It takes robots days to do what humans can do in a matter of minutes. That's why space agencies push for a manned mission - while the cost for a manned mission is much higher, there is a larger return on investment than with robots. Dollar per scientific discovery is improved.

I seriously doubt that manned missions to multiple destinations in the solar system would be as economical as robots. To sustain a mission to Mars to do what the two robots have done so far would probably be impossible at the present stage of NASA's capability. Robots can take their time and see annual changes in planetary bodies with little cost and difficulty once they are in place. And they require only a one way trip and no need for food, air or water, a huge advantage over humans.

I'm not repeating my personal opinion - I don't have any of the background to make such a judgement call. I'm getting my informtion from a couple press releases and interviews from NASA and the ESA stating such.

It's not as economical for initial surveys and whatnot - but once a scientific interest has been identifed and the list of "to dos" stack up, both NASA and the ESA have said in no uncertain terms that humans provide the best bang for the buck.

It's why we have the international space station - because humans provide faster, more accurate results for experements that may change very dynamically as the situation and environmental factors change. Experements on the ISS don't have to be anywhere near as planned as a sattelite experement, and are carried out much faster.

I don't question the economic efficiency of astronauts in low orbit where close proximity to Earth provides easy access to air, water, emergency medical help etc. but the current push for humans to explore Mars is around a twenty year project putting great budget strains on all other NASA efforts to the point of cancelling a few important ones. All efforts into interplanetary efforts are expensive but it seems to me irrational to think that human expeditions to Venus with its horrendous environment or to the dark side of Mercury or to the interesting outer planet moons like Europa or Titan would be more economic by live astronauts who not only require sustenance and air and water but are in huge danger so far from home subject to dangerous solar radiation and require a return trip as few astronauts are voluntarily suicidal. Current robotic artificial intelligence is still rather primitive but on longer trips where radio contact times lengthen to the point that absolute hands on control becomes impractical, artificial intelligence will become crucial to general operation and as AI improves (as it should within the next decade) self motivated robots with improved judgement capabilities will make all the difference between astronauts and robots.

Again, I have to restate, even with all those factors considered:

NASA and the ESA both found manned missions to other planets have the largest cost efficiency, when all factors are considered.

Neither of us have done the math for it, other than heresay and random internet speculation. They paid people to do the math, and consider all the factors anyone on this website could contrive of and more. I'm going to trust the agencies who make it their business to put people and things into space on this one.

You may not feel it's not wise to go to other planets for saftey or total budget concerns, and that's a different and very debatable issue (and not one I have an opinion on). Cost efficiency is not.

Beware of experts.

To elaborate on the comment, there has never been a human expedition to another planet so the estimates are in the realm of pure fantasy. There have been many very successful robotic interplanetary exercises which have paid off extraordinarily well. If the estimates of the NASA experts are as accurate as the success of the shuttle program which, I am sure, was looked into by the experts before it was executed, I think a reasonable margin of error can be assumed.

I'm saying I'm not willing to take the speculation of unqualified persons on the internet over reputable experts in the field - pure fantasy by defintion. While i understand it's necessary to beware experts, it's even more necessary to beware the layperson with strong opinions and no background in the subject.

It's not a matter of background, its a matter of common sense. Aside from the fact that the current administration is allocating a monstrous percentage of NASA's budget to a project that will culminate in a Martian expedition perhaps twenty years in the future with all sorts of burgeoning costs as reality impinges on planning, (take the current almost useless space station for good example) anybody who has developed an appetite for the current administrations gigantic capability to generate rather prime bullshit is somewhat off his rocker. The Martian thing is perhaps 25% science and 75% politics.Admittedly in the long run, it will be advantageous for humans in the long term to visit the planets but the robot vs astronaut discussion is quite heated between very knowledgeable experts at the moment and quite a few engineers and scientists have left NASA in protest over current policies. Current budget limitations on NASA are quite severe and several very important robotic projects were cancelled in mid-accomplishment for what might be termed the popular Star Trek syndrome.

Just look at what is required for a very expensive Martian picnic. A very long trip back and forth with deadly solar radiation all the way. The vehicle itself cannot be the tightly confined unit sent to the Moon. It must, in effect, be a mobile space station fully equipped for life support for at least a couple of years. And it must be designed for both structural and medical emergencies plus facilities where people can have some sort of free movement and equipment to preserve their body strength for operation on an alien planet. There must be a lander that, if the trip is to be worthwhile, can leave and return to the orbiting interplanetary vehicle more than once. On Mars there must be some sort of shelter constructed to house the planetary explorers in an Earth similar atmosphere for an extended stay if the huge expense is to pay off. And there must be a land vehicle to permit long trips across the landscape. And of course, multiple backups to equipment, large supplies of food and oxygen etc.

The experience with the current space station clearly indicates that things go wrong all the time and on Mars there will be no Earth close by for help. If you try to tell me that all this weighs in as cheaper and more efficient and safer than highly improved rovers on a one way trip then please permit me to have very strong doubts.