The robots sent to mars are not useful for any reasonable economic reason. Even insofar as you count speculative basic research as economically useful, there are vastly better ways to spend that money on speculative basic research on Earth.

So why go to Mars? Because either (1) you find the basic research being done about Martian geology particularly compelling or (2) you want to see it explored by humans for its own sake. If you really actually believe in (1), then by all means; send more robots. But I'll bet 100:1 that you personally have no appreciation for the basic science questions, which are mostly very technical and boring. (Hint: grand-seeming questions about life are promoted for publicity and funding reasons, but these are not the ones that actually drive the science, and we are not learning more about the origin of life from going to Mars.)

Rather, I think you'll have to admit we want to go to Mars because it is awesome. You may think sending metal under our control is just as awesome as sending flesh and blood humans, but ultimately this is an aesthetic judgement which is not grounded in rationality. Personally, I would like to see humans walk there, and I'm happy to pay my citizen-share of $100/year over the next decade to make it happen.

Pretending "aesthetics" don't matter and our hardware isn't very significantly designed to respond to emotion is a huge flaw in "purely logical" reasoning. For goodness sake didn't we already cover this in Star Trek TNG?

So let's just skip the trip to Mars and spend the money to build high-tech pyramids in the Nevada desert and sacrifice virgins.

It's still far off in the future, but we have to take one step at a time. One of those steps will be sending people on a mission there with a return ticket, eventually establish a continuously manned research base etc. etc.

So there still may be some utility in the long run.

Of course there might be other approaches to bootstrap space colonization, such as the idea of mining asteroids in orbit and maybe sending people up there in the process.

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.

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.

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.

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 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.

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.

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!)

See also: You can probably do things a roomba can't.

> Such as?

Growing potatoes?

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.

No, it doesn't. It doesn't at all! Establishing human presence on Mars is one of the core objectives of the whole program. It's one of the reasons we care about Mars. Hell, moving gradually toward making additional homes for human beings is part of why we do space exploration in general. Yes, you can gather rocks via robots and send back data and whatever else, but to claim that doing so exhausts the set of reasonable objectives for Mars missions is just silly.

Here's a thought experiment to confirm: How many probes have we flown to how many planets in the solar system? Any idea, roughly, when the first one happened, or the last? You may know, but most folks have no idea. Conversely: where in the solar system have humans been? Any idea when we first got there, or when the last trip was? Unlike all the many highly valuable probe missions we've sent, here, most people actually know something about it. This is because people care about other people and their experiences, in a way that they don't care about scientific results as such. Putting human beings on other worlds is an end in itself, and it is simply not accomplished by sending drones instead.

It is possible to put together automated missions at-scale. But not likely. Because auditors can trim back an automated mission's scope smoothly, no matter how expansive it is, in order to save money. A slightly lighter, cheaper camera, gives way to an even more slightly lighter, cheaper camera, ad infinitum. A hundred units give way to 99 units give way to 30 units give way to 1 unit. But if you try to do that with a manned mission, you start to jeopardize the public heroes you have sensationalized in order to fund the mission. You don't get to send half a human being to Mars.

All manned missions arguments I have seen are somewhat coy in this respect. Yes, geologist can make better choices on spot and take better samples than current drones, but that's not real comparison.

We should compare alternative strategies using opportunity cost.

The money used for manned mission could be used for massive fleet of of drones, satellites and technical development. Missions could be more incremental and cover more areas. Self driving cars are just taking off on earth. How does advance fleet of Mars robocars and satellites mapping Mars compare to manned mission?