Gentlemen, as someone who has followed NASA explorations for "too many years" [enjoying every moment], I have found that the public responds to them in three ways:
1). some apparently live underground with their heads pointed in downwards directions and don't even know what's going on, nor do they care;
2). some, as we have seen, see no value in pure scientific exploration. That is, in my mind sad, but is their "right". To attempt to point out to them the vanishingly small percent of annual government budget granted to such exploration is of no avail. Overfed elephants are welcome, but gnats are to be exterminated [NASA comes perilously close to losing 50% or more of its budget each recent year]. Pointing out the incredibly valuable economic "side-effects" of this research also seems to make no dent in their consciousness.
3). then there are those who find an immediate intuitive thrill in all this. What's that all about? What it is is the core of the human spirit. It is the fundamental wonder which made us who we are as a "species-in-progress". Without "quest", without "discovery", we become spiritless and without hope in the end. Everything becomes the fight for dollars and individual security.
This is why JFKs promise to go to the Moon was not only inspiring but "practical". We Americans REALLY needed to believe in ourselves again. We needed to believe that the future was bright and we would be a great part of it. We still need things like that now, So, Hurrah NASA!.
So, why this particular mission? Many years ago, I sat in the room with Jerry Soffen who was heading up the Mars Lander expedition at the time. It had on board three "chemical" experiments to test for Martian [probably microbial] life. We discussed the results: they were hopeful but ambiguous. "Life" of some kind could have been responsible, but so could some exotic "peroxide-like" inorganic chemistry. Fascinating, but crying for resolution.
Since then there have been other discoveries, semi-regularly, pointing to possible Martian microlife. So, we are going to try to really muscle-up and get the needed solid data this time.
Put-downers say why bother? That's their privilege --- one which I, however, do not honor. Why bother to discover anything in the realm of pure science? The Higgs Boson [as we discussed in a different thread] for instance? "Meaningless" discoveries are what have led to the entirety of the scientific and modern high-tech revolutions. You fill in gaps about your world, and things and ideas connect.
Martian Life would markedly increase our intuitions about the odds that the Universe is filled with life and probably intelligence. The ramifications of that are unknowable, but are bound to be profound. It also would give insights as to the "automatic-ness" of certain macromolecular pre-biotic chemical syntheses [translation/example: would DNA be inevitable?].
Passing such exploration off as impractical or uninteresting are thoughts that live in a different reality from the one that I inhabit.
In other news: NASA is covering up the finding that the first life form discovered on Mars was Neutered Doomer.