Except those risks must be evaluated against the reward. In this present day and age, what exactly do we gain from using humans instead of robots in space that justifies their expense?
Automation is good for rote tasks. People are good at improvising.
During the mission to correct Hubble's lens problem, the supplied tools and procedure failed. The mission specialist utilized scissors and a plastic cover from a log book to correct the problem.
Without that improvisation, the mission to fix Hubble's lens would have been a loss.
What we gain from having people in space depends on what you want to _do_ in space.
If it's all just drones mapping planets and space telescopes then investing in automation makes sense.
If it's manufacturing, settlement, getting some of our eggs out of this basket, then we need people out there, learning how to live off-planet.
The expense in either case, might possibly be the same.
Automation isn't cheap, missions that have to be redone because the automation fails are costly.
It may not be exactly either/or, but budget constraints coupled with the astronomical cost of using humans in space makes it nearly so.
I think the example of Hubble actually works in my favor on this point. Hubble is a relic of an old technological age. Earth-based telescopes surpassed Hubble's capabilities not too long after it was launched, and have now pretty much left it in the dust. At a fraction of the cost.
Hubble's replacement (James Webb) is quite a leap ahead, and as an IR scope it really does need to be in space, unlike Hubble. But you'll note that its location will be off-limits to humans, and it is accordingly designed to be remotely maintained.
In short, the age of low-earth-orbit, high-maintenance space telescopes is, and should be, over. I argue that other space-based platforms that require human intervention should likewise be curtailed for similar reasons.
>"Automation isn't cheap, missions that have to be redone because the automation fails are costly."
It is still orders of magnitude cheaper than sending people, and the cost of a "failed" space endeavour with people on board is infinitely greater. In cases where it's not currently feasible to use robots, it would be worth our while to wait until it is, instead of trying to use humans now.
I feel that Mars is another example in my favor. Cost estimates for sending humans to Mars are so high and so speculative that they're essentially useless outside of the insight that we cannot afford it. Compare that with the cost of robotic exploration, which is both quite affordable and spectacularly successful so far.
The gain is, actually, putting humans in the space. It's an arbitrary objective that you (or me) may not share, but it seems to be the primary objective. Other gains usually don't outweigh the costs, but are useful at marketing the idea to bot people. They lower the perceived-by-bot-people loss, to the point where the loss may be accepted as the cost for winning the human-people.
As far as I am concerned, I want human uploads in space. Durr.
The fact that humans can do so many things that robots cannot yet do. Look at it the other way: what is the most robust and fault tolerant adaptive machine with the best motor skills, the best perception system, and quick decision making system that we have available? There are some tasks that robots are better at, but as a general purpose machine humans are still the best. A robot tumbles over or gets stuck behind a stone, and you've just lost your multi billion dollar project.
The reward of human exploration is impossible to quantify. You may as well ask what is the risk reward for basic research, philosophy, religion, or art.
I agree, except for the fact that in the field of space exploration humans can now be largely substituted by machines, and will be more so as our machines advance.
Philosophy and art do indeed require lots of human intervention. Thankfully, they are cheap, as is much of the basic science research that we should be prioritizing ahead of, say, super sexy space stations.
But if we do just robotic exploration, we miss out on the unintended side effects of putting people in space.
Kidney dialysis machines for example. And basic research on bone loss which has been a huge help for Osteoperosis patients.
I think the issue here isn't that we know that putting humans in space is expensive, it is, in time as well as resources. I think the issue is that if we don't put humans in space we'll never know what advances we could have made by doing it.
Granted, but I'm not sure that the progress that can be attributed specifically to the presence of humans in space has been worth the expense.
Your two examples are instructive. I guarantee you that these medical advances would have been made in the absence of a space program. It's not a matter of if, but when. The best that be said about the scientific contribution of human bodies in orbit is that it has provided some acceleration of progress -- I know of no evidence to the contrary.
The crucial question is, what are we willing to pay for that acceleration?