When will the United States send a manned mission to Mars?
As exciting as manned space travel is, we would greatly benefit if initial explorations of the planets were done with unmanned probes. This might be the best approach at least for the next several decades, until we can master vehicle systems that will make manned missions efficient. With unmanned probes, all of the mass, engineering and fuel needed for basic life support can be eliminated or replaced with science systems. Robot systems will get better and better, and we don’t have to worry about how to process a robot’s urine or other wastes.
