Just a quick post.
Yesterday New Horizons probe has reached Pluto after a nine years long journey of 5 billions Kilometers, a distance so gigantic that light takes more than 4 hours to cover it. This is the first close encounter with the planet for a man-made object. It is a truly remarkable achievement for astronautics: can you imagine the complexity of planning a few thousands Kilometers rendezvous with one of the farthest body in the solar system nine years before it happens?
The Plutonian mountains are now believed to be made of water ice
The only problem is the speed: 16 Km/s are not enough to think about manned missions, but they’re enough to rise mission costs (expenses for nine years!). Let’s imagine for a moment a probe equipped with PNN drive: Pluto would be reached in less than three weeks and the probe could return home after the mission.
On second thought, if we could use such propulsion system would we need probes anymore? Why don’t send a human expedition instead?