I think I could make a case for this thread being bumped out of the oblivion that all pre-2000 posts are in for.
Of course, my case for this thread would consist primarily of the fact that I saw Mars through my 12-1/2" reflecting telescope 2 nights ago, but still…
Robots simply wouldn’t do the job. They cannot feel textures well, and simply do not have the reasonings that is the super computer Human brain.
I attended a seminar over colonizing space, titled “Explore and Exploit” last march. Basically we have a fairly good amount of tech to get to Mars, and even considerations of where to land. There are still enviromental challenges to get over.
BTW, the seminar did talk about the extraction from soil and atmosphere, if I could find more of that in my notes. I would share. But they seem to have disappeared in the mix of school papers.
Um, if you can get into a position where you can land on a comet, you don’t need the comet - you are already in it’s orbit, I can’t think of much to gain from attaching to it.
There are several failed robotic missions to Mars. The one you mentioned was a human error. Other mission losses are not 100% explained and could have been mechanical problems (or mechanical inadequacies).
http://www.seds.org/~spider/mars/mars-l.html
But maybe you could debate that these were human errors.
I disagree. Three astronauts have already died and yet we keep exploring (launch pad fire during Apollo era). Exploration of any frontier is dangerous and yet many people would happily volunteer to take the risk. Exploration is part of human nature, IMHO. Anyway, the extreme long-term survival of the human race (or whatever we call ourselves millions of years from now) depends on moving on to other worlds. In the shorter long-term (hundreds/thousands of years), our species would be safer if we didn’t have all our eggs in one planetary basket. In current times, exploration is a source of challange and inspiration.
I agree with that. The only rush is my impatience to see these things happen in my lifetime. I already have to wait until about 2020 before anything reaches Pluto! 
From the same link I just provided…
1992 September 25, Titan IIIe-TOS
Mars Observer (Nasa): Reached Mars on August 21, 1993, and sent some TV images on approach. Contact was lost during its orbit insertion ignition; it may have been damaged, blewn up, or simply frozen after having lost orientation.
If astronauts were aboard, there could have been more options for saving the mission (e.g., manual controls).
Is it really remotely credible to send a crew, even a crew of one, on a round trip mission of several years, with no possible option of resupply?
Robots. Only way for now. Don’t need water, don’t need food. Computers crash, people go crazy. That’s a wash.
The Zubrin clan proposes first sending a robotic mission to set up a resupply camp (extract materials from Martian soil to create rocket fuel). Then each subsequent manned mission would add one section to a biosphere (i.e., leave part of their ship behind) and use that Martian fuel supply to return home. Eventually, you would have a self-sustaining colony on Mars once you added enough pieces to complete the biosphere puzzle.
I assume you meant to type “the Zubrin plan” not “the Zubrin clan”. Unless they’re feuding with another family. 
Incidentally, could this incremental-biosphere-building trick also work for a colony on the moon? (If for no other reason than that a flight to Mars is about 20-30 times longer than a flight to the moon.)
tracer, I have the book Phobos is referring to, and oddly enough the title is the same as this thread, i.e. The Case for Mars. Great book by the way – I highly recommend it for anyone interested in Mars exploration. In fact, I believe NASA has since adopted the general plan (with some minor modifications) as THE plan for going to Mars.
A key feature of the Zubrin plan is a “live off the land” approach. But it doesn’t extract fuel from the soil. Instead, it arrives on Mars with the fuel tanks virtually empty, with just some “small” amount of H2 (say 6 tonnes), then begins reacting it with the CO2 in the atmosphere to produce CH4 and H2O. The H20 is further broken down into H2 and O2, and the H2 is recycled. More O2 is produced by splitting CO2 into CO and O2. The CH4 and the O2 is stored as rocket fuel for the return trip, with plenty left over to power combustion vehicles to explore the planet’s surface.
The humans are not launched until the return vehicle has been fully fueled by this approach and small robots have verified a suitable landing site.
So you can see, this doesn’t work for the Moon because of its lack of an atmosphere. One reason I like this plan so much, aside from the fact that it just makes sense, is its reliance on simple chemical engineering fundamentals, something a chemical engineer like myself can appreciate.