Are we not talking about spending money now? I mean if the discussion is "We should go when it's feasible," then I don't think anybody disagrees with that. But if you listen to Dr. Zubrin and others that support him or read the articles that you're linking to, they're all positioning this as possible in the very near term. And while I respect their desire to keep funding space exploration, they seem to be a very small minority, particularly with budgets so tight.

I'm all for manned space exploration - when it makes sense for us to do so and won't cost us a fortune. Despite the numerous stories about how that could be "soon," those predictions seem horribly optimistic and the benefits elaborated seem far too slight for the investment. I'd prefer to pump the money folks are talking about (usually in the $1-2 billion/year for 20 years or so) into scholarships for science and engineering students who end up figuring out the solutions to the issues. And might have a more lasting, more concrete impact here at home while they do so.

Hell, I'd prefer to spend the money figuring out more about our own oceans and ecosystems there so we can live more effectively here and satisfy both romantic and pragmatic issues here at home. Wouldn't it be great if those floating or underwater cities that we saw in comic books as kids could become a reality, particularly if they helped us solve issues around energy, food production, ecology, etc.?

"Worthiness" isn't really an issue for me. Let's figure out how to live better here before we go looking for new rocks to live on.

The first article you provided couldn't really be better for my argument. Let's take a quick look:

The combined effects of background cosmic rays from extragalactic sources and extreme radiation events from the sun make space travel too hazardous for an estimated six months there and six months return.

"The estimate now is you would exceed acceptable levels of fatal cancer," said Francis Cucinotta, chief scientist for NASA's space radiation program at the Johnson Space Center in Houston. "That's just cancer. We also worry about effects of radiation on the heart and the central nervous system."

...

Solution: Pick astronauts that have never smoked, never been around smokers, and have a built-in genetic resistance to radiation damage.

This is such a brilliant solution I can't help but wonder why we haven't applied it to other fields. For example, why don't we pick firefighters with a built-in genetic resistance fire? And soldiers with a built-in genetic resistance to bullets? Spacemen with built-in resistance to radiation? Sounds perfect so why not.

studies show that radiation can damage the vitamins in food supplies, and the loss of even one vitamin in the food chain could cause serious health effects over a long trip. ... It's expected that the crew will have to grow its own food in some kind of greenhouse

No word yet on how the plants living in the greenhouse will be protected from the radiation that is apparently so intense that it damages the dead plants.

As for "now", we both know we can't go now. But if we want to go at all, we do have to continue studying the problem, developing new technologies, etc etc.