Ion thrusters only solve the by far easier problem of propulsion. The real issue is the power source.
Solar is too low powered for anything more then station keeping.
High power nuclear reactors (>10MW) have problems with heat radiation.
Nuclear batteries are far too inefficient.
Fusion reactors small enough for space are probably still a century away, and would have the same heat radiation problems like nuclear.
For interplanetary journeys there are more promising technologies like good old Nuclear thermal (http://en.wikipedia.org/wiki/Nuclear_thermal_rocket) or Mini Mag Orion (http://science.slashdot.org/science/07/09/20/2321219.shtml)
Quite the contrary. Rockets are EXCELLENT energy-spenders. In vacuum at exhaust speed they have an efficiency of about 70% (http://en.wikipedia.org/wiki/Propulsive_efficiency). The Problem of chemical rockets is not their efficiency, but the energy density. And that problem is solved by solar(or any other form of power "beaming"), nuclear, fusion or antimatter powered vehicles.
GP may not be polite, but he's right. Lichen are the best adapted plants on Antarctica. And Antarctica is the closest Mars like environment you get on Earth, dry and cold. Some Lichens survive there with a few hours photosynthesis per year.
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Ion thrusters only solve the by far easier problem of propulsion. The real issue is the power source. Solar is too low powered for anything more then station keeping. High power nuclear reactors (>10MW) have problems with heat radiation. Nuclear batteries are far too inefficient. Fusion reactors small enough for space are probably still a century away, and would have the same heat radiation problems like nuclear. For interplanetary journeys there are more promising technologies like good old Nuclear thermal (http://en.wikipedia.org/wiki/Nuclear_thermal_rocket) or Mini Mag Orion (http://science.slashdot.org/science/07/09/20/2321219.shtml)
Quite the contrary. Rockets are EXCELLENT energy-spenders. In vacuum at exhaust speed they have an efficiency of about 70% (http://en.wikipedia.org/wiki/Propulsive_efficiency). The Problem of chemical rockets is not their efficiency, but the energy density. And that problem is solved by solar(or any other form of power "beaming"), nuclear, fusion or antimatter powered vehicles.
GP may not be polite, but he's right. Lichen are the best adapted plants on Antarctica. And Antarctica is the closest Mars like environment you get on Earth, dry and cold. Some Lichens survive there with a few hours photosynthesis per year.