I've been thinking some more on why challenge is so important to a meaningful definition of exploration and why we still call polar athletes and adventurers 'explorers' (rightly it seems to me). I think it has something to do with the super abundance of information in the world. It's a cliche to say we are drowning in it, but we are. The average scientific paper is read by 1.2 people and I've met a few 0.2 people in my time. So on a basic publicity level, attaching challenges overcome to new information (the scientists who battle through the jungle to find a new species of tree frog) works. More than 1.2 people hear about your discovery because there is a human challenge story attached.
But I mean something more fundamental than that. I think we don't value things unless we have 'paid' for them in some way. It could be as simple as money, but often we pay with blood, sweat and time. Lots of time. Spending a lot of time on something you could do in an easier way (say chopper to the north pole) has some sort of virtue all its own in this overfast world. Doing things the hard way not only earns respect, it's a kind of down-payment on the things you do find out along the way. Learning the hard way makes the lesson stick. You change inside in some way. Your demeanor becomes a kind of lesson to others. I don't just mean those frost bitten fingers, I mean what you hold to be important might change. I think this is one way explorers pass on what they have found out.