QUOTE(MID @ Jul 23 2007, 12:43 AM)

Pilot....
All of Mars is of interest. Anywhere on its surface will be fine for Man's first visit, and wherever that it, it'll be of extreme interest.
That's pretty much what I was going to say. How can anywhere on another planet not be interesting? How can a small planet with a 15 mile high volcano which posses a valley system that would stretch from the east coast to the west coast of the United States and where it can snow carbon dioxide at the poles not be interesting?
QUOTE(MID @ Jul 23 2007, 12:43 AM)

p.s., there is no "face" on Mars.
Nor pyramids nor indeed a place called Sydonya (close but no cigar, it's Cydonia). There is enough discussion on these objects in the Extraterrestrial Life & The UFO Phenomenon forum, and detailed discussion here would be taking the subject of topic. Suffice to say that there is absolutely no scientific evidence to support artificial structures on Mars and plenty to support these interesting features being natural.
As to the question asked, when we set foot on Mars is really dependent on two things; budget and political will. As political will is responsible for the budget available I suppose it could be argued that it is the only thing holding us back.
Much of the technology required already exists. A manned spacecraft to Mars will be a large vehicle (some believe as big as the ISS). We have the ability to build such a vehicle now. With the new Ares V launch vehicle which will be built for the return to the moon it will be even easier to construct large spacecraft in earth orbit.
There is more research needed in protecting astronauts from exposure to radiation in deep space, which due to the length of the mission (several months each way) will be a much MUCH bigger threat than it ever was with Apollo. In particular the threat from solar storms and Coronal Mass Ejections will need to be addressed. Due to the short period that Apollo spent outside the Van Allen belts the chances of a mission being hit by such an event was low. For a Mars mission it is almost a certainty. Without protection such an event could incapacitate or kill a crew.
We also have no experience of long term survival on another world. A mission to Mars will have almost certainly involve a stay on the surface of weeks or months. NASA's planned Moon base will provide such experience.
We also have experience of long term exposure to zero G (some of the Soviet Cosmonauts spent periods of greater than a year in orbit). What we have no knowledge of is experience with reduced G. This is something else that the moon base will teach us.
So really what is holding us back is experience not knowledge. Once that is gained we will be ready to go if the budget is available. That budget depends on the governments of the space-faring nations.
I am slightly more optimistic than some. I think, if the will to do it is there, we could see the first human boot prints on Mars within 20-25 years.