Ultimately we'll go simply because we can. There'll be excuses, the main one being prestige - either to gain prestige or prevent someone else from getting it. I can see a US-Europe consortium heading off to Mars to prevent a Russian-Chinese alliance being first.

To check for the "origins of life" will be another reason. That's been used for everything from the Moon to comets to asteroids, always with the same ambiguous, at best, results. It flys, so to speak, though. The public will buy that, again.

Preserving the race is another reason which would sell, though Earth is a bit like New York in reverse - if we can't make it here, we can't make it anywhere. That's one which would not be suasive in and of itself, but could go with the others to remove some objections from some people.

The US didn't go to the Moon because there were any really valuable scientific reasons not obtainable cheaper and more easily through other means. We went for national prestige. The USSR didn't stop their efforts because there wasn't any more science there, they stopped because there wasn't much "national prestige" in being second.

Putting off the trip long enough may allow the development of technologies which would make it less expensive and less exotic. By definition, though, it would be pushing the envelope, a frontier, along with the respect which goes to those crossing a barrier.

There's no reason besides prestige to plant a person, in person, on Mars. People take a lot of care and feeding in alien environments, and the only reason to do it is to show you can do it.

One hound's opinions.

Arf