatross, ISS. And its Earthbound jobs program partners in taxpayer fleecing, the many NASA labs with their administrative staffs and "studies" and "plans". I forgot.

-p