We've already sent a number of drones to Mars. There are rational reasons for wanting to send humans as well: Humans can do things on Mars that drones cannot, and they pave the way for possible colonization in the future.
Such as? The only thing I can think of is that they can test if the human body can endure life on Mars. Honestly, as cool as sending people to mars is, I don't think it is an idea driven by rationality at this point.
> Such as?
Growing potatoes?
mountaineers also go to potentially deadly situations voluntarily, just because the those peaks "are there". nobody gets satisfied enough from someone's else photos and says "nah, that's enough of an experience for me", albeit view doesn't offer much more. Neither they do send drones up there instead of them :) (btw that would be a nice use case for some remote high-adrenaline-vr gaming with androids!)
Beyond picking up rocks, the human can traverse the terrain more easily and s/he can climb up and down really steep slopes - even ones at a nearly 90˚ angle. Whether you'd want the human to do that due to safety concerns on an alien world is another matter, but the amount of terrain accessible to this being is far larger than most billion dollar robots.
Oh and the human being does all of this while being powered on tuna sandwiches. They might be expensive to send to Mars, but once they're there humans can explore a larger area than all rover missions combined in a single mission.
If anything Mars is a great opportunity for automation. It has no environment to destroy and with the right design it could end up exporting a constant stream of goods to humanity with zero environmental cost. Nuclear waste for example is a non issue. We could even try things like a space elevator on mars without risk of harming people on earth.
PS: For comparison the lunar lander weighed ~36,200 pounds and needed a lot less thrust to get into lunar orbit.
Assuming space elevators, you could replace the vast majority of earth manufacturing. Though, with a long lag time before arrival.
This is a great point. I haven't studied this topic much, but on the surface it seems to me investing these resources into robotics technology is more interesting. Why can't we have a robot that can do such things? I think we can.
and water and balanced nutrition and oxygen and a very narrow temperature operating range and a very short hibernate mode (cannot really go without water/food for an extended time) and have to sleep every day and sensitive to radiation and cannot operate in low pressure and need to defecate and urinate etc.
A drone/robot can be run on solar power. If there isn't enough energy it can go into hibernate mode for months. And you also have to take into account that a manned mission is planned for something like 2030. Robotics is such a rapidly evolving field that by then they will be so much more sophisticated than today.
Don't get me wrong. I think sending people to Mars will be awesome and inspiring. But I think it wouldn't be a rational decision.
This is one reason that Europa excites the public imagination despite the hideous problems of distance and proximity to a gas giant - that moon appears to have a thick crust of ice covering a liquid ocean, and thus the prospect of life - possibly alien life, possibly a means of maintaining human life.
If we found evidence of life, even fairly primitive life, there would be plenty of money and public support to study it (though not without controversy). Rocks and canyons, not so much.
See also: You can probably do things a roomba can't.
A more interesting question is: how much does it cost to send people to Mars, and if we use the same amount of money to send more robotic probes, what can a hypothetical Martian astronaut do that (equally hypothetical) Martian drone armies cannot.